Opacity Keyframes

Live demo

Code example

import {
  TimelineEngine,
  type TimelineCubicBezier,
  type TimelineKeyframeInterpolation,
  type Track,
  type ,
  Timeline,
  TimelineProvider,
  useTimeline,
  useTimelineKeyframes,
  useTimelinePlayheadTime,
  CanvasRenderer,
  fromSeconds,
  toSeconds,
} from '@techsquidtv/canvas-timeline';
import { useHTMLTimelineMedia } from '@techsquidtv/canvas-timeline-html-media-adapter';
import { Diamond, Plus, Trash2 } from 'lucide-react';
import { useCallback, useMemo, useRef, useState } from 'react';
import type { ChangeEvent, ComponentProps } from 'react';
import {
  Group as ResizablePanelGroup,
  Panel as ResizablePanel,
  Separator as ResizableHandle,
} from 'react-resizable-panels';
import type { DemoMetrics } from '../demo-instrumentation';
import {
  findClipContainingTime,
  findOpacityKeyframeNearTime,
  getOpacityValueFromClipViewportY,
  opacityKeyframeValuePadding,
  toggleOpacityKeyframeAtTime,
} from './keyframe-opacity-utils';
import {
  demoMarkers,
  demoTracks,
  opacityClipId,
  sampleDurationSeconds,
  sampleMediaUrl,
  sampleSourceId,
} from './timeline-demo-data';
import '@techsquidtv/canvas-timeline/styles.css';
import './timeline-editor.css';

const trackHeight = 64;
const keyframeSize = 6;
const keyframeValuePadding = opacityKeyframeValuePadding;
const previewLayerSelectors = {
  visuals: { trackKind: 'visual', sourceId: sampleSourceId },
} as const;

interface InterpolationPreset {
  id: string;
  label: string;
  interpolation: TimelineKeyframeInterpolation;
  easing?: TimelineCubicBezier;
}

const interpolationPresets: InterpolationPreset[] = [
  { id: 'linear', label: 'Linear', interpolation: 'linear' },
  { id: 'hold', label: 'Hold', interpolation: 'hold' },
  {
    id: 'ease',
    label: 'Ease',
    interpolation: 'bezier',
    easing: { x1: 0.42, y1: 0, x2: 0.58, y2: 1 },
  },
  {
    id: 'ease-out',
    label: 'Out',
    interpolation: 'bezier',
    easing: { x1: 0.16, y1: 1, x2: 0.3, y2: 1 },
  },
];

function getInterpolationPresetId(
  interpolation: TimelineKeyframeInterpolation | undefined,
  easing: TimelineCubicBezier | undefined
) {
  if (interpolation === 'hold') {
    return 'hold';
  }
  if (interpolation !== 'bezier') {
    return 'linear';
  }

  const matchedPreset = interpolationPresets.find(
    (preset) =>
      preset.interpolation === 'bezier' &&
      preset.easing?.x1 === easing?.x1 &&
      preset.easing?.y1 === easing?.y1 &&
      preset.easing?.x2 === easing?.x2 &&
      preset.easing?.y2 === easing?.y2
  );
  return matchedPreset?.id ?? 'ease';
}

function TrackKeyframeButton({
  track,
  label,
  locked,
}: {
  track: Track | null;
  label: string;
  locked: boolean;
}) {
  const { engine } = useTimeline();
  const playheadTime = useTimelinePlayheadTime();
  const clip = track ? findClipContainingTime(track, playheadTime) : null;
  const existingKeyframe = clip
    ? findOpacityKeyframeNearTime(clip, playheadTime, engine.zoomScale)
    : null;
  const evaluatedOpacity = clip
    ? (engine.getClipPropertyValueAtTime(clip.id, 'opacity', playheadTime) ?? clip.opacity ?? 1)
    : 1;
  const disabled = locked || !clip;

  const handleToggle = useCallback(() => {
    if (!clip || disabled) {
      return;
    }
    toggleOpacityKeyframeAtTime(engine, clip.id, playheadTime, evaluatedOpacity);
  }, [clip, disabled, engine, evaluatedOpacity, playheadTime]);

