/* ===================================
   CSS Custom Properties (Design System)
   =================================== */
:root {
    /* Colors */
    --color-primary: #00d4ff;
    --color-secondary: #7b2ff7;
    --color-accent: #ff006e;
    --color-bg-start: #0f0c29;
    --color-bg-mid: #302b63;
    --color-bg-end: #24243e;
    --color-text-primary: #ffffff;
    --color-text-secondary: #e0e0e0;
    --color-card-bg: rgba(255, 255, 255, 0.85);
    --color-card-border: rgba(123, 47, 247, 0.2);
    --color-card-text: #1a1a1a;
    --color-shadow: rgba(0, 0, 0, 0.3);

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

    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.25rem;
    --font-size-xl: 1.5rem;
    --font-size-2xl: 2rem;
    --font-size-3xl: 2.5rem;

    /* Border Radius */
    --radius-sm: 0.5rem;
    --radius-md: 1rem;
    --radius-lg: 1.5rem;
    --radius-xl: 2rem;

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

/* ===================================
   Reset & Base Styles
   =================================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: var(--font-family);
    color: var(--color-text-primary);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, var(--color-bg-start), var(--color-bg-mid), var(--color-bg-end));
    background-size: 400% 400%;
    animation: gradientShift 15s ease infinite;
    padding: var(--spacing-md);
    overflow-x: hidden;
}

@keyframes gradientShift {
    0% {
        background-position: 0% 50%;
    }

    50% {
        background-position: 100% 50%;
    }

    100% {
        background-position: 0% 50%;
    }
}

/* ===================================
   Container
   =================================== */
.container {
    max-width: 800px;
    width: 100%;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
    animation: fadeIn 0.6s ease;
}

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

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

/* ===================================
   Header
   =================================== */
.header {
    text-align: center;
    animation: slideDown 0.8s ease;
}

@keyframes slideDown {
    from {
        opacity: 0;
        transform: translateY(-30px);
    }

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

.logo-container {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-sm);
}

.logo {
    width: 60px;
    height: 60px;
    filter: drop-shadow(0 4px 12px rgba(0, 212, 255, 0.4));
    animation: float 3s ease-in-out infinite;
}

@keyframes float {

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

    50% {
        transform: translateY(-10px);
    }
}

.title {
    font-size: var(--font-size-3xl);
    font-weight: 800;
    background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    letter-spacing: -0.02em;
}

.subtitle {
    font-size: var(--font-size-lg);
    color: var(--color-text-secondary);
    font-weight: 400;
    opacity: 0.9;
}

/* ===================================
   Filter Container
   =================================== */
.filter-container {
    position: relative;
    z-index: 10;
}

.filter-toggle {
    width: 100%;
    background: linear-gradient(135deg, rgba(123, 47, 247, 0.2), rgba(0, 212, 255, 0.2));
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.3);
    border-radius: var(--radius-md);
    padding: var(--spacing-sm) var(--spacing-md);
    color: var(--color-text-primary);
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    font-weight: 600;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--spacing-sm);
    transition: all var(--transition-base);
}

.filter-toggle:hover {
    background: linear-gradient(135deg, rgba(123, 47, 247, 0.3), rgba(0, 212, 255, 0.3));
    border-color: var(--color-primary);
    transform: translateY(-2px);
    box-shadow: 0 6px 16px rgba(0, 212, 255, 0.3);
}

.filter-toggle:active {
    transform: translateY(0);
}

.filter-icon {
    font-size: var(--font-size-xl);
}

.arrow {
    transition: transform var(--transition-base);
    font-size: var(--font-size-sm);
}

.filter-toggle[aria-expanded="true"] .arrow {
    transform: rotate(180deg);
}

.category-filter {
    position: absolute;
    top: calc(100% + var(--spacing-xs));
    left: 0;
    right: 0;
    background: rgba(15, 12, 41, 0.95);
    backdrop-filter: blur(20px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: var(--radius-md);
    padding: var(--spacing-md);
    max-height: 0;
    overflow: hidden;
    opacity: 0;
    transition: all var(--transition-base);
    box-shadow: 0 8px 32px var(--color-shadow);
}

.category-filter[aria-hidden="false"] {
    max-height: 500px;
    opacity: 1;
    overflow-y: auto;
}

.category-options {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.category-option {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm);
    border-radius: var(--radius-sm);
    cursor: pointer;
    transition: background var(--transition-fast);
    user-select: none;
}

.category-option:hover {
    background: rgba(255, 255, 255, 0.1);
}

.category-option input[type="checkbox"] {
    width: 20px;
    height: 20px;
    cursor: pointer;
    accent-color: var(--color-primary);
}

