@font-face {
  font-family: "Nunito";
  font-style: normal;
  font-weight: 400 800;
  font-display: swap;
  src: url("/assets/fonts/nunito-latin.woff2") format("woff2");
}

:root {
  --bg: #faf6ee;
  --surface: #fffdf7;
  --surface-2: #f3ead9;
  --ink: #26343b;
  --ink-soft: #46565d;
  --muted: #66757b;
  --line: #e8ddcb;
  --accent: #2c7a6e;
  --accent-deep: #1f5d54;
  --accent-soft: #deece7;
  --gold: #c98f2f;
  --gold-soft: #f7e8c8;
  --success: #3d8560;
  --shadow: 0 24px 60px -40px rgba(46, 53, 49, 0.55);
  --font: "Nunito", "Segoe UI", system-ui, -apple-system, sans-serif;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  min-height: 100dvh;
  background:
    radial-gradient(1100px 520px at 50% -160px, #fffaf0 0%, rgba(255, 250, 240, 0) 70%),
    var(--bg);
  color: var(--ink);
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.5;
  -webkit-tap-highlight-color: transparent;
}

button {
  font: inherit;
  color: inherit;
}

h1, h2, h3, p {
  margin: 0;
}

.icon {
  width: 22px;
  height: 22px;
  fill: none;
  stroke: currentColor;
  stroke-width: 1.9;
  stroke-linecap: round;
  stroke-linejoin: round;
  flex: 0 0 auto;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

.skip-link {
  position: absolute;
  left: 12px;
  top: -60px;
  z-index: 50;
  padding: 10px 16px;
  border-radius: 12px;
  background: var(--ink);
  color: #fff;
  font-weight: 700;
  text-decoration: none;
  transition: top 0.15s ease;
}

.skip-link:focus {
  top: 12px;
}

/* ---------- Top bar ---------- */

.topbar {
  position: sticky;
  top: 0;
  z-index: 30;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: calc(10px + env(safe-area-inset-top)) clamp(14px, 3vw, 28px) 10px;
  background: rgba(250, 246, 238, 0.9);
  -webkit-backdrop-filter: blur(12px);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(232, 221, 203, 0.7);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--ink);
  text-decoration: none;
  border-radius: 14px;
}

.brand:focus-visible {
  outline: 3px solid var(--gold);
  outline-offset: 3px;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 42px;
  height: 42px;
  border-radius: 14px;
  background: var(--accent-soft);
  border: 1px solid #c8ded6;
  color: var(--accent-deep);
  font-weight: 800;
  font-size: 18px;
  letter-spacing: -0.04em;
}

.brand-text {
  display: flex;
  flex-direction: column;
  line-height: 1.05;
  font-size: 14px;
}

.brand-text strong {
  font-weight: 800;
  letter-spacing: -0.01em;
}

.brand-text span {
  color: var(--muted);
  font-size: 11.5px;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.top-actions {
  display: flex;
  gap: 8px;
}

.icon-btn {
  display: inline-grid;
  place-items: center;
  width: 44px;
  height: 44px;
  border-radius: 14px;
  border: 1px solid var(--line);
  background: var(--surface);
  color: var(--ink-soft);
  cursor: pointer;
  transition: background 0.15s ease, color 0.15s ease, border-color 0.15s ease;
}

.icon-btn:hover {
  background: #fff;
  color: var(--ink);
}

.icon-btn[aria-pressed="true"] {
  background: var(--accent-soft);
  border-color: #bcd8ce;
  color: var(--accent-deep);
}

.icon-btn:focus-visible,
.btn:focus-visible,
.tab:focus-visible,
.chip:focus-visible,
.level-btn:focus-visible {
  outline: 3px solid var(--gold);
  outline-offset: 2px;
}

#btnSound .icon-sound-on {
  display: none;
}

#btnSound[aria-pressed="true"] .icon-sound-on {
  display: block;
}

#btnSound[aria-pressed="true"] .icon-sound-off {
  display: none;
}

/* ---------- Page ---------- */

.page {
  width: min(100%, 940px);
  margin: 0 auto;
  padding: 12px clamp(14px, 3vw, 26px) calc(40px + env(safe-area-inset-bottom));
}

