Selection: Remove client callback for unit conversion.

Now clients provide a unit conversion context and libcss provides
code to perform unit conversion.

This reduces the amount of common code that clients have to write.

12 files changed, 390 insertions, 443 deletions

diff --git a/Makefile b/Makefile
index 0835c8f..86d6641 100644
--- a/Makefile
+++ b/Makefile
@@ -65,5 +65,6 @@ INSTALL_ITEMS := $(INSTALL_ITEMS) $(I):include/libcss/properties.h
 INSTALL_ITEMS := $(INSTALL_ITEMS) $(I):include/libcss/select.h
 INSTALL_ITEMS := $(INSTALL_ITEMS) $(I):include/libcss/stylesheet.h
 INSTALL_ITEMS := $(INSTALL_ITEMS) $(I):include/libcss/types.h
+INSTALL_ITEMS := $(INSTALL_ITEMS) $(I):include/libcss/unit.h
 INSTALL_ITEMS := $(INSTALL_ITEMS) /$(LIBDIR)/pkgconfig:lib$(COMPONENT).pc.in
 INSTALL_ITEMS := $(INSTALL_ITEMS) /$(LIBDIR):$(OUTPUT)
diff --git a/examples/example1.c b/examples/example1.c
index c36a94d..6135793 100644
--- a/examples/example1.c
+++ b/examples/example1.c
@@ -98,13 +98,22 @@ static css_error node_presentational_hint(void *pw, void *node,
 		uint32_t *nhints, css_hint **hints);
 static css_error ua_default_for_property(void *pw, uint32_t property,
 		css_hint *hint);
-static css_error compute_font_size(void *pw, const css_hint *parent,
-		css_hint *size);
 static css_error set_libcss_node_data(void *pw, void *n,
 		void *libcss_node_data);
 static css_error get_libcss_node_data(void *pw, void *n,
 		void **libcss_node_data);
 
+static css_unit_len_ctx uint_len_ctx = {
+	.viewport_width    = 800 * (1 << CSS_RADIX_POINT),
+	.viewport_height   = 600 * (1 << CSS_RADIX_POINT),
+	.font_size_default =  16 * (1 << CSS_RADIX_POINT),
+	.font_size_minimum =   6 * (1 << CSS_RADIX_POINT),
+	.device_dpi        =  96 * (1 << CSS_RADIX_POINT),
+	.root_style        = NULL, /* We don't have a root node yet. */
+	.pw                = NULL, /* We're not implementing measure callback */
+	.measure           = NULL, /* We're not implementing measure callback */
+};
+
 /* Table of function pointers for the LibCSS Select API. */
 static css_select_handler select_handler = {
 	CSS_SELECT_HANDLER_VERSION_1,
@@ -143,9 +152,8 @@ static css_select_handler select_handler = {
 	node_is_lang,
 	node_presentational_hint,
 	ua_default_for_property,
-	compute_font_size,
 	set_libcss_node_data,
-	get_libcss_node_data
+	get_libcss_node_data,
 };
 
 
@@ -237,6 +245,7 @@ int main(int argc, char **argv)
 		lwc_intern_string(element, strlen(element), &element_name);
 
 		code = css_select_style(select_ctx, element_name,
+				&uint_len_ctx,
 				&media, NULL,
 				&select_handler, 0,
 				&style);
@@ -662,68 +671,6 @@ css_error ua_default_for_property(void *pw, uint32_t property, css_hint *hint)
 	return CSS_OK;
 }
 
-css_error compute_font_size(void *pw, const css_hint *parent, css_hint *size)
-{
-	static css_hint_length sizes[] = {
-		{ FLTTOFIX(6.75), CSS_UNIT_PT },
-		{ FLTTOFIX(7.50), CSS_UNIT_PT },
-		{ FLTTOFIX(9.75), CSS_UNIT_PT },
-		{ FLTTOFIX(12.0), CSS_UNIT_PT },
-		{ FLTTOFIX(13.5), CSS_UNIT_PT },
-		{ FLTTOFIX(18.0), CSS_UNIT_PT },
-		{ FLTTOFIX(24.0), CSS_UNIT_PT }
-	};
-	const css_hint_length *parent_size;
-
-	UNUSED(pw);
-
-	/* Grab parent size, defaulting to medium if none */
-	if (parent == NULL) {
-		parent_size = &sizes[CSS_FONT_SIZE_MEDIUM - 1];
-	} else {
-		assert(parent->status == CSS_FONT_SIZE_DIMENSION);
-		assert(parent->data.length.unit != CSS_UNIT_EM);
-		assert(parent->data.length.unit != CSS_UNIT_EX);
-		parent_size = &parent->data.length;
-	}
-
-	assert(size->status != CSS_FONT_SIZE_INHERIT);
-
-	if (size->status < CSS_FONT_SIZE_LARGER) {
-		/* Keyword -- simple */
-		size->data.length = sizes[size->status - 1];
-	} else if (size->status == CSS_FONT_SIZE_LARGER) {
-		/** \todo Step within table, if appropriate */
-		size->data.length.value =
-				FMUL(parent_size->value, FLTTOFIX(1.2));
-		size->data.length.unit = parent_size->unit;
-	} else if (size->status == CSS_FONT_SIZE_SMALLER) {
-		/** \todo Step within table, if appropriate */
-		size->data.length.value =
-				FMUL(parent_size->value, FLTTOFIX(1.2));
-		size->data.length.unit = parent_size->unit;
-	} else if (size->data.length.unit == CSS_UNIT_EM ||
-			size->data.length.unit == CSS_UNIT_EX) {
-		size->data.length.value =
-			FMUL(size->data.length.value, parent_size->value);
-
-		if (size->data.length.unit == CSS_UNIT_EX) {
-			size->data.length.value = FMUL(size->data.length.value,
-					FLTTOFIX(0.6));
-		}
-
-		size->data.length.unit = parent_size->unit;
-	} else if (size->data.length.unit == CSS_UNIT_PCT) {
-		size->data.length.value = FDIV(FMUL(size->data.length.value,
-				parent_size->value), FLTTOFIX(100));
-		size->data.length.unit = parent_size->unit;
-	}
-
-	size->status = CSS_FONT_SIZE_DIMENSION;
-
-	return CSS_OK;
-}
-
 static css_error set_libcss_node_data(void *pw, void *n,
 		void *libcss_node_data)
 {
diff --git a/include/libcss/computed.h b/include/libcss/computed.h
index f4b3e21..1587d78 100644
--- a/include/libcss/computed.h
+++ b/include/libcss/computed.h
@@ -19,6 +19,7 @@ extern "C"
 #include <libcss/functypes.h>
 #include <libcss/properties.h>
 #include <libcss/types.h>
+#include <libcss/unit.h>
 
