rotate border css code example

Example 1: rotate element css

div {
  width: 80px;
  height: 80px;
  background-color: skyblue;
}

.rotated {
  transform: rotate(45deg); /* Equal to rotateZ(45deg) */
  background-color: pink;
}

Example 2: transform rotate css

<!DOCTYPE html>
<html>
<head>
<style> 
div.a {
  width: 150px;
  height: 80px;
  background-color: yellow;
  -ms-transform: rotate(20deg); /* IE 9 */
  transform: rotate(20deg);
}

div.b {
  width: 150px;
  height: 80px;
  background-color: yellow;
  -ms-transform: skewY(20deg); /* IE 9 */
  transform: skewY(20deg);
}

div.c {
  width: 150px;
  height: 80px;
  background-color: yellow;
  -ms-transform: scaleY(1.5); /* IE 9 */
  transform: scaleY(1.5);
}
</style>
</head>
<body>

<h1>The transform Property</h1>

<h2>transform: rotate(20deg):</h2>
<div class="a">Hello World!</div>
<br>

<h2>transform: skewY(20deg):</h2>
<div class="b">Hello World!</div>
<br>

<h2>transform: scaleY(1.5):</h2>
<div class="c">Hello World!</div>

</body>
</html>

Example 3: css transform property

Read this comprehensive article about CSS animation transform property. 
It also has many useful examples that help you in best way.

https://medium.com/swlh/learn-css-transform-animation-zero-to-hero-6a2a643bd56b

Example 4: css make border rotate around element

.b-border{
    display: inline-block;
    position: relative;
    border: solid #333;
    border-width: 1px 1px 0px 1px;
    padding: 20px;
    margin-bottom: 100px;
}
.b-border.border-right{
  border-width: 1px 0 1px 1px;
}

.b-border.border-right:after{
    content: "";
    position: absolute;
    right: -30px;
    border-top: 1px solid #333;
     border-left: none medium;
    top: -1px;
    left: auto;
    width: 30px;
    height: 100%;
    background: linear-gradient(to top left, white calc(50% - 1px), #000 1px, white 50%);
}
.b-border:after{
    content: "";
    position: absolute;
    left: -1px;
    bottom: -15%;
    border-left: 1px solid #333;
    height: 15%;
    width: calc(100% + 1px);
    background: linear-gradient(to right bottom, white calc(50% - 1px), #000 1px, white 50%);
}

Example 5: css make border rotate around element

<div class="b-border border-right">
    Hello :)
</div>
<p></p>
<div class="b-border" style="width: 300px;">
    Lorem ipsum dolor sit amet, consectetur 
    Lorem ipsum dolor sit amet, consectetur
    Lorem ipsum dolor sit amet, consectetur
     Lorem ipsum dolor sit amet, consectetur 
     Lorem ipsum dolor sit amet, consectetur 
</div>