/* Sudoku Glassmorphism Redesign */

/* Core Variables inherited from main.css, plus specific overrides if needed */
:root {
    --sudoku-cell-size: clamp(40px, 5vw, 60px);
    --board-gap: 2px;
}

/* ---------- Layout: Game Container ---------- */
.game-container {
    display: grid;
    grid-template-columns: 300px 1fr;
    gap: 40px;
    align-items: start;
    margin-bottom: 40px;
}

@media (max-width: 900px) {
    .game-container {
        grid-template-columns: 1fr;
        justify-items: center;
    }
}

/* ---------- Sidebar: Stats & Controls ---------- */
.stats-panel {
    background: var(--surface-1);
    backdrop-filter: blur(var(--glass-blur));
    border: 1px solid var(--border-1);
    border-radius: var(--radius-lg);
    padding: 24px;
    box-shadow: var(--shadow-md);
    display: flex;
    flex-direction: column;
    gap: 24px;
    width: 100%;
    max-width: 350px;
}

/* Stat Items */
.stat-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 12px 16px;
    background: var(--surface-2);
    border-radius: var(--radius-md);
    border: 1px solid var(--border-1);
}

.stat-label {
    font-size: 14px;
    color: var(--text-2);
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.stat-value {
    font-family: var(--font-display);
    font-size: 18px;
    font-weight: 800;
    color: var(--accent);
}

/* Controls Grid */
.controls-grid {
    display: grid;
    gap: 12px;
}

.control-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 12px;
}

/* Action Controls (Icons at bottom) */
.action-controls-sidebar {
    display: flex;
    justify-content: space-between;
    padding-top: 16px;
    border-top: 1px solid var(--border-1);
}

.action-btn {
    width: 44px;
    height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: var(--radius-full);
    background: var(--surface-2);
    border: 1px solid var(--border-1);
    color: var(--text-1);
    font-size: 20px;
    cursor: pointer;
    transition: all 0.2s ease;
}

.action-btn:hover:not(:disabled) {
    background: var(--surface-3);
    color: #fff;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
}

.action-btn:disabled {
    opacity: 0.4;
    cursor: not-allowed;
}

/* ---------- Game Area ---------- */
.game-board-area {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 32px;
    width: 100%;
}

.sudoku-board-wrapper {
    position: relative;
    padding: 16px;
    background: var(--surface-1);
    border-radius: var(--radius-xl);
    border: 1px solid var(--border-1);
    box-shadow: var(--shadow-lg);
}

.sudoku-board {
    display: grid;
    grid-template-columns: repeat(9, var(--sudoku-cell-size));
    grid-template-rows: repeat(9, var(--sudoku-cell-size));
    gap: 2px;
    background: var(--border-1);
    border: 2px solid var(--border-2);
    box-shadow: inset 0 2px 10px rgba(0, 0, 0, 0.2);
}

/* Cells */
.sudoku-cell {
    background: var(--bg-1);
    display: flex;
    align-items: center;
    justify-content: center;
    font-family: var(--font-display);
    font-size: calc(var(--sudoku-cell-size) * 0.6);
    font-weight: 600;
    color: var(--text-1);
    cursor: pointer;
    transition: all 0.1s ease;
    user-select: none;
}

.sudoku-cell:hover {
    background: var(--surface-2);
}

.sudoku-cell.selected {
    background: rgba(139, 92, 246, 0.3);
    /* Accent transparent */
    box-shadow: inset 0 0 0 2px var(--accent);
}

.sudoku-cell.highlight-number {
    background: rgba(6, 182, 212, 0.2);
    /* Cyan transparent */
}

.sudoku-cell.given {
    background: var(--surface-1);
    color: #fff;
    font-weight: 800;
}

.sudoku-cell.conflict {
    background: rgba(239, 68, 68, 0.3);
    color: #fca5a5;
    animation: shake 0.4s cubic-bezier(.36, .07, .19, .97) both;
}

@keyframes shake {

    10%,
    90% {
        transform: translate3d(-1px, 0, 0);
    }

    20%,
    80% {
        transform: translate3d(2px, 0, 0);
    }

    30%,
    50%,
    70% {
        transform: translate3d(-4px, 0, 0);
    }

    40%,
    60% {
        transform: translate3d(4px, 0, 0);
    }
}

/* 3x3 Borders */
.sudoku-cell:nth-child(3n) {
    border-right: 2px solid var(--border-2);
}

