:root {
  --bg: #0d0f14;
  --bg2: #161922;
  --bg3: #1e2330;
  --border: #2a2f3e;
  --text: #e8ecf1;
  --text2: #8892a4;
  --primary: #5c6bc0;
  --primary-h: #7986cb;
  --accent: #81c784;
  --danger: #ef5350;
  --gold: #ffd54f;
  --radius: 12px;
  --shadow: 0 8px 32px rgba(0,0,0,0.4);
}
*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{font-family:'Inter',sans-serif;background:var(--bg);color:var(--text);min-height:100vh;overflow-x:hidden}

/* NAVBAR */
.navbar{display:flex;align-items:center;justify-content:space-between;padding:0 2rem;height:64px;background:rgba(13,15,20,0.95);backdrop-filter:blur(12px);border-bottom:1px solid var(--border);position:sticky;top:0;z-index:100}
.nav-logo{display:flex;align-items:center;gap:10px;text-decoration:none;cursor:pointer}
.logo-icon{font-size:1.8rem;line-height:1}
.logo-text{font-size:1.2rem;color:var(--text);letter-spacing:-0.5px}
.logo-text strong{color:var(--primary-h)}
.nav-links{display:flex;gap:0.5rem}
.nav-link{color:var(--text2);text-decoration:none;padding:0.4rem 0.8rem;border-radius:8px;font-size:0.9rem;transition:all 0.2s;cursor:pointer}
.nav-link:hover,.nav-link.active{color:var(--text);background:var(--bg3)}
.nav-auth,.nav-user{display:flex;align-items:center;gap:0.5rem}
.user-avatar{width:36px;height:36px;border-radius:50%;background:var(--primary);display:flex;align-items:center;justify-content:center;font-weight:700;cursor:pointer;font-size:1rem;text-transform:uppercase}
.user-rating{background:var(--bg3);padding:4px 10px;border-radius:20px;font-size:0.85rem;color:var(--accent);font-weight:600}

/* BUTTONS */
.btn{padding:0.5rem 1.2rem;border-radius:8px;border:none;cursor:pointer;font-family:'Inter',sans-serif;font-size:0.875rem;font-weight:500;transition:all 0.2s;display:inline-flex;align-items:center;gap:6px}
.btn-primary{background:var(--primary);color:#fff}
.btn-primary:hover{background:var(--primary-h);transform:translateY(-1px)}
.btn-ghost{background:transparent;color:var(--text2);border:1px solid var(--border)}
.btn-ghost:hover{background:var(--bg3);color:var(--text)}
.btn-outline{background:transparent;color:var(--text);border:2px solid var(--border)}
.btn-outline:hover{border-color:var(--primary);color:var(--primary-h)}
.btn-danger{background:var(--danger);color:#fff}
.btn-danger:hover{opacity:0.85}
.btn-xl{padding:0.8rem 2rem;font-size:1rem;border-radius:12px}
.btn-sm{padding:0.3rem 0.7rem;font-size:0.8rem}
.w-full{width:100%}

/* PAGES */
.page{display:none;min-height:calc(100vh - 64px)}
.page.active{display:block}

/* HERO */
.hero{display:grid;grid-template-columns:1fr 1fr;gap:4rem;align-items:center;padding:5rem 4rem;max-width:1200px;margin:0 auto}
.hero-badge{display:inline-block;background:rgba(92,107,192,0.15);border:1px solid rgba(92,107,192,0.3);color:var(--primary-h);padding:6px 16px;border-radius:20px;font-size:0.85rem;margin-bottom:1.5rem}
.hero h1{font-size:3.5rem;font-weight:800;line-height:1.1;margin-bottom:1.5rem;font-family:'Playfair Display',serif}
.gradient-text{background:linear-gradient(135deg,var(--primary-h),var(--accent));-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}
.hero p{font-size:1.1rem;color:var(--text2);line-height:1.7;margin-bottom:2rem}
.hero-btns{display:flex;gap:1rem;flex-wrap:wrap;margin-bottom:3rem}
.hero-stats{display:flex;gap:3rem}
.stat{display:flex;flex-direction:column;gap:4px}
.stat-num{font-size:1.5rem;font-weight:700;color:var(--primary-h)}
.stat-label{font-size:0.8rem;color:var(--text2);text-transform:uppercase;letter-spacing:1px}
.hero-board{display:flex;justify-content:center;align-items:center}
.mini-board{width:320px;height:320px;border-radius:12px;overflow:hidden;box-shadow:0 0 0 3px var(--primary),var(--shadow)}

