/* Sleek two-color design */
:root {
    --primary-color: #2c3e50;
    --accent-color: #3498db;
    --white: #ffffff;
    --light-gray: #f8f9fa;
    --dark-gray: #34495e;
    --darker-gray: #2c3e50;
    --success-color: #27ae60;
    --error-color: #e74c3c;
    --warning-color: #f39c12;
    --shadow: rgba(0, 0, 0, 0.1);
    --shadow-dark: rgba(0, 0, 0, 0.2);
}

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

body {
    font-family: 'Open Sans', sans-serif;
    background: var(--white);
    min-height: 100vh;
    padding: 5px;
    color: var(--primary-color);
}

/* Mobile responsiveness */
@media (max-width: 768px) {
    body {
        padding: 2px;
    }
    
    .initial-page {
    padding: 10px;
        padding-top: 10px;
    }
    
    .initial-container {
        max-width: 100%;
        border: none !important;
        border-bottom: none !important;
        box-shadow: none !important;
    }
    
    .initial-container header {
        padding: 10px 15px;
        border: none !important;
        border-bottom: none !important;
        border-top: none !important;
        border-left: none !important;
        border-right: none !important;
        box-shadow: none !important;
        outline: none !important;
    }
    
    .initial-container header h1 {
        font-size: 1.5rem;
        margin-bottom: 8px;
    }
    
    .initial-container header .subtitle {
        font-size: 0.8rem;
        margin-bottom: 5px;
    }
    
    .mode-selection {
        margin-top: 20px;
        padding-top: 0;
        border: none !important;
        border-top: none !important;
        border-bottom: none !important;
        border-left: none !important;
        border-right: none !important;
        box-shadow: none !important;
        outline: none !important;
    }
    
    .mode-selection h2 {
        margin: 0 0 15px 0 !important;
        padding: 0 !important;
        font-size: 1.2rem !important;
    }
    
    .mode-btn {
        padding: 18px 15px !important;
        margin: 8px 0 !important;
        border-radius: 12px !important;
    }
    
    .mode-btn h3 {
        font-size: 1.1rem !important;
        margin-bottom: 4px !important;
    }
    
    .mode-btn p {
        font-size: 0.8rem !important;
        margin: 0 !important;
    }
    
    
    .game-page {
        padding-top: 5px;
    }
    
    .container {
        max-width: 100%;
        margin: 0 3px;
        border-radius: 8px;
    }
    
    /* Reduce overall page padding for mobile */
    body {
        padding: 1px;
    }
    
    header {
        padding: 10px 15px;
        border-radius: 10px 10px 0 0;
    }
    
    .header-text h1 {
        font-size: 1.3rem !important;
        margin-bottom: 3px !important;
    }
    
    .header-text .subtitle {
        font-size: 0.75rem !important;
        margin: 0 !important;
    }
    
    /* Make home button smaller on mobile */
    .header-content .control-btn {
        padding: 5px 10px !important;
        font-size: 0.8rem !important;
        border-radius: 15px !important;
    }
    
    /* Header padding on mobile */
    header {
        padding: 20px 15px !important;
    }
    
    /* Additional mobile header optimizations */
    .header-content {
        gap: 10px !important;
    }
    
    .header-text {
        flex: 1 !important;
    }
    
    .header-text h1 {
        line-height: 1.2 !important;
    }
    
    .header-text .subtitle {
        line-height: 1.3 !important;
    }
    
    .game-info {
        padding: 4px 15px;
        gap: 20px;
        flex-direction: row;
        align-items: center;
        justify-content: center;
        gap: 20px;
        flex-wrap: nowrap;
    }
    
    .timer {
        font-size: 0.9rem;
    }
    
    #timer, #daily-timer {
        font-size: 0.9rem;
    }
    
    .puzzle-counter {
        font-size: 0.9rem;
    }
    
    .timer-label, .puzzle-label, .counter-label {
        font-size: 0.9rem;
    }
    
    .instructions {
        padding: 2px 15px;
    }
    
    .instructions h3 {
        font-size: 0.6rem;
        margin-bottom: 2px;
    }
    
    .instructions li {
        font-size: 0.5rem;
        padding: 0.5px 0;
        padding-left: 6px;
    }
    
