SOURCE

console 命令行工具 X clear

                    
>
console
<div class="letter-box">
  <div class="letter-border">
  </div>
</div>
.letter-border {
  width: 100%;
  height: 100%;
  background: #fbfaf5;
}

.letter-box {
  width: 278px;
  height: 176px;
  padding: 5px;
  box-sizing: border-box;
  background: linear-gradient(
    45deg,  
    #f25953 12.5%,
    #fbfaf5 12.5%, #fbfaf5 25%, 
    #5590d6 25%,#5590d6 37.5%, 
    #fbfaf5 37.5%,#fbfaf5 50%, 
    #f25953 50%,#f25953 62.5%, 
    #fbfaf5 62.5%, #fbfaf5 75%, 
    #5590d6 75%, #5590d6 87.5%,
    #fbfaf5 87.5%, #fbfaf5 100%
  );
  background-size: 70px 70px;
}