Table of Contents

• Media Queries
• Don't use @import

Media Queries tutorial

@media not|only mediatype and (media feature and|or|not mediafeature) {
    CSS-Code;
}

• Without the only, an older browser is allowed to interpret screen and (color) as being the screen media type.
• only is not needed in modern browsers (ref)

/* Set the background color of body to tan */
body {
  background-color: tan;
}

/* On screens that are 992px or less, set the background color to blue */
@media screen and (max-width: 992px) {
  body {
    background-color: blue;
  }
}

/* On screens that are 600px or less, set the background color to olive */
@media screen and (max-width: 600px) {
  body {
    background-color: olive;
  }
}

Examples for using media queries as breakpoints:

/* For mobile phones: */
[class*="col-"] {
  width: 100%;
}
@media only screen and (min-width: 600px) {
  /* For tablets: */
  .col-s-1 {width: 8.33%;}
  .col-s-2 {width: 16.66%;}
  .col-s-3 {width: 25%;}
  .col-s-4 {width: 33.33%;}
  .col-s-5 {width: 41.66%;}
  .col-s-6 {width: 50%;}
  .col-s-7 {width: 58.33%;}
  .col-s-8 {width: 66.66%;}
  .col-s-9 {width: 75%;}
  .col-s-10 {width: 83.33%;}
  .col-s-11 {width: 91.66%;}
  .col-s-12 {width: 100%;}
}
@media only screen and (min-width: 768px) {
  /* For desktop: */
  .col-1 {width: 8.33%;}
  .col-2 {width: 16.66%;}
  .col-3 {width: 25%;}
  .col-4 {width: 33.33%;}
  .col-5 {width: 41.66%;}
  .col-6 {width: 50%;}
  .col-7 {width: 58.33%;}
  .col-8 {width: 66.66%;}
  .col-9 {width: 75%;}
  .col-10 {width: 83.33%;}
  .col-11 {width: 91.66%;}
  .col-12 {width: 100%;}
}

<div class="row">
  <div class="col-3 col-s-3">...</div>
  <div class="col-6 col-s-9">...</div>
  <div class="col-3 col-s-12">...</div>
</div>

Don't use @import discussion

Prefer <link> to @import:

<link rel='stylesheet' href='a.css'>

Or you can use the @import rule:

<style>
@import url('a.css');
</style>

• Using @import within a stylesheet adds one more roundtrip to the overall download time of the page.
• Using @import in IE causes the download order to be altered.
  • This may cause stylesheets to take longer to download, which hinders progress rendering making the page feel slower.