Responsive Design

What Is the CSS Box Model?

The CSS box model describes every rendered element as a set of nested rectangular layers — content, padding, border, and margin — and how those layers combine…

CSS Flexbox vs Grid: What Is the Difference?

Flexbox is a one-dimensional layout system for arranging items along a single row or column with flexible sizing, while CSS Grid is a two-dimensional system th…

What Are CSS Media Queries and How Do They Work?

A media query is a CSS conditional block that applies a set of styles only when the browser environment matches specified conditions, most commonly viewport wi…

What Are the Core Principles of Responsive Web Design?

Responsive design means building a single layout that adapts to any viewport using fluid grids, flexible images, and CSS media queries, rather than shipping se…

What Is the Resize Observer API and Why Is It Useful?

The Resize Observer API lets you asynchronously detect when an element’s content box (or border box) size actually changes, which is essential for responsive,…

How Does CSS Grid grid-template-areas Work?

`grid-template-areas` lets you name regions of a CSS Grid layout as a visual ASCII-art string on the container, then assign each child to one of those named re…

What Are CSS Container Queries and How Do They Differ from Media Queries?

Container queries let an element style itself based on the size of its nearest containing ancestor rather than the size of the entire viewport, using `containe…

What Are CSS Viewport Units (vh, vw, dvh, svh, lvh)?

CSS viewport units size elements relative to the browser viewport — vw and vh are percentages of the initial viewport width/height, while the newer dvh, svh, a…

How Do You Implement Dark Mode in a Web App?

Dark mode is implemented by defining theme values as CSS custom properties, switching between a light and dark set of those values based on either the user’s O…

How Do CSS Custom Media Queries (@custom-media) Work?

CSS custom media queries let you define a named, reusable media condition once with @custom-media --name (condition), and then reference it by name across your…