HTML & CSS flashcards, generated for you.

<!DOCTYPE html> — all lowercase, no version number. This must be the first line of any HTML5 document.

Block elements (div, p, h1) take full width, start on new lines, and respect margin/padding on all sides. Inline elements (span, a, strong) flow within text, only respect left/right margin/padding, and ignore top/bottom.

Inline elements have their height determined by line-height and font-size, not the height property. Use display: inline-block or display: block to set explicit height.

Content → Padding → Border → Margin. The width/height property applies only to content; use box-sizing: border-box to include padding and border in the width calculation.

Specificity determines which rule wins when styles conflict. Order (lowest to highest): element < class/attribute < ID < inline style. Use !important as last resort (lowest priority in maintainability).

Common causes: (1) another rule has higher specificity, (2) selector is too broad/narrow, (3) CSS is overridden by inline styles or !important, (4) property doesn't apply to that element type (e.g., margin on inline), (5) typo in property name.

margin: 0 auto sets top/bottom margin to 0 and left/right to auto (centers block horizontally). margin: auto sets all four sides to auto (centers both horizontally and vertically on flex/grid containers).

Float removes an element from normal flow and wraps text around it (originally for magazine layouts). It's outdated because flexbox and CSS Grid handle layout better, more intuitively, and without the side effects of float-based clearfix hacks.

relative: positioned relative to its normal position, still takes up space. absolute: removed from flow, positioned relative to nearest positioned ancestor. fixed: removed from flow, positioned relative to viewport (stays put on scroll).

Inline styles (style attribute) are hard to override and violate separation of concerns. The cascade rule: browser defaults → external/internal CSS → inline styles → !important (opposite of normal priority). Use classes instead for maintainability.