.sudoku-cell:nth-child(9n) {
    border-right: none;
}

.sudoku-cell:nth-child(n+19):nth-child(-n+27),
.sudoku-cell:nth-child(n+46):nth-child(-n+54) {
    border-bottom: 2px solid var(--border-2);
}

/* Number Selector */
.number-selector {
    width: 100%;
    max-width: 500px;
}

.number-grid {
    display: flex;
    justify-content: center;
    gap: 12px;
    flex-wrap: wrap;
}

.number-btn {
    width: 48px;
    height: 48px;
    border-radius: 12px;
    border: 1px solid var(--border-1);
    background: var(--surface-2);
    color: var(--text-0);
    font-family: var(--font-display);
    font-size: 20px;
    font-weight: 700;
    cursor: pointer;
    transition: all 0.2s cubic-bezier(0.34, 1.56, 0.64, 1);
    box-shadow: 0 4px 0 var(--border-1);
}

.number-btn:active {
    transform: translateY(4px);
    box-shadow: none;
}

.number-btn:hover {
    background: var(--surface-3);
    border-color: var(--accent);
}

.number-btn.erase {
    color: #fca5a5;
    border-color: rgba(239, 68, 68, 0.3);
}

/* Modals Refined */
.modal-content {
    background: var(--surface-1);
    backdrop-filter: blur(24px);
    border: 1px solid var(--border-1);
    border-radius: var(--radius-xl);
    padding: 40px;
    text-align: center;
    max-width: 480px;
    width: 90%;
    box-shadow: var(--shadow-xl);
}

.modal-content h2 {
    font-size: 2rem;
    margin-bottom: 16px;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.modal-tips {
    background: var(--surface-2);
    padding: 16px;
    border-radius: var(--radius-md);
    margin: 24px 0;
    text-align: left;
    font-size: 14px;
    color: var(--text-1);
}

.modal-btn {
    width: 100%;
    padding: 14px;
    border-radius: var(--radius-full);
    font-weight: 700;
    font-size: 16px;
    cursor: pointer;
    border: 1px solid transparent;
    transition: all 0.2s;
    margin-top: 12px;
}

.modal-btn.primary {
    background: var(--accent);
    color: #fff;
    box-shadow: 0 4px 15px var(--accent-glow);
}

.modal-btn.primary:hover {
    filter: brightness(1.1);
    transform: translateY(-2px);
}

.modal-btn.secondary {
    background: transparent;
    border-color: var(--border-1);
    color: var(--text-1);
}

.modal-btn.secondary:hover {
    background: var(--surface-2);
    color: #fff;
}

/* Difficulty Options in Modal */
.difficulty-options {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 12px;
    margin: 24px 0;
}

.difficulty-option {
    background: var(--surface-2);
    border: 1px solid var(--border-1);
    padding: 16px;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: 0.2s;
}

.difficulty-option:hover {
    background: var(--surface-3);
    border-color: var(--accent);
    transform: translateY(-3px);
}

.diff-icon {
    font-size: 24px;
    margin-bottom: 8px;
}

.difficulty-option h3 {
    font-size: 16px;
    margin: 0;
}

.difficulty-option p {
    font-size: 12px;
    color: var(--text-2);
    margin: 4px 0 0;
}

/* Completion Stats */
.completion-stats {
    display: flex;
    gap: 12px;
    margin: 24px 0;
}

.stat-box {
    flex: 1;
    background: var(--surface-2);
    padding: 12px;
    border-radius: var(--radius-md);
}

.stat-box .label {
    display: block;
    font-size: 11px;
    text-transform: uppercase;
    color: var(--text-2);
    margin-bottom: 4px;
}

.stat-box .val {
    font-size: 16px;
    font-weight: 700;
    color: var(--accent-2);
}

/* Responsive */
@media (max-width: 600px) {
    :root {
        --sudoku-cell-size: 9vw;
    }

    .header h1 {
        font-size: 1.5rem;
    }

    .number-btn {
        width: 36px;
        height: 36px;
        font-size: 16px;
    }
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

/* Header */
.header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: var(--surface-1);
    backdrop-filter: blur(var(--glass-blur));
    -webkit-backdrop-filter: blur(var(--glass-blur));
    padding: 24px;
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-1);
    box-shadow: var(--shadow-md);
    margin-bottom: 24px;
}