  return (
    <button
      type="button"
      className="timeline-editor-track-header-button timeline-editor-keyframe-button"
      onClick={handleToggle}
      disabled={disabled}
      title={
        existingKeyframe
          ? `Remove opacity keyframe from ${label}`
          : `Add opacity keyframe to ${label}`
      }
      aria-label={
        existingKeyframe
          ? `Remove opacity keyframe from ${label}`
          : `Add opacity keyframe to ${label}`
      }
      aria-pressed={Boolean(existingKeyframe)}
    >
      <Diamond aria-hidden="true" />
    </button>
  );
}

function TrackHeaderColumn() {
  const { state } = useTimeline();

  return (
    <Timeline.TrackHeaderList className="timeline-editor-track-headers">
      {state.tracks.map((track) => (
        <Timeline.TrackHeader key={track.id} trackId={track.id} geometry={{ trackHeight }}>
          {(header) => (
            <div className="timeline-editor-track-header-content timeline-editor-keyframe-track-header-content">
              <TrackKeyframeButton
                track={header.track}
                label={header.label}
                locked={header.locked}
              />
              <span className="timeline-editor-track-header-label">{header.label}</span>
              <Timeline.TrackHeaderResizeHandle trackId={track.id} />
            </div>
          )}
        </Timeline.TrackHeader>
      ))}
    </Timeline.TrackHeaderList>
  );
}

function TimelineLayers({
  onClipDoubleClick,
  onKeyframeDelete,
  onKeyframeDoubleClick,
}: {
  onClipDoubleClick: ComponentProps<typeof Timeline.ClipInteractionLayer>['onClipDoubleClick'];
  onKeyframeDelete: ComponentProps<typeof Timeline.KeyframeInteractionLayer>['onKeyframeDelete'];
  onKeyframeDoubleClick: ComponentProps<
    typeof Timeline.KeyframeInteractionLayer
  >['onKeyframeDoubleClick'];
}) {
  const { state } = useTimeline();

  return (
    <>
      <Timeline.PlayheadArea />
      <Timeline.PlayheadGrabber />
      <Timeline.TrackList className="timeline-track-list-overlay">
        {state.tracks.map((track) => (
          <Timeline.Track key={track.id} trackId={track.id} />
        ))}
      </Timeline.TrackList>
      <Timeline.ClipInteractionLayer
        trackHeight={trackHeight}
        onClipDoubleClick={onClipDoubleClick}
      />
      <Timeline.KeyframeInteractionLayer
        property="opacity"
        selectedClipOnly
        trackHeight={trackHeight}
        keyframeSize={keyframeSize}
        keyframeValuePadding={keyframeValuePadding}
        onKeyframeDelete={onKeyframeDelete}
        onKeyframeDoubleClick={onKeyframeDoubleClick}
      />
      <Timeline.KeyframeCurveInteractionLayer
        property="opacity"
        selectedClipOnly
        selectedKeyframeOnly
        trackHeight={trackHeight}
        keyframeSize={keyframeSize}
        curveHandleSize={7}
        keyframeValuePadding={keyframeValuePadding}
      />
      <Timeline.RangeSelector />
    </>
  );
}

function formatSeconds(seconds: number) {
  return `${seconds.toFixed(2)}s`;
}

function KeyframeOpacitySurface({ metrics }: { metrics?: DemoMetrics }) {
  const playheadTime = useTimelinePlayheadTime();
  const videoRef = useRef<HTMLVideoElement>(null);
  const [playbackError, setPlaybackError] = useState<string | null>(null);
  const sources = useMemo(
    () => ({
      [sampleSourceId]: sampleMediaUrl,
    }),
    []
  );
  const keyframes = useTimelineKeyframes({
    clipId: opacityClipId,
    property: 'opacity',
    selectedClipOnly: true,
    trackHeight,
    keyframeSize,
    keyframeValuePadding,
  });
  const selectedKeyframe = keyframes.keyframes.find((keyframe) => keyframe.selected);
  const evaluatedOpacity =
    keyframes.getPropertyValueAtTime(opacityClipId, 'opacity', playheadTime) ?? 1;
  const sliderValue = selectedKeyframe?.value ?? evaluatedOpacity;
  const activeTime = selectedKeyframe?.time ?? playheadTime;
  const interpolationPresetId = selectedKeyframe
    ? getInterpolationPresetId(selectedKeyframe.interpolation, selectedKeyframe.easing)
    : null;
  const { playing, play, pause, ready } = useHTMLTimelineMedia({
    ref: videoRef,
    sources,
    layers: previewLayerSelectors,
    onError: (message: string) => {
      metrics?.onMediaLoadFailed?.({
        demoId: 'keyframe-opacity',
        adapter: 'html-media',
        mediaType: 'video',
      });
      setPlaybackError(message);
    },
  });

