mobile-web-border

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解决移动端 1px 边框问题

主要思路是将 HTML元素border设置为0，再通过伪类::before 或 ::after 去放大、旋转实现。
我的习惯是将 scss 变量存放在 vars.scss; scss mixin 存放在 mixin.scss.

vars.scss

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$border-colors: (
  'main': #dddddd,
  'active': #0088ff,
);

mixin.scss



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// border mixin start

@mixin dpr2 {
  @media (-webkit-min-device-pixel-ratio: 2), (min-resolution: 2dppx) {
    @content;
  }
}
@mixin border-dpr2($bcolor, $border-radius) {
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  width: 200%;
  height: 200%;
  border: 1PX solid $bcolor;
  transform-origin: 0 0;
  transform: scale(0.5);
  box-sizing: border-box;
  pointer-events: none;
  border-radius: $border-radius;
}
@mixin border($bcolor: map-get($border-colors , 'main'), $border-radius: 0) {
  border: 1px solid $bcolor;
  @include dpr2 {
    position: relative;
    border: none;
    &::before {
      @include border-dpr2($bcolor, $border-radius);
    }
  }
}
@mixin border-commom-dpr2($bcolor) {
  content: '.';
  position: absolute;
  background-color: $bcolor;
  display: block;
  z-index: 1;
  font-size: 0px;
}
@mixin border-bottom-dpr2($bcolor) {
  top: auto;
  right: auto;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 1PX;
  @include border-commom-dpr2($bcolor);
  transform: scaleY(0.5);
  // rotateY(-180deg) 抖动
  // transform: rotateY(-180deg) scaleY(0.5);
}
@mixin border-top-dpr2($bcolor) {
  top: 0;
  right: auto;
  bottom: auto;
  left: 0;
  width: 100%;
  height: 1PX;
  @include border-commom-dpr2($bcolor);
  transform: scaleY(0.5);
}
@mixin border-left-dpr2($bcolor) {
  top: 0;
  right: auto;
  bottom: auto;
  left: 0;
  width: 1PX;
  height: 100%;
  @include border-commom-dpr2($bcolor);
  transform: rotateY(180deg) scaleX(0.5);
}
@mixin border-right-dpr2($bcolor) {
  top: 0;
  right: 0;
  bottom: auto;
  left: auto;
  width: 1PX;
  height: 100%;
  @include border-commom-dpr2($bcolor);
  transform: rotateY(180deg) scaleX(0.5);
}

@mixin border-bottom($bcolor: map-get($border-colors , 'main')) {
  border-bottom: 1px solid $bcolor;
  @include dpr2 {
    position: relative;
    border: none;
    &::after {
      @include border-bottom-dpr2($bcolor);
    }
  }
}
@mixin border-top($bcolor: map-get($border-colors , 'main')) {
  border-top: 1px solid $bcolor;
  @include dpr2 {
    position: relative;
    border: none;
    &::after {
      @include border-top-dpr2($bcolor);
    }
  }
}
@mixin border-left($bcolor: map-get($border-colors , 'main')) {
  border-left: 1px solid $bcolor;
  @include dpr2 {
    position: relative;
    border: none;
    &::after {
      @include border-left-dpr2($bcolor);
    }
  }
}
@mixin border-right($bcolor: map-get($border-colors , 'main')) {
  border-right: 1px solid $bcolor;
  @include dpr2 {
    position: relative;
    border: none;
    &::after {
      @include border-right-dpr2($bcolor);
    }
  }
}
// border mixin end


使用方法

如果使用 webpack 可以将 var.scss 和 mixin.scss 全局注入，方便使用。
或者在需要使用的 .scss 文件，import进入使用。

设置元素的单个边框，以上边框为例：

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// default color
.border-top {
  @include border-top;
}
// custom color
.border-top-active {
  @include border-top($active);
}

设置元素所有边框

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// default color
.border {
  @include border;
}
// custom color
.border-active {
  @include border($active);
}

Demo

活中充满了未知，充满了不确定，我们才会有继续生活下去的兴趣和愿望。 ——王小波