/* ===========================
   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;
    --success: #10b981;
    --error: #ef4444;
    --warn: #f59e0b;
    --surface: #ffffff;
    --surface2: #f8fafc;
    --keyword: #7c3aed;
    --string: #059669;
    --function: #2563eb;
    --number: #b45309;
    --table-col: #7c3aed;
    --muted: #6b7280;
}

[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;
    --surface: #1f2937;
    --surface2: #2d3748;
    --keyword: #7dd3fc;
    --string: #86efac;
    --function: #c4b5fd;
    --number: #fda4af;
    --table-col: #fcd34d;
    --muted: #9ca3af;
}

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;
}

/* ===========================
   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;
}

.hero-para {
    font-size: 1.25rem;
    margin-bottom: 2rem;
    opacity: 0.9;
}

.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);
}

[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 {
    max-width: 1600px;
    margin: 0 auto;
    padding: 3rem 2rem;
}

.layout {
    display: grid;
    grid-template-columns: 300px 1fr;
    gap: 25px;
}

@media (max-width: 1200px) {
    .layout {
        grid-template-columns: 250px 1fr;
    }
}

@media (max-width: 968px) {
    .layout {
        grid-template-columns: 1fr;
    }
}

/* ===========================
   SIDEBAR
   =========================== */

.sidebar {
    background: var(--bg-card);
    border-radius: 16px;
    border: 2px solid var(--border);
    overflow: hidden;
    box-shadow: 0 4px 20px var(--shadow);
    height: fit-content;
    position: sticky;
    top: 100px;
}

@media (max-width: 968px) {
    .sidebar {
        position: static;
    }
}

.sidebar-section {
    padding: 1.5rem;
    border-bottom: 2px solid var(--border);
}

.sidebar-section:last-child {
    border-bottom: none;
}

.sidebar-section h3 {
    font-size: 0.9rem;
    letter-spacing: 0.5px;
    text-transform: uppercase;
    color: var(--primary);
    margin-bottom: 1rem;
    font-weight: 700;
    display: flex;
    align-items: center;
    gap: 8px;
}

#challenge-list {
    display: flex;
    flex-direction: column;
    gap: 6px;
}

.challenge-item {
    padding: 10px 12px;
    border-radius: 8px;
    cursor: pointer;
    font-size: 0.9rem;
    display: flex;
    align-items: center;
    gap: 10px;
    transition: all 0.2s ease;
    border: 2px solid transparent;
    background: var(--bg-secondary);
}

.challenge-item:hover {
    background: var(--surface2);
    border-color: var(--primary);
    transform: translateX(2px);
}

.challenge-item.active {
    background: rgba(139, 92, 246, 0.1);
    border-color: var(--primary);
}

.challenge-item.done {
    opacity: 0.8;
}

.challenge-item.done .status-dot {
    background: var(--success);
}

.status-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: var(--border);
    flex-shrink: 0;
    transition: background 0.3s ease;
}

.diff-badge {
    margin-left: auto;
    font-size: 0.7rem;
    padding: 2px 8px;
    border-radius: 20px;
    font-weight: 600;
}

.diff-easy {
    background: rgba(16, 185, 129, 0.15);
    color: var(--success);
}

.diff-medium {
    background: rgba(245, 158, 11, 0.15);
    color: var(--warn);
}

.diff-hard {
    background: rgba(239, 68, 68, 0.15);
    color: var(--error);
}

/* Schema Explorer */
.table-schema {
    margin-bottom: 1rem;
}

.table-name {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.85rem;
    color: var(--table-col);
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 6px 8px;
    background: var(--bg-secondary);
    border-radius: 6px;
    transition: all 0.2s ease;
}

.table-name:hover {
    background: var(--surface2);
    color: var(--primary);
}

.table-name i {
    font-size: 0.7rem;
    transition: transform 0.2s ease;
}

.table-name.open i {
    transform: rotate(90deg);
}

.col-list {
    margin-top: 8px;
    margin-left: 24px;
    display: none;
    flex-direction: column;
    gap: 4px;
}

.col-list.open {
    display: flex;
}

.col-item {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.75rem;
    color: var(--text-secondary);
    display: flex;
    gap: 8px;
    padding: 4px 8px;
}

.col-item .col-type {
    color: var(--function);
}

/* Quick Reference */
.quick-ref {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.75rem;
    line-height: 2;
    color: var(--text-secondary);
}

.quick-ref .keyword {
    color: var(--keyword);
}

.quick-ref .function {
    color: var(--function);
}

.quick-ref .string {
    color: var(--string);
}

/* ===========================
   MAIN CONTENT
   =========================== */

.main-content {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

/* Challenge Header */
.challenge-header {
    background: var(--bg-card);
    border-radius: 16px;
    padding: 1.5rem;
    border: 2px solid var(--border);
    box-shadow: 0 4px 20px var(--shadow);
}

