:root {
    /* Colors */
    --color-primary: #667eea;
    --color-primary-dark: #764ba2;
    --color-success: #28a745;
    --color-success-light: #d4edda;
    --color-success-dark: #155724;
    --color-danger: #dc3545;
    --color-danger-light: #f8d7da;
    --color-danger-dark: #721c24;
    --color-gray: #6c757d;
    --color-gray-dark: #5a6268;
    --color-gray-light: #f8f9fa;
    --color-border: #e9ecef;
    --color-text: #333;
    --color-text-light: #666;
    --color-white: #fff;

    /* Gradients */
    --gradient-primary: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);
    --gradient-tafels: linear-gradient(135deg, #2b8cfe 0%, #00a8ce 100%);
    --gradient-optellen: linear-gradient(135deg, #23c97b 0%, #18d9c7 100%);
    --gradient-aftrekken: linear-gradient(135deg, #da507a 0%, #cea120 100%);
    --gradient-delen: linear-gradient(135deg, #816cb1 0%, #dba2cb 100%);
    --gradient-vermenigvuldigen: linear-gradient(135deg, #df7a36 0%, #df4a68 100%);
    --gradient-breuken: linear-gradient(135deg, #dfccb2 0%, #dba67f 100%);
    --gradient-kommagetallen: linear-gradient(135deg, #10bfb0 0%, #130847 100%);
    --gradient-procenten: linear-gradient(135deg, #88ddca 0%, #ddb6c3 100%);
    --gradient-kwadraten: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --gradient-wortels: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    --gradient-negatief: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
    --gradient-eenheden: linear-gradient(135deg, #43e97b 0%, #38f9d7 100%);
    --gradient-verhoudingen: linear-gradient(135deg, #fa709a 0%, #fee140 100%);
    --gradient-klokkijken: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --gradient-default: linear-gradient(135deg, #d073fb 0%, #d5375c 100%);
    --gradient-progress: linear-gradient(90deg, #4facfe 0%, #00f2fe 100%);
    --gradient-bg: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-dark) 100%);

    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 0.75rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-xxl: 3rem;

    /* Border radius */
    --radius-sm: 10px;
    --radius-md: 15px;
    --radius-lg: 20px;

    /* Font sizes */
    --font-sm: 0.9rem;
    --font-base: 1rem;
    --font-md: 1.1rem;
    --font-lg: 1.2rem;
    --font-xl: 1.5rem;
    --font-2xl: 2rem;
    --font-3xl: 2.5rem;
    --font-4xl: 3rem;
    --font-5xl: 4rem;
    --font-icon: 2.5rem;
    --font-emoji: 5rem;

    /* Shadows */
    --shadow-sm: 0 5px 20px rgba(102, 126, 234, 0.4);
    --shadow-md: 0 8px 25px rgba(0, 0, 0, 0.2);
    --shadow-lg: 0 10px 40px rgba(0, 0, 0, 0.2);
    --shadow-text: 2px 2px 4px rgba(0, 0, 0, 0.2);

    /* Transitions */
    --transition-fast: 0.2s;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;

    /* Container */
    --container-max-width: 800px;
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: var(--gradient-bg);
    min-height: 100vh;
    padding: var(--spacing-lg);
}

.container {
    max-width: var(--container-max-width);
    margin: 0 auto;
}

header {
    text-align: center;
    margin-bottom: var(--spacing-xl);

    & h1 {
        color: var(--color-white);
        font-size: var(--font-3xl);
        text-shadow: var(--shadow-text);
    }

    & p {
        color: rgba(255, 255, 255, 0.9);
        font-size: var(--font-md);
        margin-top: var(--spacing-xs);
    }
}

.card {
    background: var(--color-white);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    box-shadow: var(--shadow-lg);
}

.difficulty-tabs {
    display: flex;
    gap: var(--spacing-sm);
    justify-content: center;
    row-gap: 1rem;
    margin-bottom: var(--spacing-xl);
}

.tab-btn {
    background: var(--color-gray-light);
    color: var(--color-text);
    border: 2px solid transparent;
    padding: var(--spacing-sm) var(--spacing-xl);
    border-radius: var(--radius-md);
    font-size: var(--font-sm);
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);

