Use code styling for base branch text and secondary button styling

Co-authored-by: alexr00 <38270282+alexr00@users.noreply.github.com>

Author: Copilot

webviews/components/header.tsx

@@ -279,10 +279,10 @@ function Subtitle({ state, stateReason, isDraft, isIssue, author, base, head, co
 							<button 
 								title="Change base branch" 
 								onClick={changeBaseBranch} 
-								className="branch-tag branch-tag-button"
+								className="branch-tag-button"
 								aria-label="Change base branch"
 							>
-								{base}
+								<code className="branch-tag">{base}</code>
 							</button>
 						) : (
 							<code className="branch-tag">{base}</code>

webviews/editorWebview/index.css

@@ -542,20 +542,28 @@ body button .icon {
 }
 
 .branch-tag-button {
+	background-color: var(--vscode-button-secondaryBackground);
+	color: var(--vscode-button-secondaryForeground);
 	border: 1px solid transparent;
+	border-radius: 4px;
 	cursor: pointer;
+	padding: 0;
+	margin-top: 3px;
 	font-family: inherit;
 	font-size: inherit;
 }
 
-.branch-tag-button:hover {
-	background: var(--vscode-button-hoverBackground);
-	color: var(--vscode-button-foreground);
-	border-color: var(--vscode-button-border);
+.branch-tag-button:hover:enabled {
+	background-color: var(--vscode-button-secondaryHoverBackground);
 }
 
 .branch-tag-button:active {
-	background: var(--vscode-button-background);
+	background-color: var(--vscode-button-secondaryHoverBackground);
+}
+
+.branch-tag-button .branch-tag {
+	background: transparent;
+	margin-top: 0;
 }
 
 .merge-branches .icon-button {