有没有办法创建一个具有渐变和圆角的边框(或div)？

Question

它应该是这样的:

到目前为止的尝试:

1. 使用渐变背景加上内部元素来覆盖它,只留下一个外部"边框".该背景显然不是透明的.

body {
  background: #242424;
  height: 100%;
  width: 100%;
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: sans-serif;
  color: #FFFFFF;
}

div {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-content: center;
  align-items: center;
  width: 100%;
  height: 100vh;
}

h1 {
  margin: 2em;
  text-align: center;
}

a {
  cursor: pointer;
  transition: ease-in-out,.2s,color;
}
a:hover {
  color: #DDD;
}

.nested {
  display: block;
  max-width: 20em;
  padding: 2px;
  overflow: hidden;
  border-radius: 2em;
  background: linear-gradient(to right, #00ff00 0%, #00e5ff 100%);
}
.nested span {
  display: inline-block;
  padding: 1em;
  text-align: center;
  background: #242424;
  border-radius: 2rem;
}
.nested span p {
  padding: 0 2em;
  margin: 0;
}

.pseudo {
  display: block;
  margin-top: 20px;
  position: relative;
  border-radius: 2em;
  padding: 1em 2em;
  background: #242424;
}
.pseudo:after {
  position: absolute;
  z-index: -1;
  top: -2px;
  bottom: -2px;
  right: -2px;
  left: -2px;
  background: linear-gradient(to right, #00ff00 0%, #00e5ff 100%);
  border-radius: 2em;
  content: '';
}

<div>
    <h1>Gradient + Border Radius</h1>
    <a class="nested"><span><p>ANOTHER ONE</p></span></a>
    <a class="pseudo">AND ANOTHER ONE</a>
</div>

2. 用border-image.该角不圆.

body {
  background: url(http://subtlepatterns2015.subtlepatterns.netdna-cdn.com/patterns/ignasi_pattern_s.png);
  height: 100%;
  width: 100%;
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: sans-serif;
}

a {
  padding: 20px 40px;
  border-image: linear-gradient(to bottom right, #00aeef 0%, #7cc578 100%);
  border-image-slice: 1;
  border-radius: 10px;
}

div {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-content: center;
  align-items: center;
  width: 100%;
  height: 100vh;
}

h1 {
  margin: 2em;
  text-align: center;
}

a {
  text-decoration: none;
  font-weight: bold;
  color: black;
  cursor: pointer;
  transition: ease-in-out,.2s,color;
}
a:hover {
  color: #DDD;
}

<div>
    <h1>Gradient + [non working] Border Radius</h1>
    <a href="#">CLICK ME	</a>
</div>

Answer 1

不,你不能border-image在一个元素上使用border-radius因为根据规格,只有元素的背景基于边界半径而不是border-image.所以图像总是一个矩形(或方形).

如果需要透明中心部分(或透明内容区域),那么最好的选择是使用SVG.SVG的笔划甚至可以采用渐变作为值,因此它可以生成圆形,其边框是渐变,中心部分是透明的.

将path用于创建造型简洁关于路径命令,你可以阅读更多的在这里.

.border-with-grad {
  position: relative;
  height: 100px;
  width: 250px;
  color: white;
  line-height: 100px;
  text-align: center;
  letter-spacing: 1.5px;
}
.border-with-grad svg {
  position: absolute;
  top: 0px;
  left: 0px;
  height: 100%;
  width: 100%;
}
.border-with-grad path {
  fill: transparent;
  stroke: url(#border-gradient);
  stroke-width: 4;
}

/* Just for demo */

body {
  background-image: radial-gradient(circle, #3F9CBA 0%, #153346 100%);
  min-height: 100vh;
  font-family: sans-serif;  
}

<div class='border-with-grad'>
  <svg viewBox='0 0 250 100'>
    <defs>
      <linearGradient id='border-gradient' gradientUnits='objectBoundingBox' gradientTransform='rotate(5 0.5 0.5)'>
        <stop offset='0%' stop-color='rgb(248,244,135)' />
        <stop offset='25%' stop-color='rgb(248,244,135)' />
        <stop offset='75%' stop-color='rgb(53,176,182)' />
        <stop offset='100%' stop-color='rgb(53,176,182)' />
      </linearGradient>
    </defs>
    <path d='M50,95 a45,45 0 0,1 0,-90 h150 a45,45 0 1,1 0,90 h-150' />
  </svg>
  CLICK HERE
</div>

使用CSS,我们可以使用mask-image使中心部分透明但其浏览器支持非常差.目前只有支持webkit的浏览器支持此属性.另一种方法是利用clip-path但如果你需要支持IE和Firefox(Firefox仅支持SVG剪辑路径),那就不行了.