 struct css_hint;
 struct css_select_handler;
@@ -81,10 +82,7 @@ css_error css_computed_style_destroy(css_computed_style *style);
 css_error css_computed_style_compose(
 		const css_computed_style *restrict parent,
 		const css_computed_style *restrict child,
-		css_error (*compute_font_size)(void *pw,
-				const struct css_hint *parent,
-				struct css_hint *size),
-		void *pw,
+		const css_unit_len_ctx *unit_len_ctx,
 		css_computed_style **restrict result);
 
 /******************************************************************************
diff --git a/include/libcss/select.h b/include/libcss/select.h
index ca57456..bfaf531 100644
--- a/include/libcss/select.h
+++ b/include/libcss/select.h
@@ -18,6 +18,7 @@ extern "C"
 #include <libcss/hint.h>
 #include <libcss/types.h>
 #include <libcss/computed.h>
+#include <libcss/unit.h>
 
 typedef enum css_pseudo_element {
 	CSS_PSEUDO_ELEMENT_NONE         = 0,
@@ -123,9 +124,6 @@ typedef struct css_select_handler {
 	css_error (*ua_default_for_property)(void *pw, uint32_t property,
 			css_hint *hint);
 
-	css_error (*compute_font_size)(void *pw, const css_hint *parent,
-			css_hint *size);
-
 	/**
 	 * Set libcss_node_data on a DOM node.
 	 *
@@ -221,6 +219,7 @@ css_error css_select_default_style(css_select_ctx *ctx,
 		css_select_handler *handler, void *pw,
 		css_computed_style **style);
 css_error css_select_style(css_select_ctx *ctx, void *node,
+		const css_unit_len_ctx *unit_len_ctx,
 		const css_media *media, const css_stylesheet *inline_style,
 		css_select_handler *handler, void *pw,
 		css_select_results **result);
diff --git a/include/libcss/unit.h b/include/libcss/unit.h
new file mode 100644
index 0000000..a847077
--- /dev/null
+++ b/include/libcss/unit.h
@@ -0,0 +1,156 @@
+/*
+ * This file is part of LibCSS.
+ * Licensed under the MIT License,
+ *                http://www.opensource.org/licenses/mit-license.php
+ * Copyright 2008 John-Mark Bell <jmb@netsurf-browser.org>
+ */
+
+#ifndef libcss_unit_h_
+#define libcss_unit_h_
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+#include <libcss/types.h>
+
+/**
+ * Client callback for font measuring.
+ *
+ * \param[in]  pw     Client data.
+ * \param[in]  style  Style to measure font for, or NULL.
+ * \param[in]  unit   Either CSS_UNIT_EX, or CSS_UNIT_CH.
+ * \return length in CSS pixels.
+ */
+typedef css_fixed (*css_unit_len_measure)(
+		void *pw,
+		const css_computed_style *style,
+		const css_unit unit);
+
+/**
+ * LibCSS unit conversion context.
+ *
+ * The client callback is optional.  It is used for measuring "ch"
+ * (glyph '0' advance) and "ex" (height of the letter 'x') units.
+ * If a NULL pointer is given, LibCSS will use a fixed scaling of
+ * the "em" unit.
+ */
+typedef struct css_unit_len_ctx {
+	/**
+	 * Viewport width in CSS pixels.
+	 * Used if unit is vh, vw, vi, vb, vmin, or vmax.
+	 */
+	css_fixed viewport_width;
+	/**
+	 * Viewport height in CSS pixels.
+	 * Used if unit is vh, vw, vi, vb, vmin, or vmax.
+	 */
+	css_fixed viewport_height;
+	/**
+	 * Client default font size in CSS pixels.
+	 */
+	css_fixed font_size_default;
+	/**
+	 * Client minimum font size in CSS pixels.  May be zero.
+	 */
+	css_fixed font_size_minimum;
+	/**
+	 * DPI of the device the style is selected for.
+	 */
+	css_fixed device_dpi;
+	/**
+	 * Computed style for the document root element, needed for rem units.
+	 * May be NULL, in which case font_size_default is used instead, as
+	 * would be the case if rem unit is used on the root element.
+	 */
+	const css_computed_style *root_style;
+	/**
+	 * Optional client private word for measure callback.
+	 */
+	void *pw;
+	/**
+	 * Optional client callback for font measuring.
+	 */
+	const css_unit_len_measure measure;
+} css_unit_len_ctx;
+
+/**
+ * Convert css pixels to physical pixels.
+ *
+ * \param[in] css_pixels  Length in css pixels.
+ * \param[in] device_dpi  Device dots per inch.
+ * \return Length in device pixels.
+ */
+static inline css_fixed css_unit_css2device_px(
+		const css_fixed css_pixels,
+		const css_fixed device_dpi)
+{
+	return FDIV(FMUL(css_pixels, device_dpi), F_96);
+}
+
+/**
