上下箭头，如何优化CSS？

Question

我的问题是我想在某些部分的上方和下方显示 'arrows'（当然，我已给出类）。

这些箭头可以是底部箭头，也可以是顶部箭头，您可以为底部和顶部箭头选择左侧和右侧：

我制作了一个片段来演示，但无法正确插入 SVG，因此已将该代码替换为 background: red;。

以上代码的问题在于它在类上使用了通配符选择器，因此可能会产生干扰。所以我更喜欢 class="arrow arrow-top arrow-left" 这样的东西。但是，当您向一个部分添加两个箭头时，就会出现问题：class="arrow arrow-top arrow-left arrow-bottom arrow-right"。

关于如何优化这段代码有什么建议吗？

[class*=arrow]:before, [class*=arrow]:after {
 content: '';
 display: none;
 position: absolute;
 left: 0;
 right: 0;
 height: 50px;
 height: 12vw;
 width: 100%;
 //background-image: url("arrow.svg#svgView(preserveAspectRatio(none))");
  background-color: red;
 background-size: 100% 100%;
}
[class*=arrow-top] {
 padding-top: 50px;
 padding-top: 12vw;
}
[class*=arrow-bottom] {
 padding-bottom: 50px;
 padding-bottom: 12vw;
}

.arrow-top-left:before {
 display: block;
 top: 0;
}

.arrow-top-right:before {
 display: block;
 top: 0;
 transform: scaleX(-1);
}

.arrow-bottom-left:after {
 display: block;
 bottom: 0;
 transform: scaleY(-1);
}
.arrow-bottom-right:after {
 display: block;
 bottom: 0;
 transform: scale(-1, -1);
}

/* unessential code */

section {
  background-color: #EC644B;
  height: 300px;
  position: relative;
}
section:nth-child(odd) {
  background-color: #DCC6E0;
}
p {
  padding: 20px;
}

<section class="arrow  arrow-top   arrow-bottom-left">
  <p>Een prachtige sectie</p>
</section>
<section class="arrow-top-right  arrow-bottom-right">
  <p>Een prachtige sectie</p>
</section>
<section class="arrow-bottom-right">
  <p>Een prachtige sectie</p>
</section>

Answer 1

我会考虑线性渐变，您可以通过为每个可以组合的箭头设置两个类来轻松实现此目的：

.top-arrow,.bottom-arrow {
  margin:5px;
  min-height:200px;
  max-width:400px;
  position:relative;
  z-index:0;
  border:1px solid;
}
.top-arrow:before,
.bottom-arrow:after{
  content:"";
  position:absolute;
  top:0;
  left:0;
  right:0;
  bottom:0;
}
.top-arrow:before {
  background:
   linear-gradient(to top right,transparent 50%,red 50.5%) top left/20% 50% no-repeat,
   linear-gradient(to top left,transparent 50%,red 50.5%) top right/80% 50.5% no-repeat;
}

.bottom-arrow:after {
  background:
   linear-gradient(to bottom right,transparent 50%,pink 50.5%) bottom left /80% 50% no-repeat,
   linear-gradient(to bottom left,transparent 50%,pink 50.5%) bottom right /20% 50.5% no-repeat;
}

<div class="top-arrow bottom-arrow">
</div>
<div class="bottom-arrow">
</div>
<div class="top-arrow">
</div>

Answer 2

为什么不使用 CSS clip-path 在 :before 和 :after 中创建您想要的形状。

你会得到一个圆滑的结果，有实心的角，也很容易根据你的需要改变它们的形状。

body {
  margin: 0;
  padding: 0;
}

section {
  padding: 30px;
  height: 300px;
  width: 100%;
  background: #EC644B;
  position: relative;
}

section:nth-child(odd) {
  background: #DCC6E0
}

.arrow-top-left,
.arrow-top-right {
  padding-top: 80px;
}

.arrow-top-left:before,
.arrow-top-right:before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 80px;
  background: blue;
}

.arrow-top-left:before {
  -webkit-clip-path: polygon(20% 100%, 0 0, 100% 0);
  clip-path: polygon(20% 100%, 0 0, 100% 0);
}

.arrow-top-right:before {
  -webkit-clip-path: polygon(80% 100%, 0 0, 100% 0);
  clip-path: polygon(80% 100%, 0 0, 100% 0);
}

.arrow-bottom-left,
.arrow-bottom-right {
  padding-bottom: 80px;
}

.arrow-bottom-left:after,
.arrow-bottom-right:after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 80px;
  background: green;
}

.arrow-bottom-left:after {
  -webkit-clip-path: polygon(20% 0, 0% 100%, 100% 100%);
  clip-path: polygon(20% 0, 0% 100%, 100% 100%);
}

.arrow-bottom-right:after {
  -webkit-clip-path: polygon(80% 0, 0% 100%, 100% 100%);
  clip-path: polygon(80% 0, 0% 100%, 100% 100%);
}

<section class="arrow-top-left arrow-bottom-right">

</section>
<section class="arrow-bottom-right">

</section>
<section class="arrow-top-right">

</section>

Answer 3

一位同事考虑了这个问题并提出了这个SASS-解决方案：

.u-arrow {

    &-top,
    &-bottom {

        &-right,
        &-left {
            position: relative;


            &:before,
            &:after {
                z-index: 0;
                content: '';
                display: none;
                position: absolute;
                left: 0;
                right: 0;
                height: 50px;
                height: 12vw;
                width: 100%;
                background-size: 100% 100%;
                background-image: url("/dist/images/arrow-white-mobile.svg");

                .u-bg-blue & {
                    background-image: url("/dist/images/arrow-blue-mobile.svg");
                }

                @media (min-width: $screen-sm) {
                    background-image: url("/dist/images/arrow-white.svg");

                    .u-bg-blue & {
                        background-image: url("/dist/images/arrow-blue.svg");
                    }
                }

                @media (min-width: 1200px) {
                    height: 150px;
                }
            }
        }
    }

    &-top {

        &-left,
        &-right {
            padding-top: 50px;
            padding-top: 12vw;

            @media (min-width: 1200px) {
                padding-top: 150px;
            }

            &:before {
                display: block;
                top: 0;
            }
        }

        &-right {
            &:before {
                transform: scaleX(-1);
            }
        }
    }

    &-bottom {

        &-left,
        &-right {
            padding-bottom: 50px;
            padding-bottom: 12vw;

            @media (min-width: 1200px) {
                padding-bottom: 150px;
            }

            &:after {
                display: block;
                bottom: 0;
            }
        }

        &-left {
            &:after {
                transform: scaleY(-1);
            }
        }

        &-right {
            &:after {
                transform: scale(-1, -1);
            }
        }
    }
}

上下箭头，如何优化CSS？

Arrows top and bottom, how to optimalise CSS?

html

css

optimization

css-shapes