feat(admin): refine theme settings UI

assets/admin/src/components/form/AksRepeaterField.vue

@@ -136,10 +136,10 @@ function updateField(index, key, value) {
 }
 
 .aksrt-repeater__item {
-  border: 1px solid #eef1f6;
+  border: 1px solid var(--aksrt-color-border);
   border-radius: 8px;
   padding: 12px;
-  background: #fafbfc;
+  background: var(--aksrt-color-canvas);
 }
 
 .aksrt-repeater__item-header {
@@ -152,8 +152,8 @@ function updateField(index, key, value) {
 .aksrt-repeater__item-index {
   font-size: 12px;
   font-weight: 600;
-  color: #1890ff;
-  background: #e6f4ff;
+  color: var(--aksrt-color-primary);
+  background: var(--aksrt-color-primary-soft);
   padding: 2px 8px;
   border-radius: 4px;
 }
@@ -175,7 +175,7 @@ function updateField(index, key, value) {
   align-items: center;
   gap: 8px;
   padding: 24px;
-  color: #c0c4cc;
+  color: var(--aksrt-color-border-strong);
   font-size: 13px;
 }