:root {
  color-scheme: light;
  --bg: #f6f3eb;
  --ink: #19201d;
  --muted: #626a65;
  --panel: #ffffff;
  --line: #d9d3c4;
  --dark-square: #79936b;
  --light-square: #ede2c5;
  --accent: #276f7d;
  --accent-2: #b75d3b;
  --good: #217346;
  --ok: #4f6f9f;
  --bad: #a86416;
  --blunder: #a33434;
  --shadow: 0 20px 60px rgba(25, 32, 29, .13);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  background:
    linear-gradient(135deg, rgba(39, 111, 125, .13), transparent 38%),
    linear-gradient(315deg, rgba(183, 93, 59, .14), transparent 40%),
    var(--bg);
  color: var(--ink);
}

button, input { font: inherit; }

.app-shell {
  width: min(1480px, calc(100vw - 32px));
  margin: 0 auto;
  padding: 24px 0;
}

.topbar {
  display: grid;
  grid-template-columns: minmax(220px, 1fr) minmax(360px, 620px);
  gap: 24px;
  align-items: end;
  margin-bottom: 18px;
}

.eyebrow {
  margin: 0 0 4px;
  color: var(--accent);
  font-size: .78rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: .08em;
}

h1 {
  margin: 0;
  font-size: clamp(2.1rem, 4vw, 4.2rem);
  line-height: .95;
  letter-spacing: 0;
}

.selectors {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
}

.opening-card {
  display: grid;
  gap: 4px;
  min-height: 74px;
  padding: 14px 16px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: rgba(255,255,255,.72);
  color: var(--ink);
  text-align: left;
  cursor: pointer;
}

.opening-card span {
  font-size: 1.05rem;
  font-weight: 800;
}

.opening-card strong {
  color: var(--muted);
  font-size: .88rem;
}

.opening-card.active {
  border-color: var(--accent);
  background: #fff;
  box-shadow: 0 0 0 3px rgba(39, 111, 125, .14);
}

.workspace {
  display: grid;
  grid-template-columns: minmax(420px, 1fr) minmax(340px, 430px);
  gap: 18px;
  align-items: start;
}

.board-column, .coach-panel {
  background: rgba(255,255,255,.78);
  border: 1px solid rgba(217,211,196,.9);
  border-radius: 8px;
  box-shadow: var(--shadow);
}

.board-column { padding: 16px; }

.board-header {
  display: flex;
  justify-content: space-between;
  gap: 14px;
  align-items: center;
  margin-bottom: 14px;
}

.line-name {
  margin: 0 0 4px;
  font-weight: 900;
  font-size: 1.05rem;
}

.status-text {
  margin: 0;
  color: var(--muted);
  font-size: .95rem;
}

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

.toolbar button {
  min-height: 38px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: #fff;
  color: var(--ink);
  padding: 0 12px;
  cursor: pointer;
  font-weight: 800;
}

.toolbar button:hover, .opening-card:hover {
  border-color: var(--accent);
}

.difficulty-control {
  display: grid;
  grid-template-columns: minmax(160px, 220px) 1fr minmax(150px, 220px);
  gap: 12px;
  align-items: center;
  margin: 0 0 14px;
  padding: 10px 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: rgba(255,255,255,.72);
}

.difficulty-control label {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 10px;
  color: var(--muted);
  font-size: .86rem;
  font-weight: 900;
  text-transform: uppercase;
  letter-spacing: .04em;
}

.difficulty-control label strong {
  color: var(--accent);
  font-size: 1.15rem;
}

.difficulty-control input {
  width: 100%;
  accent-color: var(--accent);
}

.difficulty-control p {
  margin: 0;
  color: var(--muted);
  font-size: .9rem;
  font-weight: 800;
  text-align: right;
}

.rating-control {
  margin: 0 0 14px;
  padding: 10px 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: rgba(255,255,255,.72);
}

.rating-control label {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  color: var(--muted);
  font-size: .86rem;
  font-weight: 900;
  text-transform: uppercase;
  letter-spacing: .04em;
}

