如何在css3选择器的两列中交替使用颜色?-Howtoalternatecolorsintwocolumnsincss3selector?

#list>div {
  font-size: 18px;
  float: left;
  margin: 0 10px 10px 0;
  width: 150px;
}

#list>div:nth-child(2n+1) {
  clear: left;
}

#list>div:nth-child(4n+1), #list>div:nth-child(4n) {
  background-color: red;
}

#list>div:nth-child(4n+2), #list>div:nth-child(4n+3) {
  background-color: blue;
}

  
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#list>div {
  font-size: 18px;
  float: left;
  margin: 0 10px 10px 0;
  width: 150px;
  background-color: red;
}


#list>div:nth-child(4n+1) {
  background-color: blue;
}

#list>div:nth-child(4n) {
  background-color: blue;
}

#list>div:nth-child(2n+1) {
 clear:left 
}

  
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