Improves UI alignment and copy feedback clarity

Removes unnecessary spacing and minimum height from layout styles
to enhance visual consistency. Updates copy feedback to display a
clearer success message, improving user interaction and clarity.

src/App.css

@@ -651,7 +651,6 @@ select {
     align-items: center; /* 垂直居中 */
     justify-content: center; /* 横向居中 */
     gap: 10px;
-    margin-bottom: 25px;
     border-radius: var(--radius);
     overflow-x: auto;
     overflow-y: hidden;
@@ -760,7 +759,6 @@ select {
 
     .timestamp-display {
         padding: 12px;
-        min-height: 70px;
         align-items: center; /* 垂直居中 */
         justify-content: center; /* 横向居中 */
     }

src/components/CopyButton.js

@@ -17,6 +17,7 @@ const CopyButton = ({
   // 复制成功的处理
   const handleCopySuccess = useCallback(() => {
     setCopyStatus('success');
+    setBtnText('复制成功！');
     
     // 2秒后恢复
     setTimeout(() => {