  const handlePlayPause = useCallback(async () => {
    if (playing) {
      pause();
      setPlaybackError(null);
      return;
    }

    const result = await play();
    setPlaybackError(result.ok ? null : result.message);
  }, [pause, play, playing]);

  const handleSetKeyframe = useCallback(() => {
    keyframes.setKeyframe({
      clipId: opacityClipId,
      property: 'opacity',
      time: playheadTime,
      value: evaluatedOpacity,
    });
  }, [evaluatedOpacity, keyframes, playheadTime]);

  const handleDeleteKeyframe = useCallback(() => {
    if (!selectedKeyframe) {
      return;
    }

    keyframes.removeKeyframe(opacityClipId, selectedKeyframe.id);
  }, [keyframes, selectedKeyframe]);

  const handleSetInterpolationPreset = useCallback(
    (preset: InterpolationPreset) => {
      if (!selectedKeyframe) {
        return;
      }

      keyframes.updateKeyframe({
        clipId: opacityClipId,
        keyframeId: selectedKeyframe.id,
        interpolation: preset.interpolation,
        easing: preset.easing,
      });
    },
    [keyframes, selectedKeyframe]
  );

  const handleClipDoubleClick = useCallback<
    NonNullable<ComponentProps<typeof Timeline.ClipInteractionLayer>['onClipDoubleClick']>
  >((hit, details) => {
    const value = getOpacityValueFromClipViewportY(hit, details.viewportY);
    toggleOpacityKeyframeAtTime(details.engine, hit.clip.id, details.time, value);
  }, []);

  const handleKeyframeDoubleClick = useCallback<
    NonNullable<ComponentProps<typeof Timeline.KeyframeInteractionLayer>['onKeyframeDoubleClick']>
  >(
    (entry) => {
      keyframes.removeKeyframe(entry.clip.id, entry.keyframe.id);
    },
    [keyframes]
  );

  const handleKeyframeDelete = useCallback<
    NonNullable<ComponentProps<typeof Timeline.KeyframeInteractionLayer>['onKeyframeDelete']>
  >(
    (entry) => {
      keyframes.removeKeyframe(entry.clip.id, entry.keyframe.id);
    },
    [keyframes]
  );

  const handleOpacityChange = useCallback(
    (event: ChangeEvent<HTMLInputElement>) => {
      const value = Number(event.currentTarget.value);
      if (!Number.isFinite(value)) {
        return;
      }

      if (selectedKeyframe) {
        keyframes.updateKeyframe({
          clipId: opacityClipId,
          keyframeId: selectedKeyframe.id,
          value,
        });
        return;
      }

      keyframes.setKeyframe({
        clipId: opacityClipId,
        property: 'opacity',
        time: playheadTime,
        value,
      });
    },
    [keyframes, playheadTime, selectedKeyframe]
  );

