/* Pastel blue/pink theme — palette anchored to assets/logo.svg's own
   gradient (#a7d8f0 light blue -> #f4b8d0 pink, on a #fdf6fa -> #eef7fb
   near-white background), not picked independently. Blue and pink are
   deepened slightly from the logo's literal values specifically where
   they're used as button/text-on-light colors, so contrast against the
   light background stays real (WCAG-checked by eye against the ~4.5:1
   bar for body text) rather than just inverting the old dark palette.
   The piano keyboard, staff, and falling-note highway keep a dark
   "stage" background on purpose — those need strong white/black key
   contrast regardless of the page theme, the same way a dark stage
   floor under real piano keys doesn't clash with a bright room. */
:root {
  --hk-bg: #fdf6fa;
  --hk-bg-2: #eef7fb;
  --hk-panel: #ffffff;
  --hk-border: #dce8f0;
  --hk-accent: #4a9bc9;       /* deepened from logo's #a7d8f0 for contrast as a button/text color */
  --hk-accent-soft: #a7d8f0;  /* the logo's literal light blue, for soft fills/backgrounds */
  --hk-accent-2: #d9678f;     /* deepened from logo's #f4b8d0 for contrast */
  --hk-accent-2-soft: #f4b8d0; /* the logo's literal pink, for soft fills/backgrounds */
  --hk-text: #2a2a3a;
  --hk-text-dim: #6b6478;
  --hk-danger: #c6476d;
  --hk-warn: #c98a2e;
  --hk-stage-bg: #201d2b;     /* dark backdrop reserved for keyboard/staff/highway only */
  --hk-purple: #8a63d2;       /* deliberate "completed" accent for the lesson timeline (item 22) —
                                  distinct from the blue/pink base theme on purpose, not a reversion of it */
  --hk-purple-soft: #ece4fb;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: linear-gradient(135deg, var(--hk-bg), var(--hk-bg-2));
  background-attachment: fixed;
  color: var(--hk-text);
  min-height: 100vh;
}

.hk-header {
  padding: 24px 20px 8px;
  text-align: center;
}
.hk-logo { width: 64px; height: 64px; display: block; margin: 0 auto 8px; }
.hk-header h1 {
  margin: 0;
  font-size: 2rem;
  background: linear-gradient(90deg, var(--hk-accent), var(--hk-accent-2));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.hk-tagline { color: var(--hk-text-dim); margin: 4px 0 0; }

.hk-tabs {
  display: flex;
  justify-content: center;
  gap: 8px;
  padding: 16px 0;
  flex-wrap: wrap;
}
.hk-tab {
  background: var(--hk-panel);
  color: var(--hk-text-dim);
  border: 1px solid transparent;
  padding: 10px 20px;
  border-radius: 999px;
  cursor: pointer;
  font-size: 0.95rem;
}
.hk-tab-active {
  color: var(--hk-text);
  border-color: var(--hk-accent);
  background: rgba(74, 155, 201, 0.15);
}

main { max-width: 960px; margin: 0 auto; padding: 0 16px 60px; }
.hk-panel { min-height: 300px; }
.hk-hidden { display: none !important; }

.hk-footer {
  text-align: center;
  color: var(--hk-text-dim);
  font-size: 0.8rem;
  padding: 20px;
}
.hk-footer a { color: var(--hk-accent-2); }
.hk-footer-link {
  background: none; border: none; padding: 0; font: inherit; cursor: pointer;
  color: var(--hk-accent-2); text-decoration: underline;
}

/* Buttons */
.hk-btn {
  background: var(--hk-panel);
  color: var(--hk-text);
  border: 1px solid var(--hk-border);
  padding: 10px 16px;
  border-radius: 8px;
  cursor: pointer;
  font-size: 0.9rem;
  margin: 4px 4px 4px 0;
}
.hk-btn:hover { border-color: var(--hk-accent); }
.hk-btn-primary { background: var(--hk-accent); border-color: var(--hk-accent); }
.hk-btn-small { padding: 6px 10px; font-size: 0.8rem; }
.hk-btn-danger { border-color: var(--hk-danger); color: var(--hk-danger); }