+ * Convert device pixels to css pixels.
+ *
+ * \param[in] device_pixels  Length in physical pixels.
+ * \param[in] device_dpi     Device dots per inch.
+ * \return Length in css pixels.
+ */
+static inline css_fixed css_unit_device2css_px(
+		const css_fixed device_pixels,
+		const css_fixed device_dpi)
+{
+	return FDIV(FMUL(device_pixels, F_96), device_dpi);
+}
+
+/**
+ * Convert a length to points (pt).
+ *
+ * \param[in]  style   Style to perform conversion for or NULL.
+ * \param[in]  ctx     Length unit conversion context.
+ * \param[in]  length  Length to convert.
+ * \param[in]  unit    Current unit of length.
+ * \return A length in points.
+ */
+css_fixed css_unit_font_size_len2pt(
+		const css_computed_style *style,
+		const css_unit_len_ctx *ctx,
+		const css_fixed length,
+		const css_unit unit);
+
+/**
+ * Convert a length to CSS pixels.
+ *
+ * \param[in]  style   Style to perform conversion for or NULL.
+ * \param[in]  ctx     Length unit conversion context.
+ * \param[in]  length  Length to convert.
+ * \param[in]  unit    Current unit of length.
+ * \return A length in CSS pixels.
+ */
+css_fixed css_unit_len2css_px(
+		const css_computed_style *style,
+		const css_unit_len_ctx *ctx,
+		const css_fixed length,
+		const css_unit unit);
+
+/**
+ * Convert a length to device pixels.
+ *
+ * \param[in]  style   Style to perform conversion for or NULL.
+ * \param[in]  ctx     Length unit conversion context.
+ * \param[in]  length  Length to convert.
+ * \param[in]  unit    Current unit of length.
+ * \return A length in device pixels.
+ */
+css_fixed css_unit_len2device_px(
+		const css_computed_style *style,
+		const css_unit_len_ctx *ctx,
+		const css_fixed length,
+		const css_unit unit);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+
diff --git a/src/select/computed.c b/src/select/computed.c
index a1b345b..d075af9 100644
--- a/src/select/computed.c
+++ b/src/select/computed.c
@@ -12,6 +12,7 @@
 #include "select/dispatch.h"
 #include "select/propget.h"
 #include "select/propset.h"
+#include "select/unit.h"
 #include "utils/utils.h"
 
 static css_error compute_absolute_color(css_computed_style *style,
@@ -247,9 +248,7 @@ css_error css__computed_style_initialise(css_computed_style *style,
 css_error css_computed_style_compose(
 		const css_computed_style *restrict parent,
 		const css_computed_style *restrict child,
-		css_error (*compute_font_size)(void *pw,
-			const css_hint *parent, css_hint *size),
-		void *pw,
+		const css_unit_len_ctx *unit_len_ctx,
 		css_computed_style **restrict result)
 {
 	css_computed_style *composed;
@@ -275,8 +274,7 @@ css_error css_computed_style_compose(
 	}
 
 	/* Finally, compute absolute values for everything */
-	error = css__compute_absolute_values(parent, composed,
-			compute_font_size, pw);
+	error = css__compute_absolute_values(parent, composed, unit_len_ctx);
 	if (error != CSS_OK) {
 		return error;
 	}
@@ -1087,31 +1085,36 @@ uint8_t css_computed_order(const css_computed_style *style,
  *
  * \param parent             Parent style, or NULL for tree root
  * \param style              Computed style to process
- * \param compute_font_size  Callback to calculate an absolute font-size
- * \param pw                 Private word for callback
+ * \param unit_len_ctx       Client length conversion context.
  * \return CSS_OK on success.
  */
 css_error css__compute_absolute_values(const css_computed_style *parent,
 		css_computed_style *style,
-		css_error (*compute_font_size)(void *pw,
-			const css_hint *parent, css_hint *size),
-		void *pw)
+		const css_unit_len_ctx *unit_len_ctx)
 {
+	css_hint_length *ref_length = NULL;
 	css_hint psize, size, ex_size;
 	css_error error;
 
-	/* Ensure font-size is absolute */
+	/* Get reference font-size for relative sizes. */
 	if (parent != NULL) {
 		psize.status = get_font_size(parent,
 				&psize.data.length.value,
 				&psize.data.length.unit);
+		if (psize.status != CSS_FONT_SIZE_DIMENSION) {
+			return CSS_BADPARM;
+		}
+		ref_length = &psize.data.length;
 	}
 
 	size.status = get_font_size(style,
 			&size.data.length.value,
 			&size.data.length.unit);
 
