/* ===== GATE CS Rank Predictor CS - Premium Dark Theme ===== */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800;900&family=JetBrains+Mono:wght@400;500;600&display=swap');

/* ===== CSS Variables ===== */
:root {
    --bg-primary: #0a0e17;
    --bg-secondary: #111827;
    --bg-card: rgba(17, 24, 39, 0.7);
    --bg-card-hover: rgba(31, 41, 55, 0.8);
    --bg-glass: rgba(255, 255, 255, 0.03);
    --border-glass: rgba(255, 255, 255, 0.08);
    --border-hover: rgba(255, 255, 255, 0.15);

    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;

    --accent-primary: #6366f1;
    --accent-secondary: #818cf8;
    --accent-glow: rgba(99, 102, 241, 0.3);
    --accent-gradient: linear-gradient(135deg, #6366f1, #8b5cf6, #a78bfa);

    --success: #10b981;
    --success-bg: rgba(16, 185, 129, 0.1);
    --success-border: rgba(16, 185, 129, 0.3);
    --danger: #ef4444;
    --danger-bg: rgba(239, 68, 68, 0.1);
    --danger-border: rgba(239, 68, 68, 0.3);
    --warning: #f59e0b;
    --warning-bg: rgba(245, 158, 11, 0.1);
    --warning-border: rgba(245, 158, 11, 0.3);
    --info: #3b82f6;
    --info-bg: rgba(59, 130, 246, 0.1);

    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 20px;

    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.5);
    --shadow-glow: 0 0 40px rgba(99, 102, 241, 0.15);
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    min-height: 100vh;
    line-height: 1.6;
    overflow-x: hidden;
}

/* ===== Animated Background ===== */
body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background:
        radial-gradient(ellipse at 20% 20%, rgba(99, 102, 241, 0.08) 0%, transparent 50%),
        radial-gradient(ellipse at 80% 80%, rgba(139, 92, 246, 0.06) 0%, transparent 50%),
        radial-gradient(ellipse at 50% 50%, rgba(59, 130, 246, 0.04) 0%, transparent 60%);
    pointer-events: none;
    z-index: 0;
}

/* ===== Grid Pattern Overlay ===== */
body::after {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-image:
        linear-gradient(rgba(255, 255, 255, 0.02) 1px, transparent 1px),
        linear-gradient(90deg, rgba(255, 255, 255, 0.02) 1px, transparent 1px);
    background-size: 60px 60px;
    pointer-events: none;
    z-index: 0;
}

/* ===== Container ===== */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
    position: relative;
    z-index: 1;
}

/* ===== Header ===== */
.header {
    text-align: center;
    padding: 3rem 0 2rem;
    position: relative;
}

.header__badge {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.4rem 1rem;
    background: var(--bg-glass);
    border: 1px solid var(--border-glass);
    border-radius: 50px;
    font-size: 0.75rem;
    font-weight: 500;
    color: var(--accent-secondary);
    letter-spacing: 0.1em;
    text-transform: uppercase;
    margin-bottom: 1.2rem;
    backdrop-filter: blur(10px);
}

.header__badge::before {
    content: '';
    width: 6px;
    height: 6px;
    background: var(--accent-primary);
    border-radius: 50%;
    animation: pulse-dot 2s ease-in-out infinite;
}

@keyframes pulse-dot {
    0%, 100% { opacity: 1; transform: scale(1); }
    50% { opacity: 0.5; transform: scale(1.5); }
}

.header__title {
    font-size: 2.8rem;
    font-weight: 800;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 0.6rem;
    letter-spacing: -0.02em;
    line-height: 1.2;
}

.header__subtitle {
    font-size: 1.05rem;
    color: var(--text-secondary);
    font-weight: 400;
    max-width: 600px;
    margin: 0 auto;
}

/* ===== Input Card ===== */
.input-card {
    background: var(--bg-card);
    border: 1px solid var(--border-glass);
    border-radius: var(--radius-xl);
    padding: 2rem;
    margin: 2rem 0;
    backdrop-filter: blur(20px);
    box-shadow: var(--shadow-md);
    transition: border-color 0.3s ease, box-shadow 0.3s ease;
}

.input-card:hover {
    border-color: var(--border-hover);
    box-shadow: var(--shadow-lg);
}

