--- a/layout/reftests/box-properties/reftest-stylo.list
+++ b/layout/reftests/box-properties/reftest-stylo.list
@@ -5,17 +5,17 @@ fails == outline-radius-percent-1.html o
 == max-width-1.html max-width-1.html
 == max-height-1.html max-height-1.html
 fails == width-special-values-block.html width-special-values-block.html
 fails == width-special-values-float.html width-special-values-float.html
 fails == width-special-values-image-block.html width-special-values-image-block.html
 fails == width-special-values-image.html width-special-values-image.html
 fails == width-special-values-block-intrinsic.html width-special-values-block-intrinsic.html
 fails == width-special-values-float-intrinsic.html width-special-values-float-intrinsic.html
-fails == minmax-width-special-values-block-intrinsic.html minmax-width-special-values-block-intrinsic.html
+== minmax-width-special-values-block-intrinsic.html minmax-width-special-values-block-intrinsic.html
 fails == width-special-values-cell-auto.html width-special-values-cell-auto.html
 fails == width-special-values-cell-fixed.html width-special-values-cell-fixed.html
 fails == box-sizing-1.html box-sizing-1.html
 fails == box-sizing-2.html box-sizing-2.html
 fails == box-sizing-3.html box-sizing-3.html
 fails == box-sizing-4.html box-sizing-4.html
 == box-sizing-minmax-height.html box-sizing-minmax-height.html
 == box-sizing-minmax-width.html box-sizing-minmax-width.html

--- a/layout/reftests/bugs/reftest-stylo.list
+++ b/layout/reftests/bugs/reftest-stylo.list
@@ -887,17 +887,17 @@ fails == 403519-1.html 403519-1.html
 == 403656-4.html 403656-4.html
 == 403656-5.html 403656-5.html
 == 403657-1.html 403657-1.html
 == 403733-1.html 403733-1.html
 fails == 403962-1.xhtml 403962-1.xhtml # Bug 1290276
 == 404030-1.html 404030-1.html
 == 404030-1-notref.html 404030-1-notref.html
 == 404030-1-notref2.html 404030-1-notref2.html
-fails == 404123-1.html 404123-1.html
+== 404123-1.html 404123-1.html
 fails == 404123-2.html 404123-2.html
 == 404123-3.html 404123-3.html
 # may fail "randomly" on OS X, doesn't seem to be rendering usefully anyhow - bug 602469
 random-if(cocoaWidget) HTTP(..) == 404149-1.xul 404149-1.xul
 == 404180-1.html 404180-1.html
 == 404301-1.html 404301-1.html
 == 404309-1a.html 404309-1a.html
 == 404309-1b.html 404309-1b.html
@@ -1133,17 +1133,17 @@ fails == 430412-1.html 430412-1.html
 == 430813-1.html 430813-1.html
 == 430813-2.html 430813-2.html
 == 430813-3.html 430813-3.html
 == 431341-1.html 431341-1.html
 == 431341-2.html 431341-2.html
 == 431520-1.html 431520-1.html
 == 431948-1.html 431948-1.html
 == 433640-1.html 433640-1.html
-fails == 433700.html 433700.html
+== 433700.html 433700.html
 == 436356-1.html 436356-1.html
 == 436356-2.html 436356-2.html
 == 438537-1.html 438537-1.html
 == 438981-1.xhtml 438981-1.xhtml
 == 438987-1.html 438987-1.html
 fuzzy-if(skiaContent,1,3280) == 438987-2a.html 438987-2a.html
 fuzzy-if(skiaContent,1,3280) == 438987-2b.html 438987-2b.html
 fuzzy-if(skiaContent,1,3280) == 438987-2c.html 438987-2c.html

--- a/layout/reftests/forms/fieldset/reftest-stylo.list
+++ b/layout/reftests/forms/fieldset/reftest-stylo.list
@@ -12,18 +12,18 @@ fails == fieldset-overflow-auto-1.html f
 == relpos-legend-3.html relpos-legend-3.html
 == relpos-legend-4.html relpos-legend-4.html
 fails == sticky-legend-1.html sticky-legend-1.html
 fuzzy-if(skiaContent,1,40768) == abs-pos-child-sizing.html abs-pos-child-sizing.html
 == overflow-hidden.html overflow-hidden.html
 == legend-rtl.html legend-rtl.html # Bug 1340696
 fails == fieldset-grid-001.html fieldset-grid-001.html
 fails == fieldset-flexbox-001.html fieldset-flexbox-001.html
-fails == fieldset-min-width-1a.html fieldset-min-width-1a.html
-fails == fieldset-min-width-1b.html fieldset-min-width-1b.html
+== fieldset-min-width-1a.html fieldset-min-width-1a.html
+== fieldset-min-width-1b.html fieldset-min-width-1b.html
 == fieldset-min-width-2a.html fieldset-min-width-2a.html
 == fieldset-min-width-2b.html fieldset-min-width-2b.html
 == legend-overlapping-right-border-1.html legend-overlapping-right-border-1.html # Bug 1340696
 fails == fieldset-border-image-1a.html fieldset-border-image-1a.html
 fails == fieldset-border-image-1b.html fieldset-border-image-1b.html
 fails == fieldset-border-image-2a.html fieldset-border-image-2a.html
 fails == fieldset-border-image-2b.html fieldset-border-image-2b.html
 == dynamic-text-indent.html dynamic-text-indent.html

