垂直横幅与倾斜的底部

<div class="verticalbanner"></div>
.verticalbanner {
background: #f8f8f8; //ribbon color
height: 87px; // ribbon height
width: 74px; // ribbon width
}
.verticalbanner:after,.verticalbanner:before {
content: '';
position: absolute;
border-top: 15px solid #eee; // angle degree, reduce to reduce degree of angles
height: 0; // no height, no content, just border
width: 0;
top: 100%;
}
.verticalbanner:after { // right angle
border-left: 50px solid transparent;
right:0;
}
.verticalbanner:before { // left angle
border-right: 50px solid transparent;
left:0;
}
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