/* ============================
   FAANG Crack — Clean White Theme
   ============================ */

:root {
    --bg-primary: #f8f9fb;
    --bg-secondary: #ffffff;
    --bg-card: #ffffff;
    --bg-card-hover: #f0f2f5;
    --bg-input: #f4f5f7;
    --text-primary: #1a1a2e;
    --text-secondary: #444466;
    --text-muted: #7a7a99;
    --accent-primary: #4f46e5;
    --accent-secondary: #6366f1;
    --accent-gradient: linear-gradient(135deg, #4f46e5, #6366f1, #818cf8);
    --accent-glow: 0 4px 16px rgba(79, 70, 229, 0.15);
    --success: #059669;
    --success-glow: 0 0 15px rgba(5, 150, 105, 0.15);
    --warning: #d97706;
    --danger: #dc2626;
    --info: #2563eb;
    --easy: #059669;
    --medium: #d97706;
    --hard: #dc2626;
    --border: #e5e7eb;
    --border-hover: #c7c9d1;
    --glass: rgba(255, 255, 255, 0.95);
    --glass-border: #e5e7eb;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.08), 0 4px 12px rgba(0, 0, 0, 0.04);
    --shadow-lg: 0 4px 24px rgba(0, 0, 0, 0.08);
    --radius: 12px;
    --radius-sm: 8px;
    --radius-xs: 6px;
    --transition: all 0.2s ease;
    --font-main: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
}

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

html {
    scroll-behavior: smooth;
    scroll-padding-top: 80px;
}

body {
    font-family: var(--font-main);
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    overflow-x: hidden;
    min-height: 100vh;
}

/* Background Animation — subtle for white theme */
.bg-animation {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 0;
    overflow: hidden;
}

.floating-orb {
    position: absolute;
    border-radius: 50%;
    filter: blur(100px);
    opacity: 0.06;
    animation: float 20s infinite ease-in-out;
}

.orb-1 { width: 400px; height: 400px; background: #4f46e5; top: -100px; right: -100px; animation-delay: 0s; }
.orb-2 { width: 300px; height: 300px; background: #06b6d4; bottom: -50px; left: -50px; animation-delay: -5s; }
.orb-3 { width: 250px; height: 250px; background: #059669; top: 50%; left: 50%; animation-delay: -10s; }
.orb-4 { width: 350px; height: 350px; background: #8b5cf6; top: 30%; right: 20%; animation-delay: -15s; }

@keyframes float {
    0%, 100% { transform: translate(0, 0) scale(1); }
    25% { transform: translate(50px, -80px) scale(1.1); }
    50% { transform: translate(-30px, 60px) scale(0.9); }
    75% { transform: translate(60px, 40px) scale(1.05); }
}

/* Scrollbar */
::-webkit-scrollbar { width: 8px; }
::-webkit-scrollbar-track { background: var(--bg-primary); }
::-webkit-scrollbar-thumb { background: #c7c9d1; border-radius: 4px; }
::-webkit-scrollbar-thumb:hover { background: #a0a3b0; }

/* ============================
   NAVBAR
   ============================ */
.navbar {
    position: fixed;
    top: 0; left: 0; right: 0;
    z-index: 1000;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 24px;
    height: 64px;
    background: rgba(255, 255, 255, 0.92);
    backdrop-filter: blur(16px);
    border-bottom: 1px solid var(--border);
    transition: var(--transition);
}

.nav-brand {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 1.3rem;
    font-weight: 800;
    letter-spacing: -0.5px;
    color: var(--text-primary);
}

.brand-icon { font-size: 1.5rem; }
.brand-accent {
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-links { display: flex; gap: 4px; }

.nav-link {
    padding: 8px 14px;
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.85rem;
    font-weight: 500;
    border-radius: var(--radius-xs);
    transition: var(--transition);
}

.nav-link:hover {
    color: var(--text-primary);
    background: #f0f0f5;
}

.nav-link.active {
    color: var(--accent-primary);
    background: rgba(79, 70, 229, 0.08);
    font-weight: 600;
}

.nav-streak {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 6px 14px;
    background: rgba(217, 119, 6, 0.08);
    border: 1px solid rgba(217, 119, 6, 0.15);
    border-radius: 20px;
    font-size: 0.85rem;
}

.streak-fire { font-size: 1.1rem; }
.streak-count { font-weight: 700; color: var(--warning); font-family: var(--font-mono); }
.streak-label { color: var(--text-muted); font-size: 0.75rem; }

.mobile-menu-btn {
    display: none;
    background: none;
    border: 1px solid var(--border);
    color: var(--text-primary);
    font-size: 1.3rem;
    padding: 6px 10px;
    border-radius: var(--radius-xs);
    cursor: pointer;
}

