v1.4.0

Added

• FormStateOverrides, FormStateChange, FormStateKind, StyleContext.FormState / WithFormState, InteractionState.FormState and LiveDocumentStyles.ApplyFormState: checkedness, disabledness and the indeterminate state that a user or script changed, for any number of elements, on both the snapshot path (DocumentStyles.Create / WithContext) and the live path. :checked (and an option's selectedness), :disabled, :enabled, :indeterminate, :read-only and :read-write read them, with what follows from them (a disabled fieldset or optgroup, a named radio group). The live path restyles in place with no allocation in steady state and fills ChangedElementIndices as for interaction state. Without overrides every value is as before. See docs/cascade.md.
• SelectorDependencies.ScriptFormState: set on selectors that read form state a script can change.
• PseudoElementKind.Selection and PseudoElementKind.Placeholder: GetPseudoStyle on DocumentStyles and LiveDocumentStyles now serves ::selection (highlight properties only, with highlight inheritance from the parent element) and ::placeholder (text controls with a placeholder, with Chrome's user-agent defaults; ::-webkit-input-placeholder is the same). RestyleResult.PseudoElementsMayDiffer covers both. See docs/cascade.md.
• @keyframes rules in the cascade. DocumentStyles and LiveDocumentStyles gain GetKeyframesRule(name) and KeyframesRules (the winning KeyframesRule per name, with its blocks, origin and layer), ResolveKeyframes(style, name, animationIndex) and GetAnimationKeyframes(style) (the keyframes of an element's animations with var() substituted from its custom properties, flow-relative properties mapped to physical ones, same-offset blocks merged and ordered and the element's own values added at 0% and 100%, as Chrome's getKeyframes() reports them; computed once per style, allocation-free to read again). RestyleResult.ChangedKeyframes names the rules a sheet or style edit changed. The library runs no clock and interpolates nothing. New types: KeyframesRule, KeyframeBlock, KeyframeDeclaration, ResolvedKeyframes, ResolvedKeyframe, KeyframeValue. See docs/cascade.md.
• position: running(<custom-ident>) (CSS GCPM 3) is kept as a typed value: PositionValue.Running and ComputedStyle.RunningName. The accessibility tree and the checker treat a running element as Chrome renders it, in flow.

Changed

• Rules with :checked, :disabled, :enabled, :indeterminate, :read-only or :read-write are matched again for each element's cascade instead of being cached once per document, so they can follow form state. Their values are unchanged.
• transition and animation follow Chrome 156: a CSS-wide keyword as an item of a list invalidates the declaration (transition: initial 1s, animation-name: x, inherit); a negative time is the delay, not the duration (animation: x -1s); default is not a name; auto is the animation duration; none is valid in transition only for a single layer; steps(), cubic-bezier() and linear() arguments are checked. The list longhands of both are checked item by item, so a bad item drops the declaration and an earlier one stands.
• A declaration position: running(name) that used to be dropped now wins the cascade (PositionValue gains a last member, Running).

Fixed

• A cascade that rolls declarations back (revert, revert-layer, revert-rule) reuses its working lists instead of allocating them for every element, so live restyles on such pages stay allocation-free.