Tutorial Online: CSS

Responsive Web Design - Frameworks

There are many existing CSS Frameworks that offer Responsive Design.

They are free, and easy to use.

<!DOCTYPE html>
<html>
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="http://www.w3schools.com/lib/w3.css">
<body>

<div class="w3-container orange">
  <h1>W3Schools Demo</h1>
  <p>Resize this responsive page!</p>
</div>

<div class="w3-row-padding">

<div class="w3-third">
  <h2>London</h2>
  <p>London is the capital city of England.</p>
  <p>It is the most populous city in the United Kingdom,
with a metropolitan area of over 13 million inhabitants.</p>
</div>

<div class="w3-third">
  <h2>Paris</h2>
  <p>Paris is the capital of France.</p>
  <p>The Paris area is one of the largest population centers in Europe,
with more than 12 million inhabitants.</p>
</div>

<div class="w3-third">
  <h2>Tokyo</h2>
  <p>Tokyo is the capital of Japan.</p>
  <p>It is the center of the Greater Tokyo Area,
and the most populous metropolitan area in the world.</p>
</div>

</div>

</body>
</html>

Bootstrap

Another popular Framework is Bootstrap, it uses HTML, CSS and jQuery to make responsive web pages.

<!DOCTYPE html>
<html lang="en">
<head>
<title>Bootstrap Example</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet"href="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.4/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<script src="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.4/js/bootstrap.min.js"></script>
</head>
<body>

<div class="container">
  <div class="jumbotron">
    <h1>My First Bootstrap Page</h1>
  </div>
  <div class="row">
    <div class="col-sm-4">
      ...
    </div>
    <div class="col-sm-4">
      ...
    </div>
    <div class="col-sm-4">
    ...
    </div>
  </div>
</div>

</body>
</html>

Skeleton

Another popular framework is Skeleton, it uses only CSS to make responsive web pages.

<!DOCTYPE html>
<html lang="en">
<head>
<title>Skeleton Example</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="skeleton.css">
<link rel="stylesheet" href="normalize.css">
<link href="http://fonts.googleapis.com/css?family=Raleway:400,300,600" rel="stylesheet"type="text/css">
</head>
<body>

<div class="container">
  <h1>My First Skeleton Page</h1>
  <div class="row">
    <div class="one column">
      ...
    </div>
    <div class="eleven columns">
      ...
    </div>
  </div>
  <div class="row">
    <div class="one-half column">
      ...
    </div>
    <div class="one-half column">
      ...
    </div>
  </div>
</div>

</body>
</html>

Responsive Web Design - Videos

Using The width Property

If the width property is set to 100%, the video player will be responsive and scale up and down:

video {
width: 100%;
height: auto;
}

Notice that in the example above, the video player can be scaled up to be larger than its original size. A better solution, in many cases, will be to use the max-width property instead.

Using The max-width Property

If the max-width property is set to 100%, the video player will scale down if it has to, but never scale up to be larger than its original size:

video {
max-width: 100%;
height: auto;
}

Add a Video to the Example Web Page

We want to add a video in our example web page. The video will be resized to always take up all the available space:

video {
width: 100%;
height: auto;
}

Responsive Web Design - Images

Using The width Property

If the width property is set to 100%, the image will be responsive and scale up and down:

img {
width: 100%;
height: auto;
}

Notice that in the example above, the image can be scaled up to be larger than its original size. A better solution, in many cases, will be to use the max-width property instead.

Using The max-width Property

If the max-width property is set to 100%, the image will scale down if it has to, but never scale up to be larger than its original size:

img {
max-width: 100%;
height: auto;
}

Add an Image to The Example Web Page

img {
width: 100%;
height: auto;
}

Background Images

Background images can also respond to resizing and scaling.

Here we will show three different methods:

1. If the background-size property is set to "contain", the background image will scale, and try to fit the content area. However, the image will keep its aspect ratio (the proportional relationship between the image's width and height):

Here is the CSS code:

div {
    width: 100%;
    height: 400px;
    background-image: url('img_flowers.jpg');
    background-repeat: no-repeat;
    background-size: contain;
    border: 1px solid red;
}

2. If the background-size property is set to "100% 100%", the background image will stretch to cover the entire content area:

Here is the CSS code:

div {
    width: 100%;
    height: 400px;
    background-image: url('img_flowers.jpg');
    background-size: 100% 100%;
    border: 1px solid red;
}

3. If the background-size property is set to "cover", the background image will scale to cover the entire content area. Notice that the "cover" value keeps the aspect ratio, and some part of the background image may be clipped:

Here is the CSS code:

div {
    width: 100%;
    height: 400px;
    background-image: url('img_flowers.jpg');
    background-size: cover;
    border: 1px solid red;
}

Different Images for Different Devices

A large image can be perfect on a big computer screen, but useless on a small device. Why load a large image when you have to scale it down anyway? To reduce the load, or for any other reasons, you can use media queries to display different images on different devices.

Here is one large image and one smaller image that will be displayed on different devices:

/* For width smaller than 400px: */
body {
    background-image: url('img_smallflower.jpg');
}

/* For width 400px and larger: */
@media only screen and (min-width: 400px) {
    body {
        background-image: url('img_flowers.jpg');
    }
}

You can use the media query min-device-width, instead of min-width, which checks the device width, instead of the browser width. Then the image will not change when you resize the browser window:

/* For devices smaller than 400px: */
body {
    background-image: url('img_smallflower.jpg');
}

/* For devices 400px and larger: */
@media only screen and (min-device-width: 400px) {
    body {
        background-image: url('img_flowers.jpg');
    }
}

HTML5 <picture> Element

HTML5 introduced the <picture> element, which lets you define more than one image.

Browser Support

Element
<picture>	Not supported	38.0	38.0	Not supported	25.0

The <picture> element works similar to the <video> and <audio> elements. You set up different sources, and the first source that fits the preferences is the one being used:

The srcset attribute is required, and defines the source of the image.

The media attribute is optional, and accepts the media queries you find in CSS @media rule.

You should also define an <img> element for browsers that do not support the <picture> element.

Sunday, November 1, 2015

Responsive Web Design - Frameworks

Bootstrap

Skeleton

Responsive Web Design - Videos

Using The width Property

Using The max-width Property

Add a Video to the Example Web Page

Responsive Web Design - Images

Using The width Property

Using The max-width Property

Add an Image to The Example Web Page

Background Images

Different Images for Different Devices

HTML5 <picture> Element

Browser Support