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CSS3 Interview Questions - 2025 Edition

🎨 CSS Fundamentals​

  1. CSS Box Model (Content, Padding, Border, Margin)
  2. Box-sizing: content-box vs border-box
  3. CSS Specificity & Cascade Rules
  4. CSS Inheritance
  5. CSS Units (px, em, rem, %, vh, vw, vmin, vmax)
  6. CSS Reset vs Normalize
  7. CSS Variables (Custom Properties)
  8. CSS Vendor Prefixes

🎯 Selectors & Combinators​

  1. CSS Selector Types (Element, Class, ID, Attribute)
  2. Pseudo-classes (:hover, :focus, :nth-child, :first-child)
  3. Pseudo-elements (::before, ::after, ::first-line)
  4. CSS Combinators:
    • div, p (Group selector)
    • div p (Descendant selector)
    • div > p (Child selector)
    • div + p (Adjacent sibling)
    • div ~ p (General sibling)
  5. Attribute Selectors ([attr], [attr="value"])
  6. :root Selector & CSS Variables
  7. :nth-child() vs :nth-of-type()

📦 Layout & Positioning​

  1. CSS Display Property (block, inline, inline-block, none)
  2. CSS Position (static, relative, absolute, fixed, sticky)
  3. CSS Float & Clear
  4. CSS Overflow (visible, hidden, scroll, auto)
  5. CSS Z-index & Stacking Context
  6. CSS Visibility (visible, hidden, collapse)
  7. display: none vs visibility: hidden vs opacity: 0

🔧 Flexbox​

  1. Flexbox Container Properties (display: flex)
  2. flex-direction (row, column, row-reverse, column-reverse)
  3. justify-content (flex-start, center, space-between, space-around)
  4. align-items (stretch, center, flex-start, flex-end)
  5. flex-wrap (nowrap, wrap, wrap-reverse)
  6. align-content for Multi-line Flex
  7. Flex Item Properties (flex-grow, flex-shrink, flex-basis)
  8. align-self for Individual Items

🎛️ CSS Grid​

  1. Grid Container Properties (display: grid)
  2. grid-template-columns & grid-template-rows
  3. Grid Lines, Tracks, and Areas
  4. grid-gap (gap, row-gap, column-gap)
  5. Grid Item Placement (grid-column, grid-row)
  6. grid-template-areas & Named Grid Areas
  7. Auto-placement & grid-auto-flow
  8. Implicit vs Explicit Grid
  9. minmax() & repeat() Functions
  10. fr Unit in Grid

🎨 Styling & Visual Effects​

  1. CSS Colors (hex, rgb, rgba, hsl, hsla)
  2. CSS Gradients (linear-gradient, radial-gradient)
  3. CSS Shadows (box-shadow, text-shadow)
  4. CSS Borders & Border-radius
  5. CSS Opacity & Transparency
  6. CSS Filters (blur, brightness, contrast)
  7. CSS Clip-path
  8. CSS Backdrop-filter

🔤 Typography​

  1. Font Properties (font-family, font-size, font-weight)
  2. Web Fonts (@font-face, Google Fonts)
  3. font-display Property
  4. Text Properties (text-align, text-decoration, text-transform)
  5. Line-height & Letter-spacing
  6. Text Overflow & White-space
  7. CSS Writing Modes

🎭 Animations & Transitions​

  1. CSS Transitions (transition-property, duration, timing-function)
  2. CSS Transforms (translate, rotate, scale, skew)
  3. CSS Animations (@keyframes, animation properties)
  4. Animation Timing Functions (ease, linear, cubic-bezier)
  5. Transform-origin Property
  6. will-change Property for Performance
  7. CSS Motion Path

📱 Responsive Design​

  1. Media Queries (@media)
  2. Breakpoints & Mobile-first Approach
  3. Viewport Meta Tag
  4. Responsive Units (vw, vh, vmin, vmax)
  5. Container Queries (@container)
  6. Aspect-ratio Property
  7. CSS Logical Properties
  8. Responsive Images (object-fit, object-position)

🎨 Modern CSS Features​

  1. CSS Custom Properties (Variables)
  2. CSS calc() Function
  3. CSS clamp() Function
  4. CSS min() & max() Functions
  5. CSS Subgrid
  6. CSS Cascade Layers (@layer)
  7. CSS :has() Selector
  8. CSS :where() & :is() Selectors

🏗️ CSS Architecture​

  1. BEM Methodology
  2. OOCSS (Object-Oriented CSS)
  3. SMACSS Architecture
  4. Atomic CSS
  5. CSS Modules
  6. Styled Components
  7. CSS-in-JS Solutions

⚡ Performance & Optimization​

  1. CSS Loading Performance
  2. Critical CSS
  3. CSS Minification
  4. Unused CSS Removal
  5. CSS Containment
  6. GPU Acceleration with CSS
  7. Reflow & Repaint Optimization

🔧 Preprocessors & Tools​

  1. Sass/SCSS Features
  2. Less CSS Preprocessor
  3. PostCSS & Autoprefixer
  4. CSS Linting (stylelint)
  5. CSS Frameworks (Bootstrap, Tailwind)

🎯 Common Layout Patterns​

  1. Centering Techniques:
    • Horizontal centering
    • Vertical centering
    • Perfect centering (horizontal + vertical)
  2. Holy Grail Layout
  3. Sticky Footer
  4. Equal Height Columns
  5. Card Layouts
  6. Navigation Patterns
  7. Sidebar Layouts

🐛 CSS Debugging & Browser Issues​

  1. Cross-browser Compatibility
  2. CSS Debugging Techniques
  3. Browser DevTools for CSS
  4. CSS Validation
  5. Common CSS Bugs & Fixes
  6. CSS Hacks & Fallbacks

🔒 CSS Security​

  1. CSS Injection Prevention
  2. Content Security Policy for CSS
  3. Safe CSS Practices

🌟 2025 Trending Topics​

  1. CSS Houdini & Paint API
  2. CSS Scroll-driven Animations
  3. CSS View Transitions API
  4. CSS Anchor Positioning
  5. CSS Nesting (Native)
  6. CSS Color Functions (color-mix, relative colors)
  7. CSS Trigonometric Functions (sin, cos, tan)

💻 Practical Coding Challenges​

🎨 Layout Challenges​

  1. Create a Responsive Navigation Bar
  2. Build a Card Grid Layout
  3. Implement a Sticky Header
  4. Create a Sidebar Layout
  5. Build a Dashboard Layout

🎭 Animation Challenges​

  1. CSS Loading Spinners
  2. Hover Effects & Transitions
  3. Keyframe Animations
  4. CSS-only Carousel
  5. Animated Buttons

📱 Responsive Challenges​

  1. Mobile-first Responsive Design
  2. Responsive Typography
  3. Flexible Grid Systems
  4. Responsive Images
  5. Container Query Layouts

🎯 Component Challenges​

  1. CSS-only Modal
  2. Accordion Component
  3. Tooltip Component
  4. Progress Bar
  5. CSS-only Tabs

📚 Essential Resources​