CSS

Objectives:

What is CSS?

  • CSS is a "style sheet language" that lets you style the elements on your page.
  • CSS can be embedded inside HTML, but it is not HTML itself.

What can it do?

http://csszengarden.com/?cssfile=http://my.tbaytel.net/vel_lanquibo/csszengarden/styles.css

VS

http://www.csszengarden.com/218/

CSS consists of "style rules". Each style rule consists of a "selector" and "declarations" of property-value pairs:

CSS can be embedded in HTML in several ways. One way is to include all CSS in a style tag, usually inside the head tag:

<html>
<head>
<style>
body {
  color: yellow;
  background-color: green;
}
</style>
</head>

The selector is used to select which elements in the HTML page will be given the styles inside the curly braces.

 

selector {
  property: values;
}

Types of Selectors:

  1. element
  2. id
  3. class
  4. psudo class

Using different selectors

  <div>
    <p>Make the background of this text orange</p>
    <div>
      <div id="red">make this red using an id</div>
      <div class="purple">what color is this?</div>
      <div id="red" class="purple">What color will this become with both id and class??</div>
    </div>
  </div>
/*div {
  background-color: blue;
}

div p {
  background-color: orange;
}

.purple {
  background-color: purple;
}

#red {
  background-color: red;
}

*/

The Main 3:

You can select descendent items with multiple selectors

Selects any <li> element that is a descendant of any element with an id that equals "related-brands."

#related-brands li {
  color: gray;
}

The difference between the "." and the space is very important!

li.a {
  color: yellow;
}

li a {
  color: red;
}
<ul>
  <li><a href="#rice">Rice Krispies</a></li>
  <li class="a">NutriGrain</li>
</ul>

A set of "pseudo classes" can style anchor elements depending on their state.

a:link { /* unvisited link */
  color: red;
}
a:visited { /* visited link */
  color: blue;
} 
a:hover { /* moused over link */
  color: green;
}  
a:active { /* current link */
  color: purple;
} 
a:focus {  /* focused link */
  color: purple;
}

Memorize or lookup --> lookup generally

Attribute Selectors

<!DOCTYPE html>
<html>
<head>
<style>
a[target="_top"] {
    background-color: yellow;
}
</style>
</head>
<body>

<p>The links with a target attribute gets a yellow background:</p>

<a href="http://www.zombocom.com">zombocom.com</a>
<a href="http://www.imgur.com" target="_blank">imgur.com</a>
<a href="http://theoatmeal.com/" target="_top">theoatmeal.com</a>

</body>
</html>

it is possible to select attributes within an element (and useful!)

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Document</title>
  <style>
    p:nth-child(odd) {
        background: blue;
    }

    p:nth-child(even) {
        background: red;
    }
  </style>
</head>
<body>
  <h1>This is a heading</h1>
  <p>The first paragraph.</p>
  <p>The second paragraph.</p>
  <p>The third paragraph.</p>
  <p>The fourth paragraph.</p>
  <p>The fifth paragraph.</p>
  <p>The sixth paragraph.</p>
  <p>The seventh paragraph.</p>
</body>
</html>

The :nth-child selector

allows you to select one or more elements based on their source order, according to a formula.

    p:nth-child(3n+1) {
        background: blue;
    }

Generally:

  • id is more specific than a class, class is more specific than element.
  • the longer the selector, the more specific it is
  • If style rules are equally specific, the last one wins!

Some rules to follow when making IDs and class names:

  • Describe the content, not the presentation ("warning", not "redbox").
  • Use all lowercase, and hyphens ("header-info", not "headerInfo").
  • Use hyphens to show that a class or ID is part of something else. (e.g. "footer", "footer-copyright", and "footer-logo").

Naming Conventions

 

CSS Box Model

  • Content - The content of the box, where text and images appear
  • Padding - Clears an area around the content. The padding is transparent
  • Border - A border that goes around the padding and content
  • Margin - Clears an area outside the border. The margin is transparent
  <style>
  div {
      width: 300px;
      padding: 25px;
      border: 25px solid navy;
      margin: 25px;
  }
  </style>

Intermediate CSS

By Matthew Williams

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Intermediate CSS

CSS

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