.mobile-menu {
    display: none;
    position: fixed;
    top: 64px; left: 0; right: 0;
    background: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(16px);
    border-bottom: 1px solid var(--border);
    z-index: 999;
    flex-direction: column;
    padding: 12px;
}

.mobile-menu.open { display: flex; }

.mobile-link {
    padding: 12px 16px;
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.9rem;
    border-radius: var(--radius-xs);
    transition: var(--transition);
}

.mobile-link:hover { background: #f0f0f5; color: var(--text-primary); }

/* ============================
   MAIN CONTENT
   ============================ */
.main-content {
    position: relative;
    z-index: 1;
    padding-top: 80px;
    max-width: 1300px;
    margin: 0 auto;
    padding-left: 24px;
    padding-right: 24px;
    padding-bottom: 80px;
}

.section { display: none; }
.section.active { display: block; animation: fadeIn 0.3s ease; }

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

.section-header { margin-bottom: 32px; text-align: center; }

.section-header h1 {
    font-size: 2rem;
    font-weight: 800;
    letter-spacing: -1px;
    color: var(--text-primary);
    margin-bottom: 8px;
}

.section-subtitle { color: var(--text-muted); font-size: 1rem; }

/* ============================
   CARDS
   ============================ */
.card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 24px;
    transition: var(--transition);
    box-shadow: var(--shadow);
}

.card:hover { border-color: var(--border-hover); }

.card h3 {
    font-size: 1.05rem;
    font-weight: 700;
    margin-bottom: 16px;
    color: var(--text-primary);
}

/* ============================
   DASHBOARD
   ============================ */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 16px;
    margin-bottom: 24px;
}

.stat-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 20px;
    display: flex;
    align-items: center;
    gap: 16px;
    position: relative;
    overflow: hidden;
    transition: var(--transition);
    box-shadow: var(--shadow);
}

.stat-card::before {
    content: '';
    position: absolute;
    top: 0; left: 0;
    width: 4px;
    height: 100%;
}

.stat-primary::before { background: var(--accent-primary); }
.stat-success::before { background: var(--success); }
.stat-warning::before { background: var(--warning); }
.stat-info::before { background: var(--info); }

.stat-card:hover { transform: translateY(-2px); box-shadow: var(--shadow-lg); }

.stat-icon { font-size: 2rem; }

.stat-value {
    display: block;
    font-size: 2rem;
    font-weight: 800;
    font-family: var(--font-mono);
    line-height: 1;
    color: var(--text-primary);
}

.stat-label {
    display: block;
    font-size: 0.8rem;
    color: var(--text-muted);
    margin-top: 4px;
}

.stat-progress-ring {
    position: absolute;
    right: 16px; top: 50%;
    transform: translateY(-50%);
    width: 48px; height: 48px;
}

.stat-progress-ring svg { width: 100%; height: 100%; transform: rotate(-90deg); }

.ring-bg { fill: none; stroke: #e5e7eb; stroke-width: 3; }
.ring-fill { fill: none; stroke: var(--accent-primary); stroke-width: 3; stroke-linecap: round; transition: stroke-dasharray 1s ease; }

.dashboard-grid {
    display: grid;
    grid-template-columns: 1.2fr 0.8fr;
    gap: 16px;
    margin-bottom: 24px;
}

/* Progress Bars */
.progress-item { margin-bottom: 16px; }
.progress-item:last-child { margin-bottom: 0; }

.progress-header {
    display: flex;
    justify-content: space-between;
    margin-bottom: 6px;
    font-size: 0.85rem;
    color: var(--text-primary);
}

.progress-pct {
    font-family: var(--font-mono);
    font-weight: 600;
    color: var(--accent-primary);
}

.progress-bar {
    height: 8px;
    background: #e5e7eb;
    border-radius: 4px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    border-radius: 4px;
    transition: width 0.8s cubic-bezier(0.4, 0, 0.2, 1);
}

.dsa-fill { background: linear-gradient(90deg, #4f46e5, #818cf8); }
.sd-fill { background: linear-gradient(90deg, #2563eb, #60a5fa); }
.beh-fill { background: linear-gradient(90deg, #059669, #34d399); }
.cs-fill { background: linear-gradient(90deg, #ea580c, #f59e0b); }

/* Tonight Focus */
.tonight-phase {
    font-size: 1rem;
    font-weight: 600;
    color: var(--accent-primary);
    margin-bottom: 12px;
}

.tonight-tasks { list-style: none; padding: 0; }

.tonight-tasks li {
    padding: 8px 12px;
    margin-bottom: 6px;
    background: #f4f5f7;
    border-radius: var(--radius-xs);
    font-size: 0.88rem;
    border-left: 3px solid var(--accent-primary);
    color: var(--text-primary);
}

