:root {
    --bg-primary: #0a0c15;
    --bg-secondary: #12151f;
    --bg-tertiary: #1a1e2d;
    --bg-glass: rgba(18, 21, 31, 0.7);
    --accent-primary: #6366f1;
    --accent-secondary: #4f46e5;
    --accent-hover: #4338ca;
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --border-color: rgba(255, 255, 255, 0.1);
    --success: #10b981;
    --warning: #f59e0b;
    --error: #ef4444;
    --shadow-sm: 0 2px 4px rgba(0, 0, 0, 0.1);
    --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.2);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.3);
    --shadow-xl: 0 25px 50px -12px rgba(0, 0, 0, 0.4);
    --transition: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    --radius-sm: 0.375rem;
    --radius: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
}

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

body {
    font-family: 'Plus Jakarta Sans', system-ui, -apple-system, sans-serif;
    background-color: var(--bg-primary);
    background-image: 
        radial-gradient(circle at 100% 0%, rgba(99, 102, 241, 0.12) 0%, transparent 25%),
        radial-gradient(circle at 0% 100%, rgba(79, 70, 229, 0.12) 0%, transparent 25%);
    background-attachment: fixed;
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
}

::selection {
    background: var(--accent-primary);
    color: white;
}

.navbar {
    background-color: var(--bg-glass);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    padding: 1rem 2rem;
    border-bottom: 1px solid var(--border-color);
    position: fixed;
    width: 100%;
    top: 0;
    z-index: 1000;
}

.navbar-content {
    max-width: 1400px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--text-primary);
    text-decoration: none;
    letter-spacing: -0.5px;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.logo span {
    background: linear-gradient(135deg, var(--accent-primary), #8b5cf6);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.logo i {
    color: var(--accent-primary);
    font-size: 2rem;
}

.difficulty-display {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    background-color: var(--bg-tertiary);
    padding: 0.5rem 1rem;
    border-radius: 12px;
    font-weight: 500;
}

.difficulty-display i {
    color: var(--accent-primary);
}

.main-content {
    max-width: 1400px;
    margin: 7rem auto 3rem;
    padding: 0 2rem;
}

.hero {
    text-align: center;
    margin-bottom: 4rem;
    padding: 4rem;
    background: linear-gradient(135deg, 
        rgba(99, 102, 241, 0.08), 
        rgba(79, 70, 229, 0.08)
    );
    border-radius: var(--radius-xl);
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow-lg);
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: radial-gradient(
        circle at 50% 50%,
        rgba(99, 102, 241, 0.1),
        transparent 70%
    );
    pointer-events: none;
}

.hero h1 {
    font-size: 4rem;
    font-weight: 800;
    margin-bottom: 1.5rem;
    background: linear-gradient(135deg, 
        var(--accent-primary), 
        var(--accent-secondary)
    );
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    letter-spacing: -2px;
    line-height: 1.3;
    position: relative;
}

.hero p {
    color: var(--text-secondary);
    font-size: 1.25rem;
    max-width: 600px;
    margin: 0 auto;
    line-height: 1.8;
}

.chess-container {
    display: grid;
    grid-template-columns: minmax(auto, 650px) 350px;
    gap: 2.5rem;
    justify-content: center;
    align-items: start;
    margin-top: 2rem;
    position: relative;
}

.board-table {
    background: var(--bg-glass);
    padding: 2.5rem;
    border-radius: var(--radius-xl);
    box-shadow: 0 8px 32px rgba(31, 38, 135, 0.15);
    border: 1px solid var(--border-color);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
}

.board-settings {
    background: var(--bg-glass);
    padding: 2.5rem;
    border-radius: var(--radius-xl);
    box-shadow: 0 8px 32px rgba(31, 38, 135, 0.15);
    border: 1px solid var(--border-color);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    position: sticky;
    top: 120px;
    height: fit-content;
}

.difficulty-selector {
    margin: 2rem 0;
    padding: 1.5rem;
    background: var(--bg-tertiary);
    border-radius: 12px;
    border: 1px solid var(--border-color);
}

.values {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 0.5rem;
    margin-top: 1rem;
}

.values span {
    display: flex;
    align-items: center;
    justify-content: center;
    height: 40px;
    background-color: rgba(255, 255, 255, 0.1);
    color: var(--text-primary);
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    font-weight: 500;
    border: 1px solid transparent;
}

.values span:hover {
    background-color: var(--accent-primary);
    transform: translateY(-2px);
    box-shadow: var(--shadow);
}

.values .selected {
    background: linear-gradient(135deg, var(--gradient-start), var(--gradient-end));
    border: 1px solid rgba(255, 255, 255, 0.1);
    font-weight: 600;
    box-shadow: var(--shadow);
}

.controls {
    margin-top: 1.5rem;
    padding: 1rem;
    background: var(--bg-tertiary);
    border-radius: 12px;
    border: 1px solid var(--border-color);
}

.controls .buttons {
    display: flex;
    gap: 0.75rem;
    flex-wrap: wrap;
}

.controls button {
    background-color: var(--bg-tertiary); !important
    color: var(--text-primary); !important
    border: 1px solid var(--border-color);
    padding: 0.875rem 1.5rem;
    border-radius: var(--radius);
    cursor: pointer;
    font-weight: 500;
    display: flex;
    align-items: center;
    gap: 0.625rem;
    font-size: 0.9rem;
    transition: background-color 0.2s ease;
}

.controls button:hover {
    background-color: var(--accent-primary);
    color: var(--text-primary);
}