/* FEATURES */
.features{display:grid;grid-template-columns:repeat(4,1fr);gap:1.5rem;padding:3rem 4rem 5rem;max-width:1200px;margin:0 auto}
.feature-card{background:var(--bg2);border:1px solid var(--border);border-radius:var(--radius);padding:2rem;transition:all 0.3s}
.feature-card:hover{border-color:var(--primary);transform:translateY(-4px)}
.feature-icon{font-size:2rem;margin-bottom:1rem}
.feature-card h3{font-size:1rem;font-weight:600;margin-bottom:0.5rem}
.feature-card p{font-size:0.875rem;color:var(--text2);line-height:1.6}

/* PLAY PAGE */
.play-layout{display:grid;grid-template-columns:320px 1fr;gap:2rem;padding:2rem 4rem;max-width:1200px;margin:0 auto}
.time-selector{background:var(--bg2);border:1px solid var(--border);border-radius:var(--radius);padding:1.5rem}
.time-selector h2{font-size:1.1rem;font-weight:600;margin-bottom:1.5rem}
.time-groups{display:flex;flex-direction:column;gap:1.5rem;margin-bottom:1.5rem}
.group-label{font-size:0.8rem;font-weight:600;color:var(--text2);text-transform:uppercase;letter-spacing:1px;margin-bottom:0.5rem}
.time-btns{display:flex;flex-wrap:wrap;gap:0.5rem}
.time-btn,.stake-btn{padding:0.4rem 0.8rem;background:var(--bg3);border:1px solid var(--border);border-radius:8px;color:var(--text);cursor:pointer;font-family:'Inter',sans-serif;font-size:0.875rem;transition:all 0.2s}
.time-btn:hover,.time-btn.active,.stake-btn:hover,.stake-btn.active{background:var(--primary);border-color:var(--primary);color:#fff}
.searching{display:flex;align-items:center;gap:1rem;margin-top:1rem;color:var(--text2)}

/* GAME BOARD AREA */
.game-area{display:flex;flex-direction:column;gap:0.75rem;align-items:center}
.player-info{display:flex;align-items:center;gap:1rem;width:100%;max-width:480px;background:var(--bg2);border:1px solid var(--border);border-radius:var(--radius);padding:0.75rem 1rem}
.player-avatar{width:40px;height:40px;border-radius:50%;background:var(--bg3);display:flex;align-items:center;justify-content:center;font-size:1.2rem;font-weight:700;border:2px solid var(--border);text-transform:uppercase}
.player-name{font-weight:600;font-size:0.95rem}
.player-elo{font-size:0.8rem;color:var(--text2)}
.clock{margin-left:auto;font-size:1.4rem;font-weight:700;font-variant-numeric:tabular-nums;background:var(--bg3);padding:6px 14px;border-radius:8px;letter-spacing:1px}
.my-clock{color:var(--accent)}
.clock.low-time{color:var(--danger);animation:pulse 1s infinite}
@keyframes pulse{0%,100%{opacity:1}50%{opacity:0.5}}
.board-container{position:relative;width:480px;height:480px}
#chess-board{width:100%!important;height:100%!important}
.board-overlay{position:absolute;inset:0;background:rgba(0,0,0,0.75);display:flex;align-items:center;justify-content:center;border-radius:4px;z-index:10}
.result-card{background:var(--bg2);border:1px solid var(--border);border-radius:var(--radius);padding:2rem 3rem;text-align:center}
.result-card h3{font-size:1.5rem;margin-bottom:0.5rem}
.result-card p{color:var(--text2);margin-bottom:1.5rem}
.game-controls{display:flex;gap:0.5rem}
.move-list{background:var(--bg2);border:1px solid var(--border);border-radius:8px;padding:0.75rem;width:100%;max-width:480px;max-height:120px;overflow-y:auto;font-size:0.85rem;color:var(--text2);font-family:monospace}
.chat-box{background:var(--bg2);border:1px solid var(--border);border-radius:8px;width:100%;max-width:480px}
.chat-msgs{height:80px;overflow-y:auto;padding:0.5rem;font-size:0.82rem;color:var(--text2)}
.chat-input{display:flex;border-top:1px solid var(--border)}
.chat-input input{flex:1;background:transparent;border:none;outline:none;padding:0.5rem;color:var(--text);font-family:inherit;font-size:0.85rem}
.chat-input button{background:var(--primary);border:none;color:#fff;padding:0.5rem 1rem;cursor:pointer;font-size:1rem}

