:root {
    --bg: #06060e;
    --bg2: #0d0d1a;
    --bg-card: #111127;
    --bg-card2: #16163a;
    --border: #1e1e4a;
    --border-glow: #6366f1;
    --text: #e4e4f0;
    --text2: #9898c0;
    --text3: #5a5a90;
    --accent: #6366f1;
    --accent2: #a78bfa;
    --accent-glow: rgba(99, 102, 241, 0.25);
    --green: #10b981;
    --red: #ef4444;
    --orange: #f59e0b;
    --board-light: #eedbca;
    --board-dark: #b58863;
    --highlight: rgba(255, 255, 80, 0.45);
    --last-move: rgba(155, 120, 255, 0.35);
    --check: rgba(255, 50, 50, 0.5);
    --r-sm: 6px;
    --r-md: 10px;
    --r-lg: 14px;
    --shadow: 0 4px 30px rgba(0,0,0,0.5);
    --font: 'Inter', system-ui, sans-serif;
    --mono: 'JetBrains Mono', monospace;
    --ease: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { font-size: 16px; }
body { font-family: var(--font); background: var(--bg); color: var(--text); min-height: 100vh; overflow-x: hidden; }

#particles-canvas { position: fixed; inset: 0; pointer-events: none; z-index: 0; opacity: 0.35; }

/* Header */
#app-header { position: sticky; top: 0; z-index: 100; background: rgba(6,6,14,0.88); backdrop-filter: blur(18px); border-bottom: 1px solid var(--border); }
.header-inner { max-width: 1320px; margin: 0 auto; padding: 0.55rem 1.5rem; display: flex; align-items: center; justify-content: space-between; }
.logo-group { display: flex; align-items: center; gap: 0.7rem; }
.logo-icon { font-size: 1.6rem; filter: drop-shadow(0 0 12px var(--accent-glow)); }
.logo-text h1 { font-size: 1.1rem; font-weight: 800; background: linear-gradient(135deg, var(--accent2), var(--accent)); -webkit-background-clip: text; -webkit-text-fill-color: transparent; letter-spacing: -0.3px; }
.logo-subtitle { font-size: 0.6rem; color: var(--text3); letter-spacing: 1.5px; text-transform: uppercase; }
.header-stats { display: flex; gap: 1.5rem; align-items: center; }
.header-stat { display: flex; flex-direction: column; align-items: center; }
.stat-label { font-size: 0.6rem; color: var(--text3); text-transform: uppercase; letter-spacing: 1px; }
.stat-value { font-family: var(--mono); font-size: 1rem; font-weight: 700; color: var(--accent2); }

/* Language Switcher */
.lang-switcher { display: flex; gap: 0.3rem; }
.lang-btn {
    padding: 0.35rem 0.7rem;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--r-sm);
    color: var(--text3);
    font-size: 0.7rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--ease);
}
.lang-btn:hover { border-color: var(--accent); color: var(--text); }
.lang-btn.active { background: var(--accent); color: white; border-color: var(--accent); }

/* Main */
#app-main { max-width: 1320px; margin: 0 auto; padding: 1.2rem 1.5rem; position: relative; z-index: 1; }

/* Agent Config Bar */
.agent-config-bar { display: flex; align-items: center; justify-content: center; gap: 1rem; margin-bottom: 1.2rem; }
.agent-card { display: flex; align-items: center; gap: 0.75rem; padding: 0.7rem 1.2rem; background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--r-lg); flex: 1; max-width: 400px; transition: var(--ease); }
.agent-card:hover { border-color: var(--accent); box-shadow: 0 0 16px var(--accent-glow); }
.white-agent-card { border-left: 3px solid #e8e8e8; }
.black-agent-card { border-left: 3px solid #555; }
.agent-avatar { font-size: 1.8rem; line-height: 1; filter: drop-shadow(0 2px 4px rgba(0,0,0,0.4)); }
.agent-info { display: flex; flex-direction: column; flex: 1; }
.agent-title { font-size: 0.85rem; font-weight: 700; }
.agent-type { font-size: 0.68rem; color: var(--text3); font-family: var(--mono); }
.agent-score-display { text-align: center; }
.agent-wins { font-family: var(--mono); font-size: 1.6rem; font-weight: 800; background: linear-gradient(135deg, var(--green), #34d399); -webkit-background-clip: text; -webkit-text-fill-color: transparent; }
.agent-wins-label { display: block; font-size: 0.6rem; color: var(--text3); text-transform: uppercase; letter-spacing: 1px; }
.vs-badge { font-size: 0.85rem; font-weight: 800; color: var(--text3); background: var(--bg-card); border: 1px solid var(--border); border-radius: 50%; width: 40px; height: 40px; display: flex; align-items: center; justify-content: center; flex-shrink: 0; }

