Fix theme consistency, i18n completeness, CSS variable naming, and hardcoded strings

src/app/globals.css

@@ -66,7 +66,7 @@
   --input-focus-color: #eeb425;
   --navbar-height: 56px;
   --muted: var(--color-text-muted);
-  --border: color-mix(in srgb, var(--color-text-muted) 18%, transparent);
+  --border-subtle: color-mix(in srgb, var(--color-text-muted) 18%, transparent);
 }
 
 /* Dark mode (toggled by html.dark; wins over :root + ThemeVars via specificity). */
@@ -250,22 +250,6 @@ a:hover {
   transform: translateY(-3px);
   box-shadow: var(--shadow-card-hover);
 }
-.grid {
-  display: grid;
-  gap: 1rem;
-}
-.grid.cols-2 {
-  grid-template-columns: repeat(2, 1fr);
-}
-.grid.cols-3 {
-  grid-template-columns: repeat(3, 1fr);
-}
-@media (max-width: 720px) {
-  .grid.cols-2,
-  .grid.cols-3 {
-    grid-template-columns: 1fr;
-  }
-}
 .article-img {
   width: 100%;
   height: 140px;
@@ -408,7 +392,7 @@ tbody tr:hover {
 .admin-card {
   background: var(--color-navbar);
   color: var(--color-navbar-text);
-  border: 1px solid var(--border);
+  border: 1px solid var(--border-subtle);
   border-radius: 16px;
   box-shadow: var(--shadow-card);
   padding: 1.25rem;
@@ -452,7 +436,7 @@ tbody tr:hover {
 .admin-page table {
   width: 100%;
   background: var(--color-navbar);
-  border: 1px solid var(--border);
+  border: 1px solid var(--border-subtle);
   border-radius: 16px;
   overflow: hidden;
   box-shadow: var(--shadow-card);
@@ -462,7 +446,7 @@ tbody tr:hover {
 .admin-page thead th {
   background: color-mix(in srgb, var(--color-primary) 8%, var(--color-navbar));
   color: var(--color-text-muted);
-  border-bottom: 1px solid var(--border);
+  border-bottom: 1px solid var(--border-subtle);
   white-space: nowrap;
   font-size: 0.68rem;
   font-weight: 700;