    &:hover {
        background: var(--color-border);
        transform: translateY(-2px);
    }

    &.active {
        background: var(--gradient-primary);
        color: var(--color-white);
        border-color: var(--color-primary);
        box-shadow: var(--shadow-sm);
    }
}

.grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: var(--spacing-lg);
}

.grid-item {
    background: var(--gradient-default);
    border: none;
    border-radius: var(--radius-md);
    padding: var(--spacing-xl) var(--spacing-md);
    color: var(--color-white);
    font-size: var(--font-md);
    font-weight: bold;
    cursor: pointer;
    transition: transform var(--transition-fast), box-shadow var(--transition-fast);
    text-align: center;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.4);

    &:hover {
        transform: translateY(-5px);
        box-shadow: var(--shadow-md);
    }

    &.tafels {
        background: var(--gradient-tafels);
    }

    &.optellen {
        background: var(--gradient-optellen);
    }

    &.aftrekken {
        background: var(--gradient-aftrekken);
    }

    &.delen {
        background: var(--gradient-delen);
    }

    &.vermenigvuldigen {
        background: var(--gradient-vermenigvuldigen);
    }

    &.breuken {
        background: var(--gradient-breuken);
    }

    &.kommagetallen {
        background: var(--gradient-kommagetallen);
    }

    &.procenten {
        background: var(--gradient-procenten);
    }

    &.kwadraten {
        background: var(--gradient-kwadraten);
    }

    &.wortels {
        background: var(--gradient-wortels);
    }

    &.negatief {
        background: var(--gradient-negatief);
    }

    &.eenheden {
        background: var(--gradient-eenheden);
    }

    &.verhoudingen {
        background: var(--gradient-verhoudingen);
    }

    &.klokkijken {
        background: var(--gradient-klokkijken);
    }

    & .icon {
        font-size: var(--font-icon);
        margin-bottom: var(--spacing-sm);
    }
}

.back-btn {
    background: var(--color-gray);
    color: var(--color-white);
    border: none;
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-size: var(--font-base);
    margin-bottom: var(--spacing-lg);
    transition: background var(--transition-fast);

    &:hover {
        background: var(--color-gray-dark);
    }
}

.section-title {
    font-size: var(--font-xl);
    color: var(--color-text);
    margin-bottom: var(--spacing-lg);
    text-align: center;
}

/* Quiz styles */
.quiz-container {
    text-align: center;
}

.progress-bar {
    background: var(--color-border);
    border-radius: var(--radius-sm);
    height: 20px;
    margin-bottom: var(--spacing-xl);
    overflow: hidden;
}

.progress-fill {
    background: var(--gradient-progress);
    height: 100%;
    transition: width var(--transition-normal);
    border-radius: var(--radius-sm);
}

.progress-text {
    color: var(--color-text-light);
    margin-bottom: var(--spacing-sm);
    font-size: var(--font-sm);
}

.question {
    font-size: var(--font-3xl);
    color: var(--color-text);
    margin: var(--spacing-xl) 0;
    font-weight: bold;
}

.clock-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-md);
}

.time-indicator {
    font-size: var(--font-lg);
    font-weight: bold;
    padding: var(--spacing-sm) var(--spacing-lg);
    border-radius: var(--radius-md);
    background: var(--color-gray-light);
}

.sun-icon {
    color: #ff9800;
}

.moon-icon {
    color: #3f51b5;
}

.analog-clock {
    width: 250px;
    height: 250px;
    display: block;
    filter: drop-shadow(0 4px 8px rgba(0, 0, 0, 0.1));
    margin-bottom: var(--spacing-lg);
}

.answer-input {
    font-size: var(--font-2xl);
    padding: var(--spacing-sm) var(--spacing-md);
    border: 3px solid #ddd;
    border-radius: var(--radius-md);
    width: 150px;
    text-align: center;
    outline: none;
    transition: border-color var(--transition-fast);