/* Heatmap */
.heatmap-card { margin-bottom: 24px; }

.heatmap-container {
    display: grid;
    grid-template-columns: repeat(30, 1fr);
    gap: 3px;
    margin-bottom: 12px;
}

.heatmap-day {
    aspect-ratio: 1;
    border-radius: 3px;
    transition: var(--transition);
    cursor: pointer;
    position: relative;
}

.heatmap-day:hover { transform: scale(1.3); z-index: 2; }

.heatmap-day[title]::after {
    content: attr(title);
    position: absolute;
    bottom: 120%;
    left: 50%;
    transform: translateX(-50%);
    background: var(--text-primary);
    color: white;
    padding: 4px 8px;
    border-radius: 4px;
    font-size: 0.7rem;
    white-space: nowrap;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.2s;
}

.heatmap-day:hover::after { opacity: 1; }

.level-0 { background: #e5e7eb; }
.level-1 { background: #c7d2fe; }
.level-2 { background: #a5b4fc; }
.level-3 { background: #818cf8; }
.level-4 { background: #4f46e5; }

.heatmap-legend {
    display: flex;
    align-items: center;
    gap: 4px;
    justify-content: flex-end;
    font-size: 0.75rem;
    color: var(--text-muted);
}

.heatmap-box { width: 14px; height: 14px; border-radius: 2px; }

/* Check-in */
.checkin-form { display: flex; flex-direction: column; gap: 16px; }

.checkin-row { display: flex; flex-direction: column; gap: 6px; }

.checkin-row label {
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--text-primary);
}

.checkin-row input,
.checkin-row textarea {
    background: var(--bg-input);
    border: 1px solid var(--border);
    border-radius: var(--radius-xs);
    padding: 10px 14px;
    color: var(--text-primary);
    font-family: var(--font-main);
    font-size: 0.9rem;
    transition: var(--transition);
}

.checkin-row input:focus,
.checkin-row textarea:focus {
    outline: none;
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
}

.checkin-row textarea { min-height: 80px; resize: vertical; }

.confidence-btns { display: flex; gap: 8px; }

.conf-btn {
    width: 48px; height: 48px;
    border: 2px solid var(--border);
    border-radius: var(--radius-sm);
    background: var(--bg-input);
    font-size: 1.5rem;
    cursor: pointer;
    transition: var(--transition);
}

.conf-btn:hover { border-color: var(--accent-primary); transform: scale(1.1); }

.conf-btn.active {
    border-color: var(--accent-primary);
    background: rgba(79, 70, 229, 0.1);
    box-shadow: var(--accent-glow);
}

/* Buttons */
.btn {
    padding: 12px 24px;
    border: none;
    border-radius: var(--radius-sm);
    font-family: var(--font-main);
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
}

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

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--accent-glow);
}

/* ============================
   ROADMAP
   ============================ */
.roadmap-timeline {
    position: relative;
    padding-left: 40px;
}

.roadmap-timeline::before {
    content: '';
    position: absolute;
    left: 15px; top: 0; bottom: 0;
    width: 2px;
    background: linear-gradient(to bottom, var(--accent-primary), var(--success), var(--info), var(--warning), var(--danger));
}

.roadmap-phase { margin-bottom: 32px; position: relative; }

.phase-marker {
    position: absolute;
    left: -40px; top: 0;
    width: 30px; height: 30px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 2;
}

.phase-marker .phase-number {
    position: absolute; left: 40px;
    white-space: nowrap;
    font-weight: 700;
    font-size: 0.85rem;
    color: var(--accent-primary);
}

.phase-marker .phase-dates {
    position: absolute; left: 40px; top: 22px;
    white-space: nowrap;
    font-size: 0.75rem;
    color: var(--text-muted);
}

.phase-1 { background: var(--accent-primary); }
.phase-2 { background: var(--success); }
.phase-3 { background: var(--info); }
.phase-4 { background: var(--warning); }
.phase-5 { background: var(--danger); }

.phase-content {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 24px;
    margin-top: 52px;
    box-shadow: var(--shadow);
}

.phase-content h2 {
    font-size: 1.25rem;
    font-weight: 700;
    margin-bottom: 16px;
    color: var(--text-primary);
}

.phase-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 16px;
}

.phase-card {
    background: #f4f5f7;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    padding: 16px;
}

.phase-card h4 {
    font-size: 0.95rem;
    font-weight: 700;
    margin-bottom: 12px;
    color: var(--accent-primary);
}

.topic-list,
.problem-list,
.resource-list {
    list-style: none;
    padding: 0;
}