    .game-board {
        padding: 6px 4px;
    }
    
    .numbers-container {
        gap: 3px;
        margin-bottom: 6px;
        flex-wrap: wrap !important;
        justify-content: center;
        max-width: 200px;
        margin-left: auto;
        margin-right: auto;
    }
    
    .number-tile {
        width: 95px !important;
        height: 48px !important;
        font-size: 1.4rem !important;
        border-radius: 8px !important;
        border-width: 2px !important;
        flex-shrink: 1 !important;
        flex-grow: 0 !important;
    }
    
    .operations {
        gap: 6px;
        margin-bottom: 8px;
    }
    
    .operation-btn {
        width: 42px;
        height: 42px;
        font-size: 1.1rem;
    }
    

    

    

    

    
    .history-container {
        padding: 5px 15px;
        max-height: 100px;
    }
    
    .history-container h3 {
        font-size: 0.9rem;
        margin-bottom: 5px;
    }
    
    .history-item {
        font-size: 0.75rem;
        padding: 3px 8px;
        margin-bottom: 3px;
    }
    
    .result {
        padding: 5px 15px;
        font-size: 0.8rem;
        margin: 5px 15px;
    }
    
    /* Desktop overrides for larger screens */
@media (min-width: 769px) {
    .numbers-container {
        flex-wrap: nowrap;
        max-width: none;
        margin-left: 0;
        margin-right: 0;
    }
    
    .number-tile {
        width: 140px !important;
        height: 70px !important;
        font-size: 2rem !important;
        border-radius: 12px !important;
        border-width: 3px !important;
        flex-shrink: 0 !important;
        flex-grow: 0 !important;
    }
    
    .game-controls {
        flex-wrap: nowrap;
        gap: 4px;
        margin-bottom: 8px;
        max-width: 480px;
        margin-left: auto;
        margin-right: auto;
    }
}

/* Ensure function buttons are static across all screen sizes */
.undo-btn, .shuffle-btn, .reset-btn, .new-game-btn, .no-solution-btn {
    padding: 8px 28px !important;
    font-size: 0.9rem !important;
    border-radius: 20px !important;
    min-width: 100px !important;
    white-space: nowrap !important;
    flex-shrink: 0 !important;
}



/* Additional mobile optimizations */
.info-btn {
    width: 20px;
    height: 20px;
    font-size: 0.7rem;
}
    
    /* Improve touch targets while keeping compact */
    .number-tile, .operation-btn {
        min-height: 40px;
    }
    

    
    /* Reduce modal sizes for mobile */
    .modal {
        padding: 15px;
        margin: 5px;
        border-radius: 8px;
    }
    
    .modal h2 {
        font-size: 1.1rem;
        margin-bottom: 10px;
    }
    
    .modal p {
        font-size: 0.8rem;
        margin-bottom: 10px;
    }
    
    .modal-btn {
        padding: 8px 16px;
        font-size: 0.8rem;
        margin: 3px;
    }
    
    .modal {
        padding: 20px;
        margin: 10px;
        border-radius: 10px;
    }
    
    .modal h2 {
        font-size: 1.3rem;
        margin-bottom: 15px;
    }
    
    .modal p {
        font-size: 0.9rem;
        margin-bottom: 15px;
    }
    
    .modal-btn {
        padding: 10px 20px;
        font-size: 0.9rem;
        margin: 5px;
    }
    
    .share-btn {
        padding: 12px 24px;
        font-size: 1rem;
    }
    
    .play-again-btn {
        padding: 8px 16px;
        font-size: 0.85rem;
    }
    
    .puzzle-breakdown {
        font-size: 0.85rem;
    }
    
    .puzzle-breakdown h4 {
        font-size: 1rem;
        margin-bottom: 8px;
    }
    
