/* ==========================================
   📐 Math Quiz Generator - Styles
   ========================================== */

/* CSS Variables - Theme System */
:root {
    /* Light Theme (Default) */
    --bg-primary: #f0f4ff;
    --bg-secondary: #ffffff;
    --bg-card: #ffffff;
    --text-primary: #1a1a2e;
    --text-secondary: #4a4a6a;
    --text-muted: #8888aa;
    --accent-primary: #6c5ce7;
    --accent-secondary: #a29bfe;
    --accent-gradient: linear-gradient(135deg, #6c5ce7 0%, #a29bfe 100%);
    --success: #00b894;
    --error: #ff6b6b;
    --warning: #ffeaa7;
    --border-color: #e0e6ff;
    --shadow-soft: 0 4px 20px rgba(108, 92, 231, 0.1);
    --shadow-medium: 0 8px 30px rgba(108, 92, 231, 0.15);
    --shadow-strong: 0 12px 40px rgba(108, 92, 231, 0.2);
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 20px;
    --radius-full: 50px;
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --font-family: 'Nunito', -apple-system, BlinkMacSystemFont, sans-serif;
}

/* Dark Theme */
[data-theme="dark"] {
    --bg-primary: #0f0f23;
    --bg-secondary: #1a1a2e;
    --bg-card: #16213e;
    --text-primary: #eaeaea;
    --text-secondary: #b0b0c0;
    --text-muted: #6a6a8a;
    --accent-primary: #a29bfe;
    --accent-secondary: #6c5ce7;
    --accent-gradient: linear-gradient(135deg, #a29bfe 0%, #6c5ce7 100%);
    --border-color: #2a2a4a;
    --shadow-soft: 0 4px 20px rgba(0, 0, 0, 0.3);
    --shadow-medium: 0 8px 30px rgba(0, 0, 0, 0.4);
    --shadow-strong: 0 12px 40px rgba(0, 0, 0, 0.5);
}

/* Eye-Care Theme */
[data-theme="eye-care"] {
    --bg-primary: #f5f0e1;
    --bg-secondary: #faf8f0;
    --bg-card: #fffdf5;
    --text-primary: #3d3a2e;
    --text-secondary: #5a5747;
    --text-muted: #8a8775;
    --accent-primary: #7cb342;
    --accent-secondary: #aed581;
    --accent-gradient: linear-gradient(135deg, #7cb342 0%, #aed581 100%);
    --border-color: #e5e0d0;
    --shadow-soft: 0 4px 20px rgba(124, 179, 66, 0.1);
    --shadow-medium: 0 8px 30px rgba(124, 179, 66, 0.15);
    --shadow-strong: 0 12px 40px rgba(124, 179, 66, 0.2);
}

/* Reset & Base */
*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    transition: background-color var(--transition-normal), color var(--transition-normal);
}

/* App Container */
.app-container {
    max-width: 800px;
    margin: 0 auto;
    padding: 1rem;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header */
.app-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 0;
    margin-bottom: 1.5rem;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.logo-emoji {
    font-size: 2rem;
    animation: bounce 2s ease infinite;
}

@keyframes bounce {

    0%,
    100% {
        transform: translateY(0);
    }

    50% {
        transform: translateY(-5px);
    }
}

.logo h1 {
    font-size: 1.5rem;
    font-weight: 800;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

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

.theme-btn {
    width: 44px;
    height: 44px;
    border-radius: var(--radius-full);
    border: 2px solid var(--border-color);
    background: var(--bg-card);
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all var(--transition-fast);
    font-size: 1.25rem;
}

.theme-btn:hover {
    transform: scale(1.1);
    border-color: var(--accent-primary);
    box-shadow: var(--shadow-soft);
}

/* Cards */
.card {
    background: var(--bg-card);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    box-shadow: var(--shadow-soft);
    border: 1px solid var(--border-color);
    transition: all var(--transition-normal);
}

.card:hover {
    box-shadow: var(--shadow-medium);
}

/* Section Title */
.section-title {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 1.5rem;
}

