* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    background: linear-gradient(135deg, #1a1a2e 0%, #16213e 100%);
    color: #fff;
    font-family: 'Orbitron', Arial, sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    overflow: hidden;
}

/* ══════════════════════════════════
   SCREEN SYSTEM
   ══════════════════════════════════ */
.screen {
    display: none;
    position: fixed;
    top: 0; left: 0; right: 0; bottom: 0;
    justify-content: center;
    align-items: center;
}
.screen.active {
    display: flex;
}

/* ══════════════════════════════════
   MAIN MENU
   ══════════════════════════════════ */
.menu-content {
    text-align: center;
    position: relative;
    padding: 40px;
}

.menu-piece-deco {
    position: absolute;
    font-size: 120px;
    opacity: 0.06;
    top: 50%;
    transform: translateY(-50%);
    pointer-events: none;
    user-select: none;
}
.menu-piece-deco.left { left: -140px; }
.menu-piece-deco.right { right: -140px; }

.menu-title {
    font-size: 4rem;
    color: #fff;
    letter-spacing: 4px;
    line-height: 1.1;
    margin-bottom: 12px;
    text-shadow: 0 0 40px #0ff3;
}

.title-accent {
    color: #0ff;
    text-shadow: 0 0 20px #0ff8, 0 0 60px #0ff3;
    font-size: 4.5rem;
}

.menu-subtitle {
    color: #668;
    font-family: Arial, sans-serif;
    font-size: 1rem;
    letter-spacing: 2px;
    margin-bottom: 50px;
}

.menu-buttons {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 16px;
}

.menu-btn {
    width: 280px;
    padding: 16px 0;
    font-size: 1.2rem;
    font-family: 'Orbitron', Arial, sans-serif;
    letter-spacing: 3px;
    border: 1px solid #0ff4;
    border-radius: 12px;
    background: #152030;
    color: #8cf;
    cursor: pointer;
    transition: all 0.25s;
}

.menu-btn:hover {
    background: #1a4a5a;
    color: #0ff;
    border-color: #0ff;
    box-shadow: 0 0 20px #0ff4, 0 0 40px #0ff1;
    transform: translateY(-2px);
}

.menu-btn.primary-btn {
    background: linear-gradient(135deg, #0a3a4a, #0d5060);
    color: #0ff;
    border-color: #0ff8;
    font-size: 1.4rem;
    padding: 18px 0;
}

.menu-btn.primary-btn:hover {
    background: linear-gradient(135deg, #0d5060, #0a6a7a);
    box-shadow: 0 0 30px #0ff6, 0 0 60px #0ff2;
}

/* ══════════════════════════════════
   SETTINGS SCREEN
   ══════════════════════════════════ */
.settings-content {
    text-align: center;
    width: 420px;
    max-width: 90vw;
}

.settings-title {
    font-size: 2rem;
    color: #0ff;
    text-shadow: 0 0 16px #0ff8;
    margin-bottom: 32px;
    letter-spacing: 3px;
}

.settings-list {
    display: flex;
    flex-direction: column;
    gap: 4px;
    margin-bottom: 32px;
}

.setting-row {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 14px 20px;
    background: #111a28;
    border-radius: 10px;
    cursor: pointer;
    transition: background 0.15s;
    border: 1px solid transparent;
}

.setting-row:hover {
    background: #1a2a3a;
    border-color: #0ff2;
}

.setting-label {
    font-size: 0.85rem;
    color: #aac;
    letter-spacing: 1px;
    font-family: Arial, sans-serif;
}

/* Toggle switch */
.toggle-input {
    display: none;
}

.toggle-slider {
    width: 46px;
    height: 24px;
    background: #334;
    border-radius: 12px;
    position: relative;
    transition: background 0.25s;
    flex-shrink: 0;
}

.toggle-slider::after {
    content: '';
    position: absolute;
    width: 18px;
    height: 18px;
    border-radius: 50%;
    background: #667;
    top: 3px;
    left: 3px;
    transition: all 0.25s;
}

.toggle-input:checked + .toggle-slider {
    background: #0a6a7a;
}

.toggle-input:checked + .toggle-slider::after {
    background: #0ff;
    left: 25px;
    box-shadow: 0 0 8px #0ff8;
}

/* Select dropdown */
.setting-select {
    background: #1a2a3a;
    color: #8cf;
    border: 1px solid #334;
    border-radius: 6px;
    padding: 6px 12px;
    font-family: Arial, sans-serif;
    font-size: 0.85rem;
    cursor: pointer;
    outline: none;
}

.setting-select:focus {
    border-color: #0ff6;
}

/* ══════════════════════════════════
   GAME SCREEN
   ══════════════════════════════════ */
#game-screen {
    overflow-y: auto;
    align-items: flex-start;
    padding: 10px;
}

#chess-app {
    text-align: center;
    width: 100%;
    max-width: 600px;
    margin: 0 auto;
}

