:root {
  --bg: #ffffff;
  --fg: #111111;
  --muted: #666666;
  --panel: #f2f2f2;
  --panel-2: #e8e8e8;
  --border: #d6d6d6;
  --accent: #1c1c1c;
  --accent-hover: #333333;
  --accent-fg: #ffffff;
  --board-light: #ebecd0;
  --board-dark: #779556;
  --board-highlight: #f6f679;
  --board-move-dot: rgba(20, 20, 20, 0.28);
  --board-last: rgba(246, 246, 105, 0.75);
  --board-check: rgba(235, 97, 80, 0.85);
  --piece-white-fill: #fbfbf9;
  --piece-white-stroke: #2b2b2b;
  --piece-black-fill: #1c1c1c;
  --piece-black-stroke: #f5f5f5;
  --success: #1b7a3d;
  --danger: #b3261e;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.06), 0 8px 24px rgba(0, 0, 0, 0.08);
}

html[data-theme="dark"] {
  --bg: #101010;
  --fg: #eaeaea;
  --muted: #9a9a9a;
  --panel: #1a1a1a;
  --panel-2: #222222;
  --border: #333333;
  --accent: #eaeaea;
  --accent-hover: #ffffff;
  --accent-fg: #101010;
  --success: #4caf6f;
  --danger: #e5675f;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.4), 0 12px 28px rgba(0, 0, 0, 0.45);
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, "Segoe UI", Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--fg);
  transition: background-color 0.15s ease, color 0.15s ease;
}

header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.85rem 1.5rem;
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  background: var(--bg);
  z-index: 10;
}

header .brand {
  font-weight: 800;
  font-size: 1.25rem;
  letter-spacing: -0.01em;
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

header .brand::before {
  content: "\265A";
  font-size: 1.3rem;
}

nav { display: flex; align-items: center; gap: 1.25rem; }

nav a {
  color: var(--fg);
  text-decoration: none;
  font-size: 0.92rem;
  opacity: 0.85;
  transition: opacity 0.15s ease;
}

nav a:hover { opacity: 1; text-decoration: underline; }

.header-right { display: flex; align-items: center; gap: 0.75rem; }

button, .btn {
  background: var(--accent);
  color: var(--accent-fg);
  border: 1px solid var(--accent);
  padding: 0.5rem 1rem;
  border-radius: 6px;
  cursor: pointer;
  font-size: 0.9rem;
  font-weight: 600;
  transition: background-color 0.15s ease, transform 0.05s ease;
}

button:hover, .btn:hover { background: var(--accent-hover); border-color: var(--accent-hover); }
button:active, .btn:active { transform: translateY(1px); }
button:disabled { opacity: 0.5; cursor: not-allowed; }

button.secondary, .btn.secondary {
  background: transparent;
  color: var(--fg);
  border: 1px solid var(--border);
}
button.secondary:hover { background: var(--panel); border-color: var(--border); }

button.danger { background: var(--danger); border-color: var(--danger); color: #fff; }

input, textarea, select {
  background: var(--panel);
  color: var(--fg);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 0.55rem 0.7rem;
  font-size: 0.92rem;
  width: 100%;
  transition: border-color 0.15s ease, box-shadow 0.15s ease;
}

input:focus, textarea:focus, select:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 15%, transparent);
}

label { font-size: 0.85rem; color: var(--muted); display: block; margin-bottom: 0.3rem; }

main {
  max-width: 1040px;
  margin: 0 auto;
  padding: 1.75rem 1.5rem 3rem;
}

.panel {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 1.25rem;
  margin-bottom: 1.25rem;
}

.panel h2 { margin-top: 0; font-size: 1.05rem; }

.muted { color: var(--muted); }
.field { margin-bottom: 0.9rem; }

/* --- auth / login page --- */
.auth-wrap {
  display: flex;
  justify-content: center;
  padding-top: 2rem;
}

.auth-card {
  width: 100%;
  max-width: 400px;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 2rem;
  box-shadow: var(--shadow);
}

.auth-card .logo {
  text-align: center;
  font-size: 2rem;
  margin-bottom: 0.25rem;
}

.auth-card h1 {
  text-align: center;
  font-size: 1.3rem;
  margin: 0 0 1.5rem;
}

.auth-tabs {
  display: flex;
  background: var(--panel-2);
  border-radius: 999px;
  padding: 4px;
  margin-bottom: 1.5rem;
}

.auth-tabs button {
  flex: 1;
  background: transparent;
  border: none;
  color: var(--muted);
  border-radius: 999px;
  padding: 0.5rem 0;
}

.auth-tabs button.active {
  background: var(--accent);
  color: var(--accent-fg);
}

.auth-form { display: none; }
.auth-form.active { display: block; }

.auth-card .btn-submit { width: 100%; padding: 0.7rem; margin-top: 0.4rem; }

.auth-error {
  color: var(--danger);
  font-size: 0.85rem;
  margin-top: 0.75rem;
  min-height: 1.1em;
  text-align: center;
}

.profile-stats {
  display: flex;
  gap: 1.5rem;
  margin: 1rem 0 1.5rem;
  text-align: center;
}
.profile-stats .stat { flex: 1; }
.profile-stats .stat .num { font-size: 1.4rem; font-weight: 700; display: block; }
.profile-stats .stat .label { font-size: 0.75rem; color: var(--muted); text-transform: uppercase; letter-spacing: 0.04em; }