.title-icon {
    font-size: 1.5rem;
}

/* Config Groups */
.config-group {
    margin-bottom: 1.5rem;
}

.config-label {
    display: block;
    font-weight: 600;
    color: var(--text-secondary);
    margin-bottom: 0.75rem;
    font-size: 0.95rem;
}

.config-label .hint {
    font-weight: 400;
    color: var(--text-muted);
    font-size: 0.85rem;
}

/* Step Selector */
.step-selector {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.step-btn {
    flex: 1;
    min-width: 60px;
    padding: 0.75rem 1rem;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--bg-secondary);
    color: var(--text-secondary);
    font-weight: 600;
    font-size: 0.9rem;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.step-btn:hover {
    border-color: var(--accent-primary);
    color: var(--accent-primary);
}

.step-btn.active {
    background: var(--accent-gradient);
    border-color: transparent;
    color: white;
    box-shadow: var(--shadow-soft);
}

/* Range Inputs */
.range-inputs {
    display: flex;
    align-items: center;
    gap: 1rem;
    flex-wrap: wrap;
}

.range-input-group {
    flex: 1;
    min-width: 100px;
}

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

.range-input-group input {
    width: 100%;
    padding: 0.75rem 1rem;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--bg-secondary);
    color: var(--text-primary);
    font-size: 1rem;
    font-weight: 600;
    text-align: center;
    transition: all var(--transition-fast);
}

.range-input-group input:focus {
    outline: none;
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px rgba(108, 92, 231, 0.2);
}

.range-separator {
    font-size: 1.5rem;
    color: var(--text-muted);
    font-weight: 600;
}

/* Operation Grid */
.operation-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 0.75rem;
}

@media (min-width: 480px) {
    .operation-grid {
        grid-template-columns: repeat(3, 1fr);
    }
}

@media (min-width: 640px) {
    .operation-grid {
        grid-template-columns: repeat(4, 1fr);
    }
}

.op-checkbox {
    display: block;
    cursor: pointer;
}

.op-checkbox input {
    position: absolute;
    opacity: 0;
    pointer-events: none;
}

.op-box {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.25rem;
    padding: 0.75rem 0.5rem;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--bg-secondary);
    color: var(--text-secondary);
    font-size: 0.85rem;
    font-weight: 600;
    transition: all var(--transition-fast);
    text-align: center;
}

.op-checkbox:hover .op-box {
    border-color: var(--accent-primary);
    color: var(--accent-primary);
}

.op-checkbox input:checked+.op-box {
    background: var(--accent-gradient);
    border-color: transparent;
    color: white;
    box-shadow: var(--shadow-soft);
}

/* Count Selector */
.count-selector {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.count-btn {
    width: 44px;
    height: 44px;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--bg-secondary);
    color: var(--text-primary);
    font-size: 1.5rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);
    display: flex;
    align-items: center;
    justify-content: center;
}

.count-btn:hover {
    border-color: var(--accent-primary);
    color: var(--accent-primary);
}

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

.count-selector input {
    width: 80px;
    padding: 0.75rem;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--bg-secondary);
    color: var(--text-primary);
    font-size: 1.25rem;
    font-weight: 700;
    text-align: center;
}

.count-selector input:focus {
    outline: none;
    border-color: var(--accent-primary);
}

.count-unit {
    color: var(--text-muted);
    font-weight: 600;
    margin-left: 0.25rem;
}

/* Generate Button */
.generate-btn {
    width: 100%;
    padding: 1rem 2rem;
    background: var(--accent-gradient);
    border: none;
    border-radius: var(--radius-lg);
    color: white;
    font-size: 1.1rem;
    font-weight: 700;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    transition: all var(--transition-fast);
    box-shadow: var(--shadow-medium);
    margin-top: 0.5rem;
}

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

.generate-btn:active {
    transform: translateY(0);
}

.btn-icon {
    font-size: 1.25rem;
}

/* Quiz Area */
.quiz-area {
    animation: slideIn 0.4s ease;
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Quiz Header */
.quiz-header {
    margin-bottom: 1.5rem;
}

.quiz-stats {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 0.75rem;
    margin-bottom: 1rem;
}

.stat-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 0.75rem;
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
    border: 1px solid var(--border-color);
}

