三、rem
指相对于根元素的字体大小的单位。
根字体大小通常设置为10px,方便换算。
<!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title><style>html {/* 设置根字体大小 */font-size: 10px;}div{font-size: 0.5rem;}</style>
</head><body><div>文字内容</div>
</body></html>
案例
监听屏幕变化，字体等比例变化
<!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title><script>var c = () => {// 获取设备的宽度let width = document.documentElement.clientWidth;let width2 = (20 * (width / 320) > 40 ? 40 + "px" : (20 * (width / 320) + "px"));document.documentElement.style.fontSize = width2;console.log("width2", width2);}window.addEventListener('load', c);window.addEventListener('resize', c);</script><style>html {font-size: 10px;}div {font-size: 1rem;}</style>
</head><body><div>文字内容</div>
</body></html>
】)