.challenge-info {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 10px;
    flex-wrap: wrap;
    gap: 15px;
}

.challenge-info h2 {
    font-size: 1.3rem;
    font-weight: 700;
    background: var(--gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.challenge-meta {
    display: flex;
    gap: 15px;
    align-items: center;
}

.difficulty-badge {
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 600;
}

.difficulty-badge.easy {
    background: rgba(16, 185, 129, 0.15);
    color: var(--success);
}

.difficulty-badge.medium {
    background: rgba(245, 158, 11, 0.15);
    color: var(--warn);
}

.difficulty-badge.hard {
    background: rgba(239, 68, 68, 0.15);
    color: var(--error);
}

#challenge-desc {
    color: var(--text-secondary);
    font-size: 0.95rem;
    margin-bottom: 1rem;
}

.hint-section {
    margin-top: 1rem;
}

.hint-toggle {
    background: transparent;
    border: 2px solid var(--primary);
    color: var(--primary);
    padding: 6px 15px;
    border-radius: 8px;
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    transition: all 0.3s ease;
}

.hint-toggle:hover {
    background: var(--primary);
    color: white;
    transform: translateY(-2px);
    box-shadow: 0 4px 12px var(--shadow);
}

.hint-box {
    display: none;
    margin-top: 1rem;
    padding: 1rem;
    background: rgba(139, 92, 246, 0.1);
    border: 2px solid var(--primary);
    border-radius: 10px;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.9rem;
    color: var(--function);
    line-height: 1.6;
    animation: fadeIn 0.3s ease;
}

.hint-box.open {
    display: block;
}

/* Editor Container */
.editor-container {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
}

@media (max-width: 1200px) {
    .editor-container {
        grid-template-columns: 1fr;
    }
}

.editor-panel, .result-panel {
    background: var(--bg-card);
    border-radius: 16px;
    overflow: hidden;
    border: 2px solid var(--border);
    transition: all 0.3s ease;
    box-shadow: 0 4px 20px var(--shadow);
    display: flex;
    flex-direction: column;
}

.editor-panel:hover, .result-panel:hover {
    border-color: var(--primary);
    transform: translateY(-2px);
}

.panel-header {
    padding: 15px 20px;
    background: rgba(139, 92, 246, 0.1);
    border-bottom: 2px solid var(--border);
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-weight: 600;
    font-size: 0.95rem;
}

.panel-header span {
    display: flex;
    align-items: center;
    gap: 8px;
    color: var(--text-primary);
}

.panel-actions {
    display: flex;
    align-items: center;
    gap: 12px;
}

.panel-actions kbd {
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.7rem;
    padding: 3px 6px;
    background: var(--bg-secondary);
    border: 2px solid var(--border);
    border-radius: 4px;
    color: var(--text-secondary);
}

.panel-btn {
    padding: 5px 10px;
    background: var(--gradient);
    color: white;
    border: none;
    border-radius: 6px;
    font-size: 0.8rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 5px;
    transition: all 0.3s ease;
}

.panel-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px var(--shadow);
}

.panel-btn.btn-solution {
    background: rgba(139, 92, 246, 0.2);
    color: var(--primary);
    border: 2px solid var(--primary);
}

.panel-btn.btn-solution:hover {
    background: var(--primary);
    color: white;
}

textarea#sql-editor {
    width: 100%;
    height: 350px;
    padding: 20px;
    background: var(--bg-secondary);
    border: none;
    color: var(--text-primary);
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.88rem;
    line-height: 1.7;
    resize: vertical;
    transition: all 0.3s ease;
}

textarea#sql-editor:focus {
    outline: none;
    background: var(--bg-primary);
}

textarea#sql-editor::placeholder {
    color: var(--text-secondary);
}

/* Result Panel */
.result-status {
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 600;
}

.result-status.pending {
    background: rgba(107, 114, 128, 0.15);
    color: var(--text-secondary);
}

.result-status.success {
    background: rgba(16, 185, 129, 0.15);
    color: var(--success);
}

.result-status.error {
    background: rgba(239, 68, 68, 0.15);
    color: var(--error);
}

.result-content {
    flex: 1;
    min-height: 300px;
    max-height: 350px;
    overflow: auto;
    background: var(--bg-secondary);
}

.result-footer {
    padding: 10px 20px;
    border-top: 2px solid var(--border);
    font-size: 0.8rem;
    color: var(--text-secondary);
    background: rgba(139, 92, 246, 0.05);
}

/* Result Table */
.result-table {
    width: 100%;
    border-collapse: collapse;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.78rem;
}