.topic-list li,
.problem-list li {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 6px 0;
    font-size: 0.85rem;
    color: var(--text-secondary);
    border-bottom: 1px solid #f0f0f5;
}

.topic-list li:last-child,
.problem-list li:last-child { border-bottom: none; }

.roadmap-check {
    appearance: none;
    width: 18px; height: 18px; min-width: 18px;
    border: 2px solid var(--border-hover);
    border-radius: 4px;
    cursor: pointer;
    position: relative;
    transition: var(--transition);
    background: transparent;
}

.roadmap-check:checked {
    background: var(--accent-primary);
    border-color: var(--accent-primary);
}

.roadmap-check:checked::after {
    content: '✓';
    position: absolute; top: 50%; left: 50%;
    transform: translate(-50%, -50%);
    color: white;
    font-size: 0.7rem;
    font-weight: 700;
}

.problem-list a {
    color: var(--info);
    text-decoration: none;
    transition: var(--transition);
}

.problem-list a:hover { color: var(--accent-primary); text-decoration: underline; }

.diff {
    padding: 2px 8px;
    border-radius: 10px;
    font-size: 0.65rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-left: auto;
    white-space: nowrap;
}

.diff.easy { background: rgba(5, 150, 105, 0.1); color: var(--easy); }
.diff.medium { background: rgba(217, 119, 6, 0.1); color: var(--medium); }
.diff.hard { background: rgba(220, 38, 38, 0.1); color: var(--hard); }

.resource-list li { padding: 4px 0; font-size: 0.85rem; color: var(--text-secondary); }

.resource-list a {
    color: var(--info);
    text-decoration: none;
    transition: var(--transition);
}

.resource-list a:hover { color: var(--accent-primary); }

/* ============================
   SCHEDULE
   ============================ */
.schedule-container { display: flex; flex-direction: column; gap: 24px; }

.schedule-block {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    overflow: hidden;
    box-shadow: var(--shadow);
}

.schedule-phase-title {
    padding: 16px 24px;
    background: #f4f5f7;
    font-size: 1.1rem;
    font-weight: 700;
    border-bottom: 1px solid var(--border);
    color: var(--text-primary);
}

.schedule-table-wrapper { overflow-x: auto; padding: 16px; }

.schedule-table { width: 100%; border-collapse: collapse; font-size: 0.85rem; }

.schedule-table th {
    text-align: left;
    padding: 10px 14px;
    color: var(--text-muted);
    font-weight: 600;
    text-transform: uppercase;
    font-size: 0.7rem;
    letter-spacing: 1px;
    border-bottom: 1px solid var(--border);
}

.schedule-table td {
    padding: 12px 14px;
    border-bottom: 1px solid #f0f0f5;
    color: var(--text-secondary);
}

.schedule-table tr:last-child td { border-bottom: none; }
.schedule-table tr:hover td { background: #f8f9fb; }

.time-cell {
    font-family: var(--font-mono);
    font-weight: 600;
    color: var(--accent-primary) !important;
    white-space: nowrap;
    font-size: 0.8rem;
}

.schedule-table td a { color: var(--info); text-decoration: none; }
.schedule-table td a:hover { text-decoration: underline; }

/* ============================
   DSA PROBLEMS
   ============================ */
.filter-bar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 12px;
    margin-bottom: 24px;
    padding: 16px;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
}

.filter-group { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }

.filter-group label { font-size: 0.85rem; font-weight: 600; color: var(--text-muted); }

.filter-group select {
    background: var(--bg-input);
    border: 1px solid var(--border);
    border-radius: var(--radius-xs);
    padding: 8px 12px;
    color: var(--text-primary);
    font-family: var(--font-main);
    font-size: 0.8rem;
    cursor: pointer;
    transition: var(--transition);
}

.filter-group select:focus { outline: none; border-color: var(--accent-primary); }

.filter-stats {
    font-family: var(--font-mono);
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--accent-primary);
}

.problems-container { display: flex; flex-direction: column; gap: 16px; }

.pattern-group {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    overflow: hidden;
    box-shadow: var(--shadow);
}

.pattern-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 16px 20px;
    cursor: pointer;
    background: #f8f9fb;
    border-bottom: 1px solid var(--border);
    transition: var(--transition);
}

.pattern-header:hover { background: #f0f0f5; }

.pattern-title { font-weight: 700; font-size: 1rem; color: var(--text-primary); }
.pattern-count { font-family: var(--font-mono); font-size: 0.8rem; color: var(--text-muted); }

.pattern-problems { padding: 0; max-height: 0; overflow: hidden; transition: max-height 0.4s ease; }
.pattern-problems.open { max-height: 5000px; padding: 8px 0; }