.sets {
  display: flex;
  gap: 8px;
  overflow-x: auto;
  padding: 6px 2px 14px;
  scrollbar-width: none;
  scroll-snap-type: x proximity;
  -webkit-overflow-scrolling: touch;
}

.sets::-webkit-scrollbar {
  display: none;
}

.tab {
  flex: 0 0 auto;
  scroll-snap-align: start;
  border: 1px solid var(--line);
  background: var(--surface);
  color: var(--ink-soft);
  border-radius: 999px;
  padding: 10px 16px;
  font-size: 14.5px;
  font-weight: 700;
  cursor: pointer;
  transition: background 0.16s ease, color 0.16s ease, border-color 0.16s ease;
  white-space: nowrap;
}

.tab:hover {
  border-color: #d6c8b2;
  background: #fff;
}

.tab[aria-pressed="true"] {
  background: var(--ink);
  border-color: var(--ink);
  color: #fff;
}

.tab-short {
  display: none;
}

/* ---------- Lesson ---------- */

.lesson-head {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 10px 18px;
  padding: 2px 4px 12px;
}

.eyebrow {
  margin-bottom: 2px;
  color: var(--muted);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.09em;
  text-transform: uppercase;
}

.lesson-title h1 {
  font-size: var(--label-size, 48px);
  font-weight: 800;
  line-height: 1.02;
  letter-spacing: -0.02em;
  color: var(--ink);
}

.level {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: 5px;
}

.level-label {
  color: var(--muted);
  font-size: 11px;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.level-options {
  display: flex;
  gap: 2px;
  padding: 3px;
  border-radius: 999px;
  background: #efe5d3;
  border: 1px solid #e7dbc7;
}

.level-btn {
  border: 0;
  background: transparent;
  color: #776b58;
  border-radius: 999px;
  padding: 7px 12px;
  font-size: 13px;
  font-weight: 700;
  cursor: pointer;
  transition: background 0.15s ease, color 0.15s ease, box-shadow 0.15s ease;
}

.level-btn[aria-pressed="true"] {
  background: var(--surface);
  color: var(--ink);
  box-shadow: 0 1px 4px rgba(63, 52, 35, 0.13);
}

.board-card {
  padding: clamp(8px, 1.4vw, 13px);
  border: 1px solid #eee2d0;
  border-radius: 30px;
  background: var(--surface);
  box-shadow: var(--shadow);
}

.board-wrap {
  position: relative;
  height: clamp(320px, 53dvh, 610px);
  border-radius: 22px;
  overflow: hidden;
  background:
    radial-gradient(120% 90% at 50% 0%, #fffefa 0%, #fffcf4 100%);
  border: 1px solid #f2e7d5;
  touch-action: none;
}

#measureSvg {
  position: absolute;
  width: 0;
  height: 0;
  overflow: hidden;
  pointer-events: none;
}

#board {
  display: block;
  width: 100%;
  height: 100%;
  touch-action: none;
  -webkit-user-select: none;
  user-select: none;
  cursor: crosshair;
}

.caption {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 28px;
  padding: 11px 8px 1px;
  color: var(--muted);
  font-size: 14.5px;
  font-weight: 700;
  text-align: center;
  transition: color 0.2s ease;
}

.caption::before {
  content: "";
  width: 8px;
  height: 8px;
  flex: 0 0 auto;
  border-radius: 50%;
  background: var(--accent);
  opacity: 0.8;
}

.caption.nudge {
  color: #8a5a12;
}

.caption.nudge::before {
  background: var(--gold);
}

.rotate-note {
  width: max-content;
  max-width: 100%;
  margin: 2px auto 0;
  padding: 5px 12px;
  border-radius: 999px;
  background: var(--gold-soft);
  color: #7a5716;
  font-size: 12px;
  font-weight: 700;
  text-align: center;
}

/* ---------- Success ---------- */

.success {
  position: absolute;
  inset: 0;
  z-index: 5;
  display: grid;
  place-items: center;
  padding: 16px;
  background: rgba(250, 246, 238, 0.74);
  -webkit-backdrop-filter: blur(3px);
  backdrop-filter: blur(3px);
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.22s ease, visibility 0.22s ease;
}

