css double border code example

Example 1: css border style

/* 
 * border-style:
solid: A solid, continuous line.
none (default): No line is drawn.
hidden: A line is drawn, but not visible. this can be handy for adding a little extra width to an element without displaying a border.
dashed: A line that consists of dashes.
dotted: A line that consists of dots.
double: Two lines are drawn around the element.
groove: Adds a bevel based on the color value in a way that makes the element appear pressed into the document.
ridge: Similar to groove, but reverses the color values in a way that makes the element appear raised.
inset: Adds a split tone to the line that makes the element appear slightly depressed.
outset: Similar to inset, but reverses the colors in a way that makes the element appear slightly raised.
*/

/* Example using the typical solid border-style */
div {
	border: 1px solid #4e1f9d;
}

Example 2: double border color css

.double-border {
  display: block;
  clear: both;
  background: red;
  border: 5px solid yellow;
  outline: 5px solid blue;
  transition: 0.7s all ease-in;
  height: 50px;
  width: 50px;
}
.double-border:hover {
  background: yellow;
  outline-color: red;
  border-color: blue;
}
<div class="double-border"></div>