.problem-row {
    display: grid;
    grid-template-columns: 40px 1fr 80px 80px 100px;
    align-items: center;
    padding: 10px 20px;
    border-bottom: 1px solid #f0f0f5;
    transition: var(--transition);
    font-size: 0.85rem;
    cursor: pointer;
}

.problem-row:hover { background: #f4f5f7; }
.problem-row:last-child { border-bottom: none; }

.problem-checkbox {
    appearance: none;
    width: 20px; height: 20px;
    border: 2px solid var(--border-hover);
    border-radius: 50%;
    cursor: pointer;
    position: relative;
    transition: var(--transition);
}

.problem-checkbox:checked { background: var(--success); border-color: var(--success); }

.problem-checkbox:checked::after {
    content: '✓';
    position: absolute; top: 50%; left: 50%;
    transform: translate(-50%, -50%);
    color: white;
    font-size: 0.7rem;
    font-weight: 700;
}

.problem-name a { color: var(--text-primary); text-decoration: none; transition: var(--transition); font-weight: 500; }
.problem-name a:hover { color: var(--info); }

.problem-difficulty { text-align: center; }
.problem-company { font-size: 0.7rem; color: var(--text-muted); }
.problem-status { text-align: center; font-size: 0.75rem; }

.status-solved { color: var(--success); font-weight: 600; }
.status-unsolved { color: var(--text-muted); }

/* ============================
   PROBLEM DETAIL MODAL
   ============================ */
.problem-modal-overlay {
    display: none;
    position: fixed;
    top: 0; left: 0; right: 0; bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    z-index: 9999;
    justify-content: center;
    align-items: flex-start;
    padding: 40px 20px;
    overflow-y: auto;
}

.problem-modal-overlay.open { display: flex; }

.problem-modal {
    background: var(--bg-card);
    border-radius: var(--radius);
    width: 100%;
    max-width: 1100px;
    box-shadow: 0 24px 64px rgba(0, 0, 0, 0.15);
    border: 1px solid var(--border);
    overflow: hidden;
}

.modal-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 20px 24px;
    border-bottom: 1px solid var(--border);
    background: #f8f9fb;
}

.modal-header h2 {
    font-size: 1.2rem;
    font-weight: 700;
    color: var(--text-primary);
}

.modal-close {
    background: none;
    border: 1px solid var(--border);
    border-radius: var(--radius-xs);
    width: 36px; height: 36px;
    font-size: 1.2rem;
    cursor: pointer;
    color: var(--text-muted);
    transition: var(--transition);
    display: flex; align-items: center; justify-content: center;
}

.modal-close:hover { background: #fee2e2; color: var(--danger); border-color: #fca5a5; }

.modal-body { display: flex; flex-direction: column; }

.modal-problem-info {
    padding: 24px;
    border-bottom: 1px solid var(--border);
}

.modal-meta {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
    margin-bottom: 16px;
}

.modal-meta-tag {
    padding: 4px 12px;
    border-radius: 12px;
    font-size: 0.75rem;
    font-weight: 600;
}

.modal-description {
    font-size: 0.92rem;
    line-height: 1.7;
    color: var(--text-primary);
    margin-bottom: 16px;
}

.modal-description h3 {
    font-size: 1rem;
    margin-bottom: 12px;
    color: var(--text-primary);
}

.modal-description pre {
    background: #f4f5f7;
    padding: 12px 16px;
    border-radius: var(--radius-xs);
    overflow-x: auto;
    font-family: var(--font-mono);
    font-size: 0.85rem;
    margin: 8px 0;
    border: 1px solid var(--border);
    color: var(--text-primary);
}

.modal-description code {
    background: #e8e8ee;
    padding: 2px 6px;
    border-radius: 4px;
    font-family: var(--font-mono);
    font-size: 0.85rem;
    color: var(--accent-primary);
}

.modal-hints {
    padding: 16px 24px;
    background: #f8f9fb;
    border-bottom: 1px solid var(--border);
}

.modal-hints summary {
    cursor: pointer;
    font-weight: 600;
    color: var(--accent-primary);
    font-size: 0.9rem;
}

.modal-hints p {
    margin-top: 8px;
    font-size: 0.88rem;
    color: var(--text-secondary);
    line-height: 1.5;
}

/* Compiler Section */
.compiler-section {
    padding: 0;
    border-top: 1px solid var(--border);
}

.compiler-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 12px 24px;
    background: #1e293b;
    color: white;
}

.compiler-header h3 {
    font-size: 0.9rem;
    font-weight: 600;
    color: white;
    margin-bottom: 0;
}

