Add button border animation snippet

snippets/button-border.md

@@ -0,0 +1,85 @@
+### Toggle switch
+
+Creates a border animation on hover.
+
+#### HTML
+
+```html
+<button class="button">Submit</button>
+```
+
+#### CSS
+
+```css
+@import url(https://fonts.googleapis.com/css?family=BenchNine:700);
+.button {
+  background-color: #c47135;
+  border: none;
+  color: #ffffff;
+  cursor: pointer;
+  display: inline-block;
+  font-family: 'BenchNine', Arial, sans-serif;
+  font-size: 1em;
+  font-size: 22px;
+  line-height: 1em;
+  margin: 15px 40px;
+  outline: none;
+  padding: 12px 40px 10px;
+  position: relative;
+  text-transform: uppercase;
+  font-weight: 700;
+}
+
+.button:before,
+.button:after {
+  border-color: transparent;
+  -webkit-transition: all 0.25s;
+  transition: all 0.25s;
+  border-style: solid;
+  border-width: 0;
+  content: '';
+  height: 24px;
+  position: absolute;
+  width: 24px;
+}
+
+.button:before {
+  border-color: #c47135;
+  border-top-width: 2px;
+  left: 0px;
+  top: -5px;
+}
+
+.button:after {
+  border-bottom-width: 2px;
+  border-color: #c47135;
+  bottom: -5px;
+  right: 0px;
+}
+
+.button:hover,
+.button.hover {
+  background-color: #c47135;
+}
+
+.button:hover:before,
+.button.hover:before,
+.button:hover:after,
+.button.hover:after {
+  height: 100%;
+  width: 100%;
+}
+```
+
+#### Demo
+
+#### Explanation
+
+This effect is uses before and after selectors to make the border full width on hover.
+
+#### Browser support
+
+<span class="snippet__support-note">✅ No caveats.</span>
+
+<!-- tags: visual, interactivity -->
+<!-- date: 2018-10-30 -->