Cascading Style Sheets

The logo for CSS 3

Cascading Style Sheets, or CSS, is a way to change the look of HTML and XHTML web pages. CSS was designed by the W3C, and is supported well by most modern web browsers. The current version of CSS is CSS3. CSS4 is available, but is split into parts.

One advantage to using CSS is a web page can still be displayed, even if the CSS is not working or removed.

CSS code is saved in files with the .css file extension.

To import a CSS file you would use <link rel="stylesheet" href="CSS_FILE_NAME_HERE.css"> or for a folder you would use <link rel="stylesheet" href="FOLDER_NAME_HERE/CSS_FILE_NAME_HERE.css"> in HTML.

In CSS you would use @import url("CSS_FILE_NAME_HERE.css"); or for a folder you would use @import url(FOLDER_NAME_HERE/CSS_FILE_NAME_HERE.css"); to import CSS into your CSS.

You could also use @import in a set of <style>import goes here</style> tags to import the CSS in your HTML from your CSS. You could also put your CSS directly into the HTML by putting in a set of <style>css here</style> tags.

CSS Examples

Paragraphs

To make all paragraphs on a page blue and sized 20% bigger than normal text, we would apply this CSS rule to a page:

p {
color: blue;
font-size: 120%;
background-color: white
}

The p refers to all HTML elements with the <p> tag. The CSS is being used to change this element. The color and font-size are both properties and the blue and 120% are values. Each property has a set of possible values. These values can be words or numbers.

Main Title

To give the main Title on a page a solid red border underneath, we would apply this CSS rule to the page. 5px otherwise known as pixels, represents the thickness of the line:

h1 {
border-bottom: 5px solid red;
}

The h1 refers to all HTML elements with the <h1> tag. The CSS is being used to change this element. The border-bottom is the property and the 5px and solid red are values. Each property has a set of possible values. These values can be words or numbers.

Button

To give a button a hover effect and make it blue with no border, we would apply this CSS rule to this page. The CSS is being used to change this element. The button refers to all HTML elements with the <button> tag.

    button:hover {
padding:25px 35px;
}

button {
 display: block;
  color: white;
border:0px;
  transition:0.3s;
  text-align: center;
  padding: 20px 27px;
  text-decoration: none;
  background-color: rgb(0, 150, 255);
  border-radius: 15px;
  font-size:18px;
}

Preview with the HTML code <button> button </button> used:

Preview of the button being hovered over:

Other websites

• W3C
• Website about CSS3