Theme implementation basics in CSS - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a CSS theme?

A CSS theme is a set of styles that define the look and feel of a website, like colors, fonts, and spacing, which can be changed to give the site a different appearance.

beginner

How do CSS custom properties (variables) help in theme implementation?

CSS custom properties let you store values like colors or font sizes in variables. Changing these variables updates the whole theme easily without rewriting many styles.

beginner

What is the purpose of using the :root selector in theme implementation?

The :root selector targets the top-level element in HTML. Defining CSS variables here makes them available everywhere in the page for consistent theming.

intermediate

How can you switch between light and dark themes using CSS?

You can define different sets of CSS variables for light and dark themes and switch them by changing a class on the <code>body</code> or <code>html</code> element, which updates the colors across the site.

beginner

Why is accessibility important when implementing themes?

Accessibility ensures that themes have enough contrast and clear visuals so everyone, including people with vision difficulties, can read and use the website comfortably.

Which CSS feature allows easy theme color changes across a website?

A CSS grid

B CSS floats

C CSS animations

D CSS custom properties (variables)

CSS custom properties let you define colors once and reuse them, making theme changes simple.

Where should you define CSS variables for a theme to be accessible everywhere?

A Inside a media query only

B Inside each HTML element

C Inside the <code>:root</code> selector

D Inside a <code>@keyframes</code> block

The :root selector is the top-level element, so variables defined here are global.

How can you switch themes dynamically on a webpage?

A By toggling a class on the <code>body</code> or <code>html</code> element

B By changing the HTML tag names

C By editing the CSS file manually

D By refreshing the browser cache

Toggling a class changes which CSS variables or styles apply, switching themes instantly.

Why should themes have good color contrast?

A To make text readable for all users

B To use more colors

C To make the site load faster

D To reduce CSS file size

Good contrast helps users with vision difficulties read content easily.

Which CSS selector is best for defining global theme variables?

A .theme

B :root

C #header

D body > div

The :root selector targets the highest level, making variables global.

Explain how CSS custom properties help in creating and switching themes.

Think about how one change can affect many styles.

Describe the steps to implement a dark mode theme using CSS.

Consider how to organize colors and how to toggle them.