.header h1 {
    font-family: var(--font-display);
    font-size: 2.5rem;
    font-weight: 700;
    background: var(--accent-gradient);
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    margin: 0;
}

.home-btn {
    background: var(--surface-2);
    color: var(--text-0);
    border: 1px solid var(--border-1);
    padding: 10px 24px;
    border-radius: 100px;
    cursor: pointer;
    font-weight: 600;
    transition: all var(--transition-base);
    font-family: var(--font-primary);
}

.home-btn:hover {
    background: var(--surface-3);
    border-color: var(--accent);
    transform: translateY(-2px);
    box-shadow: 0 0 15px var(--accent-glow);
}

.header-info {
    display: flex;
    align-items: center;
    gap: 20px;
}

.timer {
    font-family: var(--font-display);
    font-size: 1.4rem;
    font-weight: 700;
    background: var(--surface-1);
    padding: 10px 24px;
    border-radius: var(--radius-md);
    border: 1px solid var(--border-1);
    color: var(--accent);
    display: flex;
    align-items: center;
    gap: 8px;
}

/* Game Info */
.game-info {
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: var(--surface-1);
    backdrop-filter: blur(var(--glass-blur));
    -webkit-backdrop-filter: blur(var(--glass-blur));
    padding: 24px;
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-1);
    box-shadow: var(--shadow-md);
    margin-bottom: 24px;
}

.score-panel {
    display: flex;
    gap: 30px;
}

.score-item {
    text-align: center;
}

.score-item .label {
    display: block;
    font-size: 0.85rem;
    color: var(--text-2);
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 4px;
}

.score-item .value {
    display: block;
    font-family: var(--font-display);
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--text-0);
}

.controls {
    display: flex;
    gap: 10px;
}

.control-btn {
    padding: 12px 24px;
    border: 1px solid var(--border-1);
    border-radius: 100px;
    background: var(--surface-2);
    color: var(--text-0);
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-base);
    font-size: 0.95rem;
    font-family: var(--font-primary);
}

.control-btn:hover:not(:disabled) {
    background: var(--surface-3);
    border-color: var(--accent);
    transform: translateY(-2px);
    box-shadow: 0 0 15px var(--accent-glow);
}

.control-btn:active:not(:disabled) {
    transform: translateY(0);
}

.control-btn.primary {
    background: var(--accent-gradient);
    border: none;
    color: white;
}

.control-btn.primary:hover:not(:disabled) {
    filter: brightness(1.1);
    box-shadow: 0 0 20px var(--accent-glow);
}

.control-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    background: var(--surface-1);
}

/* Difficulty Panel */
.difficulty-panel {
    background: var(--surface-1);
    backdrop-filter: blur(var(--glass-blur));
    -webkit-backdrop-filter: blur(var(--glass-blur));
    padding: 24px;
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-1);
    box-shadow: var(--shadow-md);
    margin-bottom: 24px;
    text-align: center;
    display: none;
}

.difficulty-panel h3 {
    margin-bottom: 20px;
    font-family: var(--font-display);
    font-size: 1.25rem;
    color: var(--text-0);
}

.difficulty-buttons {
    display: flex;
    justify-content: center;
    gap: 12px;
}

.difficulty-btn {
    padding: 8px 20px;
    border: 1px solid var(--border-1);
    border-radius: 100px;
    background: var(--surface-2);
    color: var(--text-0);
    cursor: pointer;
    transition: all var(--transition-base);
    font-weight: 600;
    font-family: var(--font-primary);
    font-size: 0.9rem;
}

.difficulty-btn:hover {
    background: var(--surface-3);
    border-color: var(--accent);
    transform: translateY(-2px);
}

.difficulty-btn.active {
    background: var(--accent-gradient);
    border: none;
    color: white;
    box-shadow: 0 0 15px var(--accent-glow);
}

/* Game Container */
.game-container {
    display: grid;
    grid-template-columns: 1fr auto;
    gap: 30px;
    margin-bottom: 20px;
}

/* Sudoku Board */
.sudoku-board {
    background: var(--surface-1);
    backdrop-filter: blur(var(--glass-blur));
    -webkit-backdrop-filter: blur(var(--glass-blur));
    border-radius: var(--radius-lg);
    padding: 24px;
    box-shadow: var(--shadow-xl);
    display: grid;
    grid-template-columns: repeat(9, 1fr);
    grid-template-rows: repeat(9, 1fr);
    gap: 1px;
    background-color: var(--border-1);
    border: 1px solid var(--border-1);
    aspect-ratio: 1;
    max-width: 600px;
    min-width: 450px;
    justify-self: center;
}

