/* ==========================================
   Reset & Base Styles
   ========================================== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    /* Colors - Light theme */
    --bg-primary: #fafafa;
    --bg-secondary: #f5f5f5;
    --bg-tertiary: #ffffff;
    --text-primary: #000000;
    --text-secondary: #666666;
    --text-tertiary: #999999;
    --accent-purple: #8b5cf6;
    --accent-blue: #3b82f6;
    --border-color: rgba(0, 0, 0, 0.08);
    --glass-bg: rgba(0, 0, 0, 0.02);
    --glass-border: rgba(0, 0, 0, 0.08);

    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 4rem;

    /* Typography */
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', sans-serif;

    /* Layout */
    --nav-height: 60px;
    --sidebar-width: 280px;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* ==========================================
   Navigation
   ========================================== */
.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    height: var(--nav-height);
    background: rgba(250, 250, 250, 0.9);
    backdrop-filter: blur(20px) saturate(180%);
    border-bottom: 1px solid var(--border-color);
}

.nav-container {
    max-width: 100%;
    height: 100%;
    margin: 0 auto;
    padding: 0 var(--spacing-lg);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.9375rem;
    font-weight: 500;
}

.logo-link {
    text-decoration: none;
    color: var(--text-primary);
    transition: color 0.2s ease;
}

.logo-link:hover {
    color: var(--text-secondary);
}

.logo-text {
    font-weight: 600;
}

.logo-divider {
    color: var(--text-tertiary);
}

.logo-section {
    color: var(--text-secondary);
}

.nav-links {
    display: flex;
    gap: 1.5rem;
}

.nav-link {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.875rem;
    font-weight: 500;
    transition: color 0.2s ease;
}

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

/* ==========================================
   Platform Layout
   ========================================== */
.platform-layout {
    display: flex;
    min-height: 100vh;
    padding-top: var(--nav-height);
}

/* Sidebar */
.platform-sidebar {
    width: var(--sidebar-width);
    flex-shrink: 0;
    border-right: 1px solid var(--border-color);
    padding: var(--spacing-lg);
    position: fixed;
    top: var(--nav-height);
    left: 0;
    height: calc(100vh - var(--nav-height));
    overflow-y: auto;
    background: var(--bg-primary);
}

.sidebar-search {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: 0.625rem 0.875rem;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    margin-bottom: var(--spacing-lg);
    transition: all 0.2s ease;
}

.sidebar-search:focus-within {
    border-color: rgba(0, 0, 0, 0.2);
    background: var(--bg-tertiary);
}

.search-icon {
    color: var(--text-tertiary);
    flex-shrink: 0;
}

.search-input {
    flex: 1;
    border: none;
    background: transparent;
    font-family: var(--font-sans);
    font-size: 0.875rem;
    color: var(--text-primary);
    outline: none;
}

.search-input::placeholder {
    color: var(--text-tertiary);
}

.search-shortcut {
    font-size: 0.75rem;
    color: var(--text-tertiary);
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    padding: 0.125rem 0.375rem;
    border-radius: 4px;
    font-weight: 500;
}

.sidebar-nav {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.sidebar-section {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.sidebar-heading {
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-tertiary);
    padding: var(--spacing-xs) 0;
    margin-bottom: var(--spacing-xs);
}

.sidebar-link {
    font-size: 0.9375rem;
    color: var(--text-secondary);
    text-decoration: none;
    padding: 0.375rem 0.75rem;
    border-radius: 6px;
    transition: all 0.15s ease;
    font-weight: 400;
}

.sidebar-link:hover {
    color: var(--text-primary);
    background: var(--glass-bg);
}

.sidebar-link.active {
    color: var(--text-primary);
    background: rgba(0, 0, 0, 0.05);
    font-weight: 500;
}

/* Main Content */
.platform-content {
    flex: 1;
    margin-left: var(--sidebar-width);
    padding: var(--spacing-2xl) var(--spacing-xl);
    max-width: calc(100% - var(--sidebar-width));
}

.platform-header {
    max-width: 800px;
    margin-bottom: var(--spacing-2xl);
}

.platform-title {
    font-size: clamp(2rem, 4vw, 2.75rem);
    font-weight: 700;
    letter-spacing: -0.03em;
    color: var(--text-primary);
    margin-bottom: var(--spacing-sm);
}

.platform-subtitle {
    font-size: 1.125rem;
    color: var(--text-secondary);
    line-height: 1.6;
    max-width: 600px;
}

/* Platform Cards Grid */
.platform-cards-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-lg);
    max-width: 900px;
}

.platform-card {
    display: flex;
    flex-direction: column;
    padding: var(--spacing-lg);
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    text-decoration: none;
    transition: all 0.2s ease;
}

.platform-card:hover {
    border-color: rgba(0, 0, 0, 0.15);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.04);
}

.platform-card-icon {
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-secondary);
    border-radius: 8px;
    margin-bottom: var(--spacing-md);
    color: var(--text-secondary);
}

.platform-card-title {
    font-size: 1.0625rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: var(--spacing-xs);
    letter-spacing: -0.01em;
}

.platform-card-description {
    font-size: 0.9375rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

/* ==========================================
   Animations
   ========================================== */
.fade-in {
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.5s ease, transform 0.5s ease;
}

.fade-in.visible {
    opacity: 1;
    transform: translateY(0);
}

/* ==========================================
   Responsive Design
   ========================================== */
@media (max-width: 1024px) {
    .platform-sidebar {
        width: 240px;
    }

    .platform-content {
        margin-left: 240px;
        max-width: calc(100% - 240px);
        padding: var(--spacing-xl) var(--spacing-lg);
    }
}

@media (max-width: 768px) {
    .nav-links {
        display: none;
    }

    .platform-sidebar {
        display: none;
    }

    .platform-content {
        margin-left: 0;
        max-width: 100%;
        padding: var(--spacing-lg) var(--spacing-md);
    }

    .platform-cards-grid {
        grid-template-columns: 1fr;
    }
}

/* Mobile menu toggle (for future implementation) */
.mobile-menu-toggle {
    display: none;
    background: none;
    border: none;
    padding: 0.5rem;
    cursor: pointer;
    color: var(--text-primary);
}

@media (max-width: 768px) {
    .mobile-menu-toggle {
        display: flex;
        align-items: center;
        justify-content: center;
    }
}