-	error = compute_font_size(pw, parent != NULL ? &psize : NULL, &size);
+	error = css_unit_compute_absolute_font_size(ref_length,
+			unit_len_ctx->root_style,
+			unit_len_ctx->font_size_default,
+			&size);
 	if (error != CSS_OK)
 		return error;
 
@@ -1125,7 +1128,12 @@ css_error css__compute_absolute_values(const css_computed_style *parent,
 	ex_size.status = CSS_FONT_SIZE_DIMENSION;
 	ex_size.data.length.value = INTTOFIX(1);
 	ex_size.data.length.unit = CSS_UNIT_EX;
-	error = compute_font_size(pw, &size, &ex_size);
+
+	error = css_unit_compute_absolute_font_size(
+			&size.data.length,
+			unit_len_ctx->root_style,
+			unit_len_ctx->font_size_default,
+			&ex_size);
 	if (error != CSS_OK)
 		return error;
 
diff --git a/src/select/computed.h b/src/select/computed.h
index c926cec..8b33405 100644
--- a/src/select/computed.h
+++ b/src/select/computed.h
@@ -10,6 +10,8 @@
 
 #include <libcss/computed.h>
 #include <libcss/hint.h>
+#include <libcss/unit.h>
+
 #include "autogenerated_computed.h"
 
 /**
@@ -35,8 +37,6 @@ css_error css__computed_style_initialise(css_computed_style *style,
 
 css_error css__compute_absolute_values(const css_computed_style *parent,
 		css_computed_style *style,
-		css_error (*compute_font_size)(void *pw,
-			const css_hint *parent, css_hint *size),
-		void *pw);
+		const css_unit_len_ctx *unit_len_ctx);
 
 #endif
diff --git a/src/select/select.c b/src/select/select.c
index f6efbfe..03a45fe 100644
--- a/src/select/select.c
+++ b/src/select/select.c
@@ -23,6 +23,7 @@
 #include "select/propset.h"
 #include "select/font_face.h"
 #include "select/select.h"
+#include "select/unit.h"
 #include "utils/parserutilserror.h"
 #include "utils/utils.h"
 
@@ -1164,6 +1165,7 @@ failed:
  *
  * \param ctx             Selection context to use
  * \param node            Node to select style for
+ * \param unit_len_ctx    Context for length unit conversions.
  * \param media           Currently active media specification
  * \param inline_style    Corresponding inline style for node, or NULL
  * \param handler         Dispatch table of handler functions
@@ -1181,6 +1183,7 @@ failed:
  * update the fully computed style for a node when layout changes.
  */
 css_error css_select_style(css_select_ctx *ctx, void *node,
+		const css_unit_len_ctx *unit_len_ctx,
 		const css_media *media, const css_stylesheet *inline_style,
 		css_select_handler *handler, void *pw,
 		css_select_results **result)
@@ -1353,7 +1356,7 @@ css_error css_select_style(css_select_ctx *ctx, void *node,
 		/* Only compute absolute values for the base element */
 		error = css__compute_absolute_values(NULL,
 				state.results->styles[CSS_PSEUDO_ELEMENT_NONE],
-				handler->compute_font_size, pw);
+				unit_len_ctx);
 		if (error != CSS_OK)
 			goto cleanup;
 	}
diff --git a/src/select/unit.c b/src/select/unit.c
index f9ecf83..a279ec7 100644
--- a/src/select/unit.c
+++ b/src/select/unit.c
@@ -115,14 +115,15 @@ static inline css_fixed css_unit__absolute_len2pt(
 	}
 }
 
-/* Exported function, documented in unit.h. */
+/* Exported function, documented in libcss/unit.h. */
 css_fixed css_unit_font_size_len2pt(
+		const css_computed_style *style,
 		const css_unit_len_ctx *ctx,
 		const css_fixed length,
 		const css_unit unit)
 {
 	return css_unit__absolute_len2pt(
-			ctx->ref_style,
+			style,
 			ctx->viewport_height,
 			ctx->viewport_width,
 			length,
@@ -303,15 +304,16 @@ css_fixed css_unit_len2px_mq(
 	return FMUL(length, TRUNCATEFIX(px_per_unit));
 }
 
-/* Exported function, documented in unit.h. */
+/* Exported function, documented in libcss/unit.h. */
 css_fixed css_unit_len2css_px(
+		const css_computed_style *style,
 		const css_unit_len_ctx *ctx,
 		const css_fixed length,
 		const css_unit unit)
 {
 	css_fixed px_per_unit = css_unit__px_per_unit(
 			ctx->measure,
-			ctx->ref_style,
+			style,
 			ctx->root_style,
 			ctx->font_size_default,
 			ctx->font_size_minimum,
@@ -328,15 +330,16 @@ css_fixed css_unit_len2css_px(
 	return FMUL(length, TRUNCATEFIX(px_per_unit));
 }
 
