Base: Use correct color code for Slate Blue 100

Author: https://github.com/trflynn89
Commit: e879fd29b3
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/4195
Reviewed-by: https://github.com/awesomekling ✅

Base/res/ladybird/ladybird.css

@@ -32,7 +32,7 @@
     --slate-blue-50: #97bce6;
     --slate-blue-60: #86add9;
     --slate-blue-80: #77a1d1;
-    --slate-blue-100: #8a64e5;
+    --slate-blue-100: #6d98cc;
     --slate-blue-300: #5c8ecc;
     --slate-blue-500: #5484bf;
     --slate-blue-900: #4872a3;