/* LEADERBOARD */
.leaderboard-wrap{max-width:800px;margin:3rem auto;padding:0 2rem}
.leaderboard-wrap h2{font-size:1.5rem;font-weight:700;margin-bottom:1.5rem;display:flex;align-items:center;gap:0.5rem}
.leaderboard-table{background:var(--bg2);border:1px solid var(--border);border-radius:var(--radius);overflow:hidden}
.lb-row{display:grid;grid-template-columns:50px 1fr 120px 80px 80px;align-items:center;padding:0.75rem 1rem;border-bottom:1px solid var(--border);transition:background 0.2s}
.lb-row:hover{background:var(--bg3)}
.lb-row.header{background:var(--bg3);font-size:0.8rem;text-transform:uppercase;letter-spacing:1px;color:var(--text2);font-weight:600}
.lb-rank{font-size:1rem;font-weight:700;color:var(--text2)}
.lb-rank.gold{color:var(--gold)}
.lb-rank.silver{color:#b0bec5}
.lb-rank.bronze{color:#a1887f}
.lb-name{font-weight:500;cursor:pointer}
.lb-name:hover{color:var(--primary-h)}
.lb-rating{font-weight:700;color:var(--accent)}
.lb-games,.lb-wins{color:var(--text2);font-size:0.875rem}

/* PROFILE */
.profile-wrap{max-width:900px;margin:3rem auto;padding:0 2rem}
.profile-header{background:var(--bg2);border:1px solid var(--border);border-radius:var(--radius);padding:2rem;display:flex;gap:2rem;align-items:center;margin-bottom:1.5rem}
.profile-avatar-big{width:80px;height:80px;border-radius:50%;background:var(--primary);display:flex;align-items:center;justify-content:center;font-size:2rem;font-weight:700;border:3px solid var(--primary-h);text-transform:uppercase}
.profile-username{font-size:1.8rem;font-weight:700;margin-bottom:0.25rem}
.profile-joined{color:var(--text2);font-size:0.85rem}
.profile-ratings{display:flex;gap:1.5rem;margin-top:1rem}
.rating-card{background:var(--bg3);border-radius:8px;padding:0.75rem 1.25rem;text-align:center}
.rating-type{font-size:0.75rem;text-transform:uppercase;color:var(--text2);margin-bottom:4px}
.rating-val{font-size:1.3rem;font-weight:700;color:var(--accent)}
.profile-stats-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:1rem;margin-bottom:1.5rem}
.stat-card{background:var(--bg2);border:1px solid var(--border);border-radius:var(--radius);padding:1.25rem;text-align:center}
.stat-card .sv{font-size:1.5rem;font-weight:700;color:var(--text)}
.stat-card .sl{font-size:0.8rem;color:var(--text2);margin-top:4px;text-transform:uppercase}

