diff --git a/导航栏再现.html b/导航栏再现.html
new file mode 100644
index 0000000..eb32a36
--- /dev/null
+++ b/导航栏再现.html
@@ -0,0 +1,47 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>Document</title>
+    <style>
+        .box1{
+            position: fixed;
+            width: 100%;
+            height: 50px;
+            background-color: #e4e4e4;
+            text-align: center;
+            line-height: 50px;
+            top:-80px;
+            
+        }
+        .box2{
+            width: 100%;
+            height: 1800px;
+            background-color: pink;
+           display: flex;
+           align-items: center;
+           
+        }
+        .box3{
+            width: 200px;
+            background-color: aqua;
+        }
+    </style>
+</head>
+<body>
+    <div class="box1">我又出现了</div>
+    <div class="box2">
+        <div class="box3">滑到这里再出现</div>
+    </div>
+    <script>
+        const box1=document.querySelector('.box1')
+        const box3=document.querySelector('.box3')
+        window.addEventListener('scroll',function(){
+            const n=document.documentElement.scrollTop
+     box1.style.top=n>=box3.offsetTop ? 0 : '-80px'
+
+})
+    </script>
+</body>
+</html>
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