.compiler-lang-select {
    background: #334155;
    color: white;
    border: 1px solid #475569;
    border-radius: var(--radius-xs);
    padding: 4px 10px;
    font-family: var(--font-main);
    font-size: 0.8rem;
}

.code-editor-wrapper {
    position: relative;
    background: #0f172a;
}

.code-editor {
    width: 100%;
    min-height: 250px;
    background: #0f172a;
    color: #e2e8f0;
    border: none;
    padding: 16px 20px;
    font-family: var(--font-mono);
    font-size: 0.88rem;
    line-height: 1.6;
    resize: vertical;
    tab-size: 4;
}

.code-editor:focus { outline: none; }
.code-editor::placeholder { color: #64748b; }

.compiler-actions {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 12px 24px;
    background: #1e293b;
    border-top: 1px solid #334155;
}

.btn-run {
    padding: 8px 20px;
    background: #059669;
    color: white;
    border: none;
    border-radius: var(--radius-xs);
    font-family: var(--font-main);
    font-weight: 600;
    font-size: 0.85rem;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 6px;
}

.btn-run:hover { background: #047857; }
.btn-run:disabled { opacity: 0.5; cursor: not-allowed; }

.btn-submit {
    padding: 8px 20px;
    background: var(--accent-primary);
    color: white;
    border: none;
    border-radius: var(--radius-xs);
    font-family: var(--font-main);
    font-weight: 600;
    font-size: 0.85rem;
    cursor: pointer;
    transition: var(--transition);
}

.btn-submit:hover { background: #4338ca; }

.test-cases-section {
    padding: 16px 24px;
    background: #f8f9fb;
    border-top: 1px solid var(--border);
}

.test-cases-section h4 {
    font-size: 0.85rem;
    font-weight: 700;
    margin-bottom: 12px;
    color: var(--text-primary);
}

.test-case-tabs {
    display: flex;
    gap: 8px;
    margin-bottom: 12px;
}

.test-tab {
    padding: 6px 14px;
    border: 1px solid var(--border);
    border-radius: var(--radius-xs);
    background: white;
    font-size: 0.8rem;
    cursor: pointer;
    transition: var(--transition);
    font-family: var(--font-main);
    color: var(--text-secondary);
}

.test-tab.active { background: var(--accent-primary); color: white; border-color: var(--accent-primary); }
.test-tab.pass { border-color: var(--success); color: var(--success); }
.test-tab.fail { border-color: var(--danger); color: var(--danger); }

.test-case-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 12px;
}

.test-case-content label {
    font-size: 0.78rem;
    font-weight: 600;
    color: var(--text-muted);
    display: block;
    margin-bottom: 4px;
}

.test-case-content pre {
    background: #f4f5f7;
    padding: 10px 12px;
    border-radius: var(--radius-xs);
    font-family: var(--font-mono);
    font-size: 0.82rem;
    color: var(--text-primary);
    border: 1px solid var(--border);
    min-height: 40px;
}

.output-section {
    padding: 16px 24px;
    background: #f4f5f7;
    border-top: 1px solid var(--border);
}

.output-section h4 {
    font-size: 0.85rem;
    font-weight: 700;
    margin-bottom: 8px;
    color: var(--text-primary);
}

.output-result {
    background: #0f172a;
    color: #e2e8f0;
    padding: 12px 16px;
    border-radius: var(--radius-xs);
    font-family: var(--font-mono);
    font-size: 0.85rem;
    min-height: 60px;
    white-space: pre-wrap;
}

.output-result.success { border-left: 3px solid var(--success); }
.output-result.error { border-left: 3px solid var(--danger); }

/* ============================
   SYSTEM DESIGN
   ============================ */
.sd-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: 16px;
    margin-bottom: 24px;
}

.sd-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 20px;
    transition: var(--transition);
    position: relative;
    overflow: hidden;
    box-shadow: var(--shadow);
}

.sd-card::before {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0;
    height: 3px;
    background: var(--accent-gradient);
    opacity: 0;
    transition: var(--transition);
}

.sd-card:hover::before { opacity: 1; }
.sd-card:hover { transform: translateY(-2px); box-shadow: var(--shadow-lg); }

.sd-card-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 12px;
}

.sd-card-title { font-size: 1rem; font-weight: 700; color: var(--text-primary); }

.sd-card-check {
    appearance: none;
    width: 24px; height: 24px;
    border: 2px solid var(--border-hover);
    border-radius: 6px;
    cursor: pointer;
    position: relative;
    transition: var(--transition);
}

.sd-card-check:checked { background: var(--success); border-color: var(--success); }

.sd-card-check:checked::after {
    content: '✓';
    position: absolute; top: 50%; left: 50%;
    transform: translate(-50%, -50%);
    color: white;
    font-size: 0.8rem;
    font-weight: 700;
}