.result-table th {
    padding: 10px 12px;
    text-align: left;
    background: var(--surface2);
    color: var(--table-col);
    font-weight: 600;
    border-bottom: 2px solid var(--border);
    white-space: nowrap;
    position: sticky;
    top: 0;
    z-index: 1;
}

.result-table td {
    padding: 8px 12px;
    border-bottom: 1px solid var(--border);
    color: var(--text-primary);
    white-space: nowrap;
}

.result-table tr:hover td {
    background: rgba(139, 92, 246, 0.05);
}

.result-table td.null-val {
    color: var(--text-secondary);
    font-style: italic;
}

.result-table td.num-val {
    color: var(--number);
    font-weight: 600;
}

.error-msg {
    padding: 1rem;
    color: var(--error);
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.82rem;
    line-height: 1.6;
    background: rgba(239, 68, 68, 0.1);
    border-left: 4px solid var(--error);
}

.empty-state {
    padding: 3rem 2rem;
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.9rem;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
}

.empty-state i {
    font-size: 3rem;
    opacity: 0.3;
}

/* Action Buttons */
.action-buttons {
    display: flex;
    gap: 15px;
    justify-content: center;
    flex-wrap: wrap;
    margin-top: 10px;
}

.action-buttons button {
    padding: 12px 25px;
    font-size: 0.95rem;
    font-weight: 600;
    border: none;
    border-radius: 10px;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    gap: 8px;
    position: relative;
    overflow: hidden;
}

.action-buttons button::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    width: 0;
    height: 0;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.2);
    transform: translate(-50%, -50%);
    transition: width 0.6s, height 0.6s;
}

.action-buttons button:hover::before {
    width: 300px;
    height: 300px;
}

.action-buttons button span {
    position: relative;
    z-index: 1;
}

.btn-format {
    background: var(--gradient);
    color: white;
    box-shadow: 0 4px 15px rgba(139, 92, 246, 0.4);
}

.btn-format:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(139, 92, 246, 0.6);
}

.btn-copy {
    background: rgba(52, 211, 153, 0.15);
    color: var(--secondary);
    border: 2px solid var(--secondary);
}

.btn-copy:hover {
    background: rgba(52, 211, 153, 0.25);
    transform: translateY(-2px);
}

.btn-download {
    background: rgba(251, 146, 60, 0.15);
    color: #fb923c;
    border: 2px solid #fb923c;
}

.btn-download:hover {
    background: rgba(251, 146, 60, 0.25);
    transform: translateY(-2px);
}

.btn-clear {
    background: rgba(239, 68, 68, 0.15);
    color: #ef4444;
    border: 2px solid #ef4444;
}

.btn-clear:hover {
    background: rgba(239, 68, 68, 0.25);
    transform: translateY(-2px);
}

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

.notification {
    position: fixed;
    top: 80px;
    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;
}

.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 fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

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

@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;
    }

    .challenge-info {
        flex-direction: column;
        align-items: flex-start;
    }

    .challenge-meta {
        width: 100%;
    }

    .action-buttons {
        flex-direction: column;
        align-items: center;
    }

    .action-buttons button {
        width: 100%;
        max-width: 300px;
        justify-content: 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 1rem;
    }

    textarea#sql-editor {
        height: 250px;
        padding: 15px;
        font-size: 0.8rem;
    }

    .panel-header {
        padding: 12px 15px;
        flex-direction: column;
        gap: 10px;
        align-items: flex-start;
    }

    .panel-actions {
        width: 100%;
        justify-content: space-between;
        flex-wrap: wrap;
    }

    .panel-actions kbd {
        display: none;
    }

    .panel-btn {
        flex: 1;
        justify-content: center;
    }

    .result-content {
        max-height: 250px;
    }

    .result-table {
        font-size: 0.7rem;
    }

    .result-table th,
    .result-table td {
        padding: 6px 8px;
    }

    .notification {
        left: 10px;
        right: 10px;
        width: calc(100% - 20px);
        transform: translateY(-100px);
        top: 70px;
    }

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

/* Progress Bar */
.progress-bar-wrap {
    padding: 0 1rem;
    display: flex;
    align-items: center;
    gap: 0.6rem;
    font-size: 0.72rem;
    color: var(--text-secondary);
    white-space: nowrap;
}

.progress-bar {
    width: 80px;
    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;
}

/* Flash Animation */
.result-panel.flash-success {
    animation: flashSuccess 0.5s ease;
}

@keyframes flashSuccess {
    0% {
        border-color: var(--success);
        box-shadow: 0 0 0 3px rgba(16, 185, 129, 0.2);
    }
    100% {
        border-color: var(--border);
        box-shadow: none;
    }
}