.rating-control select {
  min-height: 36px;
  min-width: 150px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: #fff;
  color: var(--ink);
  padding: 0 10px;
  font-weight: 800;
}

.board-wrap {
  display: grid;
  place-items: center;
  width: 100%;
}

.board-stage {
  width: min(78vh, 100%, 880px);
  display: grid;
  grid-template-columns: 38px minmax(0, 1fr);
  gap: 10px;
  align-items: stretch;
}

.eval-bar {
  position: relative;
  min-height: 100%;
  border: 2px solid #2b2b25;
  border-radius: 8px;
  overflow: hidden;
  background: #f8f5ec;
  box-shadow: inset 0 0 0 1px rgba(255,255,255,.65);
}

.eval-black {
  position: absolute;
  inset: 0 0 auto;
  height: 50%;
  background: #20231f;
  transition: height .22s ease;
}

.eval-score {
  position: absolute;
  left: 50%;
  bottom: 8px;
  transform: translateX(-50%);
  min-width: 30px;
  border-radius: 999px;
  background: rgba(255,255,255,.92);
  color: var(--ink);
  padding: 4px 5px;
  font-size: .74rem;
  font-weight: 950;
  text-align: center;
  box-shadow: 0 2px 8px rgba(25,32,29,.18);
}

.engine-line {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  margin-top: 9px;
  color: var(--muted);
  font-size: .86rem;
  font-weight: 800;
}

.board {
  width: min(78vh, 100%, 820px);
  aspect-ratio: 1;
  display: grid;
  grid-template-columns: repeat(8, 1fr);
  grid-template-rows: repeat(8, 1fr);
  border: 10px solid #2b2b25;
  border-radius: 8px;
  overflow: hidden;
  background: #2b2b25;
  user-select: none;
  touch-action: none;
}

.square {
  position: relative;
  display: grid;
  place-items: center;
  min-width: 0;
  min-height: 0;
}

.square.light { background: var(--light-square); }
.square.dark { background: var(--dark-square); }
.square.selected { box-shadow: inset 0 0 0 4px rgba(39,111,125,.78); }
.square.hint-from { box-shadow: inset 0 0 0 5px rgba(39,111,125,.95); }
.square.hint-to { box-shadow: inset 0 0 0 5px rgba(183,93,59,.95); }
.square.in-check {
  background:
    radial-gradient(circle at 50% 50%, rgba(192, 35, 35, .88) 0 28%, rgba(192, 35, 35, .48) 45%, rgba(192, 35, 35, .18) 66%, transparent 78%),
    var(--light-square);
}
.square.dark.in-check {
  background:
    radial-gradient(circle at 50% 50%, rgba(192, 35, 35, .9) 0 28%, rgba(192, 35, 35, .5) 45%, rgba(192, 35, 35, .18) 66%, transparent 78%),
    var(--dark-square);
}
.square.hint-to::before {
  content: "best";
  position: absolute;
  top: 7px;
  right: 7px;
  z-index: 2;
  border-radius: 999px;
  background: #fff;
  color: var(--accent-2);
  padding: 3px 7px;
  font-size: clamp(9px, 1.4vmin, 12px);
  font-weight: 950;
  text-transform: uppercase;
}
.square.last { box-shadow: inset 0 0 0 4px rgba(255,255,255,.34); }
.square.legal::after {
  content: "";
  width: 28%;
  aspect-ratio: 1;
  border-radius: 999px;
  background: rgba(25,32,29,.28);
}
.square.capture::after {
  content: "";
  position: absolute;
  inset: 10%;
  border-radius: 999px;
  border: 5px solid rgba(25,32,29,.25);
}

.piece {
  border: 0;
  background: transparent;
  cursor: grab;
  width: 100%;
  height: 100%;
  display: grid;
  place-items: center;
  color: #151815;
  font-size: clamp(32px, 8.8vmin, 86px);
  line-height: 1;
  text-shadow: 0 2px 0 rgba(255,255,255,.5);
}

