:root {
  --bg: #f3ead7;
  --card: rgba(255, 250, 242, 0.9);
  --line: #5f3214;
  --accent: #8a1c1c;
  --shadow: rgba(53, 28, 7, 0.18);
  --board-light: #e8c896;
  --board-dark: #d7ae74;
  --piece-red: #aa1d21;
  --piece-black: #1f2124;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: "Noto Serif SC", "Songti SC", serif;
  background:
    radial-gradient(circle at top, rgba(255,255,255,0.55), transparent 40%),
    linear-gradient(180deg, #f8f1e6 0%, var(--bg) 100%);
  color: #2a1709;
}

.layout {
  display: grid;
  grid-template-columns: minmax(320px, 720px) minmax(280px, 360px);
  gap: 24px;
  max-width: 1200px;
  margin: 0 auto;
  padding: 24px;
}

.board-panel,
.card {
  background: var(--card);
  border: 1px solid rgba(111, 69, 20, 0.14);
  border-radius: 20px;
  box-shadow: 0 16px 40px var(--shadow);
}

.board-panel {
  padding: 18px;
}

.topbar {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 16px;
}

.topbar h1,
.history-card h2 {
  margin: 0;
}

.status {
  margin: 0;
  color: #5f3214;
}

.sidebar {
  display: grid;
  gap: 16px;
  align-content: start;
}

.card {
  padding: 18px;
}

.field {
  display: grid;
  gap: 8px;
}

.field select,
.actions button {
  border-radius: 12px;
  border: 1px solid rgba(95, 50, 20, 0.2);
  padding: 12px 14px;
  font: inherit;
}

.actions {
  display: flex;
  gap: 12px;
  margin-top: 16px;
}

.actions button {
  flex: 1;
  background: linear-gradient(180deg, #fff, #f1dfc5);
  cursor: pointer;
}

.board {
  position: relative;
  width: min(100%, 684px);
  aspect-ratio: 9 / 10;
  margin: 0 auto;
  padding: 24px 18px;
  background:
    linear-gradient(90deg, transparent calc(50% - 1px), var(--line) calc(50% - 1px), var(--line) calc(50% + 1px), transparent calc(50% + 1px)),
    linear-gradient(var(--board-light), var(--board-dark));
  border-radius: 24px;
  overflow: hidden;
}

.board::after {
  position: absolute;
  pointer-events: none;
}

.board::after {
  content: "楚 河            汉 界";
  inset: 24px 18px auto;
  top: calc(24px + ((100% - 48px) * 4 / 9));
  height: calc((100% - 48px) / 9);
  background: rgba(239, 214, 175, 0.9);
  display: flex;
  align-items: center;
  justify-content: center;
  color: rgba(95, 50, 20, 0.7);
  font-size: clamp(18px, 2vw, 28px);
  letter-spacing: 0.35em;
  text-indent: 0.35em;
}

.board-decorations {
  position: absolute;
  inset: 0;
  pointer-events: none;
  z-index: 0;
}

.grid-line {
  position: absolute;
  background: rgba(95, 50, 20, 0.92);
}

.grid-line.horizontal {
  left: 18px;
  width: calc(100% - 36px);
  height: 2px;
  transform: translateY(-1px);
}

.grid-line.vertical {
  width: 2px;
  height: calc(((100% - 48px) / 9) * 4);
  transform: translateX(-1px);
}

.grid-line.vertical.top {
  top: 24px;
}

.grid-line.vertical.bottom {
  top: calc(24px + ((100% - 48px) / 9) * 5);
}

.palace-diagonal {
  position: absolute;
  width: calc(((100% - 36px) / 8) * 2);
  height: calc(((100% - 48px) / 9) * 2);
}

.palace-diagonal::before {
  content: "";
  position: absolute;
  inset: 0;
  background: rgba(95, 50, 20, 0.92);
  clip-path: polygon(0 49%, 49% 49%, 49% 0, 51% 0, 51% 49%, 100% 49%, 100% 51%, 51% 51%, 51% 100%, 49% 100%, 49% 51%, 0 51%);
}

.palace-diagonal.slash::before {
  clip-path: polygon(0 98%, 2% 100%, 100% 2%, 98% 0);
}

.palace-diagonal.backslash::before {
  clip-path: polygon(0 2%, 2% 0, 100% 98%, 98% 100%);
}

.intersection-mark {
  position: absolute;
  width: 26px;
  height: 26px;
  transform: translate(-13px, -13px);
}

.intersection-mark::before,
.intersection-mark::after {
  content: "";
  position: absolute;
  inset: 0;
  background-repeat: no-repeat;
}

.intersection-mark::before {
  background:
    linear-gradient(var(--line), var(--line)) 0 6px / 2px 8px no-repeat,
    linear-gradient(90deg, var(--line), var(--line)) 0 6px / 8px 2px no-repeat,
    linear-gradient(var(--line), var(--line)) 0 12px / 2px 8px no-repeat,
    linear-gradient(90deg, var(--line), var(--line)) 0 18px / 8px 2px no-repeat,
    linear-gradient(var(--line), var(--line)) 18px 6px / 2px 8px no-repeat,
    linear-gradient(90deg, var(--line), var(--line)) 12px 6px / 8px 2px no-repeat,
    linear-gradient(var(--line), var(--line)) 18px 12px / 2px 8px no-repeat,
    linear-gradient(90deg, var(--line), var(--line)) 12px 18px / 8px 2px no-repeat;
}

.cell {
  position: absolute;
  display: grid;
  place-items: center;
  left: calc(18px + ((100% - 36px) / 8) * var(--col));
  top: calc(24px + ((100% - 48px) / 9) * var(--row));
  width: min(72px, calc((100% - 36px) / 8));
  height: min(72px, calc((100% - 48px) / 9));
  transform: translate(-50%, -50%);
}

.piece {
  width: min(58px, 86%);
  aspect-ratio: 1;
  border-radius: 50%;
  border: 3px solid #cea35b;
  background: radial-gradient(circle at 30% 30%, #fffdf4, #f1d39e 66%, #d09d58);
  box-shadow: 0 5px 10px rgba(0, 0, 0, 0.16);
  font-size: clamp(22px, 2.5vw, 32px);
  font-weight: 700;
  font-family: inherit;
  cursor: pointer;
  z-index: 1;
}

.piece.red {
  color: var(--piece-red);
}

.piece.black {
  color: var(--piece-black);
}

.piece.selected {
  outline: 4px solid rgba(87, 165, 255, 0.45);
}

.target,
.capture-target {
  position: absolute;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  z-index: 0;
}

.target {
  background: rgba(54, 137, 76, 0.68);
}

.capture-target {
  width: 54px;
  height: 54px;
  border: 4px solid rgba(200, 40, 40, 0.5);
}

.history-list {
  margin: 14px 0 0;
  padding-left: 20px;
  display: grid;
  gap: 10px;
  max-height: 70vh;
  overflow: auto;
}

.round-entry {
  display: grid;
  gap: 4px;
}

.round-entry strong {
  color: #6f3e13;
}

@media (max-width: 960px) {
  .layout {
    grid-template-columns: 1fr;
  }

  .board {
    width: 100%;
  }
}