#game-top-bar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 10px;
}

#game-top-bar h1 {
    font-size: 1.4rem;
    color: #0ff;
    text-shadow: 0 0 16px #0ff6;
    letter-spacing: 2px;
}

.icon-btn {
    width: 40px;
    height: 40px;
    font-size: 22px;
    background: #152030;
    border: 1px solid #0ff3;
    border-radius: 8px;
    color: #8cf;
    cursor: pointer;
    transition: all 0.2s;
    display: flex;
    align-items: center;
    justify-content: center;
}

.icon-btn:hover {
    background: #1a4a5a;
    color: #0ff;
    border-color: #0ff;
    box-shadow: 0 0 10px #0ff4;
}

/* Board area with coordinates */
#board-area {
    display: flex;
    flex-direction: column;
    align-items: center;
    margin: 0 auto;
}

.coord-row {
    display: flex;
    justify-content: center;
    width: 512px;
    padding: 0 0 0 24px;
}

.coord-row span {
    width: 64px;
    text-align: center;
    font-size: 11px;
    color: #556;
    font-family: Arial, sans-serif;
    line-height: 18px;
}

.coord-col {
    display: flex;
    flex-direction: column;
    justify-content: center;
    width: 24px;
}

.coord-col span {
    height: 64px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 11px;
    color: #556;
    font-family: Arial, sans-serif;
}

#board-mid {
    display: flex;
    align-items: center;
}

.coords-hidden .coord-row,
.coords-hidden .coord-col {
    visibility: hidden;
}

#chessboard {
    display: grid;
    grid-template-columns: repeat(8, 64px);
    grid-template-rows: repeat(8, 64px);
    gap: 0;
    border: 3px solid #556;
    border-radius: 4px;
    box-shadow: 0 0 30px #0004, 0 0 8px #0ff3;
}

.square {
    width: 64px;
    height: 64px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    user-select: none;
    position: relative;
    transition: background 0.15s;
}

/* Theme: Classic */
.theme-classic .square.light { background: #f0d9b5; }
.theme-classic .square.dark  { background: #b58863; }

/* Theme: Blue Ice */
.theme-blue .square.light { background: #d6e4f0; }
.theme-blue .square.dark  { background: #5a8bb0; }

/* Theme: Emerald */
.theme-green .square.light { background: #e8edcc; }
.theme-green .square.dark  { background: #6d945a; }

/* Theme: Gunmetal */
.theme-gray .square.light { background: #ccc; }
.theme-gray .square.dark  { background: #666; }

.square.selected {
    background: #7bc96a !important;
}

.square.last-move {
    background: #cdd26a88 !important;
}

.square.in-check {
    background: radial-gradient(circle, #ff0000cc, #ff000044) !important;
}

.square.drag-over {
    box-shadow: inset 0 0 0 3px #0ffa;
}

.move-dot {
    width: 18px;
    height: 18px;
    border-radius: 50%;
    background: rgba(0, 0, 0, 0.2);
    position: absolute;
    pointer-events: none;
    z-index: 1;
}

.capture-ring {
    width: 58px;
    height: 58px;
    border-radius: 50%;
    border: 5px solid rgba(0, 0, 0, 0.2);
    position: absolute;
    pointer-events: none;
    z-index: 1;
}

.piece {
    font-size: 48px;
    line-height: 1;
    pointer-events: none;
    user-select: none;
    z-index: 2;
    text-shadow: 0 1px 3px rgba(0,0,0,0.4);
}

.piece.draggable {
    pointer-events: auto;
    cursor: grab;
}

.piece.dragging {
    opacity: 0.3;
}

.white-piece {
    color: #ffffff;
    -webkit-text-stroke: 1px #888;
    filter: drop-shadow(0 1px 2px rgba(0,0,0,0.3));
}

.black-piece {
    color: #000000;
    -webkit-text-stroke: 1px #000;
    filter: drop-shadow(0 1px 2px rgba(0,0,0,0.3));
}

/* Drag ghost */
#drag-ghost {
    position: fixed;
    font-size: 56px;
    pointer-events: none;
    z-index: 200;
    transform: translate(-50%, -50%);
    text-shadow: 0 2px 8px rgba(0,0,0,0.5);
    filter: drop-shadow(0 4px 8px rgba(0,0,0,0.4));
}
#drag-ghost.hidden { display: none; }

#status {
    margin-top: 14px;
    font-size: 1.1rem;
    min-height: 28px;
    color: #aac;
    letter-spacing: 1px;
}

.status-check {
    color: #f90 !important;
    font-weight: bold;
}

.status-checkmate {
    color: #f33 !important;
    font-weight: bold;
    text-shadow: 0 0 10px #f33;
}

.status-draw {
    color: #0ff !important;
}

#controls {
    margin: 12px 0;
    display: flex;
    justify-content: center;
    gap: 12px;
}

