*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
:root{
  --bg-primary:#0a0a1a;
  --bg-secondary:#12122a;
  --bg-surface:#1a1a2e;
  --bg-surface-hover:#252542;
  --bg-card:#1e1e36;
  --border-color:#2d2d4e;
  --border-glow:#4a4a7a;
  --text-primary:#e8e8f0;
  --text-secondary:#8888aa;
  --text-muted:#555577;
  --accent:#6c63ff;
  --accent-glow:rgba(108,99,255,0.3);
  --accent-secondary:#00d4aa;
  --accent-secondary-glow:rgba(0,212,170,0.3);
  --danger:#ff4757;
  --danger-glow:rgba(255,71,87,0.3);
  --warning:#ffc107;
  --success:#2ed573;
  --square-light:#2b2b45;
  --square-dark:#1a1a2e;
  --square-highlight:rgba(255,215,0,0.25);
  --square-valid:rgba(0,212,170,0.4);
  --square-check:rgba(255,71,87,0.5);
  --square-last:rgba(108,99,255,0.2);
  --piece-white-shadow:0 0 8px rgba(200,200,255,0.15);
  --piece-black-shadow:0 0 8px rgba(100,100,150,0.15);
  --radius-sm:6px;
  --radius-md:12px;
  --radius-lg:20px;
  --shadow-sm:0 2px 8px rgba(0,0,0,0.3);
  --shadow-md:0 4px 20px rgba(0,0,0,0.4);
  --shadow-lg:0 8px 40px rgba(0,0,0,0.5);
  --transition:all 0.2s ease;
  --font:'Segoe UI',system-ui,-apple-system,sans-serif;
  --font-mono:'Cascadia Code','Fira Code','JetBrains Mono',monospace
}
html,body{height:100%;font-family:var(--font);background:var(--bg-primary);color:var(--text-primary);overflow-x:hidden}
a{color:var(--accent);text-decoration:none}
a:hover{color:#8b85ff}
button{cursor:pointer;font-family:var(--font);border:none;outline:none;transition:var(--transition)}
input{font-family:var(--font);outline:none;transition:var(--transition)}

.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;padding:12px 28px;border-radius:var(--radius-sm);font-size:15px;font-weight:600;transition:var(--transition);position:relative;overflow:hidden}
.btn-primary{background:linear-gradient(135deg,var(--accent),#8b7aff);color:#fff;box-shadow:0 4px 15px var(--accent-glow)}
.btn-primary:hover{transform:translateY(-2px);box-shadow:0 6px 25px var(--accent-glow)}
.btn-secondary{background:var(--bg-surface);color:var(--text-primary);border:1px solid var(--border-color)}
.btn-secondary:hover{background:var(--bg-surface-hover);border-color:var(--border-glow)}
.btn-danger{background:linear-gradient(135deg,var(--danger),#ff6b81);color:#fff;box-shadow:0 4px 15px var(--danger-glow)}
.btn-danger:hover{transform:translateY(-2px);box-shadow:0 6px 25px var(--danger-glow)}
.btn-success{background:linear-gradient(135deg,var(--accent-secondary),#00e6b3);color:#0a0a1a;box-shadow:0 4px 15px var(--accent-secondary-glow)}
.btn-success:hover{transform:translateY(-2px);box-shadow:0 6px 25px var(--accent-secondary-glow)}
.btn-sm{padding:8px 16px;font-size:13px}
.btn:disabled{opacity:0.5;cursor:not-allowed;transform:none!important}

.card{background:var(--bg-card);border:1px solid var(--border-color);border-radius:var(--radius-md);padding:24px;box-shadow:var(--shadow-sm)}
.input{background:var(--bg-surface);border:1px solid var(--border-color);border-radius:var(--radius-sm);padding:12px 16px;color:var(--text-primary);font-size:15px;width:100%}
.input:focus{border-color:var(--accent);box-shadow:0 0 0 3px var(--accent-glow)}
.input::placeholder{color:var(--text-muted)}
.label{display:block;font-size:13px;font-weight:600;color:var(--text-secondary);margin-bottom:6px;text-transform:uppercase;letter-spacing:0.5px}