/* PUZZLES */
.puzzle-wrap{max-width:700px;margin:3rem auto;padding:0 2rem;text-align:center}
.puzzle-wrap h2{font-size:1.5rem;margin-bottom:0.5rem}
.puzzle-sub{color:var(--text2);margin-bottom:2rem}
.puzzle-board-area{display:flex;flex-direction:column;align-items:center;gap:1rem}
.puzzle-info{display:flex;gap:1rem;align-items:center;justify-content:center;flex-wrap:wrap}
.puzzle-rating-badge{background:var(--bg3);border:1px solid var(--border);border-radius:20px;padding:6px 16px;font-size:0.875rem;font-weight:600;color:var(--gold)}
.puzzle-task{background:var(--bg2);border:1px solid var(--border);border-radius:8px;padding:8px 16px;font-size:0.9rem;color:var(--text2)}
#puzzle-board{width:400px;height:400px;border-radius:8px;overflow:hidden}
.puzzle-feedback{background:var(--bg2);border:1px solid var(--border);border-radius:8px;padding:0.75rem 1.5rem;font-weight:600}
.puzzle-feedback.correct{border-color:var(--accent);color:var(--accent)}
.puzzle-feedback.wrong{border-color:var(--danger);color:var(--danger)}

/* MODALS */
.modal-bg{position:fixed;inset:0;background:rgba(0,0,0,0.7);display:flex;align-items:center;justify-content:center;z-index:1000;backdrop-filter:blur(4px)}
.modal{background:var(--bg2);border:1px solid var(--border);border-radius:var(--radius);padding:2rem;width:100%;max-width:400px;box-shadow:var(--shadow)}
.modal h2{font-size:1.3rem;font-weight:700;margin-bottom:1.5rem;text-align:center}
.modal-switch{text-align:center;font-size:0.875rem;color:var(--text2);margin-top:1rem}
.modal-switch a{color:var(--primary-h);cursor:pointer}
.form-group{margin-bottom:1rem}
.form-group label{display:block;font-size:0.85rem;color:var(--text2);margin-bottom:6px;font-weight:500}
.form-group input{width:100%;padding:0.6rem 0.9rem;background:var(--bg3);border:1px solid var(--border);border-radius:8px;color:var(--text);font-family:inherit;font-size:0.9rem;transition:border-color 0.2s;outline:none}
.form-group input:focus{border-color:var(--primary)}
.form-error{color:var(--danger);font-size:0.85rem;background:rgba(239,83,80,0.1);border-radius:6px;padding:8px 12px;margin-bottom:1rem}

/* UTILS */
.hidden{display:none!important}
.loading-spinner{display:flex;justify-content:center;padding:3rem}
.spinner{width:32px;height:32px;border:3px solid var(--border);border-top-color:var(--primary);border-radius:50%;animation:spin 0.8s linear infinite}
@keyframes spin{to{transform:rotate(360deg)}}

/* CHESSBOARD overrides */
.board-b72b1{border-radius:4px!important}
.highlight-sq{box-shadow:inset 0 0 0 4px rgba(92,107,192,0.8)!important}
.highlight-last{box-shadow:inset 0 0 0 4px rgba(129,199,132,0.6)!important}

@media(max-width:900px){
  .hero{grid-template-columns:1fr;text-align:center;padding:3rem 2rem}
  .hero-board{display:none}
  .features{grid-template-columns:1fr 1fr;padding:2rem}
  .play-layout{grid-template-columns:1fr;padding:1rem}
  .board-container{width:320px;height:320px}
}


/* ═══════════════ AI GAME MODE ═══════════════════════════════ */

/* AI Setup page */
.ai-setup {
  max-width: 900px;
  margin: 2rem auto;
  padding: 0 2rem;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2rem;
}
.ai-setup-left { display: flex; flex-direction: column; gap: 1.5rem; }
.setup-card {
  background: var(--bg2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
}
.setup-card h3 { font-size: 0.9rem; text-transform: uppercase; letter-spacing: 1px; color: var(--text2); margin-bottom: 1rem; }