/* Game Layout */
.game-layout { display: grid; grid-template-columns: 1fr 360px; gap: 1.2rem; align-items: start; }

/* Board */
.board-col { display: flex; flex-direction: column; gap: 0.75rem; }
.board-wrapper { position: relative; display: grid; grid-template-columns: 22px 1fr; grid-template-rows: 1fr 22px auto; background: var(--bg-card); border-radius: var(--r-lg); padding: 10px; border: 1px solid var(--border); box-shadow: var(--shadow); }
.chess-board { display: grid; grid-template-columns: repeat(8, 1fr); grid-template-rows: repeat(8, 1fr); aspect-ratio: 1; border-radius: var(--r-md); overflow: hidden; }
.board-coords-col { display: flex; flex-direction: column; justify-content: space-around; align-items: center; font-size: 0.6rem; color: var(--text3); font-family: var(--mono); font-weight: 600; }
.board-coords-row { display: flex; justify-content: space-around; align-items: center; font-size: 0.6rem; color: var(--text3); font-family: var(--mono); font-weight: 600; grid-column: 2; }

.turn-indicator { grid-column: 1 / -1; display: flex; align-items: center; gap: 0.5rem; padding: 0.5rem 0.75rem; font-size: 0.78rem; color: var(--text2); }
.turn-dot { width: 8px; height: 8px; border-radius: 50%; background: var(--green); animation: pulse 1.2s infinite; }
.turn-dot.paused { background: var(--orange); animation: none; }
.turn-dot.ended { background: var(--text3); animation: none; }
@keyframes pulse { 0%,100% { opacity: 1; transform: scale(1); } 50% { opacity: 0.5; transform: scale(1.3); } }

.square { display: flex; align-items: center; justify-content: center; position: relative; transition: background 0.15s ease; cursor: pointer; }
.square.light { background: var(--board-light); }
.square.dark { background: var(--board-dark); }
.square.last-move { background: var(--last-move) !important; }
.square.check { box-shadow: inset 0 0 18px var(--check); }
.square.selected { box-shadow: inset 0 0 0 3px rgba(99, 102, 241, 0.8) !important; }
.square.legal-move::after {
    content: '';
    position: absolute;
    width: 28%;
    height: 28%;
    border-radius: 50%;
    background: rgba(99, 102, 241, 0.5);
    pointer-events: none;
}
.square.legal-move:has(.piece)::after {
    width: 100%;
    height: 100%;
    border-radius: 50%;
    background: transparent;
    border: 3px solid rgba(99, 102, 241, 0.6);
}
.square.hint-move {
    box-shadow: inset 0 0 0 3px rgba(251, 191, 36, 0.8) !important;
}
.hint-label {
    position: absolute;
    top: 2px;
    right: 2px;
    background: rgba(251, 191, 36, 0.95);
    color: #000;
    font-size: 0.7rem;
    font-weight: 700;
    width: 18px;
    height: 18px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 10;
    pointer-events: none;
}

