fix: color inconsistency when blur effect is not supported

Author: dragonman225

themes/pure-ejs/assets/css/notablog.css

@@ -1,5 +1,10 @@
+:root {
+  --bg: rgb(250, 250, 246);
+  --bg-blur: rgba(250, 250, 246, 0.4);
+}
+
 body {
-  background: rgb(250, 250, 246);
+  background: var(--bg);
 }
 
 /* Navbar */
@@ -16,7 +21,7 @@ body {
   height: 50px;
   padding: 10px 20px;
   /* Background blur stuff. */
-  background-color: rgba(250, 250, 246, 0.4);
+  background-color: var(--bg-blur);
   -webkit-backdrop-filter: blur(20px);
   backdrop-filter: blur(20px);
   overflow-x: auto;
@@ -303,7 +308,7 @@ body {
 @supports (not (backdrop-filter: blur(20px))) and
   (not (-webkit-backdrop-filter: blur(20px))) {
   .Navbar {
-    background-color: white;
+    background-color: var(--bg);
   }
 }