  return (
    <div className="media-sync-demo keyframe-opacity-demo">
      <div className="media-sync-preview keyframe-opacity-preview">
        <div className="media-sync-monitor keyframe-opacity-monitor">
          <video
            ref={videoRef}
            className="media-sync-video keyframe-opacity-video"
            preload="metadata"
            playsInline
            muted
            aria-label="Opacity keyframe preview"
            style={{ opacity: evaluatedOpacity }}
          />
          <button
            type="button"
            className="media-sync-button media-sync-play-button"
            onClick={handlePlayPause}
            disabled={!ready}
          >
            {playing ? 'Pause' : 'Play'}
          </button>
        </div>
        <section
          className="media-sync-panel keyframe-opacity-panel"
          aria-label="Opacity keyframe controls"
        >
          <h3>Opacity Keyframes</h3>
          <p className="media-sync-status keyframe-opacity-status">
            {playbackError ?? (ready ? 'Ready' : 'Loading media')}
          </p>
          <dl className="media-sync-readout keyframe-opacity-readout">
            <dt>Timeline position</dt>
            <dd>{formatSeconds(toSeconds(playheadTime))}</dd>
            <dt>Opacity</dt>
            <dd>{Math.round(sliderValue * 100)}%</dd>
            <dt>{selectedKeyframe ? 'Selected keyframe' : 'Active time'}</dt>
            <dd>{formatSeconds(toSeconds(activeTime))}</dd>
            <dt>Curve</dt>
            <dd>
              {selectedKeyframe
                ? interpolationPresets.find((preset) => preset.id === interpolationPresetId)?.label
                : 'None'}
            </dd>
          </dl>
          <input
            className="keyframe-opacity-slider"
            type="range"
            min="0"
            max="1"
            step="0.01"
            value={sliderValue}
            aria-label="Opacity"
            onChange={handleOpacityChange}
          />
          <div className="keyframe-opacity-curve-controls" aria-label="Interpolation">
            {interpolationPresets.map((preset) => (
              <button
                key={preset.id}
                type="button"
                className="media-sync-button keyframe-opacity-curve-button"
                onClick={() => {
                  handleSetInterpolationPreset(preset);
                }}
                disabled={!selectedKeyframe}
                aria-pressed={interpolationPresetId === preset.id}
              >
                {preset.label}
              </button>
            ))}
          </div>
          <div className="media-sync-controls keyframe-opacity-actions">
            <button
              type="button"
              className="media-sync-button keyframe-opacity-button"
              onClick={handleSetKeyframe}
              title="Set opacity keyframe"
            >
              <Plus aria-hidden="true" />
              Set
            </button>
            <button
              type="button"
              className="media-sync-button keyframe-opacity-button"
              onClick={handleDeleteKeyframe}
              disabled={!selectedKeyframe}
              title="Delete selected keyframe"
            >
              <Trash2 aria-hidden="true" />
              Delete
            </button>
          </div>
        </section>
      </div>

      <div className="timeline-shell timeline-editor-controls-shell keyframe-opacity-timeline-shell">
        <ResizablePanelGroup
          className="timeline-editor-body-with-headers"
          orientation="horizontal"
          resizeTargetMinimumSize={{ coarse: 28, fine: 8 }}
        >
          <ResizablePanel
            defaultSize="7.75rem"
            groupResizeBehavior="preserve-pixel-size"
            maxSize="16rem"
            minSize="7.75rem"
          >
            <div className="timeline-editor-header-panel">
              <div className="timeline-stage timeline-editor-header-stage">
                <TrackHeaderColumn />
              </div>
            </div>
          </ResizablePanel>

          <ResizableHandle
            aria-label="Resize track header column"
            className="timeline-editor-column-resize-handle"
          />

          <ResizablePanel minSize="0">
            <div className="timeline-editor-timeline-panel">
              <div className="timeline-editor-stage-row">
                <div className="timeline-stage timeline-editor-timeline-stage">
                  <Timeline.Root className="timeline-fill timeline-editor-root-with-headers">
                    <CanvasRenderer showClipLabels={false} />
                    <TimelineLayers
                      onClipDoubleClick={handleClipDoubleClick}
                      onKeyframeDelete={handleKeyframeDelete}
                      onKeyframeDoubleClick={handleKeyframeDoubleClick}
                    />
                  </Timeline.Root>
                </div>
                <div className="timeline-editor-vertical-scrollbar-column">
                  <Timeline.VerticalScrollbar className="timeline-editor-vertical-scrollbar">
                    <Timeline.VerticalScrollbarThumb className="timeline-editor-vertical-scrollbar-thumb">
                      <Timeline.VerticalScrollbarHandle side="start" />
                      <Timeline.VerticalScrollbarHandle side="end" />
                    </Timeline.VerticalScrollbarThumb>
                  </Timeline.VerticalScrollbar>
                </div>
              </div>
              <div className="timeline-scrollbar-row timeline-editor-scrollbar-row">
                <Timeline.ViewportScrollbar>
                  <Timeline.ViewportScrollbarThumb>
                    <Timeline.ViewportScrollbarHandle side="start" />
                    <Timeline.ViewportScrollbarHandle side="end" />
                  </Timeline.ViewportScrollbarThumb>
                </Timeline.ViewportScrollbar>
              </div>
            </div>
          </ResizablePanel>
        </ResizablePanelGroup>
      </div>
    </div>
  );
}

