Example of an article with varying widths, font-sizes and line-heights depending on the viewport width.

Sass for Designers Example #11

/* initial rule for all viewports, including browsers that don't support @media */
article {
  font-size: 14px;
  line-height: 25px;
}

article h2 {
  font-size: 18px;
  padding-bottom: 15px;
}

/* for 300px viewports and wider (mobile first) */
@media only screen and (min-width: 300px) {
  article {
    line-height: 20px;
    width: 90%;
  }

  article h2 {
    padding-bottom: 10px; 
  }
}

/* for 600px viewports and wider */
@media only screen and (min-width: 600px) {
  article {
    line-height: 25px;
    width: 80%;
  }

  article h2 {
    padding-bottom: 15px; 
  }
}

/* for 900px viewports and wider */
@media only screen and (min-width: 900px) {
  article {
    width: 60%;
  }
}

/* for 1200px viewports and wider */
@media only screen and (min-width: 1200px) {
  article {
    font-size: 16px;
    line-height: 30px;
    width: 50%;
  }

  article h2 {
    font-size: 21px;
    line-height: 35px;
    padding-bottom: 20px; 
  }
}