-/* Exported function, documented in unit.h. */
+/* Exported function, documented in libcss/unit.h. */
 css_fixed css_unit_len2device_px(
+		const css_computed_style *style,
 		const css_unit_len_ctx *ctx,
 		const css_fixed length,
 		const css_unit unit)
 {
 	css_fixed px_per_unit = css_unit__px_per_unit(
 			ctx->measure,
-			ctx->ref_style,
+			style,
 			ctx->root_style,
 			ctx->font_size_default,
 			ctx->font_size_minimum,
@@ -361,18 +364,18 @@ css_fixed css_unit_len2device_px(
  * The computed style will have font-size with an absolute unit.
  * If no computed style is given, the client default font-size will be returned.
  *
- * \param[in]  ctx    Length unit conversion context.
- * \param[in]  style  The style to get the font-size for, or NULL.
+ * \param[in] style              Reference style.  (Element or parent, or NULL).
+ * \param[in] font_size_default  Client default font size in CSS pixels.
  * \return The font size in absolute units.
  */
 static inline css_hint_length css_unit__get_font_size(
-		const css_unit_len_ctx *ctx,
-		const css_computed_style *style)
+		const css_computed_style *style,
+		css_fixed font_size_default)
 {
 	css_hint_length size;
 
 	if (style == NULL) {
-		size.value = ctx->font_size_default;
+		size.value = font_size_default;
 		size.unit = CSS_UNIT_PX;
 	} else {
 		enum css_font_size_e status = get_font_size(
@@ -391,10 +394,24 @@ static inline css_hint_length css_unit__get_font_size(
 
 /* Exported function, documented in unit.h. */
 css_error css_unit_compute_absolute_font_size(
-		const css_unit_len_ctx *ctx,
+		const css_hint_length *ref_length,
+		const css_computed_style *root_style,
+		css_fixed font_size_default,
 		css_hint *size)
 {
-	css_hint_length ref_len;
+	css_hint_length ref_len = {
+		.value = font_size_default,
+		.unit = CSS_UNIT_PX,
+	};
+
+	if (ref_length != NULL) {
+		/* Must be absolute. */
+		assert(ref_length->unit != CSS_UNIT_EM);
+		assert(ref_length->unit != CSS_UNIT_EX);
+		assert(ref_length->unit != CSS_UNIT_PCT);
+
+		ref_len = *ref_length;
+	}
 
 	assert(size->status != CSS_FONT_SIZE_INHERIT);
 
@@ -420,20 +437,18 @@ css_error css_unit_compute_absolute_font_size(
 		assert(CSS_FONT_SIZE_XX_SMALL == 1);
 
 		size->data.length.value = FMUL(factors[size->status - 1],
-				ctx->font_size_default);
+				font_size_default);
 		size->data.length.unit = CSS_UNIT_PX;
 		size->status = CSS_FONT_SIZE_DIMENSION;
 		break;
 	}
 	case CSS_FONT_SIZE_LARGER:
-		ref_len = css_unit__get_font_size(ctx, ctx->ref_style);
 		size->data.length.value = FMUL(ref_len.value, FLTTOFIX(1.2));
 		size->data.length.unit = ref_len.unit;
 		size->status = CSS_FONT_SIZE_DIMENSION;
 		break;
 
 	case CSS_FONT_SIZE_SMALLER:
-		ref_len = css_unit__get_font_size(ctx, ctx->ref_style);
 		size->data.length.value = FDIV(ref_len.value, FLTTOFIX(1.2));
 		size->data.length.unit = ref_len.unit;
 		size->status = CSS_FONT_SIZE_DIMENSION;
@@ -443,9 +458,8 @@ css_error css_unit_compute_absolute_font_size(
 		/* Convert any relative units to absolute. */
 		switch (size->data.length.unit) {
 		case CSS_UNIT_PCT:
-			ref_len = css_unit__get_font_size(ctx, ctx->ref_style);
-			size->data.length.value = FDIV(
-					FMUL(size->data.length.value,
+			size->data.length.value = FDIV(FMUL(
+					size->data.length.value,
 					ref_len.value), INTTOFIX(100));
 			size->data.length.unit = ref_len.unit;
 			break;
@@ -454,11 +468,8 @@ css_error css_unit_compute_absolute_font_size(
 		case CSS_UNIT_EX: /* Fall-through */
 		case CSS_UNIT_CH:
 			/* Parent relative units. */
-			ref_len = css_unit__get_font_size(ctx, ctx->ref_style);
-
-			size->data.length.unit = ref_len.unit;
-			size->data.length.value = FMUL(size->data.length.value,
-						ref_len.value);
+			size->data.length.value = FMUL(
+					size->data.length.value, ref_len.value);
 
 			switch (size->data.length.unit) {
 			case CSS_UNIT_EX:
@@ -476,15 +487,17 @@ css_error css_unit_compute_absolute_font_size(
 			default:
 				break;
 			}
+			size->data.length.unit = ref_len.unit;
 			break;
 
 		case CSS_UNIT_REM:
 			/* Root element relative units. */
-			ref_len = css_unit__get_font_size(ctx, ctx->root_style);
+			ref_len = css_unit__get_font_size(root_style,
+					font_size_default);
 
 			size->data.length.unit = ref_len.unit;
-			size->data.length.value = FMUL(size->data.length.value,
-						ref_len.value);
+			size->data.length.value = FMUL(
+					size->data.length.value, ref_len.value);
 			break;
 
 		default:
diff --git a/src/select/unit.h b/src/select/unit.h
index 738c181..e4d21da 100644
--- a/src/select/unit.h
+++ b/src/select/unit.h
@@ -9,138 +9,7 @@
 #ifndef css_select_unit_h_
 #define css_select_unit_h_
 