export function KeyframeOpacityTimeline({ metrics }: { metrics?: DemoMetrics }) {
  const engine = useMemo(
    () =>
      new TimelineEngine({
        duration: fromSeconds(sampleDurationSeconds),
        playheadTime: fromSeconds(0),
        zoomScale: 32,
        tracks: demoTracks,
        markers: demoMarkers,
      }),
    []
  );

  return (
    <TimelineProvider engine={engine}>
      <KeyframeOpacitySurface metrics={metrics} />
    </TimelineProvider>
  );
}

const demoClipColors = [
  'oklch(0.62 0.16 250)',
  'oklch(0.68 0.14 145)',
  'oklch(0.72 0.16 70)',
  'oklch(0.65 0.17 25)',
  'oklch(0.58 0.18 305)',
  'oklch(0.64 0.12 195)',
] as const;

export function getDemoClipColor(index: number) {
  return demoClipColors[index % demoClipColors.length];
}

import {
  type Clip,
  type ClipHitTestResult,
  type TimelineEngine,
  type TimelineKeyframe,
  type Track,
  type ,
  toSeconds,
  type RationalTime,
} from '@techsquidtv/canvas-timeline';

export const opacityKeyframeValuePadding = 10;
const opacityKeyframeToggleRadiusPixels = 10;

export function findClipContainingTime(track: Track, time: RationalTime): Clip | null {
  const seconds = toSeconds(time);
  return (
    track.clips.find(
      (clip) => toSeconds(clip.timelineStart) <= seconds && toSeconds(clip.timelineEnd) >= seconds
    ) ?? null
  );
}

export function findOpacityKeyframeNearTime(
  clip: Clip,
  time: RationalTime,
  zoomScale: number
): TimelineKeyframe | null {
  const toleranceSeconds = opacityKeyframeToggleRadiusPixels / Math.max(1, zoomScale);
  const seconds = toSeconds(time);
  return (
    (clip.keyframes ?? []).find(
      (keyframe) =>
        keyframe.property === 'opacity' &&
        Math.abs(toSeconds(keyframe.time) - seconds) <= toleranceSeconds
    ) ?? null
  );
}

export function getOpacityValueFromClipViewportY(
  hit: ClipHitTestResult,
  viewportY: number
): number {
  const usableHeight = Math.max(1, hit.rect.height - opacityKeyframeValuePadding * 2);
  const ratio = Math.max(
    0,
    Math.min(1, (viewportY - hit.rect.y - opacityKeyframeValuePadding) / usableHeight)
  );
  return 1 - ratio;
}

export function toggleOpacityKeyframeAtTime(
  engine: TimelineEngine,
  clipId: string,
  time: RationalTime,
  value: number
): boolean {
  const found = engine.getClip(clipId);
  if (!found || found.track.locked) {
    return false;
  }

  const existing = findOpacityKeyframeNearTime(found.clip, time, engine.zoomScale);
  if (existing) {
    return engine.removeClipKeyframe(clipId, existing.id);
  }

  // Omitting interpolation lets new keyframes inherit the previous keyframe's
  // interpolation mode and easing, keeping the segment's curve character.
  return Boolean(
    engine.setClipKeyframe({
      clipId,
      property: 'opacity',
      time,
      value,
    })
  );
}

import { type Marker, type Track, fromSeconds } from '@techsquidtv/canvas-timeline';
import { getDemoClipColor } from '../demo-clip-colors';

export const sampleSourceId = 'big-buck-bunny-keyframe-preview';

export const sampleMediaUrl = '/demo-media/big-buck-bunny-preview.webm';
export const sampleDurationSeconds = 24;
export const opacityClipId = 'opacity-demo-clip';