/* Color selector */
.color-selector { display: flex; gap: 0.75rem; }
.color-btn {
  flex: 1; padding: 0.75rem;
  background: var(--bg3); border: 2px solid var(--border);
  border-radius: 10px; cursor: pointer; color: var(--text);
  font-family: inherit; font-size: 0.9rem; font-weight: 500;
  transition: all 0.2s; text-align: center;
}
.color-btn:hover { border-color: var(--primary); }
.color-btn.active { border-color: var(--primary); background: rgba(92,107,192,0.15); color: var(--primary-h); }
.color-btn .cb-icon { font-size: 1.5rem; display: block; margin-bottom: 0.25rem; }

/* Difficulty selector */
.diff-btns { display: flex; flex-direction: column; gap: 0.5rem; }
.diff-btn {
  display: flex; align-items: center; gap: 0.75rem;
  padding: 0.65rem 1rem;
  background: var(--bg3); border: 2px solid var(--border);
  border-radius: 8px; cursor: pointer; color: var(--text);
  font-family: inherit; font-size: 0.9rem;
  transition: all 0.2s; text-align: left; width: 100%;
}
.diff-btn:hover { border-color: var(--primary); }
.diff-btn.active { border-color: var(--primary); background: rgba(92,107,192,0.15); }
.diff-icon { font-size: 1.1rem; width: 24px; text-align: center; }
.diff-label { flex: 1; font-weight: 500; }
.diff-stars { color: var(--gold); font-size: 0.7rem; letter-spacing: -1px; }

/* Preview board */
.ai-preview-board {
  background: var(--bg2); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 1.5rem;
  display: flex; flex-direction: column; align-items: center; gap: 1rem;
}
.ai-preview-board h3 { font-size: 0.9rem; text-transform: uppercase; letter-spacing: 1px; color: var(--text2); }
#ai-preview { width: 320px; height: 320px; border-radius: 8px; overflow: hidden; }
.start-ai-btn { width: 100%; }

/* ── AI Game Layout ── */
.ai-game-layout {
  display: grid;
  grid-template-columns: 48px 480px 1fr;
  gap: 1.5rem;
  align-items: start;
  max-width: 1100px;
  margin: 1.5rem auto;
  padding: 0 2rem;
}

/* Eval bar */
.eval-bar-wrap { display: flex; flex-direction: column; align-items: center; gap: 4px; height: 480px; }
.eval-bar {
  width: 24px; flex: 1;
  background: #1a1a2e;
  border-radius: 12px; overflow: hidden;
  border: 1px solid var(--border);
  position: relative;
}
.eval-fill {
  position: absolute; bottom: 0; left: 0; right: 0;
  background: #f0d9b5;
  transition: height 0.5s ease;
}
.eval-num {
  font-size: 0.7rem; font-weight: 700; color: var(--text2);
  font-variant-numeric: tabular-nums;
}

/* AI board area */
.ai-board-area { display: flex; flex-direction: column; gap: 0.6rem; }

/* Thinking indicator */
.thinking-indicator {
  display: none; align-items: center; gap: 0.75rem;
  background: rgba(92,107,192,0.1);
  border: 1px solid rgba(92,107,192,0.3);
  border-radius: 8px; padding: 0.6rem 1rem;
  font-size: 0.875rem; color: var(--primary-h);
}
.thinking-indicator.visible { display: flex; }
.thinking-dots span {
  display: inline-block; width: 6px; height: 6px;
  background: var(--primary-h); border-radius: 50%; margin: 0 2px;
  animation: bounce 1.2s infinite ease-in-out;
}
.thinking-dots span:nth-child(2) { animation-delay: 0.2s; }
.thinking-dots span:nth-child(3) { animation-delay: 0.4s; }
@keyframes bounce { 0%,80%,100%{transform:scale(0.6)} 40%{transform:scale(1)} }

/* Difficulty badge */
.diff-badge {
  display: inline-flex; align-items: center; gap: 6px;
  background: var(--bg3); border: 1px solid var(--border);
  border-radius: 20px; padding: 4px 12px;
  font-size: 0.8rem; color: var(--text2);
}