    &:focus {
        border-color: #4facfe;
    }

    &.correct {
        border-color: var(--color-success);
        background: var(--color-success-light);
    }

    &.incorrect {
        border-color: var(--color-danger);
        background: var(--color-danger-light);
    }
}

.submit-btn {
    background: var(--gradient-primary);
    color: var(--color-white);
    border: none;
    padding: var(--spacing-md) 40px;
    border-radius: var(--radius-md);
    font-size: var(--font-lg);
    cursor: pointer;
    margin-top: var(--spacing-lg);
    transition: transform var(--transition-fast), box-shadow var(--transition-fast);

    &:hover {
        transform: scale(1.05);
        box-shadow: var(--shadow-sm);
    }

    &:disabled {
        opacity: 0.5;
        cursor: not-allowed;
        transform: none;
    }
}

.feedback {
    font-size: var(--font-xl);
    margin-top: var(--spacing-lg);
    padding: var(--spacing-md);
    border-radius: var(--radius-sm);
    font-weight: bold;

    &.correct {
        background: var(--color-success-light);
        color: var(--color-success-dark);
    }

    &.incorrect {
        background: var(--color-danger-light);
        color: var(--color-danger-dark);
    }
}

/* Results styles */
.results {
    text-align: center;
}

.results-score {
    font-size: var(--font-5xl);
    font-weight: bold;
    color: var(--color-text);
    margin: var(--spacing-lg) 0;
}

.results-message {
    font-size: var(--font-xl);
    color: var(--color-text-light);
    margin-bottom: var(--spacing-xxl);
}

.results-details {
    background: var(--color-gray-light);
    border-radius: var(--radius-md);
    padding: var(--spacing-lg);
    margin: var(--spacing-lg) 0;
}

.result-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-sm);
    border-bottom: 1px solid var(--color-border);

    &:last-child {
        border-bottom: none;
    }

    &.correct {
        color: var(--color-success);
    }

    &.incorrect {
        color: var(--color-danger);
    }
}

.emoji {
    font-size: var(--font-emoji);
    margin-bottom: var(--spacing-lg);
}

.btn-group {
    display: flex;
    gap: var(--spacing-md);
    justify-content: center;
    flex-wrap: wrap;
}

.btn-primary {
    background: var(--gradient-primary);
    color: var(--color-white);
    border: none;
    padding: var(--spacing-md) var(--spacing-xxl);
    border-radius: var(--radius-md);
    font-size: var(--font-md);
    cursor: pointer;
    transition: transform var(--transition-fast);

    &:hover {
        transform: scale(1.05);
    }
}

.btn-secondary {
    background: var(--color-gray);
    color: var(--color-white);
    border: none;
    padding: var(--spacing-md) var(--spacing-xl);
    border-radius: var(--radius-md);
    font-size: var(--font-md);
    cursor: pointer;
    transition: transform var(--transition-fast);

    &:hover {
        transform: scale(1.05);
    }
}

.history-btn {
    margin-top: var(--spacing-xxl);
    text-align: center;
}

/* History styles */
.history-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.history-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md);
    background: var(--color-gray-light);
    border-radius: var(--radius-sm);
    transition: transform var(--transition-fast), box-shadow var(--transition-fast);

    &:hover {
        transform: translateX(5px);
        box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    }
}

.history-info {
    display: flex;
    flex-direction: column;
    gap: 5px;
}

.history-title {
    font-weight: bold;
    color: var(--color-text);
    font-size: var(--font-base);
}

.history-date {
    font-size: var(--font-sm);
    color: var(--color-text-light);
}

.history-score {
    display: flex;
    gap: var(--spacing-xs);
    align-items: center;
    font-weight: bold;
}

.score-correct {
    color: var(--color-success);
}

.score-wrong {
    color: var(--color-danger);
}

.score-separator {
    color: var(--color-text-light);
}

.empty-history {
    text-align: center;
    padding: var(--spacing-xxl) 0;

    & .emoji {
        font-size: var(--font-emoji);
        margin-bottom: var(--spacing-lg);
    }

    & p {
        color: var(--color-text-light);
        font-size: var(--font-md);
    }
}