/* Pieces — distinct black vs white */
.piece {
    font-size: clamp(1.6rem, 5.5vw, 2.8rem);
    line-height: 1;
    user-select: none;
    position: relative;
    z-index: 2;
    will-change: transform;
}
.white-piece {
    color: #ffffff;
    text-shadow:
        -1px -1px 0 #333,
         1px -1px 0 #333,
        -1px  1px 0 #333,
         1px  1px 0 #333,
         0   -1px 0 #333,
         0    1px 0 #333,
        -1px  0   0 #333,
         1px  0   0 #333,
         0 2px 4px rgba(0,0,0,0.3);
    filter: drop-shadow(0 1px 2px rgba(0,0,0,0.2));
}
.black-piece {
    color: #1a1a1a;
    text-shadow:
        -1px -1px 0 #888,
         1px -1px 0 #888,
        -1px  1px 0 #888,
         1px  1px 0 #888,
         0   -1px 0 #888,
         0    1px 0 #888,
        -1px  0   0 #888,
         1px  0   0 #888,
         0 2px 4px rgba(0,0,0,0.4);
    filter: drop-shadow(0 1px 3px rgba(0,0,0,0.35));
}

/* Controls Bar */
.controls-bar { display: flex; align-items: center; gap: 0.5rem; flex-wrap: wrap; }
.ctrl-btn { display: flex; align-items: center; gap: 0.35rem; padding: 0.5rem 1rem; border: 1px solid var(--border); background: var(--bg-card); color: var(--text2); border-radius: var(--r-sm); font-family: var(--font); font-size: 0.78rem; font-weight: 600; cursor: pointer; transition: var(--ease); }
.ctrl-btn:hover:not(:disabled) { border-color: var(--accent); color: var(--text); box-shadow: 0 0 12px var(--accent-glow); }
.ctrl-btn:disabled { opacity: 0.4; cursor: default; }
.ctrl-primary { background: var(--accent); color: #fff; border-color: var(--accent); }
.ctrl-primary:hover:not(:disabled) { background: #5558e6; }
.ctrl-icon { font-size: 0.9rem; }
.speed-control { display: flex; align-items: center; gap: 0.5rem; margin-left: auto; }
.speed-label { font-size: 0.7rem; color: var(--text3); font-weight: 500; }
.speed-slider { width: 80px; accent-color: var(--accent); }
.speed-value { font-family: var(--mono); font-size: 0.7rem; color: var(--accent2); min-width: 45px; }

/* Panels */
.panels-col { display: flex; flex-direction: column; gap: 0.75rem; }
.panel-card { background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--r-lg); padding: 1rem 1.1rem; box-shadow: var(--shadow); }
.panel-title { font-size: 0.7rem; font-weight: 700; text-transform: uppercase; letter-spacing: 1.2px; color: var(--text3); margin-bottom: 0.75rem; }

/* Settings */
.agent-settings-row { display: grid; grid-template-columns: 1fr 1fr; gap: 0.75rem; margin-bottom: 0.75rem; }
.agent-setting { display: flex; flex-direction: column; gap: 0.35rem; }
.setting-label { font-size: 0.72rem; font-weight: 600; color: var(--text2); }
.setting-select { padding: 0.35rem 0.5rem; background: var(--bg2); border: 1px solid var(--border); border-radius: var(--r-sm); color: var(--text); font-family: var(--font); font-size: 0.72rem; cursor: pointer; outline: none; }
.setting-select:focus { border-color: var(--accent); }

.control-group { margin-bottom: 0.75rem; }
.toggle-row { display: flex; align-items: center; gap: 0.5rem; }
.toggle { position: relative; width: 36px; height: 20px; }
.toggle input { opacity: 0; width: 0; height: 0; }
.toggle-slider { position: absolute; inset: 0; background: var(--border); border-radius: 10px; cursor: pointer; transition: var(--ease); }
.toggle-slider::before { content: ''; position: absolute; width: 16px; height: 16px; left: 2px; bottom: 2px; background: var(--text); border-radius: 50%; transition: var(--ease); }
.toggle input:checked + .toggle-slider { background: var(--accent); }
.toggle input:checked + .toggle-slider::before { transform: translateX(16px); }
.toggle-label { font-size: 0.7rem; color: var(--text3); }

