.con {
height: 250px;
width: 200px;
margin: 0 auto;
overflow: hidden;
margin-top: 100px;
position: relative;
background-color: #4cd964;
}
.subscript {
color: #fff;
height: 30px;
width: 100px;
position: absolute;
right: -30px;
text-align: center;
line-height: 30px;
font-family: "黑体";
background-color: #0c60ee;
-moz-transform: rotate(45deg);
-webkit-transform: rotate(45deg);
-o-transform: rotate(45deg);
-ms-transform: rotate(45deg);
transform: rotate(45deg);
}
<div class="con">
<div class="subscript">角标</div>
</div>