:root {
    --primary: #818cf8;
    --primary-dark: #6366f1;
    --accent: #fbbf24;
    --critical: #f87171;
    --success: #34d399;
    --bg-main: #020617;
    --sidebar-bg: #0f172a;
    --card-bg: #1e293b;
    --text-main: #f1f5f9;
    --text-muted: #94a3b8;
    --glass-border: rgba(255, 255, 255, 0.05);
    --card-shadow: 0 10px 30px -5px rgba(0, 0, 0, 0.3);
    --transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

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

body {
    font-family: 'Outfit', sans-serif;
    background-color: var(--bg-main);
    color: var(--text-main);
    display: flex;
    min-height: 100vh;
    overflow-x: hidden;
}

/* Glowing Background */
.glow-bg {
    position: fixed;
    width: 100vw;
    height: 100vh;
    background: radial-gradient(circle at 50% 50%, #1e1b4b 0%, #030617 100%);
    z-index: -1;
}

.glow-bg::after {
    content: '';
    position: absolute;
    top: -10%;
    right: -10%;
    width: 40%;
    height: 40%;
    background: radial-gradient(circle, rgba(99, 102, 241, 0.1) 0%, transparent 70%);
    filter: blur(100px);
}

/* Sidebar */
.sidebar {
    width: 280px;
    background: var(--sidebar-bg);
    border-right: 1px solid var(--glass-border);
    display: flex;
    flex-direction: column;
    padding: 2rem;
    position: fixed;
    height: 100vh;
    z-index: 100;
}

.logo {
    font-size: 1.5rem;
    font-weight: 800;
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 3rem;
}

.logo span {
    background: linear-gradient(to right, #818cf8, #c084fc);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
}

.nav-links {
    list-style: none;
    flex: 1;
}

.nav-links li {
    padding: 1rem 1.25rem;
    margin-bottom: 0.5rem;
    border-radius: 12px;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 1rem;
    font-weight: 500;
    transition: var(--transition);
    color: var(--text-muted);
}

.nav-links li:hover,
.nav-links li.active {
    background: rgba(99, 102, 241, 0.1);
    color: var(--text-main);
}

.nav-links li.active {
    border-left: 4px solid var(--primary);
    background: linear-gradient(to right, rgba(99, 102, 241, 0.15), transparent);
}

.nav-links li.vibrant {
    margin-top: 2rem;
    color: var(--accent);
}

.nav-links li.vibrant-blue {
    color: #60a5fa;
}

.section-banner.protools {
    background: linear-gradient(135deg, rgba(37, 99, 235, 0.1), rgba(30, 64, 175, 0.1));
    border-color: rgba(37, 99, 235, 0.3);
}

.sidebar-footer {
    padding-top: 2rem;
    border-top: 1px solid var(--glass-border);
    font-size: 0.875rem;
    color: var(--text-muted);
    font-style: italic;
}

/* Main Content */
.content {
    flex: 1;
    margin-left: 280px;
    padding: 3rem;
    max-width: 1400px;
}

.main-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 4rem;
}

.main-header h1 {
    font-size: 2.5rem;
    font-weight: 800;
    margin-bottom: 0.5rem;
}

.main-header .highlight {
    color: var(--primary);
}

.main-header p {
    color: var(--text-muted);
    font-size: 1.1rem;
}

/* Search Bar */
.search-bar {
    position: relative;
    width: 400px;
}

.search-input {
    width: 100%;
    background: var(--sidebar-bg);
    border: 1px solid var(--glass-border);
    padding: 1rem 1.5rem;
    padding-left: 3rem;
    border-radius: 16px;
    color: white;
    font-family: inherit;
    transition: var(--transition);
}

.search-input:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 4px rgba(99, 102, 241, 0.1);
}

.search-icon {
    position: absolute;
    left: 1.25rem;
    top: 50%;
    transform: translateY(-50%);
    color: var(--text-muted);
}

/* Sections */
.section {
    display: none;
    animation: fadeIn 0.5s ease;
}

.section.active {
    display: block;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }

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

.section-banner {
    padding: 2.5rem;
    border-radius: 24px;
    margin-bottom: 3rem;
    position: relative;
    overflow: hidden;
    background: linear-gradient(135deg, rgba(99, 102, 241, 0.1), rgba(168, 85, 247, 0.1));
    border: 1px solid var(--glass-border);
}

.section-banner::before {
    content: '';
    position: absolute;
    top: 0;
    right: 0;
    width: 200px;
    height: 200px;
    background: radial-gradient(circle, rgba(99, 102, 241, 0.15) 0%, transparent 70%);
    z-index: -1;
}

/* Cards Grid */
.cards-container {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 2rem;
}

.formula-card {
    background: var(--card-bg);
    backdrop-filter: blur(12px);
    border: 1px solid var(--glass-border);
    border-radius: 24px;
    padding: 2rem;
    transition: var(--transition);
}

.formula-card:hover {
    transform: translateY(-5px);
    border-color: rgba(99, 102, 241, 0.4);
    box-shadow: 0 20px 40px -10px rgba(0, 0, 0, 0.3);
}

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
    border-bottom: 1px solid var(--glass-border);
    padding-bottom: 1rem;
}

.card-header h3 {
    font-family: 'Playfair Display', serif;
    font-size: 1.75rem;
}

.badge {
    padding: 0.4rem 0.8rem;
    background: rgba(148, 163, 184, 0.1);
    border-radius: 8px;
    font-size: 0.75rem;
    font-weight: 700;
    text-transform: uppercase;
    color: var(--text-muted);
}

