Bootstrap 5 提供了很多有用的类来帮组我们快速实现效果,不需要重复写一些 CSS 代码。
背景颜色
设置不同元素的背景颜色时,需要通过 .text-* 类来设置匹配的文本颜色:
<div class="p-3 mb-2 bg-primary text-white">.bg-primary</div>
<div class="p-3 mb-2 bg-secondary text-white">.bg-secondary</div>
<div class="p-3 mb-2 bg-success text-white">.bg-success</div>
<div class="p-3 mb-2 bg-danger text-white">.bg-danger</div>
<div class="p-3 mb-2 bg-warning text-dark">.bg-warning</div>
<div class="p-3 mb-2 bg-info text-dark">.bg-info</div>
<div class="p-3 mb-2 bg-light text-dark">.bg-light</div>
<div class="p-3 mb-2 bg-dark text-white">.bg-dark</div>
<div class="p-3 mb-2 bg-body text-dark">.bg-body</div>
<div class="p-3 mb-2 bg-white text-dark">.bg-white</div>
<div class="p-3 mb-2 bg-transparent text-dark">.bg-transparent</div>
.bg-gradient 类可以设置背景颜色渐变的效果:
<div class="p-3 mb-2 bg-primary bg-gradient text-white">.bg-primary</div>
<div class="p-3 mb-2 bg-secondary bg-gradient text-white">.bg-secondary</div>
<div class="p-3 mb-2 bg-success bg-gradient text-white">.bg-success</div>
<div class="p-3 mb-2 bg-danger bg-gradient text-white">.bg-danger</div>
<div class="p-3 mb-2 bg-warning bg-gradient text-dark">.bg-warning</div>
<div class="p-3 mb-2 bg-info bg-gradient text-dark">.bg-info</div>
<div class="p-3 mb-2 bg-light bg-gradient text-dark">.bg-light</div>
<div class="p-3 mb-2 bg-dark bg-gradient text-white">.bg-dark</div>
<div class="p-3 mb-2 bg-body bg-gradient text-dark">.bg-body</div>
<div class="p-3 mb-2 bg-white bg-gradient text-dark">.bg-white</div>
<div class="p-3 mb-2 bg-transparent bg-gradient text-dark">.bg-transparent</div>
边框
我们可以使用 border 相关类根据需要显示边框:
<span class="border"></span>
<span class="border border-0"></span>
<span class="border border-top-0"></span>
<span class="border border-right-0"></span>
<span class="border border-bottom-0"></span>
<span class="border border-left-0"></span>
<br>
<span class="border-top"></span>
<span class="border-end"></span>
<span class="border-bottom"></span>
<span class="border-start"></span>
.border-1 到 .border-5 类用于设置边框线条的宽度:
<span class="border border-1"></span>
<span class="border border-2"></span>
<span class="border border-3"></span>
<span class="border border-4"></span>
<span class="border border-5"></span>
以下设置了边框的不同颜色:
<span class="border border-primary"></span>
<span class="border border-secondary"></span>
<span class="border border-success"></span>
<span class="border border-danger"></span>
<span class="border border-warning"></span>
<span class="border border-info"></span>
<span class="border border-light"></span>
<span class="border border-dark"></span>
<span class="border border-white"></span>
rounded 相关类用于设置圆角:
<img src="..." class="rounded" alt="...">
<img src="..." class="rounded-top" alt="...">
<img src="..." class="rounded-end" alt="...">
<img src="..." class="rounded-bottom" alt="...">
<img src="..." class="rounded-start" alt="...">
<img src="..." class="rounded-circle" alt="...">
<img src="..." class="rounded-pill" alt="...">