/* AI right panel */
.ai-right-panel { display: flex; flex-direction: column; gap: 1rem; }
.panel-card {
  background: var(--bg2); border: 1px solid var(--border);
  border-radius: var(--radius); overflow: hidden;
}
.panel-header {
  display: flex; align-items: center; justify-content: space-between;
  padding: 0.75rem 1rem;
  border-bottom: 1px solid var(--border);
  font-size: 0.85rem; font-weight: 600; color: var(--text2);
  text-transform: uppercase; letter-spacing: 0.5px;
}

/* Move list with analysis */
.ai-move-list {
  max-height: 220px; overflow-y: auto;
  padding: 0.5rem;
  font-size: 0.875rem;
}
.move-row { display: flex; align-items: center; gap: 4px; padding: 2px 4px; border-radius: 4px; }
.move-row:hover { background: var(--bg3); }
.move-num { color: var(--text2); width: 28px; font-size: 0.8rem; }
.move-san {
  padding: 2px 6px; border-radius: 4px; cursor: pointer;
  transition: all 0.15s; font-weight: 500;
}
.move-san:hover { background: var(--primary); color: #fff; }
.move-san.current { background: var(--primary); color: #fff; }
.move-san.best { color: var(--accent); }
.move-san.good { color: var(--text); }
.move-san.inaccuracy { color: #ffd54f; }
.move-san.mistake { color: #ff9800; }
.move-san.blunder { color: var(--danger); }
.move-class-icon { font-size: 0.7rem; }

/* Replay controls */
.replay-controls {
  display: flex; gap: 0.5rem; padding: 0.75rem;
  border-top: 1px solid var(--border);
  justify-content: center;
}
.replay-btn {
  width: 36px; height: 36px;
  background: var(--bg3); border: 1px solid var(--border);
  border-radius: 8px; cursor: pointer; color: var(--text);
  font-size: 1rem; display: flex; align-items: center; justify-content: center;
  transition: all 0.15s;
}
.replay-btn:hover { background: var(--primary); border-color: var(--primary); color: #fff; }

/* Post-game analysis */
.analysis-panel { display: none; }
.analysis-panel.visible { display: block; }
.accuracy-circle {
  width: 80px; height: 80px;
  border-radius: 50%;
  background: conic-gradient(var(--accent) calc(var(--pct) * 1%), var(--bg3) 0);
  display: flex; align-items: center; justify-content: center;
  font-size: 1.1rem; font-weight: 700;
  margin: 1rem auto;
  position: relative;
}
.accuracy-circle::before {
  content: ''; position: absolute; inset: 8px;
  background: var(--bg2); border-radius: 50%;
}
.accuracy-circle span { position: relative; z-index: 1; }
.analysis-stats { display: grid; grid-template-columns: repeat(2,1fr); gap: 0.5rem; padding: 0 1rem 1rem; }
.analysis-stat { background: var(--bg3); border-radius: 8px; padding: 0.5rem 0.75rem; text-align: center; }
.as-num { font-size: 1.2rem; font-weight: 700; }
.as-label { font-size: 0.7rem; color: var(--text2); text-transform: uppercase; }
.as-best { color: var(--accent); }
.as-good { color: var(--text); }
.as-inaccuracy { color: #ffd54f; }
.as-mistake { color: #ff9800; }
.as-blunder { color: var(--danger); }

/* Best move arrow (shown on board after analysis) */
.best-move-hint {
  padding: 0.75rem 1rem;
  font-size: 0.85rem; color: var(--text2);
  border-top: 1px solid var(--border);
}
.best-move-hint .bm { color: var(--accent); font-weight: 600; }

/* Analyze button */
.analyze-btn-wrap { padding: 0.75rem; }

@media(max-width:900px) {
  .ai-setup { grid-template-columns: 1fr; }
  .ai-game-layout { grid-template-columns: 24px 320px 1fr; gap: 0.75rem; padding: 0 1rem; }
  .ai-board-area .board-container { width: 320px; height: 320px; }
  #ai-chess-board { width: 100% !important; height: 100% !important; }
}
@media(max-width:600px) {
  .ai-game-layout { grid-template-columns: 1fr; }
  .eval-bar-wrap { display: none; }
}