Flatten admin theme toward Tabler

src/TaxBaik.Web/wwwroot/css/admin.css

@@ -412,12 +412,14 @@ html, body {
 }
 
 .admin-main-surface {
-  border-radius: var(--radius-xl);
+  border-radius: var(--radius-lg);
   overflow: hidden;
+  box-shadow: none !important;
+  border: 1px solid var(--border-color);
 }
 
 .admin-breadcrumb-header {
-  background: linear-gradient(180deg, #FFFFFF 0%, #F8FAFC 100%);
+  background: #ffffff;
   padding-top: 0.75rem;
   padding-bottom: 0.75rem;
 }
@@ -448,13 +450,14 @@ html, body {
 
 .blog-editor-shell .card,
 .admin-page-shell .card {
-  border-radius: var(--radius-xl);
-  box-shadow: var(--shadow-sm);
+  border-radius: var(--radius-lg);
+  box-shadow: none !important;
+  border: 1px solid var(--border-color-light);
 }
 
 .blog-editor-shell .card-header,
 .admin-page-shell .card-header {
-  background: linear-gradient(180deg, #FFFFFF 0%, #F8FAFC 100%);
+  background: #ffffff;
 }
 
 .blog-editor-shell .card-footer,
@@ -479,6 +482,31 @@ html, body {
   background: #fff;
 }
 
+.admin-metric-card,
+.admin-sidebar-card {
+  box-shadow: none !important;
+  border: 1px solid var(--border-color-light) !important;
+  border-radius: var(--radius-lg) !important;
+}
+
+.admin-metric-card .card-body {
+  padding: 0.8rem 0.85rem;
+}
+
+.admin-page-header-title {
+  font-size: 1.02rem;
+  line-height: 1.15;
+  font-weight: 600;
+}
+
+.admin-page-header-subtitle {
+  font-size: 0.76rem;
+}
+
+.admin-page-header-eyebrow {
+  font-size: 0.66rem;
+}
+
 .breadcrumb-muted {
   --bs-breadcrumb-divider-color: var(--text-tertiary);
   margin-bottom: 0;