/* Discover */
.hk-discover-controls { display: flex; gap: 8px; margin: 16px 0; flex-wrap: wrap; }
.hk-discover-controls input, .hk-discover-controls select {
  background: var(--hk-panel); color: var(--hk-text); border: 1px solid var(--hk-border);
  padding: 10px; border-radius: 8px; font-size: 0.9rem;
}
.hk-discover-controls input { flex: 1; min-width: 200px; }
.hk-upload-banner {
  background: var(--hk-panel); border-radius: 10px; padding: 16px; margin: 10px 0;
}
.hk-upload-banner h3 { margin: 0 0 10px; color: var(--hk-accent-2); }
.hk-upload-banner input[type="file"] { margin-bottom: 8px; }
/* Prominent, always-first banner at the top of Discover (item 25) */
.hk-upload-banner-top {
  background: linear-gradient(135deg, var(--hk-accent-soft), var(--hk-accent-2-soft));
  border: none; margin: 0 0 16px; padding: 20px;
}
.hk-upload-banner-top h2 { margin: 0 0 8px; color: var(--hk-text); }
.hk-upload-banner-top input[type="file"] {
  background: var(--hk-panel); border-radius: 8px; padding: 8px; display: block; width: 100%;
}
.hk-scope-note {
  background: rgba(232, 184, 75, 0.1); border: 1px solid var(--hk-warn);
  padding: 12px; border-radius: 8px; font-size: 0.85rem; color: var(--hk-text-dim);
}
.hk-song-grid {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 12px; margin-top: 16px;
}
.hk-song-card {
  background: var(--hk-panel); border-radius: 10px; padding: 14px;
  border: 1px solid var(--hk-border);
  display: flex; gap: 12px;
}
.hk-song-art-slot { flex: 0 0 64px; width: 64px; height: 64px; border-radius: 8px; overflow: hidden; }
.hk-song-art-fallback {
  display: flex; align-items: center; justify-content: center; font-size: 1.6rem;
  background: var(--hk-accent-soft);
}
.hk-song-art { width: 100%; height: 100%; object-fit: cover; display: block; }
.hk-song-card-body { flex: 1 1 auto; min-width: 0; }
.hk-song-chords-glance { font-family: monospace; font-size: 0.85rem; color: var(--hk-accent); margin: 0 0 4px; }
.hk-song-card-top { display: flex; justify-content: space-between; align-items: start; gap: 8px; }
.hk-song-card h3 { margin: 0 0 4px; font-size: 1.05rem; }
.hk-song-artist, .hk-song-key { margin: 2px 0; color: var(--hk-text-dim); font-size: 0.85rem; }
.hk-song-chords { font-family: monospace; margin: 8px 0 4px; }
.hk-song-degrees { color: var(--hk-text-dim); font-size: 0.8rem; }
.hk-song-notes { font-size: 0.78rem; color: var(--hk-text-dim); }

.hk-badge {
  display: inline-block; font-size: 0.7rem; padding: 3px 8px; border-radius: 999px;
  background: var(--hk-border); color: var(--hk-text);
}
.hk-badge-confirmed { background: rgba(46, 160, 110, 0.15); color: #2e8f5e; }
.hk-badge-unverified { background: rgba(201, 138, 46, 0.15); color: var(--hk-warn); cursor: help; }
.hk-badge-match { background: rgba(74, 155, 201, 0.18); color: var(--hk-accent); margin-left: 6px; }
.hk-badge-advanced { background: rgba(198, 71, 109, 0.15); color: var(--hk-danger); margin-right: 4px; }
.hk-song-card-advanced { border-color: var(--hk-danger); }

/* Difficulty tiers */
.hk-badge-beginner { background: rgba(46, 160, 110, 0.15); color: #2e8f5e; }
.hk-badge-intermediate { background: rgba(74, 155, 201, 0.18); color: var(--hk-accent); }
.hk-badge-advanced-tier { background: rgba(217, 103, 143, 0.18); color: var(--hk-accent-2); }
.hk-tier-progress { font-size: 0.78rem; color: var(--hk-text-dim); margin: 8px 0 0; }
.hk-tier-status { }
.hk-tier-unlocked { color: #2e8f5e; }
.hk-song-card-locked {
  opacity: 0.75; display: flex; flex-direction: column; justify-content: center;
  min-height: 120px; background: var(--hk-border);
}
.hk-lock-message { font-size: 0.82rem; color: var(--hk-text-dim); margin-top: 8px; }

