--- a/servo/components/style/properties/declaration_block.rs
+++ b/servo/components/style/properties/declaration_block.rs
@@ -517,17 +517,17 @@ impl PropertyDeclarationBlock {
                     continue;
                 }
 
                 let important = self.declarations_importance[i];
                 // For declarations from parsing, non-important declarations
                 // shouldn't override existing important one.
                 if important && !importance.important() &&
                     matches!(source, DeclarationSource::Parsing) {
-                    return true;
+                    return false;
                 }
 
                 if matches!(source, DeclarationSource::Parsing) {
                     // As a compatibility hack, specially on Android,
                     // don't allow to override a prefixed webkit display
                     // value with an unprefixed version from parsing
                     // code.
                     //