fix(student page): 修复作业提交页面元素透明度异常问题

为全局样式添加强制不透明度为1的样式，修复提交时页面元素可能出现的透明显示问题

src/views/Student/index.vue

@@ -2209,6 +2209,7 @@ const handleHomeworkSubmit = async () => {
         *, *::before, *::after {
             animation: none !important;
             transition: none !important;
+            opacity: 1 !important;
         }
     `
             iframeElement.contentWindow.document.head.appendChild(style)