External CSS

External stylesheets are very ideal when you want to apply style to many pages. If you change any style in external CSS file that will effect on all pages. The file extension of CSS is ".css", for design css file save file any name with .css extension like (styles.css), the css file should not contain any HTML code.

Linking to a separate style sheet file
Using <link> tag, you can link CSS file with multiple HTML documents

<LINK REL=STYLESHEET TYPE="text/css" HREF="styles.css">

Importing a style sheet
You can import a basic sheet, and then add on extra styles to it. The import command is placed in the STYLE section mentioned above and should be the first thing in that section:

<STYLE TYPE="text/css">
<!--
@import url(style.css);
... rest of style code goes here
-->
</STYLE>