feat: Enhance site navigation styles and improve backdrop effects for better visibility

theme/assets/css/main.css

@@ -280,7 +280,9 @@ p:last-child { margin-bottom: 0; }
   background: var(--header-scrolled-bg);
   box-shadow: var(--shadow-sm);
   padding-block: .65rem;
+  -webkit-backdrop-filter: blur(8px);
   backdrop-filter: blur(8px);
+  will-change: transform;
 }
 
 .header-inner {
@@ -496,6 +498,8 @@ p:last-child { margin-bottom: 0; }
   gap: 5px;
   margin-left: auto;
   padding: 4px;
+  position: relative;
+  z-index: 101;
 }
 .nav-toggle span {
   display: block;
@@ -516,7 +520,7 @@ p:last-child { margin-bottom: 0; }
     display: block;
     position: fixed;
     top: 0; left: 0; right: 0; bottom: 0;
-    background: var(--color-dark);
+    background: var(--color-bg);
     z-index: 99;
     overflow: hidden;
   }
@@ -537,8 +541,9 @@ p:last-child { margin-bottom: 0; }
   .site-nav.open .nav-menu > li {
     width: 100%;
   }
+  .nav-toggle.open span { background: var(--color-heading); }
   .site-nav.open .nav-menu a {
-    color: #fff;
+    color: var(--color-heading);
     font-size: 1.25rem;
   }
 
@@ -548,7 +553,7 @@ p:last-child { margin-bottom: 0; }
   }
   .site-nav.open .nav-menu > li.menu-item-has-children > a::before {
     right: .25rem;
-    border-color: rgba(255,255,255,.7);
+    border-color: var(--color-text-muted);
   }
   .site-nav.open .nav-menu > li.menu-item-has-children.submenu-open > a::before {
     transform: translateY(-30%) rotate(225deg);
@@ -559,7 +564,7 @@ p:last-child { margin-bottom: 0; }
     opacity: 1;
     visibility: visible;
     pointer-events: auto;
-    background: rgba(255,255,255,.07);
+    background: var(--color-bg-alt);
     border: none;
     border-radius: var(--radius-sm);
     box-shadow: none;
@@ -574,10 +579,10 @@ p:last-child { margin-bottom: 0; }
   .site-nav.open .nav-menu .sub-menu a {
     font-size: 1rem;
     padding: .4rem .75rem;
-    color: rgba(255,255,255,.8);
+    color: var(--color-text);
   }
   .site-nav.open .nav-menu .sub-menu a:hover {
-    color: #fff;
+    color: var(--color-primary);
     background: transparent;
   }
 }
@@ -3775,7 +3780,6 @@ p:last-child { margin-bottom: 0; }
 
 [data-theme="dark"] .site-footer { background: #0D0D0D; }
 
-[data-theme="dark"] .site-nav.open { background: #111111; }
 
 [data-theme="dark"] .logo-text { color: #F5F5F5; }
 [data-theme="dark"] .logo-text strong { color: var(--color-primary); }