:root {
  color-scheme: light;
  --ink: #17212b;
  --muted: #61707f;
  --paper: #f7f3ea;
  --panel: #fffaf1;
  --line: #d8cdbb;
  --dark-square: #9a5f32;
  --light-square: #dfb875;
  --accent: #d98c28;
  --accent-dark: #9a5418;
  --blue: #295d7a;
  --green: #2f7c62;
  --danger: #b94b4b;
  --shadow: 0 14px 36px rgba(23, 33, 43, 0.14);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  background: #171717;
  color: var(--ink);
  font-family: "Segoe UI", Arial, sans-serif;
}

.win-banner {
  position: fixed;
  top: 14px;
  left: 50%;
  z-index: 20;
  transform: translate(-50%, -140%);
  width: min(92vw, 760px);
  border: 4px solid #5a3218;
  border-radius: 8px;
  background: #f8e3bd;
  box-shadow: 0 18px 38px rgba(23, 33, 43, 0.24);
  color: #17212b;
  opacity: 0;
  padding: 16px 18px;
  pointer-events: none;
  text-align: center;
  transition: transform 220ms ease, opacity 220ms ease;
}

.win-banner.show {
  opacity: 1;
  transform: translate(-50%, 0);
}

.win-banner span {
  display: block;
  font-size: clamp(2rem, 7vw, 4.5rem);
  font-weight: 1000;
  line-height: 0.95;
  text-transform: uppercase;
}

button {
  color: inherit;
  font: inherit;
}

.app-shell {
  width: min(1440px, 100%);
  margin: 0 auto;
  padding: 12px 16px;
}

.top-band {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 20px;
  padding: 10px 4px 12px;
}

.eyebrow,
.turn-label {
  margin: 0 0 4px;
  color: var(--blue);
  font-size: 0.76rem;
  font-weight: 800;
  letter-spacing: 0;
  text-transform: uppercase;
}

.top-band h1 {
  color: #ffffff;
}

h1,
h2,
h3,
p {
  overflow-wrap: anywhere;
}

h1 {
  margin: 0;
  font-size: clamp(1.8rem, 4vw, 3.4rem);
  line-height: 0.94;
}

h2 {
  margin: 0;
  font-size: 1.25rem;
  line-height: 1.15;
}

h3 {
  margin: 0 0 8px;
  font-size: 1rem;
}

.score-strip {
  display: flex;
  flex-wrap: wrap;
  justify-content: end;
  gap: 8px;
}

.score-strip span,
.badge,
.mini-badge {
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(255, 250, 241, 0.78);
  padding: 8px 12px;
  color: var(--blue);
  font-weight: 800;
  white-space: nowrap;
}

.settings-button {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #ffffff;
  color: var(--blue);
  cursor: pointer;
  font-weight: 900;
  min-height: 36px;
  padding: 7px 12px;
}

.mini-badge {
  padding: 7px 10px;
  font-size: 0.78rem;
}

.mode-switch {
  display: flex;
  gap: 8px;
  margin: 0 0 12px;
}

.mode-button {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: rgba(255, 250, 241, 0.86);
  color: var(--blue);
  cursor: pointer;
  font-weight: 900;
  padding: 9px 14px;
}

.mode-button.active {
  background: var(--blue);
  border-color: var(--blue);
  color: #ffffff;
}

.hidden {
  display: none !important;
}

.settings-overlay {
  position: fixed;
  inset: 0;
  z-index: 30;
  display: grid;
  place-items: start center;
  background: rgba(0, 0, 0, 0.58);
  padding: 72px 16px 16px;
}

.settings-panel {
  width: min(92vw, 420px);
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel);
  box-shadow: var(--shadow);
  display: grid;
  gap: 14px;
  padding: 16px;
}

.setting-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  color: var(--ink);
  font-weight: 900;
}

.setting-row output {
  color: var(--blue);
  font-weight: 900;
}

.volume-slider {
  width: 100%;
  accent-color: var(--blue);
}

.credits-box {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #ffffff;
  display: grid;
  gap: 6px;
  padding: 11px;
}

.credits-box h3,
.credits-box p {
  margin: 0;
}

.credits-box p {
  color: var(--muted);
}

.workspace {
  display: grid;
  grid-template-columns: minmax(200px, 250px) minmax(300px, 0.9fr) minmax(220px, 290px);
  gap: 14px;
  align-items: start;
}