    .puzzle-breakdown ul {
        margin-bottom: 10px;
    }
    
    .puzzle-breakdown li {
        font-size: 0.8rem;
        margin-bottom: 3px;
    }
    
    .countdown-timer {
        font-size: 0.8rem;
        margin-top: 8px;
    }
    
    .countdown-label {
        font-size: 0.75rem;
    }
    
    .countdown-time {
        font-size: 0.8rem;
    }
}

@media (max-width: 480px) {
    .header-text h1 {
        font-size: 1.1rem !important;
        margin-bottom: 2px !important;
    }
    
    .header-text .subtitle {
        font-size: 0.7rem !important;
        margin: 0 !important;
    }
    
    .header-content .control-btn {
        padding: 4px 8px !important;
        font-size: 0.75rem !important;
        border-radius: 12px !important;
    }
    
    /* Header padding for very small screens */
    header {
        padding: 18px 15px !important;
    }
    
    .initial-page {
        padding-top: 5px;
    }
    
    .mode-selection {
        margin-top: 15px;
    }
    
    .mode-selection h2 {
        margin: 0 !important;
        padding: 0 !important;
    }
    
    /* Additional mobile header optimizations for very small screens */
    .header-content {
        gap: 6px !important;
    }
    
    .header-text h1 {
        line-height: 1.0 !important;
    }
    
    .header-text .subtitle {
        line-height: 1.1 !important;
    }
    
    .game-info {
        padding: 2px 15px;
        gap: 15px;
        flex-direction: row;
        align-items: center;
        justify-content: center;
        flex-wrap: nowrap;
    }
    
    .timer {
        font-size: 0.8rem;
    }
    
    #timer, #daily-timer {
        font-size: 0.8rem;
    }
    
    .puzzle-counter {
        font-size: 0.8rem;
    }
    
    .timer-label, .puzzle-label, .counter-label {
        font-size: 0.8rem;
    }
    
    .instructions {
        padding: 1px 15px;
    }
    
    .instructions h3 {
        font-size: 0.55rem;
        margin-bottom: 1px;
    }
    
    .instructions li {
        font-size: 0.4rem;
        padding: 0.5px 0;
        padding-left: 4px;
    }
    
    .number-tile {
        width: 85px !important;
        height: 42px !important;
        font-size: 1.3rem !important;
        flex-shrink: 1 !important;
        flex-grow: 0 !important;
    }
    
    .operation-btn {
        width: 38px;
        height: 38px;
        font-size: 1rem;
    }
    

    

    
    /* Additional mobile optimizations */
    .numbers-container {
        gap: 2px;
        margin-bottom: 4px;
        flex-wrap: wrap !important;
        justify-content: center;
        max-width: 180px;
        margin-left: auto;
        margin-right: auto;
    }
    
    .operations {
        gap: 5px;
        margin-bottom: 6px;
    }
    

    
    .game-board {
        padding: 4px 4px;
    }
    

    
    .history-container {
        padding: 4px 15px;
        max-height: 80px;
    }
    
    .history-container h3 {
        font-size: 0.75rem;
        margin-bottom: 3px;
    }
    
    .history-item {
        font-size: 0.6rem;
        padding: 1px 5px;
        margin-bottom: 1px;
    }
    
    .result {
        padding: 4px 15px;
        font-size: 0.7rem;
        margin: 4px 15px;
    }
    
    .modal {
        padding: 15px;
        margin: 5px;
    }
    
    .modal h2 {
        font-size: 1.2rem;
    }
    
    .modal p {
        font-size: 0.85rem;
    }
    
    .modal-btn {
        padding: 8px 16px;
        font-size: 0.85rem;
        margin: 3px;
    }
    
    /* Improve touch targets */
    .number-tile, .operation-btn {
        min-height: 44px; /* Minimum touch target size */
    }
    

    
    /* Better spacing for small screens */
    .game-board {
        padding: 6px 8px;
    }
    
    .instructions {
        padding: 4px 10px;
    }
    
    .history-container {
        padding: 6px 10px;
        max-height: 100px;
    }
}

