咱們話不多說，直接上程式碼

這是封裝了一個函式 在外面直接 border： 1px 0 0 0 #ccc使用即可

border($border-width = 1px, $border-color = #ccc, $border-style = solid, $radius = 0)
// 為邊框位置提供定位參考
position: relative;

if $border-width == null
$border-width: 0;

border-radius: $radius;

&::after
// 用以解決邊框layer遮蓋內容
pointer-events: none;
position: absolute;
z-index: 999;
top: 0;
left: 0;
// fix當元素寬度出現小數時，邊框可能顯示不全的問題
// overflow: hidden;
content: "\0020";
border-color: $border-color;
border-style: $border-style;
border-width: $border-width;

// 適配dpr進行縮放
@media (max--moz-device-pixel-ratio: 1.49), (-webkit-max-device-pixel-ratio: 1.49), (max-device-pixel-ratio: 1.49), (max-resolution: 143dpi), (max-resolution: 1.49dppx)
width: 100%;
height: 100%;
if $radius != null {
border-radius: $radius;
}

@media (min--moz-device-pixel-ratio: 1.5) and (max--moz-device-pixel-ratio: 2.49), (-webkit-min-device-pixel-ratio: 1.5) and (-webkit-max-device-pixel-ratio: 2.49),(min-device-pixel-ratio: 1.5) and (max-device-pixel-ratio: 2.49),(min-resolution: 144dpi) and (max-resolution: 239dpi),(min-resolution: 1.5dppx) and (max-resolution: 2.49dppx)
width: 200%;
height: 200%;
transform: scale(.5)
if $radius != null {
border-radius: $radius * 2;
}

@media (min--moz-device-pixel-ratio: 2.5), (-webkit-min-device-pixel-ratio: 2.5),(min-device-pixel-ratio: 2.5), (min-resolution: 240dpi),(min-resolution: 2.5dppx)
width: 300%;
height: 300%;
transform: scale(.33333)
if $radius != null {
border-radius: $radius * 3;
}

transform-origin: 0 0;