doc(Pre): update Pre style (#6230)

Author: ArgoZhang

src/BootstrapBlazor.Server/Components/Components/Pre.razor.css

@@ -19,6 +19,12 @@
         display: none;
     }
 
+    .pre-code > pre {
+        color: #e83e8c;
+        margin-bottom: 0;
+        max-height: 260px;
+    }
+
 ::deep .btn-group {
     position: absolute;
     top: 0;

src/BootstrapBlazor.Server/Components/Layout/BaseLayout.razor.css

@@ -1,10 +1,4 @@
-::deep pre {
-    color: #e83e8c;
-    margin-bottom: 0;
-    max-height: 260px;
-}
-
-main {
+main {
     min-height: calc(100vh - var(--bs-header-height));
     position: relative;
     z-index: 10;