/* ===== Subject Toggle ===== */
.subject-toggle {
    display: flex;
    gap: 0.5rem;
    margin-top: 0.5rem;
}

.subject-btn {
    padding: 0.5rem 1.5rem;
    background: var(--bg-glass);
    border: 1px solid var(--border-glass);
    border-radius: var(--radius-md);
    color: var(--text-secondary);
    font-family: 'Inter', sans-serif;
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
}

.subject-btn:hover {
    background: var(--bg-card-hover);
    border-color: var(--border-hover);
    color: var(--text-primary);
}

.subject-btn.active {
    background: var(--accent-gradient);
    border-color: var(--accent-primary);
    color: white;
}

.input-card__label {
    display: block;
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--text-secondary);
    margin-bottom: 0.75rem;
    letter-spacing: 0.02em;
}

.input-group {
    display: flex;
    gap: 1rem;
    align-items: stretch;
}

.input-group__field {
    flex: 1;
    padding: 0.9rem 1.2rem;
    background: var(--bg-glass);
    border: 1px solid var(--border-glass);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85rem;
    outline: none;
    transition: border-color 0.3s ease, box-shadow 0.3s ease;
}

.input-group__field::placeholder {
    color: var(--text-muted);
    font-family: 'Inter', sans-serif;
}

.input-group__field:focus {
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px var(--accent-glow);
}

.input-group__btn {
    padding: 0.9rem 2rem;
    background: var(--accent-gradient);
    border: none;
    border-radius: var(--radius-md);
    color: white;
    font-family: 'Inter', sans-serif;
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    white-space: nowrap;
    transition: transform 0.2s ease, box-shadow 0.2s ease, opacity 0.2s ease;
    position: relative;
    overflow: hidden;
}

.input-group__btn:hover {
    transform: translateY(-1px);
    box-shadow: 0 4px 20px var(--accent-glow);
}

.input-group__btn:active {
    transform: translateY(0);
}

.input-group__btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
    transform: none;
}

.input-group__btn--loading::after {
    content: '';
    position: absolute;
    width: 18px;
    height: 18px;
    border: 2px solid rgba(255,255,255,0.3);
    border-top-color: white;
    border-radius: 50%;
    animation: spin 0.7s linear infinite;
    top: 50%;
    left: 50%;
    margin-top: -9px;
    margin-left: -9px;
}

.input-group__btn--loading span {
    visibility: hidden;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* ===== Error Message ===== */
.error-msg {
    display: none;
    padding: 1rem 1.5rem;
    background: var(--danger-bg);
    border: 1px solid var(--danger-border);
    border-radius: var(--radius-md);
    color: var(--danger);
    font-size: 0.9rem;
    margin-top: 1rem;
    animation: slideDown 0.3s ease;
}

.error-msg.visible {
    display: block;
}

@keyframes slideDown {
    from { opacity: 0; transform: translateY(-8px); }
    to { opacity: 1; transform: translateY(0); }
}

/* ===== Results Section ===== */
.results {
    display: none;
    animation: fadeInUp 0.6s ease;
}

.results.visible {
    display: block;
}

@keyframes fadeInUp {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}

/* ===== Score Hero Card ===== */
.score-hero {
    background: var(--bg-card);
    border: 1px solid var(--border-glass);
    border-radius: var(--radius-xl);
    padding: 3rem 2rem;
    text-align: center;
    margin: 2rem 0;
    backdrop-filter: blur(20px);
    box-shadow: var(--shadow-lg);
    position: relative;
    overflow: hidden;
}

.score-hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 200px;
    height: 2px;
    background: var(--accent-gradient);
    border-radius: 2px;
}

.score-hero__value {
    font-size: 5rem;
    font-weight: 900;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    line-height: 1;
    margin-bottom: 0.5rem;
    letter-spacing: -0.03em;
}

.score-hero__label {
    font-size: 1.1rem;
    color: var(--text-secondary);
    font-weight: 400;
}

.score-hero__bar {
    width: 80%;
    max-width: 400px;
    height: 8px;
    background: rgba(255, 255, 255, 0.06);
    border-radius: 4px;
    margin: 1.5rem auto 0;
    overflow: hidden;
}

.score-hero__bar-fill {
    height: 100%;
    background: var(--accent-gradient);
    border-radius: 4px;
    transition: width 1.5s cubic-bezier(0.4, 0, 0.2, 1);
    width: 0%;
}

