/* ===========================
   CSS VARIABLES & RESET
   =========================== */

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

:root {
    --primary: #8b5cf6;
    --primary-dark: #7c3aed;
    --secondary: #10b981;
    --bg-primary: #ffffff;
    --bg-secondary: #f8fafc;
    --bg-card: #ffffff;
    --text-primary: #1f2937;
    --text-secondary: #6b7280;
    --border: #e5e7eb;
    --shadow: rgba(0, 0, 0, 0.1);
    --shadow-lg: rgba(0, 0, 0, 0.15);
    --accent: #8b5cf6;
    /*--navbar-bg: #ffffff;*/
    --gradient: linear-gradient(135deg, #8b5cf6 0%, #10b981 100%);
    --code-bg: #1e1e1e;
    --code-text: #d4d4d4;
    
    /* Category Colors */
    --basics: #4d7cff;
    --joins: #a78bfa;
    --aggregation: #f0c040;
    --subqueries: #ff6b6b;
    --indexes: #00e5a0;
    --advanced: #f97316;
    
    --bg: #0a0c10;
    --surface: #111318;
    --card: #15181f;
    --border-dark: #1e2330;
    --muted: #6b7280;
    --text: #e8eaf0;
}

[data-theme="dark"] {
    --bg-primary: #111827;
    --bg-secondary: #1f2937;
    --bg-card: #1f2937;
    --text-primary: #f9fafb;
    --text-secondary: #d1d5db;
    --border: #374151;
    --shadow: rgba(0, 0, 0, 0.3);
    --shadow-lg: rgba(0, 0, 0, 0.5);
    /*--navbar-bg: #111827;*/
    --code-bg: #0f172a;
    --code-text: #cbd5e1;
    --bg: #111827;
    --surface: #1f2937;
    --card: #1f2937;
    --border-dark: #374151;
    --text: #f9fafb;
}

body {
    font-family: 'Inter', sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color 0.3s ease, color 0.3s ease;
    min-height: 100vh;
}

/* Grid bg */
body::before {
    content: '';
    position: fixed;
    inset: 0;
    background-image:
        linear-gradient(rgba(139, 92, 246, 0.03) 1px, transparent 1px),
        linear-gradient(90deg, rgba(139, 92, 246, 0.03) 1px, transparent 1px);
    background-size: 40px 40px;
    pointer-events: none;
    z-index: 0;
}

/* ===========================
   HERO SECTION
   =========================== */

.hero {
    background: var(--gradient);
    padding: 4rem 2rem;
    text-align: center;
    color: white;
    position: relative;
    overflow: hidden;
    border-bottom: 2px solid var(--border);
}

.hero-content {
    position: relative;
    z-index: 1;
    max-width: 800px;
    margin: 0 auto;
}

.hero-h1 {
    font-size: 3.5rem;
    font-weight: 800;
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 1rem;
    font-family: 'Inter', sans-serif;
}

.hero-para {
    font-size: 1.25rem;
    margin-bottom: 2rem;
    opacity: 0.9;
    font-family: 'Inter', sans-serif;
}

.hero-stats {
    display: flex;
    justify-content: center;
    gap: 2rem;
    flex-wrap: wrap;
}

.hero-stats span {
    background: rgba(255, 255, 255, 0.2);
    padding: 8px 20px;
    border-radius: 50px;
    display: flex;
    align-items: center;
    gap: 8px;
    backdrop-filter: blur(10px);
    font-family: 'Inter', sans-serif;
    font-size: 13px;
    font-weight: 500;
}

[data-theme="dark"] .hero {
    background: linear-gradient(to right, #111827, #1f2937);
}

[data-theme="dark"] .hero-para {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

[data-theme="dark"] .hero-h1 {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

[data-theme="dark"] .hero-stats span {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    border: 1px solid #7c3aed;
}

/* ===========================
   MAIN CONTAINER
   =========================== */

.container {
    position: relative;
    z-index: 10;
    max-width: 1300px;
    margin: 0 auto;
    padding: 3rem 2rem;
}

/* ===========================
   STATS BAR
   =========================== */

.stats-bar {
    display: flex;
    justify-content: center;
    gap: 32px;
    padding: 0 24px 24px;
    animation: fadeInDown 0.5s 0.35s ease both;
}

.stat {
    text-align: center;
}

.stat-val {
    font-family: 'Inter', sans-serif;
    font-size: 28px;
    font-weight: 700;
    color: var(--primary);
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.stat-label {
    font-family: 'Inter', sans-serif;
    font-size: 11px;
    font-weight: 600;
    color: var(--text-secondary);
    letter-spacing: 1px;
    text-transform: uppercase;
}