.stat-icon {
    font-size: 1.25rem;
    margin-bottom: 0.25rem;
}

.stat-value {
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--accent-primary);
}

.stat-label {
    font-size: 0.75rem;
    color: var(--text-muted);
    font-weight: 600;
}

.stat-item.timer .stat-value {
    font-family: 'Courier New', monospace;
    font-size: 1.25rem;
}

/* Quiz Controls */
.quiz-controls {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.control-btn {
    flex: 1;
    min-width: 120px;
    padding: 0.75rem 1rem;
    border: 2px solid var(--accent-primary);
    border-radius: var(--radius-md);
    background: transparent;
    color: var(--accent-primary);
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.35rem;
    transition: all var(--transition-fast);
}

.control-btn:hover {
    background: var(--accent-primary);
    color: white;
}

.control-btn.secondary {
    border-color: var(--text-muted);
    color: var(--text-muted);
}

.control-btn.secondary:hover {
    background: var(--text-muted);
    color: white;
}

.control-btn .btn-icon {
    font-size: 1rem;
}

/* Questions List */
.questions-list {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

/* Question Card */
.question-card {
    background: var(--bg-card);
    border-radius: var(--radius-lg);
    padding: 1.25rem;
    box-shadow: var(--shadow-soft);
    border: 2px solid var(--border-color);
    transition: all var(--transition-fast);
}

.question-card:hover {
    border-color: var(--accent-secondary);
}

.question-card.correct {
    border-color: var(--success);
    background: linear-gradient(to right, rgba(0, 184, 148, 0.05), transparent);
}

.question-card.wrong {
    border-color: var(--error);
    background: linear-gradient(to right, rgba(255, 107, 107, 0.05), transparent);
}

.question-header {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 1rem;
}

.question-number {
    width: 36px;
    height: 36px;
    background: var(--accent-gradient);
    border-radius: var(--radius-full);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-weight: 700;
    font-size: 0.9rem;
    flex-shrink: 0;
}

.question-expression {
    flex: 1;
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    font-family: 'Courier New', Consolas, monospace;
}

.question-body {
    display: flex;
    align-items: center;
    gap: 1rem;
    flex-wrap: wrap;
}

.answer-input-wrapper {
    flex: 1;
    min-width: 150px;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.answer-input-wrapper span {
    font-size: 1.25rem;
    color: var(--text-muted);
}

.answer-input {
    flex: 1;
    padding: 0.75rem 1rem;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--bg-secondary);
    color: var(--text-primary);
    font-size: 1.1rem;
    font-weight: 600;
    font-family: 'Courier New', Consolas, monospace;
    transition: all var(--transition-fast);
}

.answer-input:focus {
    outline: none;
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px rgba(108, 92, 231, 0.2);
}

.answer-input.correct {
    border-color: var(--success);
    background: rgba(0, 184, 148, 0.1);
}

.answer-input.wrong {
    border-color: var(--error);
    background: rgba(255, 107, 107, 0.1);
}

.check-btn {
    padding: 0.75rem 1.25rem;
    background: var(--accent-gradient);
    border: none;
    border-radius: var(--radius-md);
    color: white;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);
    white-space: nowrap;
}

.check-btn:hover {
    transform: scale(1.05);
}

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

/* Answer Display */
.answer-display {
    display: none;
    margin-top: 0.75rem;
    padding: 0.75rem 1rem;
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
    border-left: 4px solid var(--accent-primary);
}

.answer-display.show {
    display: block;
    animation: fadeIn 0.3s ease;
}

@keyframes fadeIn {
    from {
        opacity: 0;
    }

    to {
        opacity: 1;
    }
}

.answer-label {
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-right: 0.5rem;
}

.answer-value {
    font-weight: 700;
    color: var(--success);
    font-family: 'Courier New', Consolas, monospace;
    font-size: 1.1rem;
}

/* Feedback Icon */
.feedback-icon {
    font-size: 1.5rem;
    animation: pop 0.3s ease;
}

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

    50% {
        transform: scale(1.2);
    }

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

/* Theme Modal */
.theme-modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-normal);
    padding: 1rem;
}