.fen-row { display: flex; gap: 0.35rem; margin-bottom: 0.5rem; }
.fen-input { flex: 1; padding: 0.4rem 0.6rem; background: var(--bg2); border: 1px solid var(--border); border-radius: var(--r-sm); color: var(--text); font-family: var(--mono); font-size: 0.65rem; outline: none; }
.fen-input:focus { border-color: var(--accent); }
.btn-sm { padding: 0.4rem 0.7rem; background: var(--accent); color: #fff; border: none; border-radius: var(--r-sm); font-size: 0.7rem; font-weight: 600; cursor: pointer; font-family: var(--font); }
.preset-puzzles { display: flex; flex-wrap: wrap; gap: 0.3rem; }
.puzzle-chip { padding: 0.25rem 0.6rem; background: var(--bg2); border: 1px solid var(--border); border-radius: 20px; color: var(--text2); font-size: 0.65rem; cursor: pointer; font-family: var(--font); transition: var(--ease); }
.puzzle-chip:hover { border-color: var(--accent); color: var(--text); }

/* Eval Bar */
.eval-bar-wide { position: relative; height: 28px; border-radius: var(--r-sm); overflow: hidden; display: flex; margin-bottom: 0.75rem; border: 1px solid var(--border); }
.eval-bar-white { background: linear-gradient(90deg, #f0f0f0, #ddd); height: 100%; transition: width 0.5s ease; }
.eval-bar-black { background: linear-gradient(90deg, #333, #222); height: 100%; transition: width 0.5s ease; }
.eval-label-left, .eval-label-right { position: absolute; top: 50%; transform: translateY(-50%); font-size: 0.6rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.5px; }
.eval-label-left { left: 8px; color: #333; }
.eval-label-right { right: 8px; color: #aaa; }
.eval-center { position: absolute; left: 50%; top: 50%; transform: translate(-50%, -50%); font-family: var(--mono); font-size: 0.75rem; font-weight: 700; color: var(--accent2); background: rgba(0,0,0,0.6); padding: 0.1rem 0.4rem; border-radius: 4px; }

.engine-stats { display: flex; flex-direction: column; }
.stat-row { display: flex; justify-content: space-between; padding: 0.3rem 0; font-size: 0.72rem; color: var(--text2); border-bottom: 1px solid rgba(255,255,255,0.03); }
.stat-row span:last-child { font-family: var(--mono); font-weight: 600; color: var(--text); }

/* Move List */
.move-list { max-height: 200px; overflow-y: auto; font-family: var(--mono); font-size: 0.72rem; }
.move-list::-webkit-scrollbar { width: 3px; }
.move-list::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }
.move-list-empty { color: var(--text3); font-size: 0.72rem; font-style: italic; font-family: var(--font); }
.move-row { display: flex; gap: 0.4rem; padding: 0.2rem 0.4rem; border-radius: 3px; }
.move-row:hover { background: rgba(255,255,255,0.03); }
.move-num { color: var(--text3); min-width: 28px; }
.move-w, .move-b { flex: 1; }
.move-latest { color: var(--accent2); font-weight: 700; }

/* Match Log */
.match-log { max-height: 160px; overflow-y: auto; display: flex; flex-direction: column; gap: 0.3rem; }
.match-entry { display: flex; align-items: center; gap: 0.5rem; padding: 0.4rem 0.6rem; background: var(--bg2); border-radius: var(--r-sm); font-size: 0.72rem; border-left: 3px solid var(--border); }
.match-entry.white-win { border-left-color: #e8e8e8; }
.match-entry.black-win { border-left-color: #555; }
.match-entry.draw-result { border-left-color: var(--orange); }
.match-num { font-family: var(--mono); color: var(--text3); min-width: 20px; }
.match-result { flex: 1; font-weight: 600; }
.match-detail { font-size: 0.65rem; color: var(--text3); font-family: var(--mono); }

