web-platform

A small surface anchored to the control that opened it, holding content or controls of its own, and dismissed by clicking away or pressing Escape.

A CSS mechanism that tethers one element to another, sizing and placing it against its anchor and trying fallback positions when the default one would overflow.

A rule that responds to the size of a component's own container rather than the viewport, so one component adapts anywhere it is placed.

The box an element's percentages and offsets are measured against, which is not always its parent and changes with how the element is positioned.

The native masonry mechanism in CSS grid, where one axis keeps strict tracks and the other lets items stack into whichever lane has room.

Layout properties named by flow direction (inline start, block end) rather than by screen edge, so a layout mirrors itself in other writing modes.

Naming regions of a grid and drawing the layout as rows of those names, so items are placed by name instead of by line number.

How a picture or video is resized inside a box whose shape it does not match: stretched to fill, letterboxed to fit whole, or cropped to cover every edge.

Where content is cut to continue in the next fragment, a printed page, a column or a region, plus the rules that decide where the cut may fall.

A grid that decides its own column count from a minimum item width, so the same one line rule works at every screen size without a single breakpoint.

Snap positions declared on a scroll container so scrolling settles on a chosen item edge instead of stopping wherever momentum runs out.

A self contained depth ordering created by certain properties, inside which z-index only competes locally and can never escape to the level above.

A nested grid that borrows its parent's tracks instead of defining its own, so contents of separate children still line up with each other.

The layer above everything else in a document where fullscreen elements, modal dialogs and popovers render, escaping every ancestor's clipping and stacking order.

Closing a transient surface by clicking outside it or pressing Escape, without a dedicated close control being used.

Redirecting all events for one pointer to a chosen element, so a drag keeps reaching the control it started on even when it wanders off.

Hiding the cursor and reading only its movement deltas, so input keeps flowing past the edges of the screen instead of stopping at them.

Keeping the reader's position fixed when content loads or resizes above it, by adjusting scroll offset so the visible text does not jump.

When an inner scroller reaches its end and the gesture continues, the scroll passes to the page behind it unless that handoff is blocked.

Composing an animation on top of whatever is already animating the same property instead of replacing it, so a second nudge adds to the first rather than restarting it.

Whether an animation's first or last keyframe styles apply outside its running window, which decides if an element snaps back when it finishes or stays where it landed.

Animating a container between collapsed and its content's natural size, long impossible because height auto did not interpolate and now opened up by interpolate-size and calc-size().

An easing written as a list of sampled stops rather than a curve, which lets CSS express springs and bounces that no cubic bezier can describe.

An animation whose progress is bound to scroll position rather than to time, so scrolling back rewinds it exactly.

Animating a programmatic jump so the page travels to its destination instead of cutting there, which keeps an anchor link or a back-to-top button from losing the reader's place.

A scroll timeline measured by one element's passage through the scrollport, with named ranges for entering, being contained, covering, and exiting.

An animated change between two states of a page, where the browser photographs before and after and interpolates the elements the two have in common.

Reshaping a fallback font's size and vertical metrics in CSS so it occupies the same space as the web font and the swap shifts nothing.

Shipping only the characters a page actually needs, cutting the font file down and letting the browser fetch ranges on demand.

Cutting a block of text off after a fixed number of lines, with an ellipsis at the end of the last one.

Choosing line breaks so a short block of text has lines of roughly equal length instead of a long first line and a stub second one.

Cutting the leftover space above and below a line of text so the box hugs the cap height and baseline instead of the font's full ascent and descent.

A font file downloaded by the page rather than taken from the reader's device, declared in CSS and delivered like any other asset.

Whether a long unbroken string is allowed to split mid-word rather than overflow its container, and where that split may happen.

The declaration that a page or element supports light or dark rendering, which also tells the browser which palette to use for scrollbars and form controls.

A CSS function that blends two colours by a chosen percentage in a chosen colour space, so hover and disabled variants are derived rather than hand-picked.

A CSS keyword meaning the element's own text colour, letting borders, icons and fills inherit whatever colour the surrounding text happens to be.

An operating system mode that replaces a page's palette with a small user-chosen set of system colours, overriding almost everything an author specified.

A CSS function that takes two colours and returns the one matching the page's current colour scheme, collapsing a theme's light and dark values into one declaration.

A colour notation of lightness, chroma and hue built on Oklab, where changing the hue leaves the perceived lightness alone and equal steps look equal.

CSS notation that builds a new colour from an existing one by naming an origin colour with from and then adjusting individual channels.

Colour beyond what sRGB can express, addressed in CSS through spaces such as display-p3 and rec2020 and shown only on displays that reach that far.

The parallel tree a browser derives from the DOM, holding the role, name, state, and value that assistive technology actually reads.

A proposed API for speaking a message directly to assistive technology, without the live region trick of mutating hidden text and hoping the timing works out.

An attribute that removes an element and its whole subtree from the accessibility tree while leaving it visible on screen.

A focus style shown only when focus arrived by keyboard or another non-pointer route, so a mouse click does not leave a ring behind.

A state that removes a subtree from focus order, hit testing, and the accessibility tree at once, used to seal the background behind a dialog.

Reaching for the element that already means what you mean, so name, role, keyboard behaviour, and platform conventions arrive for free instead of being rebuilt.