:root {
    --bg-gradient: linear-gradient(135deg, #0f172a 0%, #1e293b 100%);
    --card-bg: rgba(30, 41, 59, 0.7);
    --card-hover-bg: rgba(51, 65, 85, 0.9);
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --accent-color: #38bdf8;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

body {
    font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
    background: var(--bg-gradient);
    background-attachment: fixed;
    color: var(--text-primary);
    min-height: 100vh;
    margin: 0;
    padding: 0;
    overflow-x: hidden;
}

/* Layout Wrapper */
.layout-wrapper {
    display: flex;
    min-height: 100vh;
    width: 100%;
}

/* Sidebar Styling */
.sidebar {
    width: 300px;
    height: 100vh;
    position: sticky;
    top: 0;
    background: rgba(15, 23, 42, 0.95);
    border-right: 1px solid rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(12px);
    padding: 2rem 1rem;
    overflow-y: auto;
    z-index: 1000;
    transition: transform 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    scrollbar-width: thin;
    scrollbar-color: var(--card-bg) transparent;
}

.sidebar::-webkit-scrollbar {
    width: 4px;
}

.sidebar::-webkit-scrollbar-thumb {
    background-color: var(--card-bg);
    border-radius: 10px;
}

.sidebar-header {
    margin-bottom: 2.5rem;
    padding: 0 1rem;
}

.sidebar-header h1 {
    font-size: 1.75rem;
    font-weight: 800;
    background: linear-gradient(to right, #38bdf8, #818cf8);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.sidebar-nav {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.sidebar-section {
    margin-bottom: 0.25rem;
}

.sidebar-section-header {
    width: 100%;
    display: flex;
    justify-content: space-between;
    align-items: center;
    background: none;
    border: none;
    color: var(--text-primary);
    font-size: 0.95rem;
    font-weight: 600;
    padding: 0.75rem 1rem;
    cursor: pointer;
    border-radius: 0.5rem;
    transition: var(--transition);
    text-align: left;
}

.sidebar-section-header:hover {
    background: rgba(255, 255, 255, 0.05);
    color: var(--accent-color);
}

.chevron {
    width: 7px;
    height: 7px;
    border-right: 2px solid currentColor;
    border-bottom: 2px solid currentColor;
    transform: rotate(-45deg);
    transition: transform 0.3s ease;
    margin-right: 4px;
}

.sidebar-section.expanded .chevron {
    transform: rotate(45deg);
}

.sidebar-section-links {
    list-style: none;
    padding: 0.25rem 0 0.5rem 1rem;
    display: none;
}

.sidebar-section.expanded .sidebar-section-links {
    display: block;
}

.sidebar-section-links li {
    margin-bottom: 2px;
}

.sidebar-section-links a {
    display: block;
    padding: 0.5rem 1rem;
    color: var(--text-secondary);
    font-size: 0.9rem;
    border-radius: 0.4rem;
    text-decoration: none;
    transition: var(--transition);
}

.sidebar-section-links li.active a {
    color: var(--accent-color);
    background: rgba(56, 189, 248, 0.1);
    font-weight: 600;
}

.sidebar-section-links a:hover {
    color: var(--text-primary);
    background: rgba(255, 255, 255, 0.05);
}

/* Main Content Area */
.main-container {
    flex: 1;
    display: flex;
    flex-direction: column;
    min-width: 0;
    position: relative;
}

.content-header {
    padding: 3rem 4rem 1rem;
    max-width: 1000px;
    width: 100%;
    margin: 0 auto;
}

.logo-mobile {
    display: none;
    text-decoration: none;
    margin-bottom: 1.5rem;
}

.logo-mobile h1 {
    font-size: 2.25rem;
    font-weight: 800;
    background: linear-gradient(to right, #38bdf8, #818cf8);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.site-tagline {
    font-size: 1.125rem;
    color: var(--text-secondary);
}

.content-body {
    flex: 1;
    padding: 1rem 4rem 5rem;
    width: 100%;
    max-width: 1000px;
    margin: 0 auto;
}

.page-title {
    margin-bottom: 3rem;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    padding-bottom: 1.5rem;
}

