在 CSS 中根据浏览器大小更改背景颜色

Question

I can't figure out what is wrong with this code. The background color doesn't change at all, it just stays white the entire time.

<style type="text/css">
      h1 {
        position: absolute;
        text-align: center;
        width: 100%;
        font-size: 6em;
        font-family: Roboto;
        transition: all 0.5s;
      }

      @media screen and (min-width: 0px) and (max-width: 400px) {
        background-color: red;
      }
      @media screen and (min-width: 401px) and (max-width: 599px) {
        background-color: green;
      }
      @media screen and (min-width: 600px) {
        background-color: blue;
      }
    </style>

Answer 1

Try:

@media screen and (min-width: 0px) and (max-width: 400px) {
    body { background-color: red; }
}
@media screen and (min-width: 401px) and (max-width: 599px) {
    body { background-color: green; }
}
@media screen and (min-width: 600px) {
    body { background-color: blue; }
}

The background-color property is now assigned to the body

Answer 2

You need to define the CSS for certain element in media query (like in this case body ). Here is a demo .

Try this:

h1 {
    position: absolute;
    text-align: center;
    width: 100%;
    font-size: 6em;
    font-family: Roboto;
    transition: all 0.5s;
  }

  @media screen and (min-width: 0px) and (max-width: 400px) {
    body{
      background-color: red;
    }
  }
  @media screen and (min-width: 401px) and (max-width: 599px) {
    body{
      background-color: green;
    }
  }
  @media screen and (min-width: 600px) {
    body{
      background-color: blue;
    }
  }

Answer 3

 @media screen and (min-width: 0px) and (max-width: 400px) {
   body{ background-color: red; }
 }
 @media screen and (min-width: 401px) and (max-width: 599px) {
   body{ background-color: green; }
 }
 @media screen and (min-width: 600px) {
   body{ background-color: blue; }
 }

Styles can applicable only to the body or any class onlly

Answer 4

h1 { position: absolute; text-align: center; width: 100%; transition: all 0.5s; } @media screen and (min-width: 0px) and (max-width: 400px) { body{ background-color: red; } } @media screen and (min-width: 401px) and (max-width: 599px) { body{ background-color: green; } } @media screen and (min-width: 600px) { body{ background-color: blue; } }