.sudoku-cell {
    background: var(--surface-1);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.8rem;
    font-family: var(--font-display);
    font-weight: 600;
    color: var(--text-0);
    cursor: pointer;
    transition: all var(--transition-base);
    user-select: none;
    min-height: 50px;
}

.sudoku-cell:hover {
    background: var(--surface-2);
    color: var(--accent);
}

.sudoku-cell.selected {
    background: var(--surface-3);
    color: var(--accent);
    box-shadow: inset 0 0 0 2px var(--accent);
    z-index: 1;
}

.sudoku-cell.given {
    background: #f5f5f5;
    color: #000;
    font-weight: bold;
    cursor: default;
}

.sudoku-cell.conflict {
    background: #ffebee;
    color: #d32f2f;
    border-color: #d32f2f;
}

.sudoku-cell.hint {
    background: #e8f5e8;
    color: #2e7d32;
    animation: hintPulse 0.5s ease;
}

@keyframes hintPulse {
    0% {
        transform: scale(1);
    }

    50% {
        transform: scale(1.1);
    }

    100% {
        transform: scale(1);
    }
}

/* 3x3 Box Borders */
.sudoku-cell:nth-child(3n) {
    border-right: 2px solid var(--border-2);
}

.sudoku-cell:nth-child(n+19):nth-child(-n+27),
.sudoku-cell:nth-child(n+46):nth-child(-n+54) {
    border-bottom: 2px solid var(--border-2);
}

/* Number Selector */
.number-selector {
    background: var(--surface-1);
    backdrop-filter: blur(var(--glass-blur));
    -webkit-backdrop-filter: blur(var(--glass-blur));
    padding: 24px;
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-1);
    box-shadow: var(--shadow-md);
    min-width: 240px;
}

.number-select.footer {
    text-align: center;
    margin-top: 48px;
    padding: 32px;
    color: var(--text-2);
    font-size: 0.9rem;
    border-top: 1px solid var(--border-1);
}

.footer p {
    margin-bottom: 8px;
    color: var(--text-0);
}

.number-selector h3 {
    text-align: center;
    margin-bottom: 20px;
    font-family: var(--font-display);
    font-size: 1.4rem;
    color: var(--text-0);
}

.number-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 12px;
}

.number-btn {
    aspect-ratio: 1;
    border: 1px solid var(--border-2);
    border-radius: var(--radius-sm);
    background: var(--surface-2);
    color: var(--text-0);
    font-family: var(--font-display);
    font-size: 1.75rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-base);
    display: flex;
    align-items: center;
    justify-content: center;
}

.number-btn:hover {
    background: var(--surface-3);
    border-color: var(--accent);
    color: var(--accent);
    transform: scale(1.05);
}

.number-btn:active {
    transform: scale(0.95);
}

.number-btn.erase {
    background: rgba(239, 68, 68, 0.1);
    border-color: rgba(239, 68, 68, 0.2);
}

.number-btn.erase:hover {
    background: rgba(239, 68, 68, 0.2);
    border-color: #ef4444;
}

/* Action Controls */
.action-controls {
    display: flex;
    justify-content: center;
    gap: 16px;
    margin-bottom: 32px;
}

.action-btn {
    padding: 12px 24px;
    border: 1px solid var(--border-1);
    border-radius: 100px;
    background: var(--surface-2);
    color: var(--text-0);
    cursor: pointer;
    transition: all var(--transition-base);
    font-weight: 600;
    font-family: var(--font-primary);
}

.action-btn:hover:not(:disabled) {
    background: var(--surface-3);
    border-color: var(--accent);
    transform: translateY(-2px);
    box-shadow: 0 0 15px var(--accent-glow);
}

.action-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

/* Game Overlays */
.game-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(5, 8, 20, 0.85);
    backdrop-filter: blur(var(--glass-blur));
    -webkit-backdrop-filter: blur(var(--glass-blur));
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 2000;
}

/* Modal content areas should not have click cursor */
.game-start-content,
.game-complete-content,
.game-failed-content,
.difficulty-modal-content {
    cursor: default;
}

/* Modal Header */
.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 24px;
}

.modal-header h2 {
    margin: 0;
    flex: 1;
    font-family: var(--font-display);
    font-weight: 800;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    font-size: 2rem;
}

