CSS Frameworks: Bootstrap

Orson Xu

Spring 2023

Slides credited to Joel Ross

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Bootstrap Demo (code together!)

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PollEv.com/orsonxu

Semantic Class Names

Name CSS classes based on the semantic meaning (purpose) of the element they are styling.

<div class="forum-post">...</div>

<nav class="side-nav">...</div>

<img class="avatar-icon">...</div>

<article class="breaking-news">...</article>

https://css-tricks.com/semantic-class-names/

/* can use descendant selectors for more detail */
.forum-post img { ... }

.side-nav ul a { ... }

Modular Class Names

Name CSS classes based on the (single) styling they apply. Combine multiple classes to style elements.

<div class="font-large text-red bg-secondary">...</div>

<img class="small rounded shadow">...</div>

.font-large { 
  font-size: 2em; 
  line-height: 1.4em;
}
.bg-secondary { background: #bbb; }

img.small { width: 140px; }
.rounded { border-radius: 50%; }

Demo

Link the Framework

<head>
  <!--... other elements here...-->

  <!-- link Bootstrap -->
  <link rel="stylesheet" 
        href="https://cdn.jsdelivr.net/npm/bootstrap@5.2.2/dist/css/bootstrap.min.css">

  <!-- link own stylesheets AFTER framework -->
  <link rel="stylesheet" href="css/my-style.css">
</head>

minified CSS file!

https://getbootstrap.com/

Utility Classes

Bootstrap provides rules that apply to particular classes. Give an element that class in order to style it in a certain way.

Components

Bootstrap provides components that you can easily leverage

Button

Form

A short break

Responsive Utilities

Some Bootstrap utility classes provide ways to simply the responsive design.

Examples: display, padding, margin

Bootstrap Grids

row

column

Grid Columns

There are 12 columns in the grid

Elements can take up many columns

Row 1:

Row 2:

Row 3:

Specify columns based on screen-size

Smaller screen display

A Row:

Interactive Widgets

The Bootstrap framework provides some interactive "widgets" you can use without writing separate JavaScript code, just by using specific HTML attributes.

https://getbootstrap.com/docs/5.1/components

<!-- include Bootstrap library (before your script!) -->
<!-- copy script tag from the Bootstrap home page -->
<script src="https://cdn.jsdelivr.net/npm/bootstrap@5.2.2/dist/js/bootstrap.bundle.min.js"></script>

Example: Collapsables

As a simple example, you can make an element "collapsable" so that it disappears with a button click!

https://getbootstrap.com/docs/5.3/components/collapse/

<button class="btn btn-primary" 
        data-bs-toggle="collapse" 
        data-bs-target="#collapseExample" 
        aria-expanded="false" aria-controls="collapseExample">
   Button with data-bs-target
</button>


<div class="collapse" id="collapseExample">
    Some placeholder content for the collapse component. This panel is 
    hidden by default but revealed when the user clicks the toggler.
</div>

aria for screen-readers

Example: NavBar

https://getbootstrap.com/docs/5.3/components/navbar/#toggler

An example of a NavBar with a collapsible "hamburger menu"

You can even copy it over and modify to fit your needs!

Action Items!

Read: through Chapter 10
- Now is a good time to catch up!
Problem Set 04 due Wednesday
Project Draft 1 due week from Monday

Next: JavaScript!!