refactor(UI): 优化工具栏样式并重构层叠图恢复逻辑

调整工具栏按钮和间距样式以提升视觉一致性
将层叠图恢复逻辑重构为独立函数以提高代码复用性

css/style.css

@@ -23,18 +23,19 @@ html, body {
 .toolbar {
     display: flex;
     justify-content: center;
-    gap: 8px;
-    padding: 12px 16px;
+    align-items: center;
+    gap: 6px;
+    padding: 10px 12px;
     background: #fff;
     border-bottom: 1px solid #e0e0e0;
     flex-shrink: 0;
 }
 
 .btn {
-    min-width: 72px;
-    height: 40px;
-    padding: 0 12px;
-    font-size: 15px;
+    min-width: 68px;
+    height: 36px;
+    padding: 0 10px;
+    font-size: 14px;
     border: 1px solid #ddd;
     border-radius: 6px;
     background: #fff;
@@ -65,29 +66,31 @@ html, body {
 /* 工具栏垂直分隔线 */
 .toolbar-divider-v {
     width: 1px;
-    height: 24px;
-    background: #ddd;
-    margin: 0 4px;
+    height: 20px;
+    background: #e0e0e0;
+    margin: 0 2px;
 }
 
 /* 工具栏图标按钮 */
 .toolbar-btn-icon {
-    width: 32px;
-    height: 32px;
-    font-size: 16px;
+    width: 28px;
+    height: 28px;
+    font-size: 14px;
     border: 1px solid #ddd;
-    border-radius: 6px;
+    border-radius: 5px;
     background: #fff;
-    color: #333;
+    color: #555;
     cursor: pointer;
     transition: all 0.2s;
     display: flex;
     align-items: center;
     justify-content: center;
+    padding: 0;
 }
 
 .toolbar-btn-icon:hover {
     background: #f5f5f5;
+    border-color: #ccc;
 }
 
 .toolbar-btn-icon:active {
@@ -95,8 +98,9 @@ html, body {
 }
 
 .toolbar-btn-icon:disabled {
-    opacity: 0.4;
+    opacity: 0.3;
     cursor: not-allowed;
+    background: #f5f5f5;
 }
 
 /* 文本输入框删除按钮 */