.initial-page {
    min-height: 100vh;
    display: flex;
    align-items: flex-start;
    justify-content: center;
    padding: 20px;
    padding-top: 80px;
}

.initial-container {
    max-width: 600px;
    width: 100%;
    text-align: center;
}

.initial-container header {
    background: var(--white);
    color: var(--primary-color);
    padding: 12px 20px;
    border-radius: 15px 15px 0 0;
    border-bottom: 2px solid var(--light-gray);
}

.initial-container header h1 {
    color: var(--primary-color);
}

.initial-container header .subtitle {
    color: var(--dark-gray);
}

.game-page {
    min-height: 100vh;
    padding-top: 20px;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    background: var(--white);
    border-radius: 15px;
    box-shadow: 0 15px 30px var(--shadow-dark);
    overflow: hidden;
    color: var(--primary-color);
}

header {
    background: var(--primary-color);
    color: var(--white);
    padding: 30px 20px;
    border-radius: 15px 15px 0 0;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.header-text {
    text-align: left;
}

.header-text h1 {
    font-size: 1.8rem;
    font-weight: 700;
    margin-bottom: 8px;
    color: var(--white);
}

.header-text .subtitle {
    font-size: 0.85rem;
    opacity: 0.9;
    color: var(--light-gray);
    margin: 0;
    padding-top: 2px;
}



.game-info {
    display: flex;
    justify-content: center;
    gap: 30px;
    padding: 8px 20px;
    background: var(--light-gray);
    border-bottom: 2px solid var(--accent-color);
}

.timer {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 1.1rem;
    font-weight: 600;
}

.puzzle-counter {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 1.1rem;
    font-weight: 600;
}

.timer-label, .puzzle-label, .counter-label {
    color: var(--dark-gray);
    font-size: 1.1rem;
    font-weight: 600;
}

#timer, #daily-timer {
    color: var(--accent-color);
    font-weight: 700;
    font-size: 1.1rem;
}



.instructions {
    padding: 8px 20px;
    background: var(--white);
    border-bottom: 1px solid var(--light-gray);
}

.instructions-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 8px;
}

.instructions h3 {
    color: var(--primary-color);
    font-size: 1rem;
    margin: 0;
}

.info-btn {
    background: var(--accent-color);
    color: var(--white);
    border: none;
    border-radius: 50%;
    width: 24px;
    height: 24px;
    font-size: 0.8rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.3s ease;
}

.info-btn:hover {
    background: var(--primary-color);
    transform: scale(1.1);
}

.instructions ul {
    list-style: none;
    padding-left: 0;
}

.instructions li {
    padding: 2px 0;
    padding-left: 15px;
    position: relative;
    color: var(--dark-gray);
    font-size: 0.8rem;
}

.instructions li::before {
    content: "•";
    color: var(--accent-color);
    font-weight: bold;
    position: absolute;
    left: 0;
}

.game-board {
    padding: 12px 20px;
    background: var(--white);
}

.numbers-container {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-bottom: 12px;
    justify-content: center;
}

.number-tile {
    width: 140px;
    height: 70px;
    background: var(--white);
    border: 3px solid var(--primary-color);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    font-weight: 700;
    cursor: pointer;
    transition: all 0.3s ease;
    position: relative;
    box-shadow: 0 4px 8px var(--shadow);
    color: var(--primary-color);
    transform: scale(1) !important;
    flex-shrink: 0;
    flex-grow: 0;
    /* Mobile touch optimization */
    -webkit-tap-highlight-color: transparent;
    touch-action: manipulation;
}

.number-tile:hover {
    transform: translateY(-3px) !important;
    box-shadow: 0 6px 12px var(--shadow-dark);
    border-color: var(--accent-color);
}

.number-tile.selected {
    background: var(--accent-color);
    color: var(--white);
    border-color: var(--accent-color);
}

.operations {
    display: flex;
    justify-content: center;
    gap: 10px;
    margin-bottom: 12px;
}