/* Keyboard */
.hk-keyboard-wrap { margin: 16px 0; }
.hk-keyboard {
  position: relative; height: 160px; background: var(--hk-stage-bg); border-radius: 8px;
  user-select: none; touch-action: none;
}
.hk-key { position: absolute; top: 0; box-sizing: border-box; cursor: pointer; }
.hk-key-white {
  height: 100%; background: #f5f3fa; border: 1px solid var(--hk-border); border-radius: 0 0 6px 6px;
  z-index: 1;
}
.hk-key-black {
  height: 60%; background: #141018; border: 1px solid #000; border-radius: 0 0 4px 4px;
  z-index: 2;
}
.hk-key-pressed.hk-key-white { background: #cfe3f0; }
.hk-key-pressed.hk-key-black { background: #2e5a74; }
.hk-key-highlight.hk-key-white { background: var(--hk-accent-soft); }
.hk-key-highlight.hk-key-black { background: var(--hk-accent); }
.hk-key-selectable { outline: 1px dashed var(--hk-accent-2); outline-offset: -2px; }
.hk-key-badge {
  position: absolute; bottom: 8px; left: 50%; transform: translateX(-50%);
  display: flex; flex-direction: column; align-items: center; pointer-events: none;
}
.hk-badge-number { font-size: 1.3rem; font-weight: bold; color: #1a2a33; }
.hk-badge-letter { font-size: 0.7rem; color: #1f4f66; }

/* Per-hand coloring — cohesive with the pastel theme's own two accent
   hues, not literal Synthesia blue/green: right hand uses the site's
   light-blue accent, left hand uses the pink accent — the same two
   colors already anchoring the whole palette, just assigned one per
   hand so they read as genuinely distinct at a glance. */
.hk-key-hand-right.hk-key-white { background: var(--hk-accent-soft); }
.hk-key-hand-right.hk-key-black { background: var(--hk-accent); }
.hk-key-hand-left.hk-key-white { background: var(--hk-accent-2-soft); }
.hk-key-hand-left.hk-key-black { background: var(--hk-accent-2); }
.hk-badge-hand { font-size: 1.1rem; font-weight: bold; color: #1a2a33; }
.hk-key-badge-left .hk-badge-letter { color: #7a2e49; }

/* Lessons */
.hk-lesson-map { display: flex; flex-direction: column; gap: 10px; padding: 16px 0; }
.hk-lessons-title { margin: 0 0 2px; font-size: 1.4rem; color: var(--hk-accent-2); }
.hk-streak { font-size: 1rem; margin-bottom: 8px; }
.hk-choose-list { display: flex; flex-direction: column; gap: 8px; margin: 12px 0; }
.hk-choose-btn { text-align: left; }

.hk-daily-goal { margin-bottom: 14px; }
.hk-daily-goal-label { font-size: 0.85rem; color: var(--hk-text-dim); margin-bottom: 4px; }
.hk-daily-goal-bar { height: 8px; border-radius: 999px; background: var(--hk-border); overflow: hidden; }
.hk-daily-goal-fill { height: 100%; background: linear-gradient(90deg, var(--hk-accent), var(--hk-accent-2)); transition: width 0.3s; }

.hk-badges-strip { display: flex; flex-wrap: wrap; gap: 6px; margin-bottom: 16px; }
.hk-badge-chip {
  font-size: 0.72rem; padding: 5px 10px; border-radius: 999px; border: 1px solid var(--hk-border);
  background: var(--hk-panel); color: var(--hk-text-dim); cursor: help;
}
.hk-badge-chip-earned { border-color: var(--hk-accent-2); color: var(--hk-text); background: rgba(217, 103, 143, 0.1); }
.hk-badge-chip-locked { opacity: 0.55; }
.hk-lesson-node {
  display: flex; gap: 14px; align-items: center; text-align: left;
  background: var(--hk-panel); border: 1px solid var(--hk-border); border-radius: 10px;
  padding: 14px; cursor: pointer; color: var(--hk-text);
}
.hk-lesson-node:disabled { opacity: 0.5; cursor: not-allowed; }
.hk-lesson-node.hk-done { border-color: var(--hk-accent-2); }
.hk-lesson-node-icon {
  width: 36px; height: 36px; border-radius: 50%; background: var(--hk-accent);
  display: flex; align-items: center; justify-content: center; flex-shrink: 0; font-weight: bold;
}
.hk-lesson-node-title { font-weight: bold; }
.hk-lesson-node-subtitle { color: var(--hk-accent-2); font-size: 0.85rem; }
.hk-lesson-node-desc { color: var(--hk-text-dim); font-size: 0.8rem; margin-top: 2px; }