/* ===========================
   PROGRESS BAR
   =========================== */

.progress-wrap {
    max-width: 600px;
    margin: 0 auto 28px;
    padding: 0 24px;
}

.progress-track {
    height: 4px;
    background: var(--border);
    border-radius: 2px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: var(--gradient);
    border-radius: 2px;
    transition: width 0.4s ease;
}

/* ===========================
   SEARCH
   =========================== */

.search-wrap {
    position: relative;
    max-width: 500px;
    margin: 0 auto 30px;
    padding: 0 24px;
    animation: fadeInDown 0.5s 0.25s ease both;
}

.search-wrap input {
    width: 100%;
    background: var(--bg-secondary);
    border: 2px solid var(--border);
    border-radius: 12px;
    padding: 14px 16px 14px 48px;
    font-family: 'Inter', sans-serif;
    font-size: 14px;
    font-weight: 400;
    color: var(--text-primary);
    outline: none;
    transition: all 0.3s ease;
}

.search-wrap input::placeholder {
    color: var(--text-secondary);
    font-family: 'Inter', sans-serif;
    font-weight: 400;
}

.search-wrap input:focus {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(139, 92, 246, 0.1);
}

.search-icon {
    position: absolute;
    left: 42px;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-secondary);
    font-size: 16px;
    pointer-events: none;
}

/* ===========================
   FILTER CONTROLS
   =========================== */

.controls {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    justify-content: center;
    padding: 20px 24px 30px;
    animation: fadeInDown 0.5s 0.3s ease both;
}

.filter-btn {
    font-family: 'Inter', sans-serif;
    font-size: 12px;
    font-weight: 600;
    letter-spacing: 1px;
    text-transform: uppercase;
    padding: 10px 20px;
    border-radius: 8px;
    border: 2px solid var(--border);
    background: var(--bg-card);
    color: var(--text-secondary);
    cursor: pointer;
    transition: all 0.2s ease;
}

.filter-btn:hover {
    border-color: var(--primary);
    color: var(--primary);
    transform: translateY(-2px);
}

.filter-btn.active {
    background: var(--gradient);
    color: white;
    border-color: transparent;
    box-shadow: 0 4px 15px rgba(139, 92, 246, 0.3);
}

/* ===========================
   CARD GRID
   =========================== */

.grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(380px, 1fr));
    gap: 24px;
    padding: 0 24px 40px;
    animation: fadeUp 0.4s ease both;
}

/* ===========================
   CARDS
   =========================== */

.card {
    background: var(--bg-card);
    border: 2px solid var(--border);
    border-radius: 16px;
    overflow: hidden;
    cursor: pointer;
    transition: all 0.3s ease;
    animation: fadeUp 0.4s ease both;
    position: relative;
    box-shadow: 0 4px 20px var(--shadow);
}

.card:hover {
    transform: translateY(-4px);
    border-color: var(--primary);
    box-shadow: 0 8px 30px rgba(139, 92, 246, 0.2);
}

.card.solved {
    border-color: var(--secondary);
    opacity: 0.9;
}

.card-accent {
    height: 4px;
    background: var(--border);
    transition: background 0.3s;
}

.card[data-cat="basics"] .card-accent { background: var(--basics); }
.card[data-cat="joins"] .card-accent { background: var(--joins); }
.card[data-cat="aggregation"] .card-accent { background: var(--aggregation); }
.card[data-cat="subqueries"] .card-accent { background: var(--subqueries); }
.card[data-cat="indexes"] .card-accent { background: var(--indexes); }
.card[data-cat="advanced"] .card-accent { background: var(--advanced); }

.card-head {
    display: flex;
    align-items: flex-start;
    justify-content: space-between;
    padding: 20px 20px 12px;
    gap: 10px;
}

.card-meta {
    display: flex;
    align-items: center;
    gap: 8px;
    flex-wrap: wrap;
}

.cat-tag {
    font-family: 'Inter', sans-serif;
    font-size: 10px;
    font-weight: 600;
    letter-spacing: 1px;
    text-transform: uppercase;
    padding: 4px 10px;
    border-radius: 6px;
    border: 1px solid;
}

.diff-tag {
    font-family: 'Inter', sans-serif;
    font-size: 10px;
    font-weight: 600;
    letter-spacing: 1px;
    padding: 4px 10px;
    border-radius: 6px;
}

.diff-easy {
    background: rgba(16, 185, 129, 0.1);
    color: var(--secondary);
    border: 1px solid var(--secondary);
}

