CSS (Cascading Style Sheet) enhances HTML by offering a look and feel to website pages. The HTML file you created looked fairly plain, with a standard font and font size. Using CSS, you can liven up that look, putting color and background images, modifying fonts and font sizes, drawing borders around areas, and even modifying the layout of the page itself.
CSS has its very own language, separate from HTML, but you would not use CSS without the HTML web page. This means, although HTML can stand on its own and present a page to an internet browser, CSS can not. You wouldn’t make a CSS page. Rather, you make HTML file and then use CSS to help style that page to get it to look like you want it to. Like HTML, CSS is defined by specs, with the most recent being CSS version 3, generally known as CSS3.
When You Have to Use CSS?
In the past, an HTML programmer changed fonts and colors by changing attributes on each element. If the coder wanted all the headings to look a specific way, he had to change each of those headings. Imagine doing this on a page with ten headings, and then imagine doing it on fifty web pages. The process rapidly becomes tiresome. And then think of what happens when the site owner decides he wants all the headings changed back to the original way. CSS alleviates this burden of individually changing elements and makes it so that you can apply one single style across one or more elements. You can use multiple styles to the same element, and you can target a certain style down to the individual element. For example, if you want all titles to be bold font but a certain titles should have italic, you can do that with CSS. Use CSS to make changes to the layout, look, and feel of a web page. CSS makes managing these changes easy.
What CSS Can’t Do?
CSS isn’t without restrictions. The primary limitation of CSS is that not all internet browsers support CSS in exactly the same way. One browser might interpret your layout in a slightly different way, placing items higher or lower or in a different place entirely. Also, older internet browsers do not support newer versions of CSS, specifically the CSS3 specification.
By testing in other browsers, you can see how the website will look in those internet browsers and correct layout issues prior to deploying the site to the Internet. Always test your pages in many browsers to make sure that they look and act like you desired.