-/**
- * Client callback for font measuring.
- *
- * \param[in]  pw     Client data.
- * \param[in]  style  Style to measure font for, or NULL.
- * \param[in]  unit   Either CSS_UNIT_EX, or CSS_UNIT_CH.
- * \return length in CSS pixels.
- */
-typedef css_fixed (*css_unit_len_measure)(
-		void *pw,
-		const css_computed_style *style,
-		const css_unit unit);
-
-/**
- * LibCSS unit conversion context.
- *
- * The client callback is optional.  It is used for measuring "ch"
- * (glyph '0' advance) and "ex" (height of the letter 'x') units.
- * If a NULL pointer is given, LibCSS will use a fixed scaling of
- * the "em" unit.
- */
-typedef struct css_unit_len_ctx {
-	/**
-	 * Viewport width in CSS pixels.
-	 * Used if unit is vh, vw, vi, vb, vmin, or vmax.
-	 */
-	css_fixed viewport_width;
-	/**
-	 * Viewport height in CSS pixels.
-	 * Used if unit is vh, vw, vi, vb, vmin, or vmax.
-	 */
-	css_fixed viewport_height;
-	/**
-	 * Client default font size in CSS pixels.
-	 */
-	css_fixed font_size_default;
-	/**
-	 * Client minimum font size in CSS pixels.  May be zero.
-	 */
-	css_fixed font_size_minimum;
-	/**
-	 * DPI of the device the style is selected for.
-	 */
-	css_fixed device_dpi;
-	/**
-	 * Reference style.  Most of the time, this is the element's style.
-	 * When converting a length for a typographical property, such as
-	 * font-size, then this should be the parent node.  If the node has
-	 * no parent then this may be NULL.
-	 */
-	const css_computed_style *ref_style;
-	/**
-	 * Computed style for the document root element.
-	 * May be NULL if unit is not rem.
-	 */
-	const css_computed_style *root_style;
-	/**
-	 * Client private word for measure callback.
-	 */
-	void *pw;
-	/**
-	 * Client callback for font measuring.
-	 */
-	const css_unit_len_measure measure;
-} css_unit_len_ctx;
-
-/**
- * Convert css pixels to physical pixels.
- *
- * \param[in] css_pixels  Length in css pixels.
- * \param[in] device_dpi  Device dots per inch.
- * \return Length in device pixels.
- */
-static inline css_fixed css_unit_css2device_px(
-		const css_fixed css_pixels,
-		const css_fixed device_dpi)
-{
-	return FDIV(FMUL(css_pixels, device_dpi), F_96);
-}
-
-/**
- * Convert device pixels to css pixels.
- *
- * \param[in] device_pixels  Length in physical pixels.
- * \param[in] device_dpi     Device dots per inch.
- * \return Length in css pixels.
- */
-static inline css_fixed css_unit_device2css_px(
-		const css_fixed device_pixels,
-		const css_fixed device_dpi)
-{
-	return FDIV(FMUL(device_pixels, F_96), device_dpi);
-}
-
-/**
- * Convert a length to points (pt).
- *
- * \param[in]  ctx     Length unit conversion context.
- * \param[in]  length  Length to convert.
- * \param[in]  unit    Current unit of length.
- * \return A length in points.
- */
-css_fixed css_unit_font_size_len2pt(
-		const css_unit_len_ctx *ctx,
-		const css_fixed length,
-		const css_unit unit);
-
-/**
- * Convert a length to CSS pixels.
- *
- * \param[in]  ctx     Length unit conversion context.
- * \param[in]  length  Length to convert.
- * \param[in]  unit    Current unit of length.
- * \return A length in CSS pixels.
- */
-css_fixed css_unit_len2css_px(
-		const css_unit_len_ctx *ctx,
-		const css_fixed length,
-		const css_unit unit);
-
-/**
- * Convert a length to device pixels.
- *
- * \param[in]  ctx     Length unit conversion context.
- * \param[in]  length  Length to convert.
- * \param[in]  unit    Current unit of length.
- * \return A length in device pixels.
- */
-css_fixed css_unit_len2device_px(
-		const css_unit_len_ctx *ctx,
-		const css_fixed length,
-		const css_unit unit);
+#include <libcss/unit.h>
 
 /**
  * Convert a length to CSS pixels for a media query context.
@@ -158,12 +27,16 @@ css_fixed css_unit_len2px_mq(
 /**
  * Convert relative font size units to absolute units.
  *
- * \param[in]     ctx   Length unit conversion context.
- * \param[in,out] size  The length to convert.
+ * \param[in] ref_length         Reference font-size length or NULL.
+ * \param[in] root_style         Root element style or NULL.
+ * \param[in] font_size_default  Client default font size in CSS pixels.
+ * \param[in,out] size           The length to convert.
  * \return CSS_OK on success, or appropriate error otherwise.
  */
 css_error css_unit_compute_absolute_font_size(
-		const css_unit_len_ctx *ctx,
+		const css_hint_length *ref_length,
+		const css_computed_style *root_style,
+		css_fixed font_size_default,
 		css_hint *size);
 