/* Alpine.js Transition Classes */
.transition {
    transition-property: all;
    transition-timing-function: cubic-bezier(0.4, 0, 0.2, 1);
}

.ease-out {
    transition-timing-function: cubic-bezier(0, 0, 0.2, 1);
}

.ease-in {
    transition-timing-function: cubic-bezier(0.4, 0, 1, 1);
}

.duration-150 {
    transition-duration: 150ms;
}

.duration-200 {
    transition-duration: 200ms;
}

.duration-300 {
    transition-duration: 300ms;
}

.opacity-0 {
    opacity: 0;
}

.opacity-100 {
    opacity: 1;
}

.scale-90 {
    transform: scale(0.9);
}

.scale-95 {
    transform: scale(0.95);
}

.scale-100 {
    transform: scale(1);
}

.translate-y-0 {
    transform: translateY(0);
}

.translate-y-2 {
    transform: translateY(0.5rem);
}

/* Grid item stagger animation */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.grid-item {
    animation: fadeInUp 0.4s ease-out backwards;
}

.grid-item:nth-child(1) { animation-delay: 0.05s; }
.grid-item:nth-child(2) { animation-delay: 0.1s; }
.grid-item:nth-child(3) { animation-delay: 0.15s; }
.grid-item:nth-child(4) { animation-delay: 0.2s; }
.grid-item:nth-child(5) { animation-delay: 0.25s; }
.grid-item:nth-child(6) { animation-delay: 0.3s; }
.grid-item:nth-child(7) { animation-delay: 0.35s; }
.grid-item:nth-child(8) { animation-delay: 0.4s; }

/* History item stagger animation */
@keyframes slideInRight {
    from {
        opacity: 0;
        transform: translateX(-20px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

.history-item {
    animation: slideInRight 0.3s ease-out backwards;
}

.history-item:nth-child(1) { animation-delay: 0.05s; }
.history-item:nth-child(2) { animation-delay: 0.1s; }
.history-item:nth-child(3) { animation-delay: 0.15s; }
.history-item:nth-child(4) { animation-delay: 0.2s; }
.history-item:nth-child(5) { animation-delay: 0.25s; }
.history-item:nth-child(6) { animation-delay: 0.3s; }
.history-item:nth-child(7) { animation-delay: 0.35s; }
.history-item:nth-child(8) { animation-delay: 0.4s; }
.history-item:nth-child(9) { animation-delay: 0.45s; }
.history-item:nth-child(10) { animation-delay: 0.5s; }

/* Result item stagger animation */
.result-item {
    animation: fadeInUp 0.3s ease-out backwards;
}

.result-item:nth-child(1) { animation-delay: 0.05s; }
.result-item:nth-child(2) { animation-delay: 0.1s; }
.result-item:nth-child(3) { animation-delay: 0.15s; }
.result-item:nth-child(4) { animation-delay: 0.2s; }
.result-item:nth-child(5) { animation-delay: 0.25s; }
.result-item:nth-child(6) { animation-delay: 0.3s; }
.result-item:nth-child(7) { animation-delay: 0.35s; }
.result-item:nth-child(8) { animation-delay: 0.4s; }
.result-item:nth-child(9) { animation-delay: 0.45s; }
.result-item:nth-child(10) { animation-delay: 0.5s; }

/* Responsive */
@media (max-width: 600px) {
    header h1 {
        font-size: 1.8rem;
    }

    .difficulty-tabs {
        flex-wrap: wrap;
        gap: var(--spacing-xs);
    }

    .tab-btn {
        padding: var(--spacing-xs) var(--spacing-md);
        font-size: var(--font-sm);
        flex: 1 1 auto;
        min-width: fit-content;
    }

    .question {
        font-size: var(--font-2xl);
    }

    .answer-input {
        font-size: var(--font-xl);
        width: 120px;
    }

    .grid-item {
        padding: var(--spacing-md) var(--spacing-sm);
    }

    .history-item {
        flex-direction: column;
        align-items: flex-start;
        gap: var(--spacing-sm);
    }

    .history-score {
        align-self: flex-end;
    }
}