.badge.high {
    color: var(--accent);
    background: rgba(245, 158, 11, 0.1);
}

.badge.critical {
    color: var(--critical);
    background: rgba(239, 68, 68, 0.1);
}

/* Formula Items */
.item {
    margin-bottom: 2.5rem;
    position: relative;
}

.item label {
    display: block;
    font-weight: 600;
    font-size: 0.9rem;
    color: var(--text-muted);
    margin-bottom: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.math-box {
    background: rgba(15, 23, 42, 0.5);
    padding: 1.5rem 1rem;
    border-radius: 12px;
    font-size: 1.15rem;
    text-align: center;
    border: 1px dashed var(--glass-border);
    color: #fff;
    overflow-x: auto;
    white-space: nowrap;
    max-width: 100%;
}

.math-box::-webkit-scrollbar {
    height: 4px;
}

.math-box::-webkit-scrollbar-thumb {
    background: var(--primary);
    border-radius: 10px;
}

.exam-pro-tip {
    margin-top: 0.75rem;
    font-size: 0.9rem;
    color: var(--accent);
    padding-left: 1rem;
    border-left: 2px solid var(--accent);
}

.item.highlight .math-box {
    border: 1px solid var(--primary);
    background: rgba(99, 102, 241, 0.05);
}

/* Responsive */
@media (max-width: 1024px) {
    .sidebar {
        width: 80px;
        padding: 2rem 0.5rem;
        align-items: center;
    }

    .logo span,
    .nav-links li span:not(:first-child),
    .sidebar-footer {
        display: none;
    }

    .content {
        margin-left: 80px;
        padding: 2rem;
    }
}

@media (max-width: 768px) {
    .cards-container {
        grid-template-columns: 1fr;
    }

    .main-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 2rem;
    }

    .search-bar {
        width: 100%;
    }
}

/* Pro Tools Enhancements */
.header-controls {
    display: flex;
    align-items: center;
    gap: 2rem;
}

/* Toggle Switch */
.flashcard-toggle {
    display: flex;
    align-items: center;
    gap: 1rem;
    background: var(--sidebar-bg);
    padding: 0.5rem 1rem;
    border-radius: 12px;
    border: 1px solid var(--glass-border);
}

.switch {
    position: relative;
    display: inline-block;
    width: 44px;
    height: 24px;
}

.switch input {
    opacity: 0;
    width: 0;
    height: 0;
}

.slider {
    position: absolute;
    cursor: pointer;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: #334155;
    transition: .4s;
}

.slider:before {
    position: absolute;
    content: "";
    height: 18px;
    width: 18px;
    left: 3px;
    bottom: 3px;
    background-color: white;
    transition: .4s;
}

input:checked+.slider {
    background-color: var(--primary);
}

input:checked+.slider:before {
    transform: translateX(20px);
}

.slider.round {
    border-radius: 34px;
}

.slider.round:before {
    border-radius: 50%;
}

.toggle-label {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-muted);
}

/* Pro Grid & Specifics */
.pro-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
    gap: 2rem;
}

.formula-card.wide {
    grid-column: span 2;
}

.keywords-table {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.kw-row {
    display: grid;
    grid-template-columns: 200px 1fr;
    padding: 1rem;
    background: rgba(15, 23, 42, 0.4);
    border-radius: 12px;
    gap: 1rem;
    border-left: 3px solid var(--primary);
}

.kw-q {
    font-weight: 700;
    color: var(--text-main);
}

.kw-ans {
    color: var(--accent);
}

.roadmap-container {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.roadmap-box {
    background: linear-gradient(to right, #1e1b4b, transparent);
    padding: 1.5rem;
    border-radius: 16px;
    border: 1px dashed var(--primary);
    line-height: 1.8;
}

.color-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
}

.color-item {
    padding: 1rem;
    border-radius: 12px;
    font-weight: 700;
    text-align: center;
    color: var(--text-main);
}

/* Flashcard Mode Styles */
body.flashcard-mode .math-box,
body.flashcard-mode .exam-pro-tip,
body.flashcard-mode .kw-ans {
    filter: blur(8px);
    cursor: pointer;
    transition: filter 0.3s ease;
}

body.flashcard-mode .math-box:hover,
body.flashcard-mode .exam-pro-tip:hover,
body.flashcard-mode .kw-ans:hover {
    filter: blur(0);
}

/* PYQ Badge */
.pyq-badge {
    background: rgba(248, 113, 113, 0.1);
    color: #f87171;
    padding: 0.25rem 0.75rem;
    border-radius: 6px;
    font-size: 0.75rem;
    font-weight: 700;
    display: inline-block;
    margin-bottom: 1rem;
    border: 1px solid rgba(248, 113, 113, 0.2);
}

.pyq-badge.critical {
    background: rgba(251, 191, 36, 0.1);
    color: #fbbf24;
    border-color: rgba(251, 191, 36, 0.2);
}

/* Banners for new sections */
.section-banner.mistakes {
    background: linear-gradient(135deg, rgba(239, 68, 68, 0.1), rgba(185, 28, 28, 0.1));
    border-color: rgba(239, 68, 68, 0.3);
}

/* Mistake card specific */
.formula-card.critical {
    border: 1px solid rgba(239, 68, 68, 0.3);
    background: rgba(239, 68, 68, 0.05);
}

@media (max-width: 1024px) {
    .formula-card.wide {
        grid-column: span 1;
    }
}