diff --git a/src/katex.less b/src/katex.less
index 8edf907d..dc3db550 100644
--- a/src/katex.less
+++ b/src/katex.less
@@ -547,6 +547,7 @@
     .fcolorbox {
         box-sizing: border-box;
         border: 0.04em solid;         // \fboxrule = 0.4pt
+        border-color: inherit;
     }
 
     .cancel-pad {