percentage values are relative to the nearest ancestor element

viewport units are always relative to the browser window

<a href="javascript:get_next_10();">some link</a>

1. Using another domain name means that you'll be able to not have the cookies that are used on the main domain - which means that HTTP requests will be smaller
2. No need for a full PHP/.NET/JAVA server to serve static content!
3. Use another machine to serve the static content (Including some CDN) 
4. Use another web-server to serve the static content (something more lightweight and faster)

npm install -g sass

sass source/stylesheets/index.scss build/stylesheets/index.css

-

_

$font-size

$font_size

.box {
    width: 300px * 2;
}

.box {
    width: 500px / 2;
}

.box {
    width: 100px + 200px;
}

@mixin for-phone-only {
  @media (max-width: 599px) { @content; }
}

.header-title {  
   font-size: 15px;  
   @include for-phone-only {    
      font-size: 18px; 
   }
}