:root {
    --primary-color: #FF006E;
    --secondary-color: #FB5607;
    --accent-color: #FFBE0B;
    --purple: #8338EC;
    --blue: #3A86FF;
    --dark-bg: #0a0a0a;
    --card-bg: #1a1a1a;
    --text-primary: #ffffff;
    --text-secondary: #cccccc;
    --border-color: #333;
    --success: #00ff88;
    --error: #ff4444;
    --shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
    --glow: 0 0 20px rgba(255, 0, 110, 0.3);
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, var(--dark-bg) 0%, #1a0a1a 50%, var(--dark-bg) 100%);
    color: var(--text-primary);
    min-height: 100vh;
    overflow-x: hidden;
}

.app-container {
    max-width: 100vw;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    position: relative;
}

/* Header Styles */
.app-header {
    background: linear-gradient(135deg, var(--primary-color), var(--purple));
    padding: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 100;
}

.app-header h1 {
    font-size: 1.5rem;
    font-weight: bold;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
}

.header-controls {
    display: flex;
    gap: 0.5rem;
}

/* Main Content */
.main-content {
    flex: 1;
    padding: 1rem;
    padding-bottom: 80px;
}

.content-section {
    display: none;
    animation: fadeIn 0.3s ease-in-out;
}

.content-section.active {
    display: block;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

/* Game Info */
.game-info {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
    background: var(--card-bg);
    padding: 1rem;
    border-radius: 12px;
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow);
}

.difficulty-selector select {
    background: var(--dark-bg);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
    padding: 0.5rem;
    border-radius: 8px;
    font-size: 0.9rem;
}

.game-stats {
    display: flex;
    gap: 1rem;
}

.stat {
    text-align: center;
}

.stat-label {
    display: block;
    font-size: 0.8rem;
    color: var(--text-secondary);
    margin-bottom: 0.25rem;
}

/* Game Container */
.game-container {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    align-items: center;
}

/* Puzzle Grid */
.puzzle-grid {
    display: grid;
    gap: 2px;
    background: var(--border-color);
    padding: 4px;
    border-radius: 12px;
    box-shadow: var(--shadow);
    max-width: 100%;
    margin: 0 auto;
}

.puzzle-cell {
    background: var(--card-bg);
    border: 2px solid transparent;
    border-radius: 8px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    cursor: pointer;
    transition: all 0.2s ease;
    position: relative;
    min-height: 60px;
    min-width: 60px;
}

.puzzle-cell:hover {
    background: rgba(255, 255, 255, 0.1);
    transform: scale(1.05);
}

.puzzle-cell.selected {
    border-color: var(--primary-color);
    box-shadow: 0 0 15px rgba(255, 0, 110, 0.5);
    background: rgba(255, 0, 110, 0.1);
}

.puzzle-cell.error {
    border-color: var(--error);
    background: rgba(255, 68, 68, 0.1);
    animation: shake 0.5s ease-in-out;
}

.puzzle-cell.correct {
    border-color: var(--success);
    background: rgba(0, 255, 136, 0.1);
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    25% { transform: translateX(-2px); }
    75% { transform: translateX(2px); }
}

.cell-operation {
    position: absolute;
    top: 2px;
    left: 4px;
    font-size: 0.7rem;
    color: var(--text-secondary);
    font-weight: bold;
}

.cell-number {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--text-primary);
}

.cell-number.user-input {
    color: var(--accent-color);
}

/* Game Controls */
.game-controls {
    width: 100%;
    max-width: 400px;
}

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

.number-btn, .clear-btn {
    background: linear-gradient(135deg, var(--secondary-color), var(--accent-color));
    border: none;
    color: var(--text-primary);
    padding: 1rem;
    border-radius: 12px;
    font-size: 1.2rem;
    font-weight: bold;
    cursor: pointer;
    transition: all 0.2s ease;
    box-shadow: var(--shadow);
}

.number-btn:hover, .clear-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.4);
}

.clear-btn {
    background: linear-gradient(135deg, var(--error), #cc0000);
}

.action-buttons {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
    gap: 0.5rem;
}

/* Buttons */
.btn-primary, .btn-secondary {
    padding: 0.75rem 1rem;
    border: none;
    border-radius: 8px;
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    text-decoration: none;
    color: var(--text-primary);
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color), var(--purple));
    box-shadow: var(--shadow);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 12px 40px rgba(255, 0, 110, 0.4);
}

.btn-secondary {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.1);
    border-color: var(--primary-color);
}

