/**
 * VideoNotes Design System
 * Modern dark theme with purple-blue gradient accents
 */

/* ===================================
   CSS Variables / Design Tokens
   =================================== */
:root {
    /* Colors */
    --color-bg-primary: #0a0a0f;
    --color-bg-secondary: #12121a;
    --color-bg-tertiary: #1a1a25;
    --color-bg-card: rgba(26, 26, 37, 0.7);
    --color-bg-glass: rgba(255, 255, 255, 0.05);
    
    /* Text Colors */
    --color-text-primary: #ffffff;
    --color-text-secondary: #a0a0b0;
    --color-text-muted: #6b6b7b;
    
    /* Brand Colors */
    --color-accent-primary: #7c3aed;
    --color-accent-secondary: #3b82f6;
    --color-accent-gradient: linear-gradient(135deg, #7c3aed 0%, #3b82f6 100%);
    --color-accent-glow: rgba(124, 58, 237, 0.5);
    
    /* Status Colors */
    --color-success: #10b981;
    --color-warning: #f59e0b;
    --color-error: #ef4444;
    --color-info: #3b82f6;
    
    /* Borders */
    --color-border: rgba(255, 255, 255, 0.1);
    --color-border-hover: rgba(255, 255, 255, 0.2);
    
    /* Typography */
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-size-xs: 0.75rem;
    --font-size-sm: 0.875rem;
    --font-size-base: 1rem;
    --font-size-lg: 1.125rem;
    --font-size-xl: 1.25rem;
    --font-size-2xl: 1.5rem;
    --font-size-3xl: 1.875rem;
    --font-size-4xl: 2.25rem;
    --font-size-5xl: 3rem;
    --font-size-6xl: 3.75rem;
    
    /* Spacing */
    --spacing-1: 0.25rem;
    --spacing-2: 0.5rem;
    --spacing-3: 0.75rem;
    --spacing-4: 1rem;
    --spacing-5: 1.25rem;
    --spacing-6: 1.5rem;
    --spacing-8: 2rem;
    --spacing-10: 2.5rem;
    --spacing-12: 3rem;
    --spacing-16: 4rem;
    --spacing-20: 5rem;
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-2xl: 1.5rem;
    --radius-full: 9999px;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.3);
    --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.4);
    --shadow-glow: 0 0 40px rgba(124, 58, 237, 0.3);
    
    /* Transitions */
    --transition-fast: 150ms ease;
    --transition-base: 250ms ease;
    --transition-slow: 350ms ease;
    
    /* Z-index */
    --z-dropdown: 100;
    --z-sticky: 200;
    --z-fixed: 300;
    --z-modal: 400;
    --z-tooltip: 500;
}

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

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-family);
    font-size: var(--font-size-base);
    line-height: 1.6;
    color: var(--color-text-primary);
    background: var(--color-bg-primary);
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

/* Background pattern */
body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: 
        radial-gradient(circle at 20% 20%, rgba(124, 58, 237, 0.15) 0%, transparent 50%),
        radial-gradient(circle at 80% 80%, rgba(59, 130, 246, 0.1) 0%, transparent 50%);
    pointer-events: none;
    z-index: -1;
}

a {
    color: var(--color-accent-primary);
    text-decoration: none;
    transition: color var(--transition-base);
}

a:hover {
    color: var(--color-accent-secondary);
}

img, video {
    max-width: 100%;
    height: auto;
}

button, input, select, textarea {
    font-family: inherit;
    font-size: inherit;
}

/* ===================================
   Typography
   =================================== */
h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: 1.2;
    color: var(--color-text-primary);
}

h1 { font-size: var(--font-size-5xl); }
h2 { font-size: var(--font-size-4xl); }
h3 { font-size: var(--font-size-3xl); }
h4 { font-size: var(--font-size-2xl); }
h5 { font-size: var(--font-size-xl); }
h6 { font-size: var(--font-size-lg); }

.text-gradient {
    background: var(--color-accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.text-muted {
    color: var(--color-text-muted);
}

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

/* ===================================
   Buttons
   =================================== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-2);
    padding: var(--spacing-3) var(--spacing-6);
    font-size: var(--font-size-base);
    font-weight: 500;
    border: none;
    border-radius: var(--radius-lg);
    cursor: pointer;
    transition: all var(--transition-base);
    text-decoration: none;
}

.btn-primary {
    background: var(--color-accent-gradient);
    color: white;
    box-shadow: 0 4px 15px var(--color-accent-glow);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px var(--color-accent-glow);
}

.btn-secondary {
    background: var(--color-bg-glass);
    color: var(--color-text-primary);
    border: 1px solid var(--color-border);
    backdrop-filter: blur(10px);
}

.btn-secondary:hover {
    background: var(--color-bg-tertiary);
    border-color: var(--color-border-hover);
}

.btn-outline {
    background: transparent;
    color: var(--color-accent-primary);
    border: 2px solid var(--color-accent-primary);
}

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

.btn-lg {
    padding: var(--spacing-4) var(--spacing-8);
    font-size: var(--font-size-lg);
}

.btn-sm {
    padding: var(--spacing-2) var(--spacing-4);
    font-size: var(--font-size-sm);
}

.btn-icon {
    width: 40px;
    height: 40px;
    padding: 0;
    border-radius: var(--radius-md);
}

/* ===================================
   Form Elements
   =================================== */
.form-group {
    margin-bottom: var(--spacing-5);
}

.form-label {
    display: block;
    margin-bottom: var(--spacing-2);
    font-size: var(--font-size-sm);
    font-weight: 500;
    color: var(--color-text-secondary);
}