.lesson-panel,
.coach-panel,
.board-zone {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: rgba(255, 250, 241, 0.86);
  box-shadow: var(--shadow);
}

.lesson-panel,
.coach-panel {
  padding: 12px;
}

.lesson-panel {
  max-height: calc(100vh - 96px);
  overflow-y: auto;
}

.panel-heading,
.prompt-row {
  display: flex;
  align-items: start;
  justify-content: space-between;
  gap: 12px;
}

.icon-button,
.primary-button,
.secondary-button,
.danger-button {
  border: 1px solid transparent;
  border-radius: 8px;
  cursor: pointer;
  font-weight: 800;
  transition: transform 140ms ease, background 140ms ease, border-color 140ms ease;
}

.icon-button:hover,
.primary-button:hover,
.secondary-button:hover,
.danger-button:hover,
.settings-button:hover,
.puzzle-button:hover,
.ai-button:hover,
.mode-button:hover,
.topic-toggle:hover {
  transform: translateY(-1px);
}

.icon-button {
  width: 36px;
  height: 36px;
  background: #ffffff;
  border-color: var(--line);
  color: var(--blue);
  font-size: 1.15rem;
}

.puzzle-list {
  display: grid;
  gap: 10px;
  margin-top: 14px;
}

.topic-group {
  display: grid;
  gap: 8px;
}

.topic-toggle {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #f8e3bd;
  padding: 10px 11px;
  color: var(--accent-dark);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  font-weight: 900;
  text-align: left;
  transition: transform 140ms ease, border-color 140ms ease, background 140ms ease;
}

.topic-toggle::before {
  content: "+";
  flex: 0 0 auto;
  font-size: 0.95rem;
}

.topic-toggle[aria-expanded="true"]::before {
  content: "-";
}

.topic-toggle small {
  color: var(--muted);
  font-size: 0.76rem;
  font-weight: 800;
  white-space: nowrap;
}

.topic-levels {
  display: grid;
  gap: 8px;
  padding-left: 10px;
  border-left: 3px solid rgba(154, 84, 24, 0.22);
}

.topic-levels[hidden] {
  display: none;
}

.ai-list {
  display: grid;
  gap: 8px;
  margin-top: 14px;
}

.ai-button {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #ffffff;
  padding: 10px;
  text-align: left;
  cursor: pointer;
  transition: transform 140ms ease, border-color 140ms ease, background 140ms ease;
}

.ai-button strong {
  display: block;
  margin-bottom: 3px;
  font-size: 0.92rem;
}

.ai-button span {
  color: var(--muted);
  font-size: 0.8rem;
}

.ai-button.active {
  border-color: var(--blue);
  background: #edf6f4;
}

.puzzle-button {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #ffffff;
  padding: 11px;
  text-align: left;
  cursor: pointer;
  transition: transform 140ms ease, border-color 140ms ease, background 140ms ease;
}

.puzzle-button strong {
  display: block;
  margin-bottom: 3px;
  font-size: 0.95rem;
}

.puzzle-button span {
  color: var(--muted);
  font-size: 0.83rem;
}

.puzzle-button.active {
  border-color: var(--blue);
  background: #edf6f4;
}

.puzzle-button.solved::after {
  content: "Solved";
  display: inline-block;
  margin-top: 8px;
  color: var(--green);
  font-size: 0.78rem;
  font-weight: 900;
  text-transform: uppercase;
}

.board-zone {
  min-width: 0;
  padding: 12px;
}

.prompt-row {
  min-height: 54px;
}

.badge {
  flex: 0 0 auto;
  background: #f8e3bd;
  color: var(--accent-dark);
}

.board-wrap {
  display: grid;
  grid-template-columns: 22px minmax(240px, 520px);
  grid-template-rows: minmax(240px, 520px) 22px;
  gap: 4px;
  width: min(100%, 546px);
  margin: 8px auto 0;
}

.rank-labels {
  display: grid;
  grid-template-rows: repeat(8, 1fr);
  align-items: center;
  justify-items: center;
  color: var(--muted);
  font-size: 0.78rem;
  font-weight: 800;
}