/* Calculator Styles */
.calculator-container {
    max-width: 400px;
    margin: 0 auto;
}

.calculator-container h2 {
    text-align: center;
    margin-bottom: 2rem;
    color: var(--accent-color);
}

.calculator {
    background: var(--card-bg);
    padding: 1.5rem;
    border-radius: 16px;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
}

.calculator-display {
    margin-bottom: 1rem;
}

.calculator-display input {
    width: 100%;
    padding: 1rem;
    font-size: 1.5rem;
    text-align: right;
    background: var(--dark-bg);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    color: var(--text-primary);
}

.calculator-buttons {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 0.5rem;
}

.calc-btn {
    padding: 1rem;
    border: none;
    border-radius: 8px;
    font-size: 1.1rem;
    font-weight: bold;
    cursor: pointer;
    transition: all 0.2s ease;
    background: var(--secondary-color);
    color: var(--text-primary);
}

.calc-btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow);
}

.calc-btn.operator {
    background: var(--purple);
}

.calc-btn.equals {
    background: var(--primary-color);
    grid-row: span 2;
}

.calc-btn.clear {
    background: var(--error);
}

.calc-btn.zero {
    grid-column: span 2;
}

/* Tutorial Styles */
.tutorial-container {
    max-width: 600px;
    margin: 0 auto;
}

.tutorial-container h2 {
    text-align: center;
    margin-bottom: 2rem;
    color: var(--accent-color);
}

.tutorial-content {
    background: var(--card-bg);
    padding: 2rem;
    border-radius: 16px;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
    margin-bottom: 1rem;
    min-height: 300px;
}

.tutorial-step {
    display: none;
}

.tutorial-step.active {
    display: block;
    animation: fadeIn 0.3s ease-in-out;
}

.tutorial-step h3 {
    color: var(--primary-color);
    margin-bottom: 1rem;
}

.tutorial-step p {
    line-height: 1.6;
    margin-bottom: 1rem;
    color: var(--text-secondary);
}

.tutorial-step ul {
    margin-left: 1.5rem;
    line-height: 1.8;
    color: var(--text-secondary);
}

.tutorial-example {
    margin: 1rem 0;
    display: flex;
    justify-content: center;
}

.mini-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 2px;
    background: var(--border-color);
    padding: 4px;
    border-radius: 8px;
}

.mini-cell {
    background: var(--card-bg);
    border: 2px solid var(--primary-color);
    border-radius: 4px;
    padding: 0.5rem;
    display: flex;
    flex-direction: column;
    align-items: center;
    min-width: 50px;
    min-height: 50px;
}

.operation {
    font-size: 0.7rem;
    color: var(--text-secondary);
}

.number {
    font-size: 1.2rem;
    font-weight: bold;
    color: var(--accent-color);
}

.tutorial-navigation {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem;
    background: var(--card-bg);
    border-radius: 12px;
    box-shadow: var(--shadow);
}

.step-indicator {
    color: var(--text-secondary);
    font-weight: bold;
}

#current-step {
    color: var(--primary-color);
}

/* FAQ Styles */
.faq-container {
    max-width: 800px;
    margin: 0 auto;
}

.faq-container h2 {
    text-align: center;
    margin-bottom: 2rem;
    color: var(--accent-color);
}

.faq-item {
    background: var(--card-bg);
    margin-bottom: 1rem;
    border-radius: 12px;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
    overflow: hidden;
}

.faq-question {
    width: 100%;
    padding: 1.5rem;
    background: transparent;
    border: none;
    color: var(--text-primary);
    font-size: 1rem;
    font-weight: 600;
    text-align: left;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: background 0.2s ease;
}

.faq-question:hover {
    background: rgba(255, 255, 255, 0.05);
}

.faq-question[aria-expanded="true"] .faq-icon {
    transform: rotate(45deg);
    color: var(--primary-color);
}

.faq-icon {
    transition: transform 0.3s ease, color 0.3s ease;
    font-size: 1.2rem;
}

.faq-answer {
    padding: 0 1.5rem 1.5rem;
    color: var(--text-secondary);
    line-height: 1.6;
    animation: slideDown 0.3s ease-out;
}

.faq-answer[hidden] {
    display: none;
}

@keyframes slideDown {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Bottom Navigation */
.bottom-nav {
    position: fixed;
    bottom: 0;
    left: 0;
    right: 0;
    background: linear-gradient(135deg, var(--card-bg) 0%, #2a2a2a 100%);
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: space-around;
    padding: 0.5rem 0;
    z-index: 1000;
    box-shadow: 0 -4px 20px rgba(0, 0, 0, 0.3);
}