.page-title h1 {
    font-size: 2.75rem;
    font-weight: 800;
    color: var(--text-primary);
}

/* Markdown Content Styling */
a {
    color: var(--accent-color);
    text-decoration: none;
    transition: var(--transition);
}

a:hover {
    text-decoration: underline;
}

.grid-container {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1.5rem;
    width: 100%;
    margin-top: 2.5rem;
}

.topic-card {
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 2.5rem 1.5rem;
    background: var(--card-bg);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 1rem;
    color: var(--text-primary) !important;
    text-decoration: none;
    font-size: 1.1rem;
    font-weight: 600;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    transition: var(--transition);
    backdrop-filter: blur(8px);
}

.topic-card:hover {
    background: var(--card-hover-bg);
    transform: translateY(-5px);
    border-color: var(--accent-color);
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.2);
    color: var(--accent-color) !important;
}

main h1, main h2, main h3 {
    margin-top: 3rem;
    margin-bottom: 1.5rem;
    color: var(--accent-color);
    font-weight: 700;
}

main p {
    margin-bottom: 1.5rem;
    line-height: 1.8;
    font-size: 1.1rem;
    color: #e2e8f0;
}

main ul, main ol {
    margin-bottom: 1.5rem;
    margin-left: 1.5rem;
}

main li {
    margin-bottom: 0.75rem;
    line-height: 1.7;
    color: #e2e8f0;
}

main code {
    background: rgba(255, 255, 255, 0.1);
    padding: 0.2rem 0.4rem;
    border-radius: 0.25rem;
    font-family: 'ui-monospace', 'SFMono-Regular', 'Menlo', 'Monaco', 'Consolas', monospace;
    font-size: 0.9em;
    color: var(--accent-color);
}

main pre {
    background: rgba(15, 23, 42, 0.6);
    padding: 1.5rem;
    border-radius: 0.75rem;
    overflow-x: auto;
    margin-bottom: 1.75rem;
    border: 1px solid rgba(255, 255, 255, 0.1);
}

main pre code {
    background: none;
    padding: 0;
    color: var(--text-primary);
}

footer {
    padding: 4rem 2rem;
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.9rem;
    border-top: 1px solid rgba(255, 255, 255, 0.05);
}

/* Mobile Toggle Button */
.mobile-menu-toggle {
    display: none;
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    z-index: 2000;
    background: var(--accent-color);
    border: none;
    border-radius: 50%;
    width: 60px;
    height: 60px;
    cursor: pointer;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 5px;
    box-shadow: 0 8px 25px rgba(56, 189, 248, 0.4);
    transition: var(--transition);
}

.mobile-menu-toggle:active {
    transform: scale(0.9);
}

.bar {
    width: 24px;
    height: 2.5px;
    background: #0f172a;
    border-radius: 2px;
    transition: var(--transition);
}

.mobile-menu-toggle.active .bar:nth-child(1) {
    transform: translateY(7.5px) rotate(45deg);
}

.mobile-menu-toggle.active .bar:nth-child(2) {
    opacity: 0;
}

.mobile-menu-toggle.active .bar:nth-child(3) {
    transform: translateY(-7.5px) rotate(-45deg);
}

/* Responsive Overrides */
@media (max-width: 1024px) {
    .sidebar {
        position: fixed;
        left: 0;
        top: 0;
        transform: translateX(-100%);
        height: 100vh;
        width: 300px;
        box-shadow: 20px 0 50px rgba(0, 0, 0, 0.6);
    }
    
    .sidebar.open {
        transform: translateX(0);
    }
    
    .mobile-menu-toggle {
        display: flex;
    }
    
    .content-header, .content-body {
        padding-left: 2rem;
        padding-right: 2rem;
    }
    
    .logo-mobile {
        display: block;
    }
}

@media (max-width: 640px) {
    .content-header, .content-body {
        padding-left: 1.25rem;
        padding-right: 1.25rem;
    }
    
    .page-title h1 {
        font-size: 2.25rem;
    }
    
    .grid-container {
        grid-template-columns: 1fr;
    }
}