--- a/layout/style/test/stylo-failures.md
+++ b/layout/style/test/stylo-failures.md
@@ -66,17 +66,17 @@ to mochitest command.
     * test_bug221428.html [1]
     * test_css_eof_handling.html: also relies on \@-moz-document [1]
   * @keyframes
     * test_keyframes_rules.html [1]
     * test_rules_out_of_sheets.html [1]
     * test_bug887741_at-rules_in_declaration_lists.html `rules[2]` [1]
   * @support
     * test_supports_rules.html [1]
-* test_box_size_keywords.html: moz-prefixed intrinsic size keyword value [64]
+* test_box_size_keywords.html: moz-prefixed intrinsic size keyword value [16]
 * test_bug357614.html: case-insensitivity for old attrs in attr selector servo/servo#15006 [2]
 * mapped attribute not supported
   * test_html_attribute_computed_values.html: also list-style-type [8]
 * test_bug387615.html: servo/servo#15006 [1]
 * test_bug397427.html: @import issue bug 1331291 and CSSOM support of @import [1]
 * console support:
   * test_bug413958.html `monitorConsole` [3]
   * test_parser_diagnostics_unprintables.html [550]
@@ -256,20 +256,20 @@ to mochitest command.
     * ... `-moz-repeating-` [298]
   * webkit-prefixed gradient functions servo/servo#15441
     * test_value_storage.html `-webkit-gradient` [225]
     * ... `-webkit-linear-gradient` [40]
     * ... `-webkit-radial-gradient` [105]
     * ... `-webkit-repeating-` [35]
   * moz-prefixed intrinsic width values
     * test_flexbox_flex_shorthand.html `-moz-fit-content` [4]
-    * test_value_storage.html `-moz-max-content` [52]
-    * ... `-moz-min-content` [12]
-    * ... `-moz-fit-content` [12]
-    * ... `-moz-available` [10]
+    * test_value_storage.html `-moz-max-content` [46]
+    * ... `-moz-min-content` [6]
+    * ... `-moz-fit-content` [6]
+    * ... `-moz-available` [4]
   * -moz-element() function for <image> servo/servo#15443
     * test_value_storage.html `-moz-element` [49]
   * -moz-anchor-decoration value on text-decoration
     * test_value_storage.html `-moz-anchor-decoration` [10]
   * several prefixed values in cursor property
     * test_value_storage.html `cursor` [4]
   * moz-prefixed values of overflow shorthand bug 1330888
     * test_bug319381.html [8]

--- a/servo/components/style/properties/longhand/position.mako.rs
+++ b/servo/components/style/properties/longhand/position.mako.rs
@@ -196,17 +196,24 @@
                 pub struct SpecifiedValue(${MinMax}Length);
 
                 #[inline]
                 pub fn get_initial_value() -> computed_value::T {
                     use values::computed::${MinMax}Length;
                     ${MinMax}Length::${initial}
                 }
                 fn parse(context: &ParserContext, input: &mut Parser) -> Result<SpecifiedValue, ()> {
-                    ${MinMax}Length::parse(context, input).map(SpecifiedValue)
+                    let ret = ${MinMax}Length::parse(context, input);
+                    // Keyword values don't make sense in the block direction; don't parse them
+                    % if "block" in size:
+                        if let Ok(${MinMax}Length::ExtremumLength(..)) = ret {
+                            return Err(())
+                        }
+                    % endif
+                    ret.map(SpecifiedValue)
                 }
 
                 impl ToCss for SpecifiedValue {
                     fn to_css<W>(&self, dest: &mut W) -> fmt::Result where W: fmt::Write {
                         self.0.to_css(dest)
                     }
                 }
 

--- a/servo/components/style/values/mod.rs
+++ b/servo/components/style/values/mod.rs
@@ -187,12 +187,12 @@ impl<A: ToComputedValue, B: ToComputedVa
             Either::Second(ref a) => Either::Second(ToComputedValue::from_computed_value(a)),
         }
     }
 }
 
 // A type for possible values for min- and max- flavors of width,
 // height, block-size, and inline-size.
 define_css_keyword_enum!(ExtremumLength:
-                         "max-content" => MaxContent,
-                         "min-content" => MinContent,
-                         "fit-content" => FitContent,
-                         "fill-available" => FillAvailable);
+                         "-moz-max-content" => MaxContent,
+                         "-moz-min-content" => MinContent,
+                         "-moz-fit-content" => FitContent,
+                         "-moz-available" => FillAvailable);