[data-theme="dark"]{color-scheme:dark}

::-webkit-scrollbar{width:6px;height:6px}
::-webkit-scrollbar-track{background:var(--bg-secondary)}
::-webkit-scrollbar-thumb{background:var(--border-color);border-radius:3px}
::-webkit-scrollbar-thumb:hover{background:var(--border-glow)}

@keyframes fadeIn{from{opacity:0;transform:translateY(10px)}to{opacity:1;transform:translateY(0)}}
@keyframes slideUp{from{opacity:0;transform:translateY(30px)}to{opacity:1;transform:translateY(0)}}
@keyframes pulse{0%,100%{opacity:1}50%{opacity:0.5}}
@keyframes shake{0%,100%{transform:translateX(0)}20%,60%{transform:translateX(-4px)}40%,80%{transform:translateX(4px)}}
@keyframes glow{0%,100%{box-shadow:0 0 5px var(--accent-glow)}50%{box-shadow:0 0 20px var(--accent-glow)}}
@keyframes checkPulse{0%,100%{box-shadow:0 0 0 0 rgba(255,71,87,0.4)}50%{box-shadow:0 0 0 15px rgba(255,71,87,0)}}
@keyframes confetti{0%{transform:translateY(0) rotate(0deg);opacity:1}100%{transform:translateY(-500px) rotate(720deg);opacity:0}}
@keyframes slideInRight{from{transform:translateX(100%);opacity:0}to{transform:translateX(0);opacity:1}}
@keyframes countdown{from{width:100%}to{width:0%}}
@keyframes popIn{0%{transform:scale(0.8);opacity:0}70%{transform:scale(1.05)}100%{transform:scale(1);opacity:1}}

.fade-in{animation:fadeIn 0.3s ease}
.slide-up{animation:slideUp 0.4s ease}

.main-header{
  background:linear-gradient(180deg,var(--bg-secondary),transparent);
  border-bottom:1px solid var(--border-color);
  padding:16px 32px;
  display:flex;
  align-items:center;
  justify-content:space-between;
  position:sticky;
  top:0;
  z-index:100;
  backdrop-filter:blur(20px)
}
.main-header .logo{font-size:22px;font-weight:800;background:linear-gradient(135deg,var(--accent),var(--accent-secondary));-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}
.main-header .logo-sub{font-size:13px;color:var(--text-muted);-webkit-text-fill-color:var(--text-muted)}
.main-header nav{display:flex;gap:16px;align-items:center}

.landing-page{min-height:100vh;display:flex;flex-direction:column}
.landing-content{flex:1;display:flex;align-items:center;justify-content:center;padding:40px 20px}
.landing-inner{max-width:520px;width:100%;text-align:center}
.landing-title{font-size:48px;font-weight:800;line-height:1.1;margin-bottom:16px}
.landing-title span{background:linear-gradient(135deg,var(--accent),var(--accent-secondary));-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}
.landing-sub{font-size:18px;color:var(--text-secondary);margin-bottom:40px;line-height:1.6}
.landing-actions{display:flex;flex-direction:column;gap:16px;align-items:center}
.landing-card{background:var(--bg-card);border:1px solid var(--border-color);border-radius:var(--radius-lg);padding:32px;width:100%;text-align:left;animation:slideUp 0.5s ease}
.landing-card h3{font-size:16px;margin-bottom:16px;color:var(--text-primary)}
.landing-card .input-group{display:flex;gap:12px}
.landing-card .input-group .input{flex:1}
.divider{display:flex;align-items:center;gap:16px;width:100%;margin:8px 0;color:var(--text-muted);font-size:13px}
.divider::before,.divider::after{content:'';flex:1;height:1px;background:var(--border-color)}
.room-code-display{display:flex;align-items:center;gap:8px;background:var(--bg-primary);border:1px solid var(--border-color);border-radius:var(--radius-sm);padding:8px 12px;margin-top:12px;font-size:14px}
.room-code-display code{font-family:var(--font-mono);font-size:18px;font-weight:700;letter-spacing:2px;color:var(--accent-secondary);flex:1;text-align:center}
.room-code-display .copy-btn{background:none;border:none;color:var(--text-secondary);padding:4px 8px;border-radius:4px;cursor:pointer;transition:var(--transition)}
.room-code-display .copy-btn:hover{color:var(--accent-secondary);background:var(--bg-surface)}
.status-msg{margin-top:12px;padding:10px 16px;border-radius:var(--radius-sm);font-size:14px}
.status-msg.error{background:rgba(255,71,87,0.15);border:1px solid rgba(255,71,87,0.3);color:var(--danger)}
.status-msg.success{background:rgba(0,212,170,0.15);border:1px solid rgba(0,212,170,0.3);color:var(--accent-secondary)}