export const demoTracks: Track<'visual'>[] = [
  {
    id: 'opacity-video-track',
    kind: 'visual',
    name: 'Opacity',
    locked: false,
    muted: false,
    visible: true,
    selected: true,
    targeted: true,
    height: 64,
    clips: [
      {
        id: opacityClipId,
        sourceId: sampleSourceId,
        timelineStart: fromSeconds(0),
        timelineEnd: fromSeconds(sampleDurationSeconds),
        sourceStart: fromSeconds(0),
        selected: true,
        color: getDemoClipColor(1),
        label: 'Opacity keyframes',
        keyframes: [
          {
            id: 'opacity-kf-0',
            property: 'opacity',
            time: fromSeconds(0),
            value: 1,
            interpolation: 'linear',
          },
          {
            id: 'opacity-kf-1',
            property: 'opacity',
            time: fromSeconds(5),
            value: 0.28,
            interpolation: 'linear',
          },
          {
            id: 'opacity-kf-2',
            property: 'opacity',
            time: fromSeconds(10),
            value: 0.82,
            interpolation: 'bezier',
            easing: { x1: 0.16, y1: 1, x2: 0.3, y2: 1 },
          },
          {
            id: 'opacity-kf-3',
            property: 'opacity',
            time: fromSeconds(15),
            value: 0.42,
            interpolation: 'linear',
          },
          {
            id: 'opacity-kf-4',
            property: 'opacity',
            time: fromSeconds(sampleDurationSeconds),
            value: 1,
            interpolation: 'linear',
          },
        ],
      },
    ],
  },
];

export const demoMarkers: Marker[] = [
  {
    id: 'fade-down',
    time: fromSeconds(5),
    label: 'Fade',
  },
  {
    id: 'hold-step',
    time: fromSeconds(10),
    label: 'Peak',
  },
];

.timeline-editor-body-with-headers {
  --demo-editor-scrollbar-gutter-size: 1.5rem;
  --demo-editor-scrollbar-track-size: 0.625rem;
  --demo-editor-scrollbar-gutter-padding: calc(
    (var(--demo-editor-scrollbar-gutter-size) - var(--demo-editor-scrollbar-track-size)) / 2
  );
  --demo-editor-scrollbar-gutter-padding-inline: calc(
    (var(--demo-editor-scrollbar-gutter-size) - var(--demo-editor-scrollbar-track-size) - 2px) / 2
  );
  --demo-editor-scrollbar-surface: var(--background);

  width: 100%;
  min-width: 0;
  min-height: 0;
  overflow: hidden;
}

.timeline-editor-header-panel,
.timeline-editor-timeline-panel {
  display: grid;
  min-width: 0;
  min-height: 0;
  height: 100%;
  grid-template-rows: minmax(0, 1fr) auto;
  overflow: hidden;
}

.timeline-editor-header-stage {
  min-height: 0;
  overflow: hidden;
}

.timeline-editor-timeline-stage {
  min-height: 0;
}

.timeline-editor-stage-row {
  display: grid;
  min-width: 0;
  min-height: 0;
  grid-template-columns: minmax(0, 1fr) auto;
}

.timeline-editor-vertical-scrollbar-column {
  box-sizing: border-box;
  display: flex;
  width: var(--demo-editor-scrollbar-gutter-size);
  min-height: 0;
  align-items: stretch;
  justify-content: center;
  background: var(--demo-editor-scrollbar-surface);
  padding-block: var(--demo-editor-scrollbar-gutter-padding);
  padding-inline: var(--demo-editor-scrollbar-gutter-padding-inline);
}

.timeline-editor-vertical-scrollbar {
  width: var(--demo-editor-scrollbar-track-size);
  min-height: 0;
}

.timeline-editor-track-headers {
  width: 100%;
  height: 100%;
}

.timeline-editor-root-with-headers .timeline-track-list-overlay {
  inset: 0;
}

.timeline-editor-track-header-content {
  display: grid;
  width: 100%;
  min-width: 0;
  align-items: center;
  gap: 0.3rem;
}