.sd-card-desc { font-size: 0.85rem; color: var(--text-secondary); margin-bottom: 12px; line-height: 1.5; }

.sd-card-companies { display: flex; gap: 6px; flex-wrap: wrap; margin-bottom: 12px; }

.company-tag {
    padding: 3px 10px;
    border-radius: 12px;
    font-size: 0.7rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.tag-google { background: rgba(66, 133, 244, 0.1); color: #4285f4; }
.tag-meta { background: rgba(24, 119, 242, 0.1); color: #1877f2; }
.tag-amazon { background: rgba(255, 153, 0, 0.1); color: #cc7a00; }
.tag-apple { background: rgba(100, 100, 110, 0.1); color: #636373; }
.tag-netflix { background: rgba(229, 9, 20, 0.1); color: #e50914; }
.tag-atlassian { background: rgba(0, 82, 204, 0.1); color: #0052cc; }

.sd-card-links { display: flex; gap: 8px; flex-wrap: wrap; }

.sd-link {
    font-size: 0.75rem;
    color: var(--info);
    text-decoration: none;
    padding: 4px 10px;
    background: rgba(37, 99, 235, 0.06);
    border-radius: 12px;
    transition: var(--transition);
}

.sd-link:hover { background: rgba(37, 99, 235, 0.12); }

/* Concepts Grid */
.concepts-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
    gap: 10px;
}

.concept-item {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 8px 12px;
    background: #f4f5f7;
    border-radius: var(--radius-xs);
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.concept-check {
    appearance: none;
    width: 18px; height: 18px; min-width: 18px;
    border: 2px solid var(--border-hover);
    border-radius: 4px;
    cursor: pointer;
    position: relative;
    transition: var(--transition);
}

.concept-check:checked { background: var(--accent-primary); border-color: var(--accent-primary); }

.concept-check:checked::after {
    content: '✓';
    position: absolute; top: 50%; left: 50%;
    transform: translate(-50%, -50%);
    color: white;
    font-size: 0.65rem;
    font-weight: 700;
}

/* ============================
   BEHAVIORAL
   ============================ */
.star-card { margin-bottom: 24px; }

.star-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px; }

.star-step {
    text-align: center;
    padding: 16px;
    background: #f4f5f7;
    border-radius: var(--radius-sm);
    border: 1px solid var(--border);
}

.star-letter {
    width: 48px; height: 48px;
    border-radius: 50%;
    background: var(--accent-gradient);
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 12px;
    font-size: 1.3rem;
    font-weight: 800;
    color: white;
}

.star-step h4 { font-size: 0.95rem; margin-bottom: 8px; color: var(--text-primary); }
.star-step p { font-size: 0.8rem; color: var(--text-secondary); line-height: 1.5; }

.behavioral-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: 16px;
    margin-bottom: 24px;
}

.beh-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 20px;
    transition: var(--transition);
    box-shadow: var(--shadow);
}

.beh-card:hover { border-color: var(--border-hover); }

.beh-card-header { display: flex; align-items: center; gap: 10px; margin-bottom: 12px; }

.beh-card-tag {
    padding: 3px 10px;
    border-radius: 10px;
    font-size: 0.7rem;
    font-weight: 600;
    background: rgba(79, 70, 229, 0.08);
    color: var(--accent-primary);
}

.beh-card h4 { font-size: 0.95rem; font-weight: 700; color: var(--text-primary); }

.beh-questions { list-style: none; padding: 0; }

.beh-questions li {
    display: flex;
    align-items: flex-start;
    gap: 8px;
    padding: 6px 0;
    font-size: 0.85rem;
    color: var(--text-secondary);
    border-bottom: 1px solid #f0f0f5;
}

.beh-questions li:last-child { border-bottom: none; }

.beh-check {
    appearance: none;
    width: 16px; height: 16px; min-width: 16px;
    margin-top: 3px;
    border: 2px solid var(--border-hover);
    border-radius: 3px;
    cursor: pointer;
    transition: var(--transition);
    position: relative;
}

.beh-check:checked { background: var(--success); border-color: var(--success); }

.beh-check:checked::after {
    content: '✓';
    position: absolute; top: 50%; left: 50%;
    transform: translate(-50%, -50%);
    color: white;
    font-size: 0.6rem;
    font-weight: 700;
}

/* Story Bank */
.story-bank-card { margin-top: 0; }
.story-hint { font-size: 0.85rem; color: var(--text-muted); margin-bottom: 16px; }

.story-item {
    background: #f4f5f7;
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    padding: 16px;
    margin-bottom: 12px;
}