.category-option label {
    flex: 1;
    cursor: pointer;
    font-size: var(--font-size-base);
    font-weight: 500;
}

/* ===================================
   Question Card
   =================================== */
.question-card {
    background: var(--color-card-bg);
    backdrop-filter: blur(10px);
    border: 2px solid var(--color-card-border);
    border-radius: var(--radius-xl);
    padding: var(--spacing-xl);
    min-height: 300px;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-lg);
    position: relative;
    overflow: hidden;
    box-shadow: 0 12px 48px rgba(123, 47, 247, 0.15), 0 4px 16px rgba(0, 212, 255, 0.1);
    transition: all var(--transition-base);
}

.question-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 16px 56px rgba(123, 47, 247, 0.2), 0 8px 24px rgba(0, 212, 255, 0.15);
    border-color: var(--color-primary);
}

.category-badge {
    background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
    color: var(--color-text-primary);
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-xl);
    font-size: var(--font-size-sm);
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    box-shadow: 0 4px 12px rgba(0, 212, 255, 0.3);
}



.question-text {
    font-size: var(--font-size-2xl);
    font-weight: 700;
    text-align: center;
    line-height: 1.4;
    color: var(--color-card-text);
    z-index: 1;
    opacity: 1;
    transform: scale(1);
    transition: all var(--transition-base);
}

.question-text.fade-out {
    opacity: 0;
    transform: scale(0.9);
}

.question-text.fade-in {
    animation: questionAppear 0.6s cubic-bezier(0.34, 1.56, 0.64, 1);
}

@keyframes questionAppear {
    0% {
        opacity: 0;
        transform: scale(0.8) translateY(20px);
    }

    100% {
        opacity: 1;
        transform: scale(1) translateY(0);
    }
}

.dice-decoration {
    display: none;
}

.dice-icon {
    display: none;
}

/* ===================================
   Next Button
   =================================== */
.next-button {
    background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
    color: var(--color-text-primary);
    border: none;
    border-radius: var(--radius-xl);
    padding: var(--spacing-md) var(--spacing-xl);
    font-family: var(--font-family);
    font-size: var(--font-size-lg);
    font-weight: 700;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    box-shadow: 0 8px 24px rgba(0, 212, 255, 0.4);
    transition: all var(--transition-base);
    position: relative;
    overflow: hidden;
}

.next-button::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.3), transparent);
    transition: left var(--transition-slow);
}

.next-button:hover::before {
    left: 100%;
}

.next-button:hover {
    transform: translateY(-3px) scale(1.02);
    box-shadow: 0 12px 36px rgba(0, 212, 255, 0.6);
}

.next-button:active {
    transform: translateY(-1px) scale(0.98);
}

.button-dice {
    width: 24px;
    height: 24px;
    animation: wiggle 1s ease-in-out infinite;
}

@keyframes wiggle {

    0%,
    100% {
        transform: rotate(0deg);
    }

    25% {
        transform: rotate(-10deg);
    }

    75% {
        transform: rotate(10deg);
    }
}

/* ===================================
   Footer
   =================================== */
.footer {
    text-align: center;
    padding: var(--spacing-md);
    color: var(--color-text-secondary);
    font-size: var(--font-size-base);
    opacity: 0.8;
}

/* ===================================
   Responsive Design
   =================================== */
@media (max-width: 768px) {
    :root {
        --font-size-2xl: 1.5rem;
        --font-size-3xl: 2rem;
        --spacing-xl: 2rem;
    }

    .logo {
        width: 50px;
        height: 50px;
    }

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

    .subtitle {
        font-size: var(--font-size-base);
    }

    .filter-toggle {
        font-size: 0.875rem;
    }

    .category-option label {
        font-size: 0.875rem;
    }

    .question-card {
        min-height: 250px;
        padding: var(--spacing-lg);
    }

    .question-text {
        font-size: 1.75rem;
    }

    .category-badge {
        font-size: 0.75rem;
    }

    .dice-decoration {
        bottom: var(--spacing-sm);
        right: var(--spacing-sm);
    }

    .dice-icon {
        width: 60px;
        height: 60px;
    }

    .next-button {
        padding: var(--spacing-md) var(--spacing-lg);
        font-size: var(--font-size-base);
    }
}

@media (max-width: 480px) {
    body {
        padding: var(--spacing-sm);
    }

    .container {
        gap: var(--spacing-md);
    }

    .filter-toggle {
        font-size: 0.8125rem;
    }

    .category-option label {
        font-size: 0.8125rem;
    }

    .question-text {
        font-size: 2rem;
    }

    .category-badge {
        font-size: 0.7rem;
        padding: 0.375rem var(--spacing-sm);
    }

    .next-button {
        font-size: 0.9375rem;
    }
}