.success.show {
  opacity: 1;
  visibility: visible;
}

.success-card {
  width: min(330px, 100%);
  padding: 22px 24px 20px;
  border-radius: 24px;
  background: var(--surface);
  border: 1px solid var(--line);
  box-shadow: 0 26px 60px -30px rgba(43, 53, 49, 0.5);
  text-align: center;
  transform: translateY(6px) scale(0.97);
  transition: transform 0.28s cubic-bezier(0.2, 0.8, 0.2, 1);
}

.success.show .success-card {
  transform: translateY(0) scale(1);
}

.success-star {
  display: inline-grid;
  place-items: center;
  width: 52px;
  height: 52px;
  margin-bottom: 6px;
  color: var(--gold);
  animation: bob 2.4s ease-in-out infinite;
}

.success-star svg {
  width: 46px;
  height: 46px;
  fill: var(--gold-soft);
  stroke: var(--gold);
  stroke-width: 1.6;
  stroke-linejoin: round;
}

.success-kicker {
  color: var(--success);
  font-size: 11.5px;
  font-weight: 800;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.success h2 {
  margin-top: 2px;
  font-size: 28px;
  font-weight: 800;
  letter-spacing: -0.02em;
}

#successText {
  margin-top: 4px;
  color: var(--muted);
  font-size: 14.5px;
  font-weight: 600;
}

.listen {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  margin-top: 12px;
  padding: 8px 16px;
  border: 1px solid #cfe2dc;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent-deep);
  font-size: 14px;
  font-weight: 800;
  cursor: pointer;
}

.listen .icon {
  width: 18px;
  height: 18px;
}

.listen:active {
  transform: translateY(1px);
}

.listen[hidden] {
  display: none;
}

.success-actions {
  display: grid;
  grid-template-columns: 1fr 1.15fr;
  gap: 8px;
  margin-top: 18px;
}

@keyframes bob {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-3px); }
}

/* ---------- Controls ---------- */

.controls {
  display: grid;
  grid-template-columns: 1fr 1fr 1.15fr;
  gap: 9px;
  padding: 12px 2px 0;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 7px;
  min-height: 50px;
  padding: 10px 14px;
  border: 1px solid var(--line);
  border-radius: 16px;
  background: var(--surface);
  color: var(--ink);
  font-size: 14.5px;
  font-weight: 800;
  cursor: pointer;
  transition: background 0.15s ease, transform 0.1s ease, border-color 0.15s ease;
}

.btn .icon {
  width: 19px;
  height: 19px;
}

.btn:hover {
  background: #fff;
  border-color: #d9cbb6;
}

.btn:active {
  transform: translateY(1px);
}

.btn:disabled {
  opacity: 0.45;
  cursor: default;
}

.btn.primary {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}

.btn.primary:hover {
  background: var(--accent-deep);
  border-color: var(--accent-deep);
}

/* ---------- Picker ---------- */

.picker {
  margin-top: 24px;
}

.picker-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  padding: 0 4px 9px;
}

.picker-head h2 {
  font-size: 15px;
  font-weight: 800;
  letter-spacing: -0.01em;
}

.progress-pill {
  padding: 5px 11px;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent-deep);
  font-size: 12px;
  font-weight: 800;
  white-space: nowrap;
}

.chips {
  display: flex;
  gap: 8px;
  overflow-x: auto;
  padding: 5px 2px 14px;
  scrollbar-width: none;
  -webkit-overflow-scrolling: touch;
}

.chips::-webkit-scrollbar {
  display: none;
}

.chip {
  position: relative;
  flex: 0 0 auto;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 52px;
  height: 52px;
  padding: 0 10px;
  border: 1px solid var(--line);
  border-radius: 15px;
  background: var(--surface);
  color: var(--ink);
  font-size: 21px;
  font-weight: 800;
  cursor: pointer;
  scroll-snap-align: center;
  transition: background 0.15s ease, color 0.15s ease, border-color 0.15s ease;
}

.chip:hover {
  border-color: #d4c6b0;
  background: #fff;
}

.chip.wide {
  min-width: 66px;
  font-size: 18px;
}

.chip[aria-current="true"] {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}

