简体中文
<length>
用于表示距离尺寸的 CSS 数据类型。许多 CSS 属性会用到长度,比如 width、margin、padding。<percentage>
表述一个百分比值。许多 CSS 属性 可以取百分比值,用以根据父对象来确定大小。百分比值由一个<number>
具体数值后跟着%符号构成。就像其他在 css 里的单位一样,在%和数值之间是不允许有空格的。rpx
是一个以设备750px为基准的单位,750rpx即为屏幕宽度,375rpx即为屏幕一半宽度。它比较适合适配不同宽度的手机。但rpx的性能和精度不如px,如果px可满足需求,尽量使用px。名称 | Android | iOS | web | 描述 |
---|---|---|---|---|
% | 3.9 | 4.11 | 4.0 | app平台仅width、height、padding(-)、margin(-)、top、left、right、bottom、flex-basis等属性支持 |
fr | x | x | 4.0 | |
px | 3.9 | 4.11 | 4.0 | |
rpx | 3.9 | 4.11 | 4.0 | |
upx | x | x | 4.0 | |
em | 3.9 | 4.11 | 4.0 | |
rem | x | x | 4.0 | |
cap | x | x | 4.0 | |
ch | x | x | 4.0 | |
cm | x | x | 4.0 | |
cqb | x | x | 4.0 | |
cqh | x | x | 4.0 | |
cqi | x | x | 4.0 | |
cqmax | x | x | 4.0 | |
cqmin | x | x | 4.0 | |
cqw | x | x | 4.0 | |
dvb | x | x | 4.0 | |
dvh | x | x | 4.0 | |
dvi | x | x | 4.0 | |
dvw | x | x | 4.0 | |
ex | x | x | 4.0 | |
ic | x | x | 4.0 | |
in | x | x | 4.0 | |
lh | x | x | 4.0 | |
lvb | x | x | 4.0 | |
lvh | x | x | 4.0 | |
lvi | x | x | 4.0 | |
lvw | x | x | 4.0 | |
mm | x | x | 4.0 | |
pc | x | x | 4.0 | |
pt | x | x | 4.0 | |
q | x | x | 4.0 | |
rcap | x | x | 4.0 | |
rch | x | x | 4.0 | |
rex | x | x | 4.0 | |
ric | x | x | 4.0 | |
rlh | x | x | 4.0 | |
svb | x | x | 4.0 | |
svh | x | x | 4.0 | |
svi | x | x | 4.0 | |
svw | x | x | 4.0 | |
vb | x | x | 4.0 | |
vh | x | x | 4.0 | |
vi | x | x | 4.0 | |
vmax | x | x | 4.0 | |
vmin | x | x | 4.0 | |
vw | x | x | 4.0 |
注意
长度默认值差异
<length>
可以不设置单位,不设置单位时当做 px 处理<length>
必须设置单位,不设置单位时当做无效值处理 <length>
指定明确单位。单位精度差异
0.5px
很难正常显示。但app可以正常显示。rpx
和百分比
,比px
更容易产生浮点数,所以如果px能满足需求,尽量不用rpx和百分比。性能差异
名称 | Android | iOS | web | 描述 |
---|---|---|---|---|
px | 3.9 | 4.11 | 4.0 | |
rpx | 3.9 | 4.11 | 4.0 | |
upx | x | x | 4.0 | |
em | 3.9 | 4.11 | 4.0 | app平台仅line-height属性支持 |
rem | x | x | 4.0 | |
cap | x | x | 4.0 | |
ch | x | x | 4.0 | |
cm | x | x | 4.0 | |
cqb | x | x | 4.0 | |
cqh | x | x | 4.0 | |
cqi | x | x | 4.0 | |
cqmax | x | x | 4.0 | |
cqmin | x | x | 4.0 | |
cqw | x | x | 4.0 | |
dvb | x | x | 4.0 | |
dvh | x | x | 4.0 | |
dvi | x | x | 4.0 | |
dvw | x | x | 4.0 | |
ex | x | x | 4.0 | |
ic | x | x | 4.0 | |
in | x | x | 4.0 | |
lh | x | x | 4.0 | |
lvb | x | x | 4.0 | |
lvh | x | x | 4.0 | |
lvi | x | x | 4.0 | |
lvw | x | x | 4.0 | |
mm | x | x | 4.0 | |
pc | x | x | 4.0 | |
pt | x | x | 4.0 | |
q | x | x | 4.0 | |
rcap | x | x | 4.0 | |
rch | x | x | 4.0 | |
rex | x | x | 4.0 | |
ric | x | x | 4.0 | |
rlh | x | x | 4.0 | |
svb | x | x | 4.0 | |
svh | x | x | 4.0 | |
svi | x | x | 4.0 | |
svw | x | x | 4.0 | |
vb | x | x | 4.0 | |
vh | x | x | 4.0 | |
vi | x | x | 4.0 | |
vmax | x | x | 4.0 | |
vmin | x | x | 4.0 | |
vw | x | x | 4.0 |