.hk-lesson-player { padding: 12px 0; }
.hk-lesson-exit { background: none; border: none; color: var(--hk-text-dim); cursor: pointer; margin-bottom: 8px; }
.hk-lesson-content { min-height: 120px; }
.hk-big-degree {
  font-size: 4rem; font-weight: bold; text-align: center; color: var(--hk-accent);
  display: flex; flex-direction: column; align-items: center; line-height: 1;
}
.hk-big-letter { font-size: 1.2rem; color: var(--hk-text-dim); margin-top: 4px; }
.hk-step-indicator { color: var(--hk-text-dim); font-size: 0.8rem; }
.hk-honest-note { font-size: 0.8rem; color: var(--hk-text-dim); font-style: italic; }

/* ----- Lesson layout: main content + persistent right-side timeline ---- */
.hk-lessons-layout { display: flex; gap: 20px; align-items: flex-start; }
.hk-lesson-main { flex: 1 1 auto; min-width: 0; }
.hk-lesson-sidebar { flex: 0 0 240px; position: sticky; top: 12px; }
@media (max-width: 860px) {
  .hk-lessons-layout { flex-direction: column; }
  .hk-lesson-sidebar { flex: 1 1 auto; position: static; width: 100%; order: -1; }
}

.hk-roadmap {
  background: var(--hk-panel);
  border: 1px solid var(--hk-border);
  border-radius: 14px;
  padding: 14px;
}
.hk-roadmap-heading { margin: 0 0 4px; font-size: 1rem; }
.hk-roadmap-count { margin: 0 0 10px; }
.hk-roadmap-list { display: flex; flex-direction: column; gap: 6px; max-height: 70vh; overflow-y: auto; }
.hk-roadmap-node {
  display: flex;
  align-items: center;
  gap: 8px;
  width: 100%;
  text-align: left;
  padding: 8px 10px;
  border-radius: 10px;
  border: 1px solid var(--hk-border);
  background: var(--hk-bg);
  font-size: 0.8rem;
  cursor: pointer;
  position: relative;
}
.hk-roadmap-node:disabled { opacity: 0.5; cursor: not-allowed; }
.hk-roadmap-num {
  flex: 0 0 auto;
  width: 22px;
  height: 22px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.7rem;
  background: var(--hk-accent-soft);
  color: var(--hk-text);
}
.hk-roadmap-label { flex: 1 1 auto; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
/* Purple is the deliberate, distinct "completed" accent on this
   timeline specifically — the rest of the site keeps item 17's
   blue/pink re-theme untouched. */
.hk-roadmap-node.hk-roadmap-done {
  background: var(--hk-purple-soft);
  border-color: var(--hk-purple);
}
.hk-roadmap-node.hk-roadmap-done .hk-roadmap-num {
  background: var(--hk-purple);
  color: #fff;
}
.hk-roadmap-node.hk-roadmap-current {
  border-color: var(--hk-accent-2);
  box-shadow: 0 0 0 2px var(--hk-accent-2-soft);
}
.hk-roadmap-here {
  position: absolute;
  right: 8px;
  top: -9px;
  background: var(--hk-accent-2);
  color: #fff;
  font-size: 0.6rem;
  padding: 2px 6px;
  border-radius: 999px;
}

/* ----- Wallaby mascot narrator (items 22/23) ---------------------------- */
.hk-mascot-row { display: flex; align-items: flex-start; gap: 10px; margin: 10px 0; }
.hk-mascot-avatar { width: 48px; height: 48px; flex: 0 0 auto; border-radius: 50%; background: var(--hk-bg-2); }
.hk-mascot-bubble {
  background: var(--hk-panel);
  border: 1px solid var(--hk-border);
  border-radius: 14px;
  padding: 10px 14px;
  flex: 1 1 auto;
}
.hk-mascot-bubble h3 { margin-top: 0; }
.hk-mascot-bubble p:last-child { margin-bottom: 0; }

/* ----- Level-up celebration (item 21) ------------------------------------ */
.hk-levelup { text-align: center; }
.hk-levelup-badge { font-size: 1.3rem; margin: 10px 0; }
.hk-lesson-controls { margin-top: 10px; }

.hk-staff { width: 100%; height: 140px; background: var(--hk-stage-bg); border-radius: 8px; }
.hk-staff-line { stroke: #4a6a8a; stroke-width: 1; }
.hk-staff-note { fill: var(--hk-accent-2); }
.hk-staff-note-dim { fill: #46425c; }
.hk-staff-accidental { fill: var(--hk-accent-2); font-size: 14px; font-weight: bold; }
.hk-staff-keysig { fill: var(--hk-warn); font-size: 16px; font-weight: bold; }