/* Close Button */
.close-btn {
    background: var(--surface-2);
    border: 1px solid var(--border-1);
    color: var(--text-0);
    width: 36px;
    height: 36px;
    border-radius: var(--radius-full);
    font-size: 20px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition-base);
    padding: 0;
    margin-left: 16px;
}

.close-btn:hover {
    background: rgba(255, 255, 255, 0.3);
    border-color: rgba(255, 255, 255, 0.5);
    transform: scale(1.1);
}

.close-btn:active {
    transform: scale(0.95);
}

.game-overlay.hidden {
    display: none;
}

.game-start-content,
.game-complete-content,
.game-failed-content,
.difficulty-modal-content {
    background: var(--surface-1);
    backdrop-filter: blur(var(--glass-blur));
    -webkit-backdrop-filter: blur(var(--glass-blur));
    padding: 48px;
    border-radius: var(--radius-xl);
    border: 1px solid var(--border-1);
    text-align: center;
    box-shadow: var(--shadow-xl);
    max-width: 500px;
    width: 90%;
    position: relative;
}

.game-failed-content {
    border-color: rgba(239, 68, 68, 0.3);
}

.difficulty-modal-content {
    max-width: 800px;
    width: 95%;
}

/* Difficulty Selection Modal */
.difficulty-options {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 16px;
    margin: 32px 0;
}

.difficulty-option {
    background: var(--surface-2);
    border: 1px solid var(--border-1);
    border-radius: var(--radius-lg);
    padding: 24px;
    cursor: pointer;
    transition: all var(--transition-base);
}

.difficulty-option:hover {
    background: var(--surface-3);
    border-color: var(--accent);
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.difficulty-option.selected {
    background: var(--surface-3);
    border-color: var(--accent);
    transform: scale(1.05);
    box-shadow: 0 0 20px var(--accent-glow);
}

.difficulty-icon {
    font-size: 3rem;
    margin-bottom: 12px;
    display: block;
}

.difficulty-option h3 {
    margin: 12px 0;
    font-family: var(--font-display);
    font-size: 1.5rem;
    color: var(--text-0);
}

.difficulty-option p {
    margin: 4px 0;
    color: var(--text-2);
    font-size: 0.95rem;
}

.time-estimate {
    font-style: italic;
    color: var(--accent) !important;
    opacity: 0.9 !important;
}

.difficulty-stars {
    margin-top: 16px;
    font-size: 1.25rem;
    color: var(--accent);
}

.modal-actions {
    margin-top: 20px;
}

.game-start-content h2,
.game-complete-content h2 {
    font-size: 2.5rem;
    font-family: var(--font-display);
    font-weight: 800;
    margin-bottom: 20px;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.game-start-content p,
.game-complete-content p {
    font-size: 1.2rem;
    margin-bottom: 20px;
    opacity: 0.9;
}

.tip {
    font-size: 1rem !important;
    opacity: 0.8 !important;
    margin-bottom: 30px !important;
}

/* Completion Stats */
.completion-stats {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 16px;
    margin: 32px 0;
}

.stat-item {
    text-align: center;
    background: var(--surface-2);
    padding: 20px;
    border-radius: var(--radius-md);
    border: 1px solid var(--border-1);
}

.stat-label {
    display: block;
    font-size: 0.85rem;
    color: var(--text-2);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 4px;
}

.stat-value {
    display: block;
    font-family: var(--font-display);
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--accent);
}

.completion-actions,
.failed-actions {
    display: flex;
    gap: 16px;
    justify-content: center;
    flex-wrap: wrap;
    margin-top: 24px;
}

.completion-actions .control-btn,
.failed-actions .control-btn {
    flex: 1;
    min-width: 120px;
    max-width: 180px;
}

/* Failed Game Styles */
.failed-tips {
    margin: 32px 0;
    text-align: left;
}

.tip-item {
    display: flex;
    align-items: center;
    gap: 16px;
    margin-bottom: 16px;
    background: var(--surface-2);
    padding: 20px;
    border-radius: var(--radius-md);
    border: 1px solid var(--border-1);
}

.tip-icon {
    font-size: 1.75rem;
    flex-shrink: 0;
}

.tip-text {
    font-size: 1rem;
    color: var(--text-1);
}

/* Instructions */
.instructions {
    background: var(--surface-1);
    backdrop-filter: blur(var(--glass-blur));
    -webkit-backdrop-filter: blur(var(--glass-blur));
    padding: 32px;
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-1);
    box-shadow: var(--shadow-md);
    margin-top: 32px;
}