/* ===== Stats Grid ===== */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
    margin: 1.5rem 0;
}

.stat-card {
    background: var(--bg-card);
    border: 1px solid var(--border-glass);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    backdrop-filter: blur(10px);
    transition: transform 0.2s ease, border-color 0.3s ease;
}

.stat-card:hover {
    transform: translateY(-2px);
    border-color: var(--border-hover);
}

.stat-card__icon {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
}

.stat-card__value {
    font-size: 1.8rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 0.2rem;
}

.stat-card__label {
    font-size: 0.8rem;
    color: var(--text-muted);
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.08em;
}

.stat-card--correct .stat-card__value { color: var(--success); }
.stat-card--wrong .stat-card__value { color: var(--danger); }
.stat-card--unanswered .stat-card__value { color: var(--warning); }
.stat-card--total .stat-card__value { color: var(--info); }

/* ===== Section Breakdown ===== */
.breakdown-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.5rem;
    margin: 1.5rem 0;
}

.breakdown-card {
    background: var(--bg-card);
    border: 1px solid var(--border-glass);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    backdrop-filter: blur(10px);
}

.breakdown-card__title {
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.06em;
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.breakdown-card__row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.6rem 0;
    border-bottom: 1px solid rgba(255, 255, 255, 0.04);
}

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

.breakdown-card__row-label {
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.breakdown-card__row-value {
    font-size: 0.95rem;
    font-weight: 600;
    font-family: 'JetBrains Mono', monospace;
}

/* ===== Section Title ===== */
.section-title {
    font-size: 1.3rem;
    font-weight: 700;
    color: var(--text-primary);
    margin: 2.5rem 0 1rem;
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.section-title__line {
    flex: 1;
    height: 1px;
    background: var(--border-glass);
}

/* ===== Results Table ===== */
.table-container {
    background: var(--bg-card);
    border: 1px solid var(--border-glass);
    border-radius: var(--radius-lg);
    overflow: hidden;
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow-sm);
}

.table-wrapper {
    overflow-x: auto;
}

.results-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.88rem;
}

.results-table thead {
    background: rgba(255, 255, 255, 0.03);
    position: sticky;
    top: 0;
}

.results-table th {
    padding: 1rem 1.2rem;
    font-weight: 600;
    color: var(--text-secondary);
    text-align: left;
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    border-bottom: 1px solid var(--border-glass);
    white-space: nowrap;
}

.results-table td {
    padding: 0.85rem 1.2rem;
    border-bottom: 1px solid rgba(255, 255, 255, 0.03);
    color: var(--text-primary);
    white-space: nowrap;
}

.results-table tbody tr {
    transition: background-color 0.15s ease;
}

.results-table tbody tr:hover {
    background: rgba(255, 255, 255, 0.02);
}

.results-table tbody tr:last-child td {
    border-bottom: none;
}

/* ===== Table Badges ===== */
.badge {
    display: inline-flex;
    align-items: center;
    padding: 0.25rem 0.65rem;
    border-radius: 6px;
    font-size: 0.75rem;
    font-weight: 600;
    letter-spacing: 0.02em;
}

.badge--mcq {
    background: var(--info-bg);
    color: var(--info);
    border: 1px solid rgba(59, 130, 246, 0.2);
}

.badge--msq {
    background: rgba(168, 85, 247, 0.1);
    color: #a855f7;
    border: 1px solid rgba(168, 85, 247, 0.2);
}

.badge--nat {
    background: rgba(236, 72, 153, 0.1);
    color: #ec4899;
    border: 1px solid rgba(236, 72, 153, 0.2);
}

.badge--ga {
    background: rgba(245, 158, 11, 0.1);
    color: var(--warning);
    border: 1px solid var(--warning-border);
}

.badge--cs {
    background: rgba(6, 182, 212, 0.1);
    color: #06b6d4;
    border: 1px solid rgba(6, 182, 212, 0.2);
}

.badge--da {
    background: rgba(16, 185, 129, 0.1);
    color: #10b981;
    border: 1px solid rgba(16, 185, 129, 0.2);
}

.result-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 26px;
    height: 26px;
    border-radius: 50%;
    font-size: 0.85rem;
    font-weight: 700;
}

.result-icon--correct {
    background: var(--success-bg);
    color: var(--success);
    border: 1px solid var(--success-border);
}