.controls button i {
    font-size: 1rem;
}

.controls button.disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.controls button.disabled:hover {
    transform: none;
    background-color: rgba(255, 255, 255, 0.1);
}

.turns-history {
    margin-top: 2rem;
    height: 300px;
    overflow-y: auto;
    padding: 1.5rem;
    background: var(--bg-tertiary);
    border-radius: 12px;
    border: 1px solid var(--border-color);
    scrollbar-width: thin;
    scrollbar-color: var(--accent-primary) rgba(255, 255, 255, 0.1);
}

.turns-history::-webkit-scrollbar {
    width: 8px;
}

#selectside {
    margin-top: 1rem;
}

.turns-history::-webkit-scrollbar-track {
    background: rgba(255, 255, 255, 0.05);
    border-radius: 4px;
}

.turns-history::-webkit-scrollbar-thumb {
    background: var(--accent-primary);
    border-radius: 4px;
    border: 2px solid var(--bg-tertiary);
}

.turns-history::-webkit-scrollbar-thumb:hover {
    background: var(--accent-secondary);
}

.turns-history ol {
    list-style-type: none;
    counter-reset: move;
}

.turns-history ol li {
    counter-increment: move;
    margin-bottom: 0.5rem;
    padding: 0.5rem;
    border-radius: 6px;
    transition: background-color 0.2s ease;
}

.turns-history ol li:hover {
    background-color: rgba(255, 255, 255, 0.05);
}

.turns-history ol li::before {
    content: counter(move) ".";
    color: var(--accent-primary);
    font-weight: 600;
    margin-right: 0.5rem;
}

.action-buttons {
    display: grid;
    gap: 1rem;
    margin-top: 2rem;
}

.btn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.75rem;
    padding: 1rem;
    border-radius: 12px;
    cursor: pointer;
    transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
    font-weight: 600;
    border: 1px solid var(--border-color);
}

.btn-new-game {
    background: linear-gradient(135deg, var(--gradient-start), var(--gradient-end));
    color: white;
}

.btn-new-game:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow);
    opacity: 0.9;
}

.btn-resign {
    background-color: rgba(239, 68, 68, 0.2);
    color: var(--error);
}

.btn-resign:hover {
    background-color: var(--error);
    color: white;
    transform: translateY(-2px);
}

.btn-analyze {
    background-color: rgba(34, 197, 94, 0.2);
    color: var(--success);
}

.btn-analyze:hover {
    background-color: var(--success);
    color: white;
    transform: translateY(-2px);
}

.status {
    margin-top: 1rem;
    padding: 1rem;
    background-color: rgba(255, 255, 255, 0.05);
    border-radius: 8px;
    text-align: center;
    font-weight: 500;
}

.section-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.section-title i {
    color: var(--accent-primary);
}

@media (max-width: 1200px) {
    .chess-container {
        grid-template-columns: minmax(auto, 600px) 300px;
    }
}

@media (max-width: 1024px) {
    .chess-container {
        grid-template-columns: 1fr;
    }

    .board-settings {
        position: static;
        margin-top: 2rem;
    }

    .hero h1 {
        font-size: 2.5rem;
    }
}

@media (max-width: 640px) {
    .main-content {
        padding: 0 1rem;
        margin-top: 5rem;
    }

    .hero {
        padding: 1.5rem;
        margin-bottom: 2rem;
    }

    .hero h1 {
        font-size: 2rem;
    }

    .hero p {
        font-size: 1.1rem;
    }

    .values {
        grid-template-columns: repeat(5, 1fr);
    }

    .controls .buttons {
        grid-template-columns: repeat(3, 1fr);
    }
}

.fade-in {
    animation: fadeIn 0.3s ease-out;
}


.game-analyze {
    display: block;
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    background-color: var(--bg-secondary);
    padding: 0.75rem 1.5rem;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    text-align: center;
    margin: 1rem 0;
    transition: transform var(--transition), box-shadow var(--transition);
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

.promotion {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 1rem;
    box-shadow: var(--shadow-lg);
}

.promotion span {
    display: inline-block;
    padding: 0.75rem 1.25rem;
    margin: 0.25rem;
    background-color: var(--bg-tertiary);
    color: var(--text-primary);
    border-radius: 8px;
    cursor: pointer;
    transition: all 0.2s ease;
    font-weight: 500;
}

.promotion span:hover {
    background-color: var(--accent-primary);
    transform: translateY(-2px);
}

.popup {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 1.5rem;
    margin-bottom: 2rem;
    box-shadow: var(--shadow-lg);
}

.popup label {
    display: block;
    margin-bottom: 1rem;
    font-weight: 500;
    color: var(--text-primary);
}

.popup textarea {
    width: 100%;
    padding: 0.75rem;
    border-radius: 8px;
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    font-family: 'Plus Jakarta Sans', sans-serif;
    margin-bottom: 1rem;
    resize: vertical;
    min-height: 100px;
}

.popup button {
    background: var(--accent-primary);
    color: white;
    border: none;
    padding: 0.75rem 1.5rem;
    border-radius: 8px;
    cursor: pointer;
    font-weight: 500;
    transition: all 0.2s ease;
}

.popup button:hover {
    background: var(--accent-hover);
    transform: translateY(-2px);
}

.popup button.no {
    background: var(--error);
}

.popup .close {
    position: absolute;
    top: 1rem;
    right: 1rem;
    cursor: pointer;
    color: var(--text-secondary);
}

.popup .close:hover {
    color: var(--text-primary);
}