/* Saved */
.hk-saved section { margin-bottom: 24px; }
.hk-empty { color: var(--hk-text-dim); }
.hk-saved-row {
  display: flex; justify-content: space-between; align-items: center; gap: 10px;
  background: var(--hk-panel); border-radius: 8px; padding: 10px 14px; margin-bottom: 8px;
  flex-wrap: wrap;
}

/* Practice */
.hk-practice-header { display: flex; gap: 10px; flex-wrap: wrap; align-items: center; }
.hk-practice-header select {
  background: var(--hk-panel); color: var(--hk-text); border: 1px solid var(--hk-border);
  padding: 10px; border-radius: 8px; flex: 1; min-width: 200px;
}
.hk-practice-meta { color: var(--hk-text-dim); font-size: 0.85rem; }
.hk-timeline {
  position: relative; height: 50px; background: var(--hk-panel); border-radius: 8px;
  margin: 10px 0; cursor: pointer; overflow: hidden; touch-action: none;
}
.hk-timeline-cursor { cursor: grab; }
.hk-timeline-chord {
  position: absolute; top: 0; height: 100%; border-right: 1px solid var(--hk-border);
  display: flex; align-items: center; justify-content: center; font-size: 0.8rem;
  color: var(--hk-text-dim);
}
.hk-timeline-cursor {
  position: absolute; top: 0; width: 2px; height: 100%; background: var(--hk-accent-2);
  pointer-events: none;
}
.hk-practice-controls { margin: 10px 0; }
.hk-calibration-panel { background: var(--hk-panel); border-radius: 10px; padding: 16px; margin-top: 10px; }
.hk-cal-status { color: var(--hk-accent-2); font-size: 0.85rem; min-height: 1.2em; }
.hk-upload-section {
  margin-top: 24px; padding: 16px; background: var(--hk-panel); border-radius: 10px;
  font-size: 0.85rem; color: var(--hk-text-dim);
}
.hk-upload-section input { margin-top: 8px; }

/* Practice modes */
.hk-mode-picker { display: flex; gap: 8px; margin: 10px 0; flex-wrap: wrap; }
.hk-mode-btn {
  background: var(--hk-panel); color: var(--hk-text-dim); border: 1px solid var(--hk-border);
  padding: 8px 14px; border-radius: 999px; cursor: pointer; font-size: 0.85rem;
}
.hk-mode-active { color: var(--hk-text); border-color: var(--hk-accent-2); background: rgba(217, 103, 143, 0.15); }
.hk-mode-desc { color: var(--hk-text-dim); font-size: 0.82rem; margin: 0 0 10px; }

.hk-sections { display: flex; gap: 6px; flex-wrap: wrap; margin-bottom: 8px; }
.hk-section-pill {
  font-size: 0.75rem; padding: 4px 10px; border-radius: 999px; background: var(--hk-border);
  color: var(--hk-text-dim); border: 1px solid transparent;
}
.hk-section-active { border-color: var(--hk-accent-2); color: var(--hk-accent-2); }

.hk-ear-correct { color: var(--hk-accent-2) !important; font-weight: bold; }

/* Camera overlay */
.hk-camera-panel { margin-top: 10px; }
.hk-camera-note { font-size: 0.82rem; color: var(--hk-text-dim); }
.hk-camera-stage { position: relative; max-width: 480px; }
.hk-camera-stage video {
  width: 100%; border-radius: 10px; background: #000; display: block;
}
.hk-camera-stage canvas {
  position: absolute; top: 0; left: 0; width: 100%; height: 100%; touch-action: none;
}

/* Falling-note highway */
.hk-highway-slot { margin: 10px 0 0; }
.hk-highway-wrap { position: relative; width: 100%; height: 160px; background: var(--hk-stage-bg); border-radius: 8px 8px 0 0; overflow: hidden; }
.hk-highway-canvas { display: block; width: 100%; height: 100%; }

.hk-repertoire-list { list-style: none; padding: 0; }
.hk-repertoire-list li { background: var(--hk-panel); border-radius: 8px; padding: 10px 14px; margin-bottom: 8px; }

