ul { padding:10px 1px; overflow:hidden; } li { float:left; outline:1px solid gray; text-align:center; line-height:2; } /* one item */ li:first-child:nth-last-child(1) { width: 100%; } /* two items */ li:first-child:nth-last-child(2), li:first-child:nth-last-child(2) ~ li { width: 50%; } /* three items */ li:first-child:nth-last-child(3), li:first-child:nth-last-child(3) ~ li { width: 33.3333%; } /* four items */ li:first-child:nth-last-child(4), li:first-child:nth-last-child(4) ~ li { width: 25%; }
<ul> <li>1</li> </ul> <ul> <li>1</li> <li>2</li> </ul> <ul> <li>1</li> <li>2</li> <li>3</li> </ul> <ul> <li>1</li> <li>2</li> <li>3</li> <li>4</li> </ul>