.operation-btn {
    width: 50px;
    height: 50px;
    border: none;
    border-radius: 50%;
    font-size: 1.4rem;
    font-weight: 700;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 4px 8px var(--shadow);
    background: var(--primary-color);
    color: var(--white);
    /* Mobile touch optimization */
    -webkit-tap-highlight-color: transparent;
    touch-action: manipulation;
}

.operation-btn:hover {
    transform: scale(1.1);
    box-shadow: 0 6px 12px var(--shadow-dark);
    background: var(--accent-color);
}

.operation-btn.selected {
    background: var(--accent-color);
    transform: scale(1.1);
}

.operation-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
    background: var(--light-gray);
    color: var(--dark-gray);
}

.game-controls {
    display: flex;
    justify-content: center;
    gap: 4px;
    flex-wrap: nowrap;
    margin-bottom: 8px;
    max-width: 480px;
    margin-left: auto;
    margin-right: auto;
}

.control-btn {
    padding: 8px 28px;
    border: none;
    border-radius: 20px;
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 3px 6px var(--shadow);
    /* Mobile touch optimization */
    -webkit-tap-highlight-color: transparent;
    touch-action: manipulation;
    min-width: 100px;
    white-space: nowrap;
    flex-shrink: 0;
}

.undo-btn {
    background: var(--dark-gray);
    color: var(--white);
}

.shuffle-btn {
    background: var(--dark-gray);
    color: var(--white);
}

.reset-btn {
    background: var(--primary-color);
    color: var(--white);
}

.home-btn {
    background: var(--dark-gray);
    color: var(--white);
}

.no-solution-btn {
    background: var(--error-color);
    color: var(--white);
}

.new-game-btn {
    background: var(--success-color);
    color: var(--white);
}

.control-btn:hover {
    transform: translateY(-1px);
    box-shadow: 0 4px 8px var(--shadow-dark);
}

.control-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
}

.history {
    padding: 10px 20px;
    background: var(--light-gray);
    border-top: 1px solid var(--light-gray);
    max-height: 150px;
    overflow-y: auto;
    margin-top: 20px;
}

.history h3 {
    color: var(--primary-color);
    margin-bottom: 8px;
    font-size: 0.9rem;
}

#history-container {
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.history-item {
    padding: 4px 8px;
    background: var(--white);
    border-radius: 6px;
    font-size: 0.75rem;
    color: var(--dark-gray);
    border-left: 3px solid var(--accent-color);
}

.result {
    padding: 10px 20px;
    text-align: center;
    font-size: 0.9rem;
    font-weight: 600;
    min-height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.result.success {
    background: var(--success-color);
    color: var(--white);
    font-size: 1rem;
    font-weight: 700;
    padding: 15px 20px;
    border-radius: 8px;
    margin: 10px 20px;
}

.result.error {
    background: var(--error-color);
    color: var(--white);
}

.result.info {
    background: var(--accent-color);
    color: var(--white);
}

/* Modal Styles */
.modal {
    display: none;
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(5px);
}

.modal-content {
    background-color: var(--white);
    margin: 10% auto;
    padding: 0;
    border-radius: 15px;
    width: 85%;
    max-width: 350px;
    box-shadow: 0 20px 40px var(--shadow-dark);
    animation: modalSlideIn 0.3s ease-out;
}

@keyframes modalSlideIn {
    from {
        opacity: 0;
        transform: translateY(-50px) scale(0.9);
    }
    to {
        opacity: 1;
        transform: translateY(0) scale(1);
    }
}

.modal-header {
    background: var(--success-color);
    color: var(--white);
    padding: 15px;
    text-align: center;
    border-radius: 15px 15px 0 0;
}

.modal-header h2 {
    font-size: 1.3rem;
    margin-bottom: 3px;
}

.modal-header p {
    font-size: 0.9rem;
    opacity: 0.9;
}

.modal-body {
    padding: 15px;
    text-align: center;
}

.time-display {
    margin-bottom: 15px;
}

.time-label {
    display: block;
    font-size: 0.8rem;
    color: var(--dark-gray);
    margin-bottom: 3px;
}

