Dark Mode

A modal (or modal dialog) is a UI element that overlays the main content to demand user attention and interaction before they can return to the underlying page. Modals are used for confirmations, forms, alerts, and content previews. Proper implementation requires focus trapping, keyboard accessibility (Escape to close), and preventing background scroll — making accessible modals more complex than they appear.

Storybook is an open-source tool for building and testing UI components in isolation, outside of your main application. Developers define "stories" — different states and variations of a component — which are rendered in a dedicated browser-based workshop. It supports React, Vue, Angular, and other frameworks, making it invaluable for component documentation, visual regression testing, and collaboration between designers and developers.

Internationalization (i18n) is the process of designing software so it can be adapted to different languages, regions, and cultures without code changes. This involves externalizing strings, supporting right-to-left (RTL) layouts, handling date/number/currency formatting, and accommodating text expansion. Libraries like react-intl, next-intl, and i18next provide the infrastructure for managing translations and locale-aware formatting in JavaScript applications.

CSS Custom Properties (also called CSS Variables) let you define reusable values with `--my-variable` syntax and reference them anywhere using `var(--my-variable)`. Unlike preprocessor variables in Sass or Less, they are live in the browser, cascade through the DOM, and can be updated dynamically with JavaScript. They're essential for theming systems, dark mode implementations, and maintaining consistent design tokens across large stylesheets.

Accessibility (often abbreviated a11y) is the practice of designing and building websites and apps so they can be used by everyone, including people with visual, motor, auditory, or cognitive disabilities. This involves proper semantic markup, keyboard navigation support, sufficient color contrast, and screen reader compatibility. Beyond being an ethical responsibility, accessibility is increasingly a legal requirement in many jurisdictions.

Flutter is Google's open-source UI toolkit for building natively compiled applications for mobile, web, and desktop from a single Dart codebase. Unlike React Native which maps to platform-native UI components, Flutter renders everything with its own high-performance Skia/Impeller rendering engine, giving developers pixel-perfect control over every element on screen. This approach ensures identical visual output across platforms but means Flutter widgets don't automatically adopt platform-specific design conventions.