.game-page{min-height:100vh;display:flex;flex-direction:column}
.game-container{flex:1;display:flex;gap:24px;padding:24px;max-width:1400px;margin:0 auto;width:100%;align-items:flex-start}
.game-main{flex:1;display:flex;flex-direction:column;align-items:center;gap:16px;min-width:0}
.game-sidebar{width:320px;flex-shrink:0;display:flex;flex-direction:column;gap:16px}

.player-info{display:flex;align-items:center;gap:12px;padding:12px 16px;background:var(--bg-card);border:1px solid var(--border-color);border-radius:var(--radius-md);min-height:56px;transition:var(--transition);position:relative}
.player-info.active{background:var(--bg-surface);border-color:var(--accent);box-shadow:0 0 20px var(--accent-glow)}
.player-info .avatar{width:36px;height:36px;border-radius:50%;display:flex;align-items:center;justify-content:center;font-size:18px;font-weight:700;flex-shrink:0}
.player-info .avatar.white{background:linear-gradient(135deg,#e8e8f0,#c0c0d0);color:#1a1a2e}
.player-info .avatar.black{background:linear-gradient(135deg,#2d2d4e,#1a1a2e);color:#e8e8f0;border:1px solid var(--border-color)}
.player-info .info{flex:1;min-width:0}
.player-info .info .name{font-weight:600;font-size:14px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.player-info .info .status{font-size:12px;color:var(--text-muted)}
.player-info .timer{font-family:var(--font-mono);font-size:20px;font-weight:700;letter-spacing:1px;color:var(--text-primary)}
.player-info .timer.warning{color:var(--warning);animation:pulse 1s infinite}
.player-info .timer.danger{color:var(--danger);animation:pulse 0.5s infinite}
.player-info .timer.flag{color:var(--danger);animation:shake 0.3s infinite}

