設置登錄html背景 background-image: url();

background-image: url(圖片的相對路徑);
如：
background-image: url(../static/images/背景.jpg);

<style>
    body{
        background-image: url(../static/images/背景.jpg);
        background-size: 100% 100%;
        background-repeat: no-repeat;
        background-attachment: fixed;
    }
</style>

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