.piece.black {
  color: #22201f;
  text-shadow: 0 2px 0 rgba(255,255,255,.2);
}

.piece:active { cursor: grabbing; }

.coord {
  position: absolute;
  left: 5px;
  bottom: 3px;
  font-size: clamp(9px, 1.5vmin, 13px);
  color: rgba(25,32,29,.58);
  font-weight: 900;
  pointer-events: none;
}

.coach-panel {
  padding: 18px;
  position: sticky;
  top: 16px;
}

.coach-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.ai-toggle {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  color: var(--muted);
  font-size: .86rem;
  font-weight: 800;
}

.result-badge {
  display: inline-grid;
  place-items: center;
  min-height: 34px;
  margin: 12px 0 10px;
  padding: 0 12px;
  border-radius: 999px;
  color: #fff;
  font-weight: 900;
}

.result-badge.neutral { background: #59625d; }
.result-badge.best { background: var(--good); }
.result-badge.acceptable { background: var(--ok); }
.result-badge.mistake { background: var(--bad); }
.result-badge.blunder { background: var(--blunder); }

.coach-panel h2 {
  margin: 0 0 16px;
  font-size: 1.5rem;
  line-height: 1.12;
  letter-spacing: 0;
}

.coach-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
  margin-bottom: 12px;
}

.coach-grid div {
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 10px;
  background: #fff;
}

.coach-grid span {
  display: block;
  color: var(--muted);
  font-size: .76rem;
  font-weight: 900;
  text-transform: uppercase;
  letter-spacing: .06em;
  margin-bottom: 4px;
}

.coach-grid strong {
  display: block;
  overflow-wrap: anywhere;
}

.coach-panel section {
  border-top: 1px solid var(--line);
  padding-top: 12px;
  margin-top: 12px;
}

.coach-panel h3 {
  margin: 0 0 6px;
  font-size: .88rem;
  text-transform: uppercase;
  color: var(--accent);
  letter-spacing: .06em;
}

.coach-panel p {
  margin: 0;
  color: #303833;
  line-height: 1.45;
}

.opponent-details {
  border-top: 1px solid var(--line);
  padding-top: 12px;
  margin-top: 12px;
}

.opponent-details summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  cursor: pointer;
  color: var(--accent);
  font-size: .88rem;
  font-weight: 900;
  text-transform: uppercase;
  letter-spacing: .06em;
}

.opponent-details summary strong {
  color: var(--ink);
  font-size: .9rem;
  text-transform: none;
  letter-spacing: 0;
}

.opponent-details p {
  margin-top: 8px;
}

.move-list {
  display: grid;
  gap: 6px;
  max-height: 200px;
  overflow: auto;
  margin: 16px 0 0;
  padding: 12px 0 0 24px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-weight: 750;
}

@media (max-width: 980px) {
  .topbar, .workspace {
    grid-template-columns: 1fr;
  }
  .coach-panel {
    position: static;
  }
  .board {
    width: min(100%, 92vw);
  }
  .board-stage {
    width: min(100%, 92vw);
  }
}

@media (max-width: 560px) {
  .app-shell {
    width: min(100vw - 18px, 1480px);
    padding: 12px 0;
  }
  .selectors, .coach-grid {
    grid-template-columns: 1fr;
  }
  .board-column, .coach-panel {
    padding: 12px;
  }
  .board-header {
    align-items: flex-start;
    flex-direction: column;
  }
  .difficulty-control {
    grid-template-columns: 1fr;
  }
  .rating-control label {
    align-items: flex-start;
    flex-direction: column;
  }
  .difficulty-control p {
    text-align: left;
  }
  .toolbar {
    justify-content: flex-start;
  }
  .board {
    border-width: 6px;
  }
  .board-stage {
    grid-template-columns: 30px minmax(0, 1fr);
    gap: 7px;
  }
  .eval-score {
    font-size: .65rem;
    min-width: 25px;
  }
}