.file-labels {
  grid-column: 2;
  display: grid;
  grid-template-columns: repeat(8, 1fr);
  align-items: center;
  justify-items: center;
  color: var(--muted);
  font-size: 0.78rem;
  font-weight: 800;
}

.chess-board {
  grid-column: 2;
  display: grid;
  grid-template-columns: repeat(8, 1fr);
  grid-template-rows: repeat(8, 1fr);
  overflow: hidden;
  border: 5px solid #5a3218;
  border-radius: 8px;
  aspect-ratio: 1;
  background: #5a3218;
  box-shadow:
    inset 0 0 0 1px rgba(255, 235, 192, 0.42),
    0 8px 20px rgba(54, 28, 12, 0.24);
}

.square {
  position: relative;
  display: grid;
  place-items: center;
  min-width: 0;
  min-height: 0;
  border: 0;
  padding: 0;
  cursor: pointer;
  line-height: 1;
}

.square.light {
  background: #dfb875;
}

.square.dark {
  background: #8d542b;
}

.square.selected {
  outline: 4px solid rgba(41, 93, 122, 0.86);
  outline-offset: -4px;
}

.square.target::before,
.square.answer::before,
.square.miss::before,
.square.legal::before,
.square.last-move::before {
  content: "";
  position: absolute;
  inset: 18%;
  border-radius: 50%;
  pointer-events: none;
}

.square.target::before {
  background: rgba(41, 93, 122, 0.26);
}

.square.legal::before {
  background: rgba(41, 93, 122, 0.28);
  inset: 32%;
}

.square.last-move::before {
  border: 4px solid rgba(217, 140, 40, 0.82);
}

.square.answer::before {
  border: 5px solid rgba(47, 124, 98, 0.84);
}

.square.miss::before {
  border: 5px solid rgba(185, 75, 75, 0.84);
}

.piece {
  position: absolute;
  inset: 0;
  z-index: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100%;
  height: 100%;
  font-size: clamp(1.75rem, 6vw, 4.25rem);
  line-height: 1;
  transform: translateY(-0.02em);
}

.piece.black {
  color: #000000;
}

.piece.white {
  color: #ffffff;
}

.controls {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 10px;
  margin-top: 10px;
}

.primary-button,
.secondary-button {
  min-height: 38px;
  padding: 8px 12px;
}

.primary-button {
  background: var(--accent);
  color: #231308;
}

.secondary-button {
  background: #ffffff;
  border-color: var(--line);
  color: var(--blue);
}

.danger-button {
  min-height: 40px;
  background: var(--danger);
  color: #ffffff;
  padding: 9px 12px;
}

.feedback {
  min-height: 58px;
  margin-top: 10px;
  border-left: 5px solid var(--blue);
  border-radius: 8px;
  background: #ffffff;
  padding: 10px 12px;
  color: var(--ink);
  font-weight: 700;
  line-height: 1.35;
}

.feedback.success {
  border-color: var(--green);
}

.feedback.try {
  border-color: var(--danger);
}

.coach-panel {
  display: grid;
  gap: 10px;
}

.coach-card {
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #ffffff;
  padding: 11px;
}

.coach-card p {
  margin: 0;
  color: var(--muted);
  line-height: 1.45;
}

.checklist {
  display: grid;
  gap: 9px;
  margin: 0;
  padding-left: 18px;
  color: var(--muted);
  line-height: 1.35;
}

@media (max-width: 1040px) {
  .workspace {
    grid-template-columns: minmax(210px, 260px) minmax(320px, 1fr);
  }

  .coach-panel {
    grid-column: 1 / -1;
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .coach-panel h2 {
    grid-column: 1 / -1;
  }
}

@media (max-width: 760px) {
  .app-shell {
    padding: 12px;
  }

  .top-band {
    align-items: start;
    flex-direction: column;
  }

  .score-strip {
    justify-content: start;
  }

  .workspace,
  .coach-panel {
    grid-template-columns: 1fr;
  }

  .lesson-panel {
    order: 2;
  }

  .board-zone {
    order: 1;
  }

  .coach-panel {
    order: 3;
  }

  .board-wrap {
    grid-template-columns: 20px minmax(230px, 1fr);
    grid-template-rows: minmax(230px, 1fr) 22px;
  }

  .piece {
    font-size: clamp(1.45rem, 10vw, 3.2rem);
  }
}