fix: 调整图文工具栏布局，解决顶部遮挡问题，图片透明度滑块添加百分比

js/script.js

@@ -18,6 +18,7 @@
     const textTools = document.getElementById('textTools');
     const imageTools = document.getElementById('imageTools');
     const opacitySlider = document.getElementById('opacitySlider');
+    const opacityValue = document.getElementById('opacityValue');
     const boldBtn = document.getElementById('boldBtn');
     const italicBtn = document.getElementById('italicBtn');
     const colorPicker = document.getElementById('colorPicker');
@@ -108,6 +109,7 @@
         opacitySlider.addEventListener('input', (e) => {
             if (selectedOverlay) {
                 selectedOverlay.style.opacity = e.target.value / 100;
+                opacityValue.textContent = e.target.value + '%';
             }
         });
 
@@ -525,6 +527,7 @@
         // 更新透明度滑块为当前层叠图的透明度
         const currentOpacity = overlayEl.style.opacity || '1';
         opacitySlider.value = parseFloat(currentOpacity) * 100;
+        opacityValue.textContent = opacitySlider.value + '%';
     }
 
     // 计算图片滑动边界