/* ===================================================================
   Mobile responsiveness — real breakpoints, verified by resizing a
   real browser viewport to phone widths, not just added and assumed.
   Two tiers: tablet-ish (<=640px) and phone (<=420px). The on-screen
   keyboard is the hard case — real piano keys need a minimum physical
   width to stay tappable, so on narrow screens it becomes horizontally
   scrollable at a fixed minimum width instead of being squished to
   illegibly thin slivers.
   =================================================================== */
@media (max-width: 640px) {
  main { padding: 0 10px 40px; }
  .hk-header { padding: 16px 12px 8px; }
  .hk-header h1 { font-size: 1.5rem; }
  .hk-tagline { font-size: 0.85rem; }

  .hk-tabs { gap: 6px; padding: 10px 8px; overflow-x: auto; flex-wrap: nowrap; justify-content: flex-start; -webkit-overflow-scrolling: touch; }
  .hk-tab { padding: 10px 14px; font-size: 0.85rem; flex: 0 0 auto; min-height: 44px; }

  .hk-song-grid { grid-template-columns: 1fr; }
  .hk-discover-controls { flex-direction: column; }
  .hk-discover-controls input, .hk-discover-controls select { width: 100%; }

  .hk-practice-header { flex-direction: column; align-items: stretch; }
  .hk-practice-header select, .hk-practice-header .hk-btn { width: 100%; }

  .hk-mode-picker { flex-wrap: wrap; }
  .hk-mode-btn { flex: 1 1 auto; min-height: 44px; text-align: center; }

  .hk-practice-controls .hk-btn { min-height: 44px; padding: 10px 18px; }

  .hk-lesson-node { padding: 12px; gap: 10px; }
  .hk-lesson-node-icon { width: 32px; height: 32px; font-size: 0.9rem; }
  .hk-lesson-node-title { font-size: 0.95rem; }

  .hk-big-degree { font-size: 3rem; }

  /* The keyboard's keys are positioned with percentage left/width
     (relative to the keyboard element's own box), so the whole keyboard
     naturally scales down to fit any viewport width without ever
     overflowing it — the real fix needed here is just giving it a
     shorter, phone-appropriate height so keys aren't absurdly tall and
     thin, and confirming (verified by real viewport resizing) that it
     never forces horizontal page scroll. The falling-note highway uses
     the identical percentage layout for the same reason, so it scales
     in lockstep with the keyboard beneath it. */
  .hk-highway-wrap, .hk-keyboard { height: 130px; }
}

@media (max-width: 420px) {
  .hk-header h1 { font-size: 1.3rem; }
  .hk-big-degree { font-size: 2.5rem; }
  .hk-btn { padding: 10px 14px; font-size: 0.85rem; }
  .hk-highway-wrap, .hk-keyboard { height: 105px; }
  .hk-key-badge { bottom: 4px; }
  .hk-badge-number { font-size: 1rem; }
  .hk-song-card { padding: 12px; }
}

/* How It Works */
.hk-how { padding: 16px 0 40px; }
.hk-how-sub { color: var(--hk-text-dim); margin-top: -8px; }
.hk-how-section { background: var(--hk-panel); border-radius: 10px; padding: 18px; margin-bottom: 16px; }
.hk-how-section h3 { margin-top: 0; color: var(--hk-accent-2); }
.hk-wave-demo { margin-top: 12px; }
.hk-wave-demo canvas { width: 100%; max-width: 600px; height: 120px; background: var(--hk-stage-bg); border-radius: 8px; display: block; }
.hk-wave-controls { margin-top: 8px; display: flex; align-items: center; gap: 10px; color: var(--hk-text-dim); font-size: 0.85rem; }
.hk-wave-controls input[type="range"] { flex: 1; }
.hk-overtone-diagram { margin-top: 12px; }
.hk-overtone-svg { width: 100%; max-width: 560px; height: auto; display: block; background: var(--hk-stage-bg); border-radius: 8px; }
.hk-overtone-label { fill: var(--hk-text-dim); font-size: 11px; }

/* Playback speed control */
.hk-speed-picker { display: flex; align-items: center; gap: 6px; margin: 4px 0 10px; flex-wrap: wrap; }
.hk-speed-label { color: var(--hk-text-dim); font-size: 0.82rem; margin-right: 2px; }
.hk-speed-btn {
  background: var(--hk-panel); color: var(--hk-text-dim); border: 1px solid var(--hk-border);
  padding: 6px 12px; border-radius: 999px; cursor: pointer; font-size: 0.8rem; min-height: 32px;
}
.hk-speed-active { color: var(--hk-text); border-color: var(--hk-accent); background: rgba(124, 92, 255, 0.15); }