.timeline-editor-track-header-button {
  display: inline-grid;
  width: 1.45rem;
  height: 1.45rem;
  place-items: center;
  padding: 0;
  border: 1px solid color-mix(in oklch, var(--foreground) 10%, transparent);
  border-radius: calc(var(--radius) - 0.125rem);
  background: color-mix(in oklch, var(--background) 80%, transparent);
  color: var(--muted-foreground);
  cursor: pointer;
  transition:
    border-color 150ms ease,
    color 150ms ease,
    background-color 150ms ease,
    opacity 150ms ease;
}

.timeline-editor-track-header-button svg {
  width: 0.85rem;
  height: 0.85rem;
}

.timeline-editor-track-header-button:hover,
.timeline-editor-track-header-button[aria-pressed='true'] {
  border-color: color-mix(in oklch, var(--primary) 55%, transparent);
  background: color-mix(in oklch, var(--primary) 12%, var(--background));
  color: var(--foreground);
}

.timeline-editor-track-header-button:disabled,
.timeline-editor-track-header-button:disabled:hover {
  cursor: not-allowed;
  opacity: 0.52;
}

.timeline-editor-track-header-label {
  min-width: 0;
  justify-self: start;
  overflow: hidden;
  color: var(--foreground);
  font-size: 0.7rem;
  text-align: left;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.timeline-editor-scrollbar-row {
  display: grid;
  min-height: var(--demo-editor-scrollbar-gutter-size);
  grid-template-columns: minmax(0, 1fr) var(--demo-editor-scrollbar-gutter-size);
  padding: 0;
  background: var(--demo-editor-scrollbar-surface);
}

.timeline-editor-scrollbar-row .timeline-viewport-scrollbar {
  width: auto;
  min-width: 0;
  height: var(--demo-editor-scrollbar-track-size);
  align-self: center;
  margin-inline: var(--demo-editor-scrollbar-gutter-padding);
}

.timeline-editor-scrollbar-row .timeline-viewport-scrollbar-handle {
  width: var(--demo-editor-scrollbar-track-size);
}

.timeline-editor-column-resize-handle {
  position: relative;
  width: 0.8rem;
  flex: 0 0 0.8rem;
  background: var(--muted);
  cursor: col-resize;
  outline: none;
}

.timeline-editor-column-resize-handle::before {
  position: absolute;
  inset-block: 0;
  left: 50%;
  width: 2px;
  background: var(--border);
  content: '';
  transform: translateX(-50%);
  transition:
    background-color 150ms ease,
    box-shadow 150ms ease;
}

.timeline-editor-column-resize-handle:hover::before,
.timeline-editor-column-resize-handle:focus-visible::before,
.timeline-editor-column-resize-handle[data-resize-handle-active]::before {
  background: var(--primary);
  box-shadow: 0 0 0 2px color-mix(in oklch, var(--primary) 28%, transparent);
}

.media-sync-demo {
  display: grid;
  gap: 1rem;
  margin-top: 1rem;
}

.media-sync-preview {
  display: grid;
  grid-template-columns: minmax(0, 1.1fr) minmax(16rem, 0.55fr);
  align-items: stretch;
  gap: 1rem;
}

.media-sync-monitor,
.media-sync-panel {
  overflow: hidden;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--card);
  color: var(--foreground);
}

.media-sync-monitor {
  position: relative;
  display: grid;
  min-height: 18rem;
  background: var(--muted);
}

.media-sync-canvas,
.media-sync-video {
  width: 100%;
  height: 100%;
  min-height: 18rem;
  object-fit: contain;
  background: var(--muted);
}

.media-sync-panel {
  display: grid;
  align-content: start;
  gap: 0.8rem;
  padding: 1rem;
}

.media-sync-panel h3 {
  margin: 0;
  font-size: 0.95rem;
}

.media-sync-status {
  margin: 0;
  color: var(--muted-foreground);
  font-size: 0.85rem;
  line-height: 1.45;
}

.media-sync-readout {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 0.35rem 0.7rem;
  margin: 0;
  font-size: 0.8rem;
}

.media-sync-readout dt {
  color: var(--muted-foreground);
}

.media-sync-readout dd {
  margin: 0;
  color: var(--foreground);
  font-family: var(--font-mono);
}