.diff-medium {
    background: rgba(245, 158, 11, 0.1);
    color: #f59e0b;
    border: 1px solid #f59e0b;
}

.diff-hard {
    background: rgba(239, 68, 68, 0.1);
    color: #ef4444;
    border: 1px solid #ef4444;
}

.solved-icon {
    font-size: 20px;
    color: var(--secondary);
    opacity: 0;
    transition: opacity 0.3s;
    flex-shrink: 0;
}

.card.solved .solved-icon {
    opacity: 1;
}

.card-q {
    padding: 0 20px 16px;
    font-size: 16px;
    font-weight: 600;
    line-height: 1.5;
    color: var(--text-primary);
    font-family: 'Inter', sans-serif;
}

.card-divider {
    border: none;
    border-top: 1px solid var(--border);
    margin: 0 20px;
}

/* ===========================
   ANSWER SECTION
   =========================== */

.answer-section {
    display: none;
    padding: 20px;
    background: var(--bg-secondary);
    animation: slideDown 0.25s ease;
}

.card.open .answer-section {
    display: block;
}

.answer-label {
    font-family: 'Inter', sans-serif;
    font-size: 10px;
    font-weight: 600;
    letter-spacing: 2px;
    text-transform: uppercase;
    color: var(--primary);
    margin-bottom: 12px;
}

.answer-text {
    font-size: 14px;
    font-weight: 400;
    line-height: 1.7;
    color: var(--text-secondary);
    margin-bottom: 16px;
}

.answer-text strong {
    color: var(--text-primary);
    font-weight: 600;
}

pre {
    margin: 16px 0 12px;
    background: var(--code-bg);
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 16px;
    overflow-x: auto;
    font-family: 'Consolas', 'Monaco', 'Courier New', monospace;
    font-size: 13px;
    line-height: 1.6;
    color: var(--code-text);
}

/* Syntax Highlighting */
.kw {
    color: #569cd6;
    font-weight: bold;
}
.fn {
    color: #dcdcaa;
}
.str {
    color: #ce9178;
}
.cm {
    color: #6a9955;
    font-style: italic;
}
.num {
    color: #b5cea8;
}

.tip-box {
    margin-top: 16px;
    padding: 12px 16px;
    background: rgba(139, 92, 246, 0.04);
    border-left: 3px solid var(--primary);
    border-radius: 0 8px 8px 0;
    font-family: 'Inter', sans-serif;
    font-size: 12px;
    font-weight: 500;
    color: var(--primary);
    line-height: 1.6;
}

.tip-box span {
    color: var(--text-secondary);
    font-weight: 400;
}

/* ===========================
   CARD FOOTER
   =========================== */

.card-foot {
    padding: 12px 20px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.reveal-btn {
    font-family: 'Inter', sans-serif;
    font-size: 11px;
    font-weight: 600;
    letter-spacing: 1px;
    text-transform: uppercase;
    color: var(--text-secondary);
    background: none;
    border: none;
    cursor: pointer;
    transition: color 0.2s;
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 8px 12px;
    border-radius: 6px;
}

.reveal-btn:hover {
    color: var(--primary);
    background: rgba(139, 92, 246, 0.05);
}

.reveal-btn .arrow {
    display: inline-block;
    transition: transform 0.2s;
    font-size: 14px;
}

.card.open .reveal-btn .arrow {
    transform: rotate(180deg);
}

.card.open .reveal-btn {
    color: var(--primary);
}

.mark-btn {
    font-family: 'Inter', sans-serif;
    font-size: 11px;
    font-weight: 600;
    padding: 8px 16px;
    border-radius: 6px;
    border: 2px solid var(--border);
    background: none;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all 0.2s;
    letter-spacing: 0.5px;
}

.mark-btn:hover {
    border-color: var(--secondary);
    color: var(--secondary);
    background: rgba(16, 185, 129, 0.05);
}

.card.solved .mark-btn {
    background: rgba(16, 185, 129, 0.1);
    border-color: var(--secondary);
    color: var(--secondary);
}

/* ===========================
   NO RESULTS
   =========================== */

.no-results {
    display: none;
    text-align: center;
    padding: 60px 24px;
    color: var(--text-secondary);
    font-family: 'Inter', sans-serif;
    font-size: 14px;
    font-weight: 400;
    background: var(--bg-card);
    border: 2px dashed var(--border);
    border-radius: 16px;
    margin: 0 24px;
}

.no-results i {
    font-size: 48px;
    color: var(--primary);
    margin-bottom: 16px;
    opacity: 0.5;
}

