Web Front-end
CSS Tutorial
Why does a 100% height div only fill the page when the DOCTYPE is removed?
Why does a 100% height div only fill the page when the DOCTYPE is removed?
Why does height 100% work when DOCTYPE is removed?
This code snippet attempts to fill the entire page with a green div:
<!DOCTYPE HTML> <html> <body>
However, it doesn't work as expected. The div remains invisible. If we remove the DOCTYPE declaration (), the div suddenly expands to fill the entire page. This raises two questions:
How do I make the div fill the page without removing the DOCTYPE declaration?
To make the div fill the page without removing the DOCTYPE, simply set the height of the root element (html) to 100%:
html { height: 100%; }Why does removing the DOCTYPE declaration make it work?
When a DOCTYPE is present, the browser renders the page in standards mode. In standards mode, percentage heights of child elements are treated as height: auto if the parent element has no explicit height. This is why the div doesn't fill the page in standards mode.
However, when the DOCTYPE is absent, the browser switches to quirks mode. In quirks mode, percentage heights of child elements are measured relative to the viewport. This means that the div in the example above will fill the entire page in quirks mode because its height is set to 100% of the viewport height.
Conclusion
It's important to always include a DOCTYPE declaration to ensure that the page renders in standards mode. Quirks mode is unreliable and unpredictable, and it should be avoided at all costs. The preferred DOCTYPE declaration is simply:
<!DOCTYPE html>
The above is the detailed content of Why does a 100% height div only fill the page when the DOCTYPE is removed?. For more information, please follow other related articles on the PHP Chinese website!
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
1664
14
1423
52
1317
25
1268
29
1246
24
How to Create an Animated Countdown Timer With HTML, CSS and JavaScript
Apr 11, 2025 am 11:29 AM
Have you ever needed a countdown timer on a project? For something like that, it might be natural to reach for a plugin, but it’s actually a lot more
HTML Data Attributes Guide
Apr 11, 2025 am 11:50 AM
Everything you ever wanted to know about data attributes in HTML, CSS, and JavaScript.
A Proof of Concept for Making Sass Faster
Apr 16, 2025 am 10:38 AM
At the start of a new project, Sass compilation happens in the blink of an eye. This feels great, especially when it’s paired with Browsersync, which reloads
While You Weren't Looking, CSS Gradients Got Better
Apr 11, 2025 am 09:16 AM
One thing that caught my eye on the list of features for Lea Verou's conic-gradient() polyfill was the last item:
A Comparison of Static Form Providers
Apr 16, 2025 am 11:20 AM
Let’s attempt to coin a term here: "Static Form Provider." You bring your HTML
How to Build Vue Components in a WordPress Theme
Apr 11, 2025 am 11:03 AM
The inline-template directive allows us to build rich Vue components as a progressive enhancement over existing WordPress markup.
PHP is A-OK for Templating
Apr 11, 2025 am 11:04 AM
PHP templating often gets a bad rap for facilitating subpar code — but that doesn't have to be the case. Let’s look at how PHP projects can enforce a basic
The Three Types of Code
Apr 11, 2025 pm 12:02 PM
Every time I start a new project, I organize the code I’m looking at into three types, or categories if you like. And I think these types can be applied to