.media-sync-controls {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.media-sync-button {
  min-height: 2.15rem;
  padding: 0.4rem 0.75rem;
  border: 1px solid var(--input);
  border-radius: calc(var(--radius) - 0.25rem);
  background: var(--background);
  color: var(--foreground);
  cursor: pointer;
  font: inherit;
  font-size: 0.82rem;
  transition:
    background-color 150ms ease,
    border-color 150ms ease,
    color 150ms ease;
}

.media-sync-button:hover {
  border-color: var(--foreground);
  background: var(--accent);
  color: var(--accent-foreground);
}

.media-sync-button:disabled {
  cursor: not-allowed;
  opacity: 0.45;
}

.media-sync-button-active,
.media-sync-button-active:hover {
  border-color: var(--foreground);
  background: var(--foreground);
  color: var(--background);
}

.media-sync-play-button {
  position: absolute;
  bottom: 1rem;
  left: 1rem;
  z-index: 2;
  min-width: 4.8rem;
  background: color-mix(in oklch, var(--background) 84%, transparent);
  box-shadow: 0 0.75rem 1.75rem color-mix(in oklch, var(--foreground) 24%, transparent);
  backdrop-filter: blur(10px);
}

.keyframe-opacity-demo {
  min-width: 0;
}

.keyframe-opacity-preview {
  min-width: 0;
}

.keyframe-opacity-monitor {
  background:
    linear-gradient(
      45deg,
      color-mix(in oklch, var(--foreground) 8%, transparent) 25%,
      transparent 25%
    ),
    linear-gradient(
      -45deg,
      color-mix(in oklch, var(--foreground) 8%, transparent) 25%,
      transparent 25%
    ),
    linear-gradient(
      45deg,
      transparent 75%,
      color-mix(in oklch, var(--foreground) 8%, transparent) 75%
    ),
    linear-gradient(
      -45deg,
      transparent 75%,
      color-mix(in oklch, var(--foreground) 8%, transparent) 75%
    ),
    var(--card);
  background-position:
    0 0,
    0 8px,
    8px -8px,
    -8px 0;
  background-size: 16px 16px;
}

.keyframe-opacity-video {
  background: transparent;
}

.keyframe-opacity-panel {
  min-width: 0;
}

.keyframe-opacity-readout {
  font-variant-numeric: tabular-nums;
}

.keyframe-opacity-actions {
  align-items: center;
}

.keyframe-opacity-curve-controls {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 0.35rem;
}

.keyframe-opacity-curve-button {
  min-width: 0;
  min-height: 1.8rem;
  padding-inline: 0.45rem;
  font-size: 0.74rem;
}

.keyframe-opacity-curve-button[aria-pressed='true'],
.keyframe-opacity-curve-button[aria-pressed='true']:hover {
  border-color: var(--foreground);
  background: var(--foreground);
  color: var(--background);
}

.keyframe-opacity-button {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
}

.keyframe-opacity-button svg {
  width: 0.85rem;
  height: 0.85rem;
}

.keyframe-opacity-slider {
  width: 100%;
  height: 4px;
  appearance: none;
  border-radius: 9999px;
  background: var(--border);
  outline: none;
}

.keyframe-opacity-slider::-webkit-slider-thumb {
  width: 14px;
  height: 14px;
  appearance: none;
  border: 2px solid var(--card);
  border-radius: 9999px;
  background: var(--primary);
  cursor: pointer;
}

.keyframe-opacity-slider::-moz-range-thumb {
  width: 14px;
  height: 14px;
  border: 2px solid var(--card);
  border-radius: 9999px;
  background: var(--primary);
  cursor: pointer;
}

.keyframe-opacity-status {
  min-height: 1.2em;
}

.keyframe-opacity-timeline-shell {
  --demo-editor-shell-height: 12rem;
  width: 100%;
  max-width: 100%;
  height: var(--demo-editor-shell-height);
  min-height: 0;
}

.keyframe-opacity-timeline-shell .timeline-stage {
  min-height: 0;
}

.timeline-editor-keyframe-track-header-content {
  grid-template-columns: auto minmax(0, 1fr) auto;
}

.timeline-editor-keyframe-button[aria-pressed='true'] svg {
  fill: currentcolor;
}

@media (max-width: 720px) {
  .keyframe-opacity-preview {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 820px) {
  .media-sync-preview {
    grid-template-columns: minmax(0, 1fr);
  }
}