- Semantic HTML
- Document Object Model (DOM)
- HTML parsing
- The HTML5 specification
- Progressive Web Apps (PWA)
- Web components
- Shadow DOM
- Custom elements
- The template element
- The canvas element
- The video element
- The audio element
- Responsive design
- Accessibility (a11y)_
- HTML forms
- Server-sent events (SSE)
- Web sockets
- Web storage (localStorage and sessionStorage)
- Web workers
- IndexedDB
- WebRTC
- Drag and drop API
- Geolocation API
- Offline web applications
- CORS (Cross-Origin Resource Sharing)
- Cross-site scripting (XSS) prevention
- Content Security Policy (CSP)
- HTTPS (Hypertext Transfer Protocol Secure)
- HTTP/2
- Cache control headers
- HTML5 Boilerplate
- Microformats
- Microdata
- RDFa
- Structured data
- Data attributes
- The picture element
- The source element
- The object element
- The embed element
- The iframe element
- The header element
- The footer element
- The nav element
- The article element
- The section element
- The aside element
- The main element
- The time element
- The figure element
- The figcaption element
- The details element
- The summary element
- The mark element
- The meter element
- The progress element
- The ruby element
- The rt element
- The rp element
- The command element
- The menu element
- The dialog element
- The output element
- The keygen element
- The source element
- The track element
- The map element
- The area element
- The datalist element
- The select element
- The option element
- The label element
- The fieldset element
- The legend element
- The input element
- The button element
- The textarea element
- The progress element
- The meter element
- The details element
- The summary element
- The wbr element
- The bdi element
- The bdo element
- The data element
- The keygen element
- The output element
- The progress element
- The ruby element
- The menuitem element
- The command element
- The menu element
- The dialog element
- The track element
- The source element
- The video element
- The audio element
- The time element
- The picture element
- The canvas element
- CSS specificity
- CSS inheritance
- The box model
- Positioning
- Display property
- Flexbox layout
- Grid layout
- CSS transforms
- CSS transitions
- CSS animations
- CSS filters
- CSS variables (custom properties)
- Media queries
- Responsive typography
- The cascade
- Pseudo-classes
- Pseudo-elements
- Attribute selectors
- Combinators
- Child selectors
- Adjacent sibling selectors
- General sibling selectors
- Attribute selectors with values
- Structural pseudo-classes
- Custom fonts
- Font stacking
- Font smoothing
- Font loading strategies
- Color theory
- HSL and HSLA color values
- CSS gradients
- CSS shapes
- CSS clip-path
- CSS masks
- CSS variables in calc()
- The calc() function
- CSS counters
- The content property
- The quotes property
- The attr() function
- The counter() function
- The :empty pseudo-class
- The :not() pseudo-class
- The :checked pseudo-class
- The :target pseudo-class
- The :hover pseudo-class
- The :focus pseudo-class
- The :active pseudo-class
- The :visited pseudo-class
- The ::before and ::after pseudo-elements
- The ::first-letter and ::first-line pseudo-elements
- The ::selection pseudo-element
- The ::placeholder pseudo-element
- The transform property
- The transform-origin property
- The perspective property
- The backface-visibility property
- The transition property
- The transition-timing-function property
- The transition-delay property
- The animation property
- The animation-name property
- The animation-duration property
- The animation-timing-function property
- The animation-delay property
- The animation-iteration-count property
- The animation-direction property
- The animation-fill-mode property
- The filter property
- The contrast() function
- The brightness() function
- The blur() function
- The drop-shadow() function
- The grayscale() function
- The hue-rotate() function
- The invert() function
- The opacity property
- The text-shadow property
- The box-shadow property
- The grid-template-columns property
- The grid-template-rows property
- The grid-template-areas property
- The grid-template property
- The grid-column-start property
- The grid-column-end property
- The grid-row-start property
- The grid-row-end property
- The grid-column property
- The grid-row property
- The grid-area property
- The justify-content property
- The align-content property
- The justify-items property
- The align-items property
- The gap property
- The justify-self property
- The align-self property
- The order property
- The writing-mode property
- The direction property