/* Game Mode Switcher */
.game-mode-switcher {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 0.4rem;
    margin-bottom: 0.8rem;
}
.mode-btn {
    padding: 0.5rem 0.8rem;
    background: var(--bg2);
    border: 1px solid var(--border);
    border-radius: var(--r-sm);
    color: var(--text2);
    font-size: 0.72rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--ease);
}
.mode-btn:hover { border-color: var(--accent); color: var(--text); background: var(--bg-card); }
.mode-btn.active {
    background: var(--accent);
    color: white;
    border-color: var(--accent);
    box-shadow: 0 2px 8px var(--accent-glow);
}

/* Endgame Selector */
.endgame-selector { display: grid; grid-template-columns: 1fr 1fr; gap: 0.5rem; margin-bottom: 0.6rem; }

/* Hint Button */
.ctrl-hint { background: linear-gradient(135deg, #f59e0b, #d97706); border-color: #f59e0b; }
.ctrl-hint:hover { background: linear-gradient(135deg, #d97706, #b45309); }
.ctrl-hint:disabled { background: var(--bg2); border-color: var(--border); opacity: 0.5; }

/* Hint Tooltip */
.hint-tooltip {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    background: var(--bg-card);
    border: 2px solid #f59e0b;
    border-radius: var(--r-lg);
    padding: 1rem 1.5rem;
    box-shadow: 0 8px 40px rgba(245, 158, 11, 0.3);
    z-index: 300;
    animation: fadeInScale 0.3s ease;
}
.hint-title {
    font-size: 0.9rem;
    font-weight: 700;
    color: #f59e0b;
    margin-bottom: 0.6rem;
}
.hint-move {
    font-family: var(--mono);
    font-size: 0.85rem;
    padding: 0.4rem 0;
    color: var(--text);
}
.hint-score {
    float: right;
    color: var(--accent2);
    font-weight: 700;
}
.hint-info {
    margin-top: 0.5rem;
    padding-top: 0.5rem;
    border-top: 1px solid var(--border);
    font-size: 0.7rem;
    color: var(--text3);
    text-align: center;
}
@keyframes fadeInScale {
    from { opacity: 0; transform: translate(-50%, -50%) scale(0.9); }
    to { opacity: 1; transform: translate(-50%, -50%) scale(1); }
}

/* Move Scores */
.move-score {
    font-size: 0.65rem;
    color: var(--accent2);
    margin-left: 0.3rem;
    opacity: 0.8;
}

/* Panel Header */
.panel-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.6rem;
}
.toggle-scores-btn {
    padding: 0.3rem 0.6rem;
    background: var(--bg2);
    border: 1px solid var(--border);
    border-radius: var(--r-sm);
    color: var(--text3);
    font-size: 0.65rem;
    cursor: pointer;
    transition: var(--ease);
}
.toggle-scores-btn:hover { border-color: var(--accent); color: var(--text); }
.toggle-scores-btn.active { background: var(--accent); color: white; border-color: var(--accent); }

/* Game Over Overlay */
.gameover-overlay { position: fixed; top: 0; left: 0; right: 0; z-index: 200; display: flex; justify-content: center; pointer-events: none; }
.gameover-banner { margin-top: 80px; padding: 1rem 2.5rem; background: var(--bg-card); border: 1px solid var(--accent); border-radius: var(--r-lg); box-shadow: 0 8px 40px rgba(99,102,241,0.3); display: flex; align-items: center; gap: 1rem; animation: slideDown 0.4s ease; }
.gameover-icon { font-size: 2rem; }
.gameover-text { font-size: 1rem; font-weight: 700; }
.gameover-sub { font-size: 0.72rem; color: var(--text3); }
@keyframes slideDown { from { transform: translateY(-30px); opacity: 0; } to { transform: translateY(0); opacity: 1; } }

/* Responsive */
@media (max-width: 900px) {
    .game-layout { grid-template-columns: 1fr; }
    .agent-config-bar { flex-direction: column; }
    .agent-card { max-width: 100%; }
    .header-inner { flex-direction: column; gap: 0.5rem; }
    .header-stats { gap: 1rem; }
}