markdown 纯CSS中的渐变阴影

Posted 2021-05-06

# Gradient shadow in pure CSS

![alt text](https://lab.tungu.me/external/img/gradient-shadow-btn.jpg)


###### HTML
```html
<button>Let's Go !</button>
```

---

###### CSS
*Declare colors*
```css
html, :root {
  --purple: #7f00ff;
  --pink: #e100ff;
}
```

*Styling our button*
```css
button {
  font-family: "Roboto", sans-serif;
  font-size: 16px;
  position: relative;
  outline: none;
  border: none;
  -webkit-appearance: none;
  -webkit-tap-highlight-color: transparent;
  cursor: pointer;
  -webkit-user-select: none;
  -moz-user-select: none;
  -ms-user-select: none;
  user-select: none;
  padding: 0.75em 1.75em;
  border-radius: 50px;
  display: inline-block;
  color: #fff;
  
  /* Our gradient */
  background: -webkit-gradient(linear, left top, right top, from(var(--purple)), to(var(--pink)));
  background: linear-gradient(to right, var(--purple), var(--pink));
}
```

*Now, let's create our shadow*
```css
button::after {
  content: "";
  position: absolute;
  z-index: -1;
  bottom: -10px;
  left: 5%;
  height: 110%;
  width: 90%;
  opacity: 0.8;
  border-radius: 50px;
  
  /* Declaring our shadow color inherit from the parent (button) */
  background: inherit;
  
  /* Blurring the element for shadow effect */
  -webkit-filter: blur(6px);
  -moz-filter: blur(6px);
  -o-filter: blur(6px);
  -ms-filter: blur(6px);
  filter: blur(6px);
  
  /* Transition for the magic */
  -webkit-transition: all 0.2s;
  transition: all 0.2s;
}
```

*We have our button and her shadow, now change the style for hover*
```css
button:hover::after {
  /* Changing blur effect */
  -webkit-filter: blur(4px);
  -moz-filter: blur(4px);
  -o-filter: blur(4px);
  -ms-filter: blur(4px);
  filter: blur(4px);

  /* And change the style properties */
  width: 100%;
  bottom: -5px;
  left: 0;
}
```

*For more interactivity, change the active effect*
```css
button:hover:active::after {
  -webkit-filter: blur(10px);
  -moz-filter: blur(10px);
  -o-filter: blur(10px);
  -ms-filter: blur(10px);
  filter: blur(10px);
}
```

### Easy no ?
*For some bug and impovements on IE and Edge*
```css
/* Edge does not support blur effect, so we can just delete the shadow */

@supports (-ms-ime-align: auto) {
  button::after, button:hover::after, button:active::after {
    display: none;
  }
}


/* And IE does not support CSS variables and blur effect, so.. */

@media screen and (-ms-high-contrast: active), (-ms-high-contrast: none) {
  /* Fix css var by calling the hexa colors */
  button {
    background: -webkit-gradient(linear, left top, right top, from(#7f00ff), to(#e100ff));
    background: linear-gradient(to right, #7f00ff, #e100ff);
  }
  /* Deleting the shadow */
  button::after, button:hover::after, button:active::after {
    display: none;
  }
}
```

[A live version is here](https://codepen.io/tunguska/pen/KovRbg)