css 高度自适应铺满全屏

html:

    
    
    



    
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css:

.HolyGrail {
    display: flex;
    flex-direction: column;
    background-color: blueviolet;
}

header,
footer {
    height: 100px;
    background-color: aquamarine;
}

body {
    padding: 0;
    margin: 0;
    min-height: 100vh;
}

.HolyGrail-body {
    flex: 1;
    background-color: brown;
}

这里需要注意的是设置body的min-height: 100vh;以及margin: 0;