.rating-badge {
  display: inline-block;
  background: var(--panel-2);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 0.15rem 0.6rem;
  font-size: 0.78rem;
  font-weight: 700;
}

/* --- board --- */
.board-wrap { display: flex; gap: 1.5rem; flex-wrap: wrap; align-items: flex-start; }

#board {
  display: grid;
  grid-template-columns: repeat(8, 52px);
  grid-template-rows: repeat(8, 52px);
  border: 2px solid var(--border);
  border-radius: 4px;
  overflow: hidden;
  width: max-content;
  box-shadow: var(--shadow);
}

.sq {
  position: relative;
  width: 52px;
  height: 52px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 40px;
  line-height: 1;
  user-select: none;
  cursor: pointer;
  transition: background-color 0.1s ease;
}

.sq.light { background: var(--board-light); }
.sq.dark { background: var(--board-dark); }
.sq.selected { box-shadow: inset 0 0 0 3px rgba(20, 85, 30, 0.65); }
.sq:hover { filter: brightness(1.06); }
.sq.last-move::before {
  content: "";
  position: absolute;
  inset: 0;
  background: var(--board-last);
}
.sq.in-check::before {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(circle, var(--board-check) 0%, transparent 72%);
}

.sq .piece {
  position: relative;
  z-index: 1;
  transition: transform 0.08s ease;
}
.sq .piece.piece-white {
  color: var(--piece-white-fill);
  text-shadow:
    -1.5px 0 var(--piece-white-stroke), 1.5px 0 var(--piece-white-stroke),
    0 -1.5px var(--piece-white-stroke), 0 1.5px var(--piece-white-stroke),
    1px 1px 2px rgba(0, 0, 0, 0.35);
}
.sq .piece.piece-black {
  color: var(--piece-black-fill);
  text-shadow:
    -1px 0 var(--piece-black-stroke), 1px 0 var(--piece-black-stroke),
    0 -1px var(--piece-black-stroke), 0 1px var(--piece-black-stroke),
    1px 1px 2px rgba(0, 0, 0, 0.25);
}
.sq:hover .piece { transform: scale(1.08); }

.sq .coord {
  position: absolute;
  font-size: 10px;
  font-weight: 700;
  opacity: 0.65;
  z-index: 2;
  font-family: -apple-system, "Segoe UI", Helvetica, Arial, sans-serif;
}
.sq .coord.file { right: 3px; bottom: 1px; }
.sq .coord.rank { left: 3px; top: 1px; }
.sq.light .coord { color: var(--board-dark); }
.sq.dark .coord { color: var(--board-light); }
.sq .move-dot {
  position: absolute;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--board-move-dot);
  z-index: 1;
}
.sq .move-dot.capture {
  width: 100%;
  height: 100%;
  border-radius: 0;
  background: transparent;
  box-shadow: inset 0 0 0 4px var(--board-move-dot);
}

.side-panel { min-width: 260px; flex: 1; }

.move-list {
  display: grid;
  grid-template-columns: 2rem 1fr 1fr;
  gap: 0.15rem 0.5rem;
  font-size: 0.88rem;
  max-height: 220px;
  overflow-y: auto;
}
.move-list .mv-num { color: var(--muted); }

.status-banner {
  padding: 0.6rem 0.9rem;
  border-radius: 8px;
  font-size: 0.9rem;
  font-weight: 600;
  margin-bottom: 0.75rem;
}
.status-banner.ongoing { background: var(--panel-2); }
.status-banner.check { background: color-mix(in srgb, var(--danger) 15%, var(--panel)); color: var(--danger); }
.status-banner.over { background: color-mix(in srgb, var(--success) 15%, var(--panel)); color: var(--success); }

.theme-toggle { border-radius: 999px; padding: 0.4rem 0.9rem; }

table { border-collapse: collapse; width: 100%; }
th, td { text-align: left; padding: 0.55rem 0.6rem; border-bottom: 1px solid var(--border); }
th { color: var(--muted); font-size: 0.78rem; text-transform: uppercase; letter-spacing: 0.03em; font-weight: 600; }
tr.me { background: var(--panel-2); }
.rank-cell { font-weight: 700; color: var(--muted); width: 2.5rem; }

.course-card, .game-card {
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.9rem 1rem;
  margin-bottom: 0.6rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}
.game-card .meta { font-size: 0.85rem; color: var(--muted); }

/* --- promotion picker modal --- */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.45);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 100;
}
.modal-box {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1.25rem;
  box-shadow: var(--shadow);
  text-align: center;
}
.promo-choices { display: flex; gap: 0.6rem; margin-top: 0.75rem; }
.promo-choices button {
  font-size: 1.8rem;
  padding: 0.4rem 0.7rem;
  background: var(--panel-2);
  color: var(--fg);
  border: 1px solid var(--border);
}
.promo-choices button:hover { background: var(--board-highlight); }

.tabs-row { display: flex; gap: 0.5rem; margin-bottom: 1rem; }
.tabs-row button { background: transparent; color: var(--fg); border: 1px solid var(--border); }
.tabs-row button.active { background: var(--accent); color: var(--accent-fg); border-color: var(--accent); }