.nav-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-decoration: none;
    color: var(--text-secondary);
    padding: 0.5rem;
    border-radius: 8px;
    transition: all 0.2s ease;
    min-width: 60px;
}

.nav-item:hover {
    color: var(--primary-color);
    background: rgba(255, 0, 110, 0.1);
}

.nav-item.active {
    color: var(--primary-color);
    background: rgba(255, 0, 110, 0.1);
}

.nav-item i {
    font-size: 1.2rem;
    margin-bottom: 0.25rem;
}

.nav-item span {
    font-size: 0.7rem;
    font-weight: 500;
}

/* Modal Styles */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.8);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 2000;
    backdrop-filter: blur(5px);
}

.modal[hidden] {
    display: none;
}

.modal-content {
    background: var(--card-bg);
    padding: 2rem;
    border-radius: 16px;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
    max-width: 90vw;
    max-width: 400px;
    text-align: center;
    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-content h2 {
    color: var(--success);
    margin-bottom: 1rem;
}

.completion-stats {
    margin: 1.5rem 0;
    display: flex;
    justify-content: space-around;
}

.completion-stats .stat {
    text-align: center;
}

.modal-actions {
    display: flex;
    gap: 1rem;
    justify-content: center;
    margin-top: 1.5rem;
}

/* Footer */
footer {
    text-align: center;
    padding: 1rem;
    color: var(--text-secondary);
    font-size: 0.8rem;
    background: var(--dark-bg);
    border-top: 1px solid var(--border-color);
}

/* Responsive Design */
@media (max-width: 480px) {
    .app-header {
        padding: 0.75rem;
    }
    
    .app-header h1 {
        font-size: 1.25rem;
    }
    
    .main-content {
        padding: 0.75rem;
        padding-bottom: 80px;
    }
    
    .game-info {
        flex-direction: column;
        gap: 1rem;
        text-align: center;
    }
    
    .puzzle-cell {
        min-height: 50px;
        min-width: 50px;
    }
    
    .cell-number {
        font-size: 1.2rem;
    }
    
    .number-pad {
        grid-template-columns: repeat(5, 1fr);
        gap: 0.25rem;
    }
    
    .number-btn, .clear-btn {
        padding: 0.75rem;
        font-size: 1rem;
    }
    
    .action-buttons {
        gap: 0.25rem;
    }
    
    .btn-primary, .btn-secondary {
        padding: 0.6rem 0.5rem;
        font-size: 0.8rem;
    }
    
    .tutorial-content {
        padding: 1.5rem;
    }
    
    .modal-content {
        padding: 1.5rem;
        margin: 1rem;
    }
    
    .modal-actions {
        flex-direction: column;
    }
}

@media (min-width: 768px) {
    .app-container {
        max-width: 1200px;
        margin: 0 auto;
    }
    
    .game-container {
        flex-direction: row;
        align-items: flex-start;
        justify-content: center;
        gap: 2rem;
    }
    
    .puzzle-grid {
        flex-shrink: 0;
    }
    
    .game-controls {
        max-width: 300px;
    }
    
    .puzzle-cell {
        min-height: 80px;
        min-width: 80px;
    }
    
    .cell-number {
        font-size: 2rem;
    }
    
    .bottom-nav {
        position: relative;
        background: var(--card-bg);
        border-radius: 12px;
        margin: 1rem;
        box-shadow: var(--shadow);
    }
    
    .main-content {
        padding-bottom: 1rem;
    }
}

/* Holographic Effects */
.holographic {
    background: linear-gradient(45deg, 
        var(--primary-color) 0%, 
        var(--secondary-color) 25%, 
        var(--accent-color) 50%, 
        var(--purple) 75%, 
        var(--blue) 100%);
    background-size: 400% 400%;
    animation: holographicShift 3s ease-in-out infinite;
}

@keyframes holographicShift {
    0%, 100% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
}

.glow-effect {
    box-shadow: 0 0 20px rgba(255, 0, 110, 0.3),
                0 0 40px rgba(255, 0, 110, 0.2),
                0 0 60px rgba(255, 0, 110, 0.1);
}

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

/* Focus styles for keyboard navigation */
button:focus-visible,
select:focus-visible,
.nav-item:focus-visible,
.puzzle-cell:focus-visible {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

/* High contrast mode */
@media (prefers-contrast: high) {
    :root {
        --card-bg: #000000;
        --text-primary: #ffffff;
        --text-secondary: #ffffff;
        --border-color: #ffffff;
    }
}