.final-time {
    display: block;
    font-size: 1.8rem;
    font-weight: 700;
    color: var(--accent-color);
}

.copy-btn {
    background: var(--accent-color);
    color: var(--white);
    border: none;
    padding: 8px 16px;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 4px 8px var(--shadow);
}

.copy-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 12px var(--shadow-dark);
    background: var(--primary-color);
}

.share-btn {
    padding: 10px 20px;
    font-size: 0.9rem;
    font-weight: 700;
}

.modal-footer {
    padding: 12px 15px 15px;
    text-align: center;
}

.play-again-btn {
    background: var(--dark-gray);
    color: var(--white);
    border: none;
    padding: 8px 20px;
    border-radius: 25px;
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 4px 8px var(--shadow);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 5px;
    text-align: center;
    width: 100%;
    max-width: 200px;
    margin: 0 auto;
}

.play-again-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 12px var(--shadow-dark);
    background: var(--primary-color);
}

.countdown-timer {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 2px;
    margin-top: 5px;
    text-align: center;
    width: 100%;
}

.countdown-label {
    font-size: 0.7rem;
    opacity: 0.9;
    font-weight: 500;
    color: var(--white);
}

.countdown-time {
    font-size: 0.8rem;
    font-weight: 700;
    color: var(--accent-color);
    background: rgba(255, 255, 255, 0.1);
    padding: 2px 6px;
    border-radius: 4px;
}

.keyboard-instructions h4 {
    color: var(--primary-color);
    margin: 20px 0 10px 0;
    font-size: 1.1rem;
    font-weight: 600;
}

.keyboard-instructions h4:first-child {
    margin-top: 0;
}

.keyboard-instructions ul {
    list-style: none;
    padding-left: 0;
    margin-bottom: 20px;
}

.keyboard-instructions li {
    padding: 6px 0;
    color: var(--dark-gray);
    font-size: 0.95rem;
    border-bottom: 1px solid var(--light-gray);
}

.keyboard-instructions li:last-child {
    border-bottom: none;
}

.close-btn {
    background: var(--dark-gray);
    color: var(--white);
    border: none;
    padding: 10px 20px;
    border-radius: 25px;
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 4px 8px var(--shadow);
}

.close-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 12px var(--shadow-dark);
    background: var(--primary-color);
}

.mode-selection {
    margin-top: 40px;
}

.mode-selection h2 {
    color: var(--primary-color);
    font-size: 1.5rem;
    margin-bottom: 30px;
    font-weight: 600;
}

.mode-buttons {
    display: flex;
    flex-direction: column;
    gap: 20px;
    max-width: 400px;
    margin: 0 auto;
}

.mode-btn {
    background: var(--white);
    border: 3px solid var(--primary-color);
    border-radius: 15px;
    padding: 25px 20px;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 8px 16px var(--shadow);
    text-align: left;
}

.mode-btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 12px 24px var(--shadow-dark);
    border-color: var(--accent-color);
}

.mode-btn h3 {
    color: var(--primary-color);
    font-size: 1.3rem;
    margin-bottom: 8px;
    font-weight: 600;
}

.mode-btn p {
    color: var(--dark-gray);
    font-size: 0.9rem;
    margin: 0;
}

.daily-challenge-btn {
    border-color: var(--success-color);
}

.daily-challenge-btn:hover {
    border-color: var(--success-color);
    background: var(--success-color);
    color: var(--white);
}

.daily-challenge-btn:hover h3,
.daily-challenge-btn:hover p {
    color: var(--white);
}

.practice-btn {
    border-color: var(--accent-color);
}

.practice-btn:hover {
    border-color: var(--accent-color);
    background: var(--accent-color);
    color: var(--white);
}

.practice-btn:hover h3,
.practice-btn:hover p {
    color: var(--white);
}

.puzzle-counter {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 0.9rem;
    font-weight: 600;
}

