三、rem
指相對于根元素的字體大小的單位。
根字體大小通常設置為10px,方便換算。
<!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 {/* 設置根字體大小 */font-size: 10px;}div{font-size: 0.5rem;}</style>
</head><body><div>文字內容</div>
</body></html>
案例
監聽屏幕變化，字體等比例變化
<!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 = () => {// 獲取設備的寬度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>文字內容</div>
</body></html>
】)