.chip.done:not([aria-current="true"]) {
  background: #edf5f1;
  border-color: #c7e0d5;
  color: var(--accent-deep);
}

.chip .tick {
  position: absolute;
  top: -5px;
  right: -4px;
  display: grid;
  place-items: center;
  width: 17px;
  height: 17px;
  border-radius: 50%;
  background: var(--success);
  border: 2px solid var(--bg);
  color: #fff;
  font-size: 9px;
  font-weight: 800;
  line-height: 1;
}

.chips .group-gap {
  flex: 0 0 8px;
}

/* ---------- Help sheet ---------- */

.sheet {
  width: min(560px, calc(100vw - 28px));
  padding: 0;
  border: 1px solid var(--line);
  border-radius: 26px;
  background: var(--surface);
  color: var(--ink);
  box-shadow: 0 40px 100px -30px rgba(34, 42, 38, 0.55);
}

.sheet::backdrop {
  background: rgba(35, 45, 43, 0.34);
  -webkit-backdrop-filter: blur(2px);
  backdrop-filter: blur(2px);
}

.sheet-head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 14px;
  padding: 22px 22px 8px;
}

.sheet-head h2 {
  font-size: 24px;
  font-weight: 800;
  letter-spacing: -0.02em;
}

.sheet-head .eyebrow {
  color: var(--accent-deep);
}

.sheet-body {
  max-height: min(72dvh, 600px);
  overflow-y: auto;
  padding: 6px 22px 24px;
  -webkit-overflow-scrolling: touch;
}

.help-block {
  padding: 16px 0;
  border-top: 1px solid #f0e6d6;
}

.help-block:first-child {
  border-top: 0;
}

.help-block h3 {
  margin-bottom: 7px;
  font-size: 14px;
  font-weight: 800;
  letter-spacing: 0.02em;
}

.help-block p,
.steps li,
.tips li {
  color: var(--ink-soft);
  font-size: 14.5px;
  line-height: 1.55;
}

.steps {
  margin: 0;
  padding-left: 20px;
  display: grid;
  gap: 7px;
}

.tips {
  margin: 0;
  padding-left: 19px;
  display: grid;
  gap: 7px;
}

.tips li::marker {
  color: var(--accent);
}

.help-block.quiet {
  margin-top: 4px;
  padding: 15px 16px;
  border: 0;
  border-radius: 16px;
  background: #f6eddd;
}

.help-block.quiet h3 {
  margin-bottom: 4px;
}

.help-block.quiet p {
  font-size: 13.5px;
}

/* ---------- Responsive ---------- */

@media (max-width: 600px) {
  .tab {
    padding: 9px 12px;
    font-size: 13px;
  }

  .tab-long {
    display: none;
  }

  .tab-short {
    display: inline;
  }
}

@media (max-width: 520px) {
  .brand-mark {
    width: 38px;
    height: 38px;
    border-radius: 12px;
    font-size: 16px;
  }

  .brand-text {
    font-size: 13px;
  }

  .lesson-head {
    flex-direction: column;
    align-items: flex-start;
    gap: 8px;
    padding-bottom: 10px;
  }

  .level {
    align-items: flex-start;
  }

  .level-label {
    display: none;
  }

  .level-btn {
    padding: 7px 10px;
    font-size: 12.5px;
  }

  .board-wrap {
    height: clamp(300px, 48dvh, 500px);
  }

  .caption {
    font-size: 13.5px;
    min-height: 26px;
    padding-top: 9px;
  }

  .controls {
    gap: 7px;
  }

  .btn {
    min-height: 48px;
    padding: 9px 8px;
    font-size: 13.5px;
    gap: 5px;
  }

  .btn .icon {
    width: 17px;
    height: 17px;
  }
}

@media (max-width: 360px) {
  .brand-text {
    display: none;
  }

  .btn {
    font-size: 13px;
  }
}

@media (min-width: 1100px) {
  .page {
    width: min(100%, 980px);
  }
}

@media (max-height: 560px) and (orientation: landscape) {
  .topbar {
    position: static;
  }

  .board-wrap {
    height: 300px;
  }

  .page {
    padding-top: 6px;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }
}