 #endif
diff --git a/test/data/select/tests1.dat b/test/data/select/tests1.dat
index ccce94d..919ca88 100644
--- a/test/data/select/tests1.dat
+++ b/test/data/select/tests1.dat
@@ -59,7 +59,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -173,7 +173,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -291,7 +291,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -410,7 +410,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -529,7 +529,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -648,7 +648,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -757,7 +757,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -867,7 +867,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -977,7 +977,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -1086,7 +1086,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -1200,7 +1200,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -1314,7 +1314,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -1429,7 +1429,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -1547,7 +1547,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -1664,7 +1664,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -1787,7 +1787,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -1910,7 +1910,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -2033,7 +2033,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -2160,7 +2160,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -2286,7 +2286,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -2410,7 +2410,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -2533,7 +2533,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -2656,7 +2656,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -2779,7 +2779,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -2902,7 +2902,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -3025,7 +3025,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -3148,7 +3148,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -3271,7 +3271,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -3394,7 +3394,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -3517,7 +3517,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -3640,7 +3640,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 10.600pt
+font-size: 13.342px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -3763,7 +3763,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 14.391pt
+font-size: 19.187px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -3886,7 +3886,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 24pt
+font-size: 32px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -4009,7 +4009,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 18pt
+font-size: 24px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -4132,7 +4132,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 13.500pt
+font-size: 18px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -4255,7 +4255,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -4378,7 +4378,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 9.750pt
+font-size: 13px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -4501,7 +4501,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 7.500pt
+font-size: 10px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -4624,7 +4624,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 6.750pt
+font-size: 9px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -4870,7 +4870,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -4986,7 +4986,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -5102,7 +5102,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -5218,7 +5218,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -5331,7 +5331,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -5445,7 +5445,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -5559,7 +5559,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -5673,7 +5673,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -5783,7 +5783,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -5894,7 +5894,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -6004,7 +6004,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -6114,7 +6114,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -6224,7 +6224,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -6334,7 +6334,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -6444,7 +6444,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -6556,7 +6556,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -6666,7 +6666,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -6776,7 +6776,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -6887,7 +6887,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -6997,7 +6997,7 @@ flex-shrink: 3.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -7107,7 +7107,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -7217,7 +7217,7 @@ flex-shrink: 0.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -7327,7 +7327,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -7437,7 +7437,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -7547,7 +7547,7 @@ flex-shrink: 0.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -7657,7 +7657,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -7766,7 +7766,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -7875,7 +7875,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -7984,7 +7984,7 @@ flex-shrink: 30.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -8095,7 +8095,7 @@ flex-shrink: 3.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -8206,7 +8206,7 @@ flex-shrink: 3.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -8315,7 +8315,7 @@ flex-shrink: 0.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -8426,7 +8426,7 @@ flex-shrink: 0.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -8537,7 +8537,7 @@ flex-shrink: 3.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -8648,7 +8648,7 @@ flex-shrink: 3.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -8757,7 +8757,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -8866,7 +8866,7 @@ flex-shrink: 1.000
 flex-wrap: wrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -8975,7 +8975,7 @@ flex-shrink: 1.000
 flex-wrap: wrap-reverse
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -9084,7 +9084,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -9193,7 +9193,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -9302,7 +9302,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -9411,7 +9411,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -9520,7 +9520,7 @@ flex-shrink: 1.000
 flex-wrap: wrap-reverse
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -9631,7 +9631,7 @@ flex-shrink: 1.000
 flex-wrap: wrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -9742,7 +9742,7 @@ flex-shrink: 1.000
 flex-wrap: wrap-reverse
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -9851,7 +9851,7 @@ flex-shrink: 0.899
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -9960,7 +9960,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -10069,7 +10069,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -10178,7 +10178,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -10287,7 +10287,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -10396,7 +10396,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -10505,7 +10505,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -10616,7 +10616,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -10727,7 +10727,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -10836,7 +10836,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -10945,7 +10945,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -11054,7 +11054,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -11165,7 +11165,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -11274,7 +11274,7 @@ flex-shrink: 3.780
 flex-wrap: wrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -11385,7 +11385,7 @@ flex-shrink: 3.780
 flex-wrap: wrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -11494,7 +11494,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -11603,7 +11603,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -11712,7 +11712,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -11821,7 +11821,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -11930,7 +11930,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -12039,7 +12039,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -12148,7 +12148,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -12257,7 +12257,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -12366,7 +12366,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -12475,7 +12475,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -12584,7 +12584,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -12693,7 +12693,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -12802,7 +12802,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -12911,7 +12911,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -13020,7 +13020,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -13129,7 +13129,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -13238,7 +13238,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -13347,7 +13347,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -13456,7 +13456,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -13565,7 +13565,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -13674,7 +13674,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -13783,7 +13783,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -13892,7 +13892,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
@@ -14020,7 +14020,7 @@ flex-shrink: 1.000
 flex-wrap: nowrap
 float: none
 font-family: sans-serif
-font-size: 12pt
+font-size: 16px
 font-style: normal
 font-variant: normal
 font-weight: normal
diff --git a/test/select.c b/test/select.c
index 664994e..8226a8b 100644
--- a/test/select.c
+++ b/test/select.c
@@ -159,13 +159,15 @@ static css_error node_presentational_hint(void *pw, void *node,
 		uint32_t *nhints, css_hint **hints);
 static css_error ua_default_for_property(void *pw, uint32_t property,
 		css_hint *hints);
-static css_error compute_font_size(void *pw, const css_hint *parent,
-		css_hint *size);
 static css_error set_libcss_node_data(void *pw, void *n,
 		void *libcss_node_data);
 static css_error get_libcss_node_data(void *pw, void *n,
 		void **libcss_node_data);
 
