See the Pen CSS - Close Button by Molly Kan (@mollykannn) on CodePen.
HTML
<div class="sample-1">
<span class="sample-1-close"></span>
</div>
<div class="sample-2">
<div class="sample-2-close">
<div class="sample-2-close--left"></div>
<div class="sample-2-close--right"></div>
</div>
</div>
CSS
.sample-1-close {
position: absolute;
cursor: pointer;
color: #fff;
font-size: 50px;
font-family: Arial,sans-serif;
border-radius: 50px;
background: #605F61;
line-height: 0px;
padding: 23px 9px 23px 9px;
}
.sample-1-close:before {
content: "\00d7";
}
.sample-2-close {
position:relative;
cursor: pointer;
top:0;
left:0;
width:50px;
height:50px;
}
.sample-2-close--left, .sample-2-close--right {
position:absolute;
width: 0;
top: 22px;
left: 9px;
height: 5px;
border-style:solid;
border-width:0 0 0 30px;
}
.sample-2-close--left {
border-color:#000;
transform: rotate(45deg);
}
.sample-2-close--right {
border-color:#000;
transform: rotate(-45deg);
}