rounded-0 到 rounded-3 类用于设置圆角的大小:
<img src="..." class="rounded-0" alt="...">
<img src="..." class="rounded-1" alt="...">
<img src="..." class="rounded-2" alt="...">
<img src="..." class="rounded-3" alt="...">
浮动与清除浮动
元素向右浮动使用 .float-end 类,向左浮动使用 .float-start 类, .clearfix 类用于清除浮动:
<div class="clearfix">
<span class="float-start">Float left</span>
<span class="float-end">Float right</span>
</div>
也可以根据屏幕尺寸来设置浮动效果(.float--left|right – 表示 sm (>=576px), md (>=768px), lg (>=992px), xl (>=1200px) or xxl (>=1400px)):
<div class="float-sm-end">小屏幕向右浮动</div><br>
<div class="float-md-end">中等屏幕向右浮动</div><br>
<div class="float-lg-end">大屏幕向右浮动</div><br>
<div class="float-xl-end">超大屏幕向右浮动</div><br>
<div class="float-xxl-end">特大屏幕向右浮动</div><br>
<div class="float-none">没有浮动</div>
居中对齐
使用 .mx-auto 类来设置元素居中对齐 (添加 margin-left 和 margin-right 为 auto):
<div class="mx-auto bg-warning" style="width:150px">居中对齐</div>
宽度与高度
宽度使用 w-* (.w-25, .w-50, .w-75, .w-100, .mw-auto, .mw-100) 类来设置。
<div class="w-25 bg-warning">宽度为 25%</div>
<div class="w-50 bg-warning">宽度为 50%</div>
<div class="w-75 bg-warning">宽度为 75%</div>
<div class="w-100 bg-warning">宽度为 100%</div>
<div class="w-auto bg-warning">自动设置宽度</div>
<div class="mw-100 bg-warning">最大宽度为 100%</div>
高度使用 h-* (.h-25, .h-50, .h-75, .h-100, .mh-auto, .mh-100) 类来设置。
<div style="height:200px;background-color:#ddd">
<div class="h-25 d-inline-block p-2 bg-warning">高度为 25%</div>
<div class="h-50 d-inline-block p-2 bg-warning">高度为 50%</div>
<div class="h-75 d-inline-block p-2 bg-warning">高度为 75%</div>
<div class="h-100 d-inline-block p-2 bg-warning">高度为 100%</div>
<div class="h-auto d-inline-block p-2 bg-warning">自动设置高度</div>
<div class="mh-100 d-inline-block p-2 bg-warning" style="height:500px">最大高度为 100%</div>
</div>
间距
间距设置语法如下:
{property}{sides}-{size}
property 代表属性,包含:
m
– 用来设置margin
p
– 用来设置padding
sides 主要指方向:
t
– 用来设置margin-top
或padding-top
b
– 用来设置margin-bottom
或padding-bottom
l
– 用来设置margin-left
或padding-left
r
– 用来设置margin-right
或padding-right
x
– 用来设置*-left
和*-right
y
– 用来设置*-top
和*-bottom
- blank – 用来设置元素在四个方向的
margin
或padding
size 指的是边距的大小:
0
– 设置margin
或padding
为0
1
– 设置margin
或padding
为$spacer * .25
2
– 设置margin
或padding
为$spacer * .5
3
– 设置margin
或padding
为$spacer
4
– 设置margin
或padding
为$spacer * 1.5
5
– 设置margin
或padding
为$spacer * 3
auto
– 设置margin
为 auto
看下部分边距的源码设置:
.mt-0 {
margin-top: 0 !important;
}
.ml-1 {
margin-left: ($spacer * .25) !important;
}
.px-2 {
padding-left: ($spacer * .5) !important;
padding-right: ($spacer * .5) !important;
}
.p-3 {
padding: $spacer !important;
}
<div class="mx-auto" style="width: 200px;">
元素设置居中
</div>
<form >
<div class="form-row">
<div class="form-group">
<label for="text" class="mt-2">设置 margin-top:</label>
<input type="text" class="form-control" id="text" placeholder="email">
<label for="color" class="mt-2">颜色:</label>
<input type="color" id="color" class="form-control" style="width: 60px;padding: 4px;" autocomplete="off" value="#656565">
</div>
</div>
</form>