.result-icon--wrong {
    background: var(--danger-bg);
    color: var(--danger);
    border: 1px solid var(--danger-border);
}

.result-icon--unanswered {
    background: var(--warning-bg);
    color: var(--warning);
    border: 1px solid var(--warning-border);
}

.score-cell {
    font-family: 'JetBrains Mono', monospace;
    font-weight: 600;
}

.score-cell--positive { color: var(--success); }
.score-cell--negative { color: var(--danger); }
.score-cell--zero { color: var(--text-muted); }

.answer-cell {
    font-family: 'JetBrains Mono', monospace;
    font-weight: 500;
}

/* ===== Filter Tabs ===== */
.filter-tabs {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1rem;
    flex-wrap: wrap;
}

.filter-tab {
    padding: 0.45rem 1rem;
    background: var(--bg-glass);
    border: 1px solid var(--border-glass);
    border-radius: 50px;
    color: var(--text-secondary);
    font-size: 0.8rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
    font-family: 'Inter', sans-serif;
}

.filter-tab:hover {
    background: var(--bg-card-hover);
    border-color: var(--border-hover);
    color: var(--text-primary);
}

.filter-tab.active {
    background: var(--accent-primary);
    border-color: var(--accent-primary);
    color: white;
}

/* ===== Footer ===== */
.footer {
    text-align: center;
    padding: 3rem 0 2rem;
    color: var(--text-muted);
    font-size: 0.8rem;
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
    .container {
        padding: 1rem;
    }

    .header__title {
        font-size: 2rem;
    }

    .input-group {
        flex-direction: column;
    }

    .score-hero__value {
        font-size: 3.5rem;
    }

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

    .breakdown-grid {
        grid-template-columns: 1fr;
    }

    .results-table {
        font-size: 0.8rem;
    }

    .results-table th,
    .results-table td {
        padding: 0.7rem 0.8rem;
    }
}

/* ── FAQ Accordion ── */
.faq-section {
    margin-top: 3rem;
    padding: 0 0.5rem;
    max-width: 720px;
    margin-left: auto;
    margin-right: auto;
}

.faq-section__title {
    font-size: 1.3rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 1.2rem;
    text-align: center;
}

.faq-item {
    margin-bottom: 12px;
    background: var(--bg-card);
    border: 1px solid var(--border-glass);
    border-radius: 12px;
    overflow: hidden;
    transition: border-color 0.3s ease, box-shadow 0.3s ease;
}

.faq-item:hover {
    border-color: rgba(139, 92, 246, 0.35);
}

.faq-item[open] {
    border-color: rgba(139, 92, 246, 0.4);
    box-shadow: 0 0 20px rgba(139, 92, 246, 0.08);
}

.faq-item summary {
    cursor: pointer;
    font-weight: 600;
    color: var(--text-primary);
    font-size: 0.95rem;
    padding: 16px 20px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    list-style: none;
    user-select: none;
    transition: background 0.2s ease;
}

.faq-item summary:hover {
    background: rgba(139, 92, 246, 0.06);
}

/* Remove default marker/triangle */
.faq-item summary::-webkit-details-marker {
    display: none;
}

.faq-item summary::marker {
    display: none;
    content: "";
}

/* Chevron icon */
.faq-item summary::after {
    content: "";
    flex-shrink: 0;
    width: 10px;
    height: 10px;
    border-right: 2px solid var(--text-secondary);
    border-bottom: 2px solid var(--text-secondary);
    transform: rotate(45deg);
    transition: transform 0.3s ease, border-color 0.3s ease;
}

.faq-item[open] summary::after {
    transform: rotate(-135deg);
    border-color: #a78bfa;
}

.faq-item__answer {
    padding: 0 20px 18px;
    color: var(--text-secondary);
    font-size: 0.88rem;
    line-height: 1.7;
    animation: faqSlideDown 0.3s ease;
}

@keyframes faqSlideDown {
    from {
        opacity: 0;
        transform: translateY(-8px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@media (max-width: 480px) {
    .header__title {
        font-size: 1.6rem;
    }

    .stats-grid {
        grid-template-columns: 1fr;
    }

    .faq-item summary {
        font-size: 0.88rem;
        padding: 14px 16px;
    }

    .faq-item__answer {
        padding: 0 16px 14px;
        font-size: 0.84rem;
    }
}