diff --git a/任务1和任务2.html b/任务1和任务2.html
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+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>Document</title>
+</head>
+<body>
+    <div class="header">
+        我是头部
+    </div>
+    <div class="main">
+        <div class="content">
+            秒杀模块
+        </div>
+    </div>
+    <!--回到顶部按钮-->
+    <div id="toTop" style="position: fixed; bottom: 70px; right: 50px; border-radius: 50%; background-color: rgba(0,0,0,0.1); height: 30px;width: 30px; display: none;flex-direction: column; justify-content: center; align-items: center;">
+        <img src="./assets/top.png" style="height: 20px; width: 20px;" alt="">
+    </div>
+</body>
+<style>
+    .header{
+        position: fixed;
+        top: -80px;
+        left: 0;
+        width: 100%;
+        height: 80px;
+        background-color: skyblue;
+        text-align: center;
+        color: #fff;
+        line-height: 80px;
+        font-size: 30px;
+        transition: all 0.3s;
+    }
+    .main{
+        height: 1800px;
+        width: 1000px;
+        background-color: pink;
+    }
+    .content{
+        position: absolute;
+        top: 500px;
+        background-color: gray;
+    }
+</style>
+<script>
+    const content = document.querySelector('.content')
+    const header = document.querySelector('.header')
+    const toTop = document.querySelector('#toTop')
+
+    window.addEventListener('scroll',function(){
+        const n = document.documentElement.scrollTop
+        let viewScrollTop = document.documentElement.scrollTop
+        if(n>=content.offsetTop){
+            header.style.top = 0
+        }else{
+            header.style.top = '-80px'
+        }
+        if(viewScrollTop>400){
+            toTop.style.display = 'flex'
+        }else{
+            toTop.style.display = 'none'
+
+        }
+    })
+    toTop.addEventListener('click',()=>{
+        document.documentElement.scrollTop = 0
+    })
+
+</script>
+</html>
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