--- a/servo/components/style/values/specified/color.rs
+++ b/servo/components/style/values/specified/color.rs
@@ -9,17 +9,17 @@ use cssparser::{BasicParseErrorKind, Num
 #[cfg(feature = "gecko")]
 use gecko_bindings::structs::nscolor;
 use itoa;
 use parser::{Parse, ParserContext};
 #[cfg(feature = "gecko")]
 use properties::longhands::system_colors::SystemColor;
 use std::fmt::{self, Write};
 use std::io::Write as IoWrite;
-use style_traits::{CssType, CssWriter, ParseError, StyleParseErrorKind};
+use style_traits::{CssType, CssWriter, KeywordsCollectFn, ParseError, StyleParseErrorKind};
 use style_traits::{SpecifiedValueInfo, ToCss, ValueParseErrorKind};
 use super::AllowQuirks;
 use values::computed::{Color as ComputedColor, Context, ToComputedValue};
 use values::specified::calc::CalcNode;
 
 /// Specified color value
 #[derive(Clone, Debug, MallocSizeOf, PartialEq)]
 pub enum Color {
@@ -424,16 +424,25 @@ impl ToComputedValue for RGBAColor {
 impl From<Color> for RGBAColor {
     fn from(color: Color) -> RGBAColor {
         RGBAColor(color)
     }
 }
 
 impl SpecifiedValueInfo for Color {
     const SUPPORTED_TYPES: u8 = CssType::COLOR;
+
+    fn collect_completion_keywords(f: KeywordsCollectFn) {
+        // We are not going to insert all the color names here. Caller and
+        // devtools should take care of them. XXX Actually, transparent
+        // should probably be handled that way as well.
+        // XXX `currentColor` should really be `currentcolor`. But let's
+        // keep it consistent with the old system for now.
+        f(&["rgb", "rgba", "hsl", "hsla", "currentColor", "transparent"]);
+    }
 }
 
 /// Specified value for the "color" property, which resolves the `currentcolor`
 /// keyword to the parent color instead of self's color.
 #[cfg_attr(feature = "gecko", derive(MallocSizeOf))]
 #[derive(Clone, Debug, PartialEq, SpecifiedValueInfo, ToCss)]
 pub struct ColorPropertyValue(pub Color);
 

--- a/servo/ports/geckolib/glue.rs
+++ b/servo/ports/geckolib/glue.rs
@@ -1017,19 +1017,28 @@ pub unsafe extern "C" fn Servo_Property_
     found: *mut bool,
     result: *mut nsTArray<nsStringRepr>,
 ) {
     let prop_id = parse_enabled_property_name!(prop_name, found, ());
     // Use B-tree set for unique and sorted result.
     let mut values = BTreeSet::<&'static str>::new();
     prop_id.collect_property_completion_keywords(&mut |list| values.extend(list.iter()));
 
+    let mut extras = vec![];
+    if values.contains("transparent") {
+        // This is a special value devtools use to avoid inserting the
+        // long list of color keywords. We need to prepend it to values.
+        extras.push("COLOR");
+    }
+
     let result = result.as_mut().unwrap();
-    bindings::Gecko_ResizeTArrayForStrings(result, values.len() as u32);
-    for (src, dest) in values.iter().zip(result.iter_mut()) {
+    let len = extras.len() + values.len();
+    bindings::Gecko_ResizeTArrayForStrings(result, len as u32);
+
+    for (src, dest) in extras.iter().chain(values.iter()).zip(result.iter_mut()) {
         dest.write_str(src).unwrap();
     }
 }
 
 #[no_mangle]
 pub extern "C" fn Servo_Property_IsAnimatable(property: nsCSSPropertyID) -> bool {
     use style::properties::animated_properties;
     animated_properties::nscsspropertyid_is_animatable(property)