.board-wrapper{position:relative;width:min(85vw,700px);aspect-ratio:1;border-radius:var(--radius-md);overflow:hidden;box-shadow:var(--shadow-lg);border:2px solid var(--border-color);background:var(--bg-secondary)}
.board-wrapper .board{display:grid;grid-template-columns:repeat(8,1fr);grid-template-rows:repeat(8,1fr);width:100%;height:100%;position:relative;user-select:none}
.board-wrapper .square{position:relative;display:flex;align-items:center;justify-content:center;cursor:pointer;transition:background 0.15s ease}
.board-wrapper .square.light{background:var(--square-light)}
.board-wrapper .square.dark{background:var(--square-dark)}
.board-wrapper .square.last-move{background:var(--square-last)}
.board-wrapper .square.valid-move{cursor:pointer}
.board-wrapper .square.valid-move::after{content:'';position:absolute;width:30%;height:30%;border-radius:50%;background:var(--square-valid);pointer-events:none;animation:popIn 0.15s ease}
.board-wrapper .square.valid-capture{cursor:pointer}
.board-wrapper .square.valid-capture::after{content:'';position:absolute;inset:3px;border-radius:50%;border:4px solid var(--square-valid);pointer-events:none;animation:popIn 0.15s ease}
.board-wrapper .square.selected{background:var(--square-highlight)!important}
.board-wrapper .square.check{background:var(--square-check)!important;animation:checkPulse 1s infinite}
.board-wrapper .square .piece{width:85%;height:85%;background-size:contain;background-repeat:no-repeat;background-position:center;cursor:grab;transition:transform 0.1s ease;position:relative;z-index:2;pointer-events:none}
.board-wrapper .square .piece:hover{transform:scale(1.08)}
.board-wrapper .square .piece.dragging{opacity:0.6;transform:scale(1.1)}
.board-wrapper .coords{position:absolute;pointer-events:none;z-index:3;font-size:10px;font-weight:600;color:var(--text-muted);font-family:var(--font-mono)}
.board-wrapper .coords.file{bottom:2px;right:4px}
.board-wrapper .coords.rank{top:2px;left:4px}
.board-wrapper .square.dark .coords{color:rgba(255,255,255,0.15)}
.board-wrapper .square.light .coords{color:rgba(255,255,255,0.15)}

.game-controls{display:flex;gap:8px;flex-wrap:wrap;justify-content:center;width:100%}
.game-controls .btn{flex:1;min-width:90px;padding:10px 16px;font-size:13px}

.sidebar-panel{background:var(--bg-card);border:1px solid var(--border-color);border-radius:var(--radius-md);overflow:hidden}
.sidebar-panel .panel-header{padding:12px 16px;border-bottom:1px solid var(--border-color);display:flex;align-items:center;justify-content:space-between}
.sidebar-panel .panel-header h3{font-size:13px;font-weight:600;text-transform:uppercase;letter-spacing:0.5px;color:var(--text-secondary)}
.sidebar-panel .panel-body{padding:0;max-height:280px;overflow-y:auto}

.move-history{font-family:var(--font-mono);font-size:13px}
.move-history .move-row{display:flex;padding:4px 16px;align-items:center;gap:8px;transition:var(--transition)}
.move-history .move-row:hover{background:var(--bg-surface)}
.move-history .move-row .move-num{color:var(--text-muted);width:32px;text-align:right;flex-shrink:0}
.move-history .move-row .move-w,.move-history .move-row .move-b{padding:2px 6px;border-radius:4px;flex:1;cursor:default}
.move-history .move-row .move-w{color:var(--text-primary)}
.move-history .move-row .move-b{color:var(--text-secondary)}
.move-history .move-row.highlight .move-w,.move-history .move-row.highlight .move-b{background:var(--square-last);border-radius:4px}

.chat-box{display:flex;flex-direction:column}
.chat-messages{flex:1;overflow-y:auto;padding:12px 16px;min-height:120px;max-height:200px;display:flex;flex-direction:column;gap:6px}
.chat-messages .chat-msg{font-size:13px;line-height:1.4;animation:fadeIn 0.2s ease}
.chat-messages .chat-msg .chat-name{font-weight:600;margin-right:6px}
.chat-messages .chat-msg .chat-name.white{color:var(--text-primary)}
.chat-messages .chat-msg .chat-name.black{color:var(--accent-secondary)}
.chat-messages .chat-msg .chat-text{color:var(--text-secondary);word-break:break-word}
.chat-messages .chat-empty{color:var(--text-muted);font-size:13px;text-align:center;padding:20px 0}
.chat-input-area{display:flex;gap:8px;padding:8px 12px;border-top:1px solid var(--border-color)}
.chat-input-area .input{flex:1;padding:8px 12px;font-size:13px;background:var(--bg-primary)}
.chat-input-area .chat-send-btn{padding:8px 12px;background:var(--accent);color:#fff;border-radius:var(--radius-sm);font-size:13px}
.chat-input-area .chat-send-btn:hover{background:#8b7aff}