/* ===========================
   NOTIFICATION
   =========================== */

.notification {
    position: fixed;
    top: 20px;
    right: 20px;
    padding: 16px 24px;
    background: var(--gradient);
    color: white;
    border-radius: 10px;
    box-shadow: 0 4px 20px rgba(139, 92, 246, 0.4);
    transform: translateX(400px);
    transition: transform 0.4s ease;
    z-index: 1000;
    font-weight: 500;
    display: flex;
    align-items: center;
    gap: 10px;
    font-family: 'Inter', sans-serif;
    font-size: 13px;
}

.notification.show {
    transform: translateX(0);
}

.notification.error {
    background: linear-gradient(135deg, #ef4444 0%, #dc2626 100%);
}

.notification.success {
    background: linear-gradient(135deg, #10b981 0%, #059669 100%);
}

.notification.warning {
    background: linear-gradient(135deg, #f59e0b 0%, #d97706 100%);
}

/* ===========================
   ANIMATIONS
   =========================== */

@keyframes fadeInDown {
    from {
        opacity: 0;
        transform: translateY(-12px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes fadeUp {
    from {
        opacity: 0;
        transform: translateY(16px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

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

/* ===========================
   RESPONSIVE DESIGN
   =========================== */

@media (max-width: 968px) {
    .grid {
        grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
        gap: 20px;
    }
}

@media (max-width: 768px) {

    .hero-h1 {
        font-size: 2rem;
        flex-direction: column;
        gap: 0.5rem;
    }

    .hero-para {
        font-size: 1rem;
    }

    .hero-stats {
        gap: 1rem;
    }

    .hero-stats span {
        padding: 6px 15px;
        font-size: 0.9rem;
    }

    .container {
        padding: 2rem 1rem;
    }

    .stats-bar {
        gap: 20px;
    }

    .stat-val {
        font-size: 24px;
    }

    .controls {
        gap: 8px;
        padding: 15px 20px;
    }

    .filter-btn {
        font-size: 10px;
        padding: 8px 16px;
    }

    .grid {
        grid-template-columns: 1fr;
        padding: 0 15px 30px;
    }

    .card-head {
        flex-direction: column;
        align-items: flex-start;
    }

    .solved-icon {
        align-self: flex-end;
    }

    .card-foot {
        flex-direction: column;
        gap: 10px;
        align-items: stretch;
    }

    .reveal-btn {
        justify-content: center;
    }

    .mark-btn {
        width: 100%;
        text-align: center;
    }

    .cookie-buttons {
        flex-direction: column;
    }

    .cookie-btn {
        width: 100%;
        justify-content: center;
    }

    .cookie-settings-buttons {
        flex-direction: column;
    }

    .cookie-settings-btn {
        width: 100%;
        justify-content: center;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 1.5rem 0.5rem;
    }

    .hero-h1 {
        font-size: 1.5rem;
    }

    .hero-stats {
        flex-direction: column;
        align-items: center;
    }

    .hero-stats span {
        width: 100%;
        justify-content: center;
    }

    .stats-bar {
        flex-direction: column;
        gap: 10px;
    }

    .stat {
        display: flex;
        align-items: center;
        justify-content: space-between;
        padding: 8px 20px;
        background: var(--bg-card);
        border: 1px solid var(--border);
        border-radius: 10px;
    }

    .stat-val {
        -webkit-text-fill-color: initial;
        color: var(--primary);
        font-size: 20px;
    }

    .search-wrap input {
        padding: 12px 12px 12px 42px;
        font-size: 13px;
    }

    .search-icon {
        left: 36px;
    }

    .controls {
        flex-direction: column;
        padding: 10px;
    }

    .filter-btn {
        width: 100%;
        text-align: center;
    }

    .card {
        margin: 0 5px;
    }

    .card-q {
        font-size: 14px;
    }

    pre {
        font-size: 11px;
        padding: 12px;
    }

    .notification {
        left: 10px;
        right: 10px;
        width: calc(100% - 20px);
        transform: translateY(-100px);
    }

    .notification.show {
        transform: translateY(0);
    }

    .no-results {
        margin: 0 10px;
        padding: 40px 15px;
    }

    .no-results i {
        font-size: 36px;
    }

    .tip-box {
        font-size: 11px;
        padding: 10px 12px;
    }

    .answer-text {
        font-size: 13px;
    }

    .card-foot {
        padding: 12px;
    }

    .reveal-btn, .mark-btn {
        font-size: 10px;
        padding: 8px 12px;
    }
}