CSS拉伸邊框是一種可以讓元素的邊框變得可拉伸的技術，它可以用來為頁面添加更加動態的設計效果，提升頁面的交互性。下面，我們將介紹幾種常見的CSS拉伸邊框效果。

1. 連續邊框效果

.box {
border: 2px solid #000;
border-image: linear-gradient(to right, #000 0%, #fff 50%, #000 100%);
border-image-slice: 1;
}

2. 標簽式邊框效果

.box {
border: 10px solid red;
border-left-color: green;
border-right-color: green;
border-top-color: blue;
border-bottom-color: blue;
position: relative;
}
.box::before {
content: "";
position: absolute;
top: -10px;
left: -10px;
width: 10px;
height: 10px;
border-right: 10px solid green;
border-bottom: 10px solid blue;
}
.box::after {
content: "";
position: absolute;
bottom: -10px;
right: -10px;
width: 10px;
height: 10px;
border-left: 10px solid green;
border-top: 10px solid blue;
}

3. 折角邊框效果

.box {
border: 10px solid red;
position: relative;
}
.box::before {
content: "";
position: absolute;
top: -10px;
left: -10px;
width: 0;
height: 0;
border-top: 10px solid transparent;
border-bottom: 10px solid red;
border-left: 10px solid transparent;
border-right: 10px solid red;
}
.box::after {
content: "";
position: absolute;
bottom: -10px;
right: -10px;
width: 0;
height: 0;
border-top: 10px solid red;
border-bottom: 10px solid transparent;
border-left: 10px solid red;
border-right: 10px solid transparent;
}

通過使用CSS拉伸邊框技術，我們可以為頁面添加更加豐富多彩的設計效果，大大提升頁面的交互性和用戶體驗。