Does anyone know what went wrong with this CSS? ? ?

Question

*{margin: 0px;padding: 0px;}
.header{width;100%;height:40px;background-color:#ccc;}Does anyone know where this CSS went wrong? ? ? Since there is no response

Answer 1

Add a float and try. It may not be a block-level element. Also, width:100%; replace it with mine

Answer 2

Clear your browser’s cache and take a look

Answer 3

Do you have the class name .header

Answer 4

.header{width;100%;height:40px;

Look carefully. Is there a colon or a semicolon after width? ? ? What should it be? 》? ? ? ?