.counter-label {
    color: var(--dark-gray);
}

#puzzle-counter {
    color: var(--accent-color);
    font-weight: 700;
    font-size: 1.2rem;
}

.modal-close-btn {
    position: absolute;
    top: 15px;
    right: 20px;
    background: none;
    border: none;
    font-size: 1.5rem;
    color: var(--white);
    cursor: pointer;
    width: 30px;
    height: 30px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
    transition: all 0.3s ease;
}

.modal-close-btn:hover {
    background: rgba(255, 255, 255, 0.2);
}

.modal-header {
    position: relative;
}

.puzzle-breakdown {
    margin: 20px 0;
    text-align: left;
}

.puzzle-breakdown h4 {
    color: var(--primary-color);
    margin-bottom: 10px;
    font-size: 1rem;
    font-weight: 600;
}

.puzzle-breakdown ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

.puzzle-breakdown li {
    padding: 5px 0;
    color: var(--dark-gray);
    font-size: 0.9rem;
    border-bottom: 1px solid var(--light-gray);
}

.puzzle-breakdown li:last-child {
    border-bottom: none;
}

/* Combining animation where tiles merge together */
@keyframes combine {
    0% {
        transform: scale(1) !important;
        opacity: 1;
    }
    25% {
        transform: scale(1.05) !important;
        opacity: 0.8;
    }
    50% {
        transform: scale(1.1) !important;
        opacity: 0.6;
    }
    75% {
        transform: scale(1.05) !important;
        opacity: 0.8;
    }
    100% {
        transform: scale(1) !important;
        opacity: 1;
    }
}

@keyframes combineGlow {
    0% {
        box-shadow: 0 4px 8px var(--shadow);
    }
    50% {
        box-shadow: 0 0 15px var(--accent-color), 0 0 25px var(--accent-color);
    }
    100% {
        box-shadow: 0 4px 8px var(--shadow);
    }
}

@keyframes merge {
    0% {
        transform: scale(1) translateX(0) !important;
        opacity: 1;
    }
    50% {
        transform: scale(0.8) translateX(15px) !important;
        opacity: 0.7;
    }
    100% {
        transform: scale(0) translateX(30px) !important;
        opacity: 0;
    }
}

@keyframes mergeTarget {
    0% {
        transform: scale(1) !important;
        opacity: 1;
    }
    50% {
        transform: scale(1.2) !important;
        opacity: 0.8;
    }
    100% {
        transform: scale(1) !important;
        opacity: 1;
    }
}

.combining {
    animation: combine 0.6s ease-in-out, combineGlow 0.6s ease-in-out;
}

.merging {
    animation: merge 0.6s ease-in-out;
}

.merge-target {
    animation: mergeTarget 0.6s ease-in-out;
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    25% { transform: translateX(-5px); }
    75% { transform: translateX(5px); }
}

.shake {
    animation: shake 0.5s ease-in-out;
}

@keyframes numberFadeOut {
    0% {
        opacity: 1;
    }
    100% {
        opacity: 0;
    }
}

@keyframes numberFadeIn {
    0% {
        opacity: 0;
    }
    100% {
        opacity: 1;
    }
}

.number-fade-out {
    animation: numberFadeOut 0.4s ease-out forwards !important;
    transform: none !important;
}

.number-fade-in {
    animation: numberFadeIn 0.4s ease-out forwards !important;
    transform: none !important;
}

/* Responsive design */
@media (max-width: 768px) {
    body {
        padding: 5px;
    }
    
    header h1 {
        font-size: 1.8rem;
    }
    
    .game-info {
        justify-content: center;
    }
    
    .numbers-container {
        gap: 8px;
        justify-content: center;
    }
    
    .number-tile {
        width: 120px;
        height: 60px;
        font-size: 1.8rem;
        flex-shrink: 0;
        flex-grow: 0;
    }
    
    .operations {
        gap: 8px;
    }
    
    .operation-btn {
        width: 45px;
        height: 45px;
        font-size: 1.3rem;
    }
    

    

    
    .modal-content {
        margin: 10% auto;
        width: 95%;
    }
}