+static css_unit_len_ctx unit_len_ctx = {
+	.font_size_default = 16 * (1 << CSS_RADIX_POINT),
+};
+
 static css_select_handler select_handler = {
 	CSS_SELECT_HANDLER_VERSION_1,
 
@@ -203,9 +205,9 @@ static css_select_handler select_handler = {
 	node_is_lang,
 	node_presentational_hint,
 	ua_default_for_property,
-	compute_font_size,
+
 	set_libcss_node_data,
-	get_libcss_node_data
+	get_libcss_node_data,
 };
 
 static css_error resolve_url(void *pw,
@@ -765,7 +767,12 @@ static void run_test_select_tree(css_select_ctx *select,
 	css_select_results *sr;
 	struct node *n = NULL;
 
-	assert(css_select_style(select, node, &ctx->media, NULL,
+	if (node->parent == NULL) {
+		unit_len_ctx.root_style = NULL;
+	}
+
+
+	assert(css_select_style(select, node, &unit_len_ctx, &ctx->media, NULL,
 			&select_handler, ctx, &sr) == CSS_OK);
 
 	if (node->parent != NULL) {
@@ -773,7 +780,7 @@ static void run_test_select_tree(css_select_ctx *select,
 		assert(css_computed_style_compose(
 				node->parent->sr->styles[ctx->pseudo_element],
 				sr->styles[ctx->pseudo_element],
-				compute_font_size, NULL,
+				&unit_len_ctx,
 				&composed) == CSS_OK);
 		css_computed_style_destroy(sr->styles[ctx->pseudo_element]);
 		sr->styles[ctx->pseudo_element] = composed;
@@ -786,6 +793,10 @@ static void run_test_select_tree(css_select_ctx *select,
 				buf, buflen);
 	}
 
+	if (node->parent == NULL) {
+		unit_len_ctx.root_style = node->sr->styles[ctx->pseudo_element];
+	}
+
 	for (n = node->children; n != NULL; n = n->next) {
 		run_test_select_tree(select, n, ctx, buf, buflen);
 	}
@@ -1606,68 +1617,6 @@ css_error ua_default_for_property(void *pw, uint32_t property, css_hint *hint)
 	return CSS_OK;
 }
 
-css_error compute_font_size(void *pw, const css_hint *parent, css_hint *size)
-{
-	static css_hint_length sizes[] = {
-		{ FLTTOFIX(6.75), CSS_UNIT_PT },
-		{ FLTTOFIX(7.50), CSS_UNIT_PT },
-		{ FLTTOFIX(9.75), CSS_UNIT_PT },
-		{ FLTTOFIX(12.0), CSS_UNIT_PT },
-		{ FLTTOFIX(13.5), CSS_UNIT_PT },
-		{ FLTTOFIX(18.0), CSS_UNIT_PT },
-		{ FLTTOFIX(24.0), CSS_UNIT_PT }
-	};
-	const css_hint_length *parent_size;
-
-	UNUSED(pw);
-
-	/* Grab parent size, defaulting to medium if none */
-	if (parent == NULL) {
-		parent_size = &sizes[CSS_FONT_SIZE_MEDIUM - 1];
-	} else {
-		assert(parent->status == CSS_FONT_SIZE_DIMENSION);
-		assert(parent->data.length.unit != CSS_UNIT_EM);
-		assert(parent->data.length.unit != CSS_UNIT_EX);
-		parent_size = &parent->data.length;
-	}
-
-	assert(size->status != CSS_FONT_SIZE_INHERIT);
-
-	if (size->status < CSS_FONT_SIZE_LARGER) {
-		/* Keyword -- simple */
-		size->data.length = sizes[size->status - 1];
-	} else if (size->status == CSS_FONT_SIZE_LARGER) {
-		/** \todo Step within table, if appropriate */
-		size->data.length.value =
-				FMUL(parent_size->value, FLTTOFIX(1.2));
-		size->data.length.unit = parent_size->unit;
-	} else if (size->status == CSS_FONT_SIZE_SMALLER) {
-		/** \todo Step within table, if appropriate */
-		size->data.length.value =
-				FDIV(parent_size->value, FLTTOFIX(1.2));
-		size->data.length.unit = parent_size->unit;
-	} else if (size->data.length.unit == CSS_UNIT_EM ||
-			size->data.length.unit == CSS_UNIT_EX) {
-		size->data.length.value =
-			FMUL(size->data.length.value, parent_size->value);
-
-		if (size->data.length.unit == CSS_UNIT_EX) {
-			size->data.length.value = FMUL(size->data.length.value,
-					FLTTOFIX(0.6));
-		}
-
-		size->data.length.unit = parent_size->unit;
-	} else if (size->data.length.unit == CSS_UNIT_PCT) {
-		size->data.length.value = FDIV(FMUL(size->data.length.value,
-				parent_size->value), FLTTOFIX(100));
-		size->data.length.unit = parent_size->unit;
-	}
-
-	size->status = CSS_FONT_SIZE_DIMENSION;
-
-	return CSS_OK;
-}
-
 static css_error set_libcss_node_data(void *pw, void *n,
 		void *libcss_node_data)
 {