#controls button {
    padding: 8px 24px;
    font-size: 14px;
    font-family: 'Orbitron', Arial, sans-serif;
    border-radius: 6px;
    border: 1px solid #0ff6;
    background: #152030;
    color: #8cf;
    cursor: pointer;
    transition: all 0.2s;
    letter-spacing: 1px;
}

#controls button:hover {
    background: #1a4a5a;
    color: #0ff;
    border-color: #0ff;
    box-shadow: 0 0 10px #0ff4;
}

#move-history {
    margin: 10px auto;
    width: 516px;
    max-width: 100%;
    background: #111a;
    color: #bbc;
    padding: 12px 14px;
    border-radius: 8px;
    border: 1px solid #334;
    min-height: 40px;
    max-height: 120px;
    overflow-y: auto;
    text-align: left;
    font-size: 14px;
    font-family: 'Courier New', monospace;
    line-height: 1.6;
}

.move-num {
    color: #667;
}

/* Promotion modal */
#promotion-modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0,0,0,0.7);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 100;
}

#promotion-modal.hidden {
    display: none;
}

#promotion-choices {
    background: #23234b;
    border-radius: 16px;
    padding: 20px 24px;
    display: flex;
    gap: 12px;
    box-shadow: 0 0 40px #0ff4;
    border: 2px solid #0ff6;
}

.promo-btn {
    font-size: 48px;
    width: 72px;
    height: 72px;
    display: flex;
    align-items: center;
    justify-content: center;
    border: 2px solid #556;
    border-radius: 12px;
    background: #1a1a2e;
    cursor: pointer;
    transition: all 0.15s;
}

.promo-btn:hover {
    background: #2a3a5e;
    border-color: #0ff;
    box-shadow: 0 0 12px #0ff6;
}

/* ══════════════════════════════════
   AI BUTTON (MENU)
   ══════════════════════════════════ */
.menu-btn.ai-btn {
    background: linear-gradient(135deg, #1a0a3a, #2d1050);
    color: #c8f;
    border-color: #a0f8;
}

.menu-btn.ai-btn:hover {
    background: linear-gradient(135deg, #2d1050, #4a1a6a);
    box-shadow: 0 0 30px #a0f6, 0 0 60px #a0f2;
    color: #e0f;
    border-color: #c0f;
    transform: translateY(-2px);
}

/* ══════════════════════════════════
   AI INFO BAR
   ══════════════════════════════════ */
#ai-info {
    background: linear-gradient(135deg, #0a1520, #152535);
    border: 1px solid #0ff3;
    border-radius: 10px;
    padding: 12px 16px;
    margin-bottom: 10px;
}

#ai-info.hidden { display: none; }

.ai-info-row {
    display: flex;
    justify-content: space-around;
    align-items: center;
    gap: 16px;
}

.ai-stat {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 4px;
}

.ai-stat-label {
    font-size: 0.6rem;
    color: #556;
    letter-spacing: 2px;
    font-family: Arial, sans-serif;
}

.ai-stat-value {
    font-size: 1.1rem;
    color: #0ff;
    text-shadow: 0 0 8px #0ff6;
    font-weight: 700;
}

.ai-xp-bar {
    height: 3px;
    background: #1a2a3a;
    border-radius: 2px;
    margin-top: 10px;
    overflow: hidden;
}

.ai-xp-fill {
    height: 100%;
    background: linear-gradient(90deg, #0ff, #0af);
    border-radius: 2px;
    width: 0%;
    transition: width 0.5s ease;
}

/* ══════════════════════════════════
   AI THINKING INDICATOR
   ══════════════════════════════════ */
#ai-thinking {
    padding: 8px 0;
    color: #0ff;
    font-size: 0.85rem;
    letter-spacing: 1px;
    text-align: center;
}

#ai-thinking.hidden { display: none; }

.thinking-dots span {
    animation: thinkDot 1.4s infinite;
    opacity: 0;
}

.thinking-dots span:nth-child(1) { animation-delay: 0s; }
.thinking-dots span:nth-child(2) { animation-delay: 0.2s; }
.thinking-dots span:nth-child(3) { animation-delay: 0.4s; }

@keyframes thinkDot {
    0%, 20% { opacity: 0; }
    50% { opacity: 1; }
    100% { opacity: 0; }
}

/* ══════════════════════════════════
   RESET AI BUTTON (SETTINGS)
   ══════════════════════════════════ */
.reset-row {
    margin-top: 12px;
    border-color: #f334 !important;
}

.setting-btn-sm {
    padding: 6px 18px;
    font-family: 'Orbitron', Arial, sans-serif;
    font-size: 0.7rem;
    letter-spacing: 2px;
    border: 1px solid #f336;
    border-radius: 6px;
    background: #2a1015;
    color: #f88;
    cursor: pointer;
    transition: all 0.2s;
}

.setting-btn-sm:hover {
    background: #4a1520;
    color: #f44;
    border-color: #f44;
    box-shadow: 0 0 10px #f442;
}