.theme-modal.show {
    opacity: 1;
    visibility: visible;
}

.theme-modal-content {
    background: var(--bg-card);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    width: 100%;
    max-width: 360px;
    box-shadow: var(--shadow-strong);
    transform: translateY(20px);
    transition: transform var(--transition-normal);
}

.theme-modal.show .theme-modal-content {
    transform: translateY(0);
}

.theme-modal-content h3 {
    text-align: center;
    margin-bottom: 1.25rem;
    color: var(--text-primary);
    font-size: 1.1rem;
}

.theme-options {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.theme-option {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1rem;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    background: var(--bg-secondary);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.theme-option:hover {
    border-color: var(--accent-primary);
}

.theme-option.active {
    border-color: var(--accent-primary);
    background: rgba(108, 92, 231, 0.1);
}

.theme-preview {
    width: 40px;
    height: 40px;
    border-radius: var(--radius-md);
    border: 2px solid var(--border-color);
}

.theme-preview.light {
    background: linear-gradient(135deg, #f0f4ff 50%, #ffffff 50%);
}

.theme-preview.dark {
    background: linear-gradient(135deg, #0f0f23 50%, #16213e 50%);
}

.theme-preview.eye-care {
    background: linear-gradient(135deg, #f5f0e1 50%, #fffdf5 50%);
}

.theme-name {
    font-weight: 600;
    color: var(--text-primary);
}

/* Footer */
.app-footer {
    margin-top: auto;
    padding: 1.5rem 0 1rem;
    text-align: center;
    color: var(--text-muted);
    font-size: 0.85rem;
}

/* Utility Classes */
.hidden {
    display: none !important;
}

/* Responsive Adjustments */
@media (max-width: 480px) {
    .app-header h1 {
        font-size: 1.25rem;
    }

    .quiz-stats {
        grid-template-columns: repeat(2, 1fr);
    }

    .quiz-controls {
        flex-direction: column;
    }

    .control-btn {
        min-width: 100%;
    }

    .question-expression {
        font-size: 1.1rem;
    }
}

/* Print Styles */
@media print {

    .app-header,
    .config-panel,
    .quiz-controls,
    .theme-modal,
    .app-footer,
    .check-btn,
    .answer-input-wrapper {
        display: none !important;
    }

    .question-card {
        break-inside: avoid;
        box-shadow: none;
        border: 1px solid #ccc;
    }

    body {
        background: white;
        color: black;
    }

    .quiz-area {
        display: block !important;
    }
}

/* Scrollbar Styling */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: var(--bg-secondary);
}

::-webkit-scrollbar-thumb {
    background: var(--accent-secondary);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--accent-primary);
}

/* Focus Visible for Accessibility */
*:focus-visible {
    outline: 2px solid var(--accent-primary);
    outline-offset: 2px;
}

/* Answer Actions */
.answer-actions {
    margin-top: 0.75rem;
}

.show-answer-btn {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    padding: 0.5rem 1rem;
    background: var(--bg-secondary);
    border: 2px solid var(--accent-secondary);
    border-radius: var(--radius-md);
    color: var(--accent-primary);
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);
}

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

.show-answer-btn .btn-icon {
    font-size: 1rem;
}

/* Answer Header */
.answer-header {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    margin-bottom: 0.75rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px dashed var(--border-color);
}

/* Answer Steps */
.answer-steps {
    margin-top: 0.5rem;
}

.steps-title {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

.calculation-steps {
    display: flex;
    flex-direction: column;
    gap: 0.35rem;
}

.step-item {
    font-size: 0.85rem;
    color: var(--text-secondary);
    padding: 0.35rem 0.5rem;
    background: rgba(108, 92, 231, 0.05);
    border-radius: var(--radius-sm);
    line-height: 1.5;
}

[data-theme="dark"] .step-item {
    background: rgba(162, 155, 254, 0.1);
}

[data-theme="eye-care"] .step-item {
    background: rgba(124, 179, 66, 0.1);
}

/* Question Hint */
.question-hint {
    font-size: 0.8rem;
    color: var(--text-muted);
    font-weight: 400;
    margin-left: 0.5rem;
}