.story-header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 8px; }

.story-title-input {
    background: transparent;
    border: none;
    color: var(--text-primary);
    font-family: var(--font-main);
    font-size: 0.95rem;
    font-weight: 600;
    width: 80%;
}

.story-title-input:focus { outline: none; }

.story-delete {
    background: none;
    border: none;
    color: var(--danger);
    cursor: pointer;
    font-size: 1rem;
    opacity: 0.5;
    transition: var(--transition);
}

.story-delete:hover { opacity: 1; }

.story-textarea {
    width: 100%;
    min-height: 80px;
    background: white;
    border: 1px solid var(--border);
    border-radius: var(--radius-xs);
    padding: 10px;
    color: var(--text-primary);
    font-family: var(--font-main);
    font-size: 0.85rem;
    resize: vertical;
    transition: var(--transition);
}

.story-textarea:focus { outline: none; border-color: var(--accent-primary); }

/* ============================
   RESOURCES
   ============================ */
.resources-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(400px, 1fr));
    gap: 20px;
}

.resource-category {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 24px;
    box-shadow: var(--shadow);
}

.resource-category h3 {
    font-size: 1.1rem;
    font-weight: 700;
    margin-bottom: 16px;
    padding-bottom: 12px;
    border-bottom: 1px solid var(--border);
    color: var(--text-primary);
}

.resource-links { display: flex; flex-direction: column; gap: 8px; }

.resource-link {
    display: flex;
    align-items: flex-start;
    gap: 12px;
    padding: 12px;
    text-decoration: none;
    background: #f8f9fb;
    border: 1px solid transparent;
    border-radius: var(--radius-sm);
    transition: var(--transition);
}

.resource-link:hover {
    border-color: var(--border-hover);
    background: #f0f0f5;
    transform: translateX(4px);
}

.resource-icon { font-size: 1.5rem; margin-top: 2px; }

.resource-link strong {
    display: block;
    color: var(--text-primary);
    font-size: 0.9rem;
    margin-bottom: 2px;
}

.resource-link p { font-size: 0.8rem; color: var(--text-muted); line-height: 1.4; }

/* ============================
   TOAST
   ============================ */
.toast {
    position: fixed;
    bottom: -100px;
    left: 50%;
    transform: translateX(-50%);
    padding: 12px 24px;
    background: white;
    border: 1px solid var(--success);
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    gap: 8px;
    z-index: 10000;
    transition: bottom 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    box-shadow: 0 8px 32px rgba(5, 150, 105, 0.15);
    color: var(--text-primary);
}

.toast.show { bottom: 32px; }

.toast-icon { font-size: 1.2rem; }
.toast-text { font-size: 0.85rem; font-weight: 500; color: var(--text-primary); }

/* ============================
   RESPONSIVE
   ============================ */
@media (max-width: 1024px) {
    .stats-grid { grid-template-columns: repeat(2, 1fr); }
    .dashboard-grid { grid-template-columns: 1fr; }
    .star-grid { grid-template-columns: repeat(2, 1fr); }
    .resources-grid { grid-template-columns: 1fr; }
    .test-case-content { grid-template-columns: 1fr; }
}

@media (max-width: 768px) {
    .nav-links { display: none; }
    .nav-streak { display: none; }
    .mobile-menu-btn { display: block; }

    .main-content { padding-left: 16px; padding-right: 16px; }
    .section-header h1 { font-size: 1.6rem; }
    .stats-grid { grid-template-columns: repeat(2, 1fr); }
    .heatmap-container { grid-template-columns: repeat(15, 1fr); }
    .roadmap-timeline { padding-left: 24px; }
    .roadmap-timeline::before { left: 6px; }
    .phase-marker { left: -24px; width: 24px; height: 24px; }
    .phase-marker .phase-number { left: 30px; font-size: 0.75rem; }
    .phase-marker .phase-dates { left: 30px; font-size: 0.65rem; }
    .phase-grid { grid-template-columns: 1fr; }
    .problem-row { grid-template-columns: 30px 1fr 60px; }
    .problem-company, .problem-status { display: none; }
    .sd-grid { grid-template-columns: 1fr; }
    .behavioral-grid { grid-template-columns: 1fr; }
    .star-grid { grid-template-columns: 1fr; }
    .modal-body { flex-direction: column; }

    .problem-modal { max-width: 100%; margin: 0 10px; }
}

@media (max-width: 480px) {
    .stats-grid { grid-template-columns: 1fr; }
    .stat-value { font-size: 1.5rem; }
    .filter-group { flex-direction: column; align-items: flex-start; }
    .schedule-table { font-size: 0.75rem; }
    .time-cell { font-size: 0.7rem !important; }
}