.instructions h3 {
    text-align: center;
    margin-bottom: 32px;
    font-family: var(--font-display);
    font-size: 1.75rem;
    color: var(--accent);
}

.instruction-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 24px;
}

.instruction-item {
    display: flex;
    align-items: flex-start;
    gap: 20px;
    background: var(--surface-2);
    padding: 24px;
    border-radius: var(--radius-md);
    border: 1px solid var(--border-1);
    transition: all var(--transition-base);
}

.instruction-item:hover {
    background: var(--surface-3);
    border-color: var(--accent);
    transform: translateY(-2px);
}

.instruction-icon {
    font-size: 2.5rem;
    flex-shrink: 0;
}

.instruction-text h4 {
    margin-bottom: 8px;
    font-family: var(--font-display);
    font-size: 1.2rem;
    color: var(--text-0);
}

.instruction-text p {
    color: var(--text-2);
    line-height: 1.5;
    font-size: 0.95rem;
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        padding: 16px;
    }

    .header {
        flex-direction: column;
        gap: 16px;
        padding: 20px;
    }

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

    .game-info {
        flex-direction: column;
        gap: 24px;
        padding: 20px;
    }

    .score-panel {
        justify-content: center;
        gap: 24px;
        width: 100%;
    }

    .controls {
        flex-wrap: wrap;
        justify-content: center;
        width: 100%;
    }

    .difficulty-buttons {
        flex-wrap: wrap;
        gap: 10px;
    }

    .difficulty-btn {
        flex: 1;
        min-width: 90px;
        padding: 8px 16px;
        font-size: 0.9rem;
    }

    .game-container {
        grid-template-columns: 1fr;
        gap: 24px;
    }

    .sudoku-board {
        max-width: 100%;
        min-width: auto;
        padding: 16px;
        border-radius: var(--radius-md);
    }

    .sudoku-cell {
        font-size: 1.5rem;
        min-height: 44px;
    }

    .difficulty-modal-content {
        max-width: 95%;
        padding: 32px 20px;
    }

    .difficulty-options {
        grid-template-columns: repeat(2, 1fr);
        gap: 12px;
    }

    .number-selector {
        order: -1;
        min-width: auto;
        padding: 20px;
    }

    .number-grid {
        grid-template-columns: repeat(5, 2fr);
    }

    .action-controls {
        flex-wrap: wrap;
        gap: 12px;
    }

    .action-btn {
        flex: 1;
        min-width: 120px;
        padding: 12px 16px;
        font-size: 0.9rem;
    }

    .instruction-grid {
        grid-template-columns: 1fr;
    }

    .completion-stats {
        grid-template-columns: 1fr;
        gap: 16px;
    }

    .completion-actions,
    .failed-actions {
        flex-direction: column;
        gap: 12px;
    }

    .completion-actions .control-btn,
    .failed-actions .control-btn {
        flex: none;
        max-width: none;
    }
}

@media (max-width: 480px) {
    .header h1 {
        font-size: 1.75rem;
    }

    .score-item .value {
        font-size: 1.4rem;
    }

    .sudoku-cell {
        font-size: 1.25rem;
        min-height: 40px;
    }

    .number-btn {
        font-size: 1.4rem;
        min-height: 44px;
    }
}

/* SEO content & Recommendations (Sudoku Online specific) */
.seo-content-section {
    margin-top: 64px;
    padding: 48px;
    background: var(--surface-1);
    border-radius: var(--radius-xl);
    border: 1px solid var(--border-1);
    color: var(--text-1);
}

.seo-content-section h2,
.seo-content-section h3 {
    color: var(--text-0);
    font-family: var(--font-display);
}

.similar-games,
.other-games {
    margin-top: 64px;
}


/* High contrast mode support */
@media (prefers-contrast: high) {
    .sudoku-cell {
        border: 2px solid #000;
    }

    .sudoku-cell.selected {
        border-color: #0066cc;
        background: #e6f3ff;
    }

    .sudoku-cell.conflict {
        border-color: #cc0000;
        background: #ffe6e6;
    }
}

/* Reduced motion preference */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }

    .sudoku-cell {
        transition: none;
    }

    .control-btn,
    .action-btn,
    .difficulty-btn,
    .number-btn {
        transition: none;
    }
}