.modal-overlay{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(8px);animation:fadeIn 0.2s ease}
.modal-overlay.hidden{display:none}
.modal-content{background:var(--bg-card);border:1px solid var(--border-color);border-radius:var(--radius-lg);padding:32px;max-width:420px;width:90%;text-align:center;box-shadow:var(--shadow-lg);animation:popIn 0.3s ease}
.modal-content h2{font-size:24px;margin-bottom:8px}
.modal-content p{color:var(--text-secondary);margin-bottom:20px;line-height:1.5}
.modal-content .modal-icon{font-size:48px;margin-bottom:12px;display:block}
.modal-content .modal-actions{display:flex;gap:12px;justify-content:center}
.modal-content .modal-actions .btn{flex:1}

.promotion-modal .promo-pieces{display:flex;gap:12px;justify-content:center;margin:20px 0}
.promotion-modal .promo-piece{width:72px;height:72px;border-radius:var(--radius-sm);background:var(--bg-surface);border:2px solid var(--border-color);cursor:pointer;display:flex;align-items:center;justify-content:center;padding:8px;transition:var(--transition)}
.promotion-modal .promo-piece:hover{border-color:var(--accent);background:var(--bg-surface-hover);transform:scale(1.1)}
.promotion-modal .promo-piece img{width:100%;height:100%;object-fit:contain}

.confetti-container{position:fixed;inset:0;pointer-events:none;z-index:1001;overflow:hidden}
.confetti-piece{position:absolute;width:10px;height:10px;border-radius:2px;animation:confetti 2s ease-out forwards}

.spinner{width:20px;height:20px;border:2px solid var(--border-color);border-top-color:var(--accent);border-radius:50%;animation:spin 0.6s linear infinite;display:inline-block}
@keyframes spin{to{transform:rotate(360deg)}}

.toast{position:fixed;top:20px;right:20px;background:var(--bg-card);border:1px solid var(--border-color);border-radius:var(--radius-sm);padding:12px 20px;box-shadow:var(--shadow-md);z-index:2000;animation:slideInRight 0.3s ease;font-size:14px;max-width:300px}
.toast.success{border-color:var(--accent-secondary)}
.toast.error{border-color:var(--danger)}
.toast.info{border-color:var(--accent)}

.waiting-overlay{position:absolute;inset:0;background:rgba(10,10,26,0.85);display:flex;flex-direction:column;align-items:center;justify-content:center;z-index:10;border-radius:var(--radius-md);backdrop-filter:blur(4px)}
.waiting-overlay.hidden{display:none}
.waiting-overlay .spinner{width:40px;height:40px;border-width:3px;margin-bottom:16px}
.waiting-overlay p{font-size:16px;color:var(--text-secondary);margin-bottom:8px}
.waiting-overlay .room-code{font-family:var(--font-mono);font-size:28px;font-weight:700;letter-spacing:4px;color:var(--accent-secondary);margin-bottom:4px}
.waiting-overlay .room-link{font-size:12px;color:var(--text-muted);word-break:break-all;max-width:90%;margin-top:8px}

@media(max-width:1024px){
  .game-container{flex-direction:column;align-items:center;padding:16px}
  .game-sidebar{width:100%;max-width:560px}
  .board-wrapper{width:100%;max-width:640px}
}
@media(max-width:600px){
  .landing-title{font-size:32px}
  .game-container{padding:8px}
  .board-wrapper{width:100%;border-radius:var(--radius-sm)}
  .player-info{padding:8px 12px}
  .player-info .timer{font-size:16px}
  .main-header{padding:12px 16px}
  .main-header .logo{font-size:18px}
}
.drag-ghost{position:fixed;pointer-events:none;z-index:10000;background-size:contain;background-repeat:no-repeat;background-position:center;opacity:0.9;filter:drop-shadow(0 6px 16px rgba(0,0,0,0.6));transition:none;image-rendering:pixelated}
.board-wrapper.dragging .square{cursor:grabbing}
.board-wrapper.dragging .square .piece{cursor:grabbing}