.form-input {
    width: 100%;
    padding: var(--spacing-3) var(--spacing-4);
    font-size: var(--font-size-base);
    color: var(--color-text-primary);
    background: var(--color-bg-tertiary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    transition: all var(--transition-base);
}

.form-input:focus {
    outline: none;
    border-color: var(--color-accent-primary);
    box-shadow: 0 0 0 3px rgba(124, 58, 237, 0.2);
}

.form-input::placeholder {
    color: var(--color-text-muted);
}

.form-input:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.form-input-error {
    border-color: var(--color-error);
}

.form-error {
    margin-top: var(--spacing-2);
    font-size: var(--font-size-sm);
    color: var(--color-error);
}

.form-hint {
    margin-top: var(--spacing-2);
    font-size: var(--font-size-sm);
    color: var(--color-text-muted);
}

/* Password strength indicator */
.password-strength {
    height: 4px;
    margin-top: var(--spacing-2);
    background: var(--color-bg-glass);
    border-radius: var(--radius-full);
    overflow: hidden;
}

.password-strength-bar {
    height: 100%;
    transition: width var(--transition-base), background var(--transition-base);
}

.password-strength-weak { width: 25%; background: var(--color-error); }
.password-strength-fair { width: 50%; background: var(--color-warning); }
.password-strength-good { width: 75%; background: var(--color-info); }
.password-strength-strong { width: 100%; background: var(--color-success); }

/* Checkbox */
.checkbox-wrapper {
    display: flex;
    align-items: center;
    gap: var(--spacing-2);
    cursor: pointer;
}

.checkbox-input {
    width: 20px;
    height: 20px;
    accent-color: var(--color-accent-primary);
}

/* ===================================
   Cards
   =================================== */
.card {
    background: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-xl);
    backdrop-filter: blur(20px);
    transition: all var(--transition-base);
}

.card:hover {
    border-color: var(--color-border-hover);
    transform: translateY(-2px);
}

.card-glass {
    background: var(--color-bg-glass);
    backdrop-filter: blur(20px);
}

.card-body {
    padding: var(--spacing-6);
}

.card-header {
    padding: var(--spacing-5) var(--spacing-6);
    border-bottom: 1px solid var(--color-border);
}

.card-title {
    font-size: var(--font-size-xl);
    font-weight: 600;
}

/* ===================================
   Navigation
   =================================== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: var(--z-fixed);
    padding: var(--spacing-4) 0;
    background: rgba(10, 10, 15, 0.8);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--color-border);
}

.navbar-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    max-width: 1280px;
    margin: 0 auto;
    padding: 0 var(--spacing-6);
}

.navbar-brand {
    display: flex;
    align-items: center;
    gap: var(--spacing-2);
    font-size: var(--font-size-xl);
    font-weight: 700;
    color: var(--color-text-primary);
}

.navbar-brand svg, .navbar-brand img {
    width: 32px;
    height: 32px;
}

.navbar-nav {
    display: flex;
    align-items: center;
    gap: var(--spacing-8);
    list-style: none;
}

.navbar-link {
    font-size: var(--font-size-sm);
    font-weight: 500;
    color: var(--color-text-secondary);
    transition: color var(--transition-base);
}

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

.navbar-actions {
    display: flex;
    align-items: center;
    gap: var(--spacing-4);
}

/* ===================================
   Layout
   =================================== */
.container {
    max-width: 1280px;
    margin: 0 auto;
    padding: 0 var(--spacing-6);
}

.container-sm {
    max-width: 640px;
}

.container-lg {
    max-width: 1536px;
}

.section {
    padding: var(--spacing-20) 0;
}

.section-header {
    text-align: center;
    margin-bottom: var(--spacing-12);
}

.section-title {
    font-size: var(--font-size-4xl);
    margin-bottom: var(--spacing-4);
}

.section-subtitle {
    font-size: var(--font-size-lg);
    color: var(--color-text-secondary);
    max-width: 600px;
    margin: 0 auto;
}

/* Grid */
.grid {
    display: grid;
    gap: var(--spacing-6);
}

.grid-cols-2 { grid-template-columns: repeat(2, 1fr); }
.grid-cols-3 { grid-template-columns: repeat(3, 1fr); }
.grid-cols-4 { grid-template-columns: repeat(4, 1fr); }

@media (max-width: 1024px) {
    .grid-cols-4 { grid-template-columns: repeat(2, 1fr); }
    .grid-cols-3 { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 768px) {
    .grid-cols-4, .grid-cols-3, .grid-cols-2 { 
        grid-template-columns: 1fr; 
    }
}

/* Flex utilities */
.flex { display: flex; }
.flex-col { flex-direction: column; }
.items-center { align-items: center; }
.justify-center { justify-content: center; }
.justify-between { justify-content: space-between; }
.gap-2 { gap: var(--spacing-2); }
.gap-4 { gap: var(--spacing-4); }
.gap-6 { gap: var(--spacing-6); }

/* ===================================
   Sidebar (Dashboard)
   =================================== */
.sidebar {
    position: fixed;
    top: 0;
    left: 0;
    bottom: 0;
    width: 260px;
    background: var(--color-bg-secondary);
    border-right: 1px solid var(--color-border);
    padding: var(--spacing-6);
    display: flex;
    flex-direction: column;
    z-index: var(--z-fixed);
}

.sidebar-brand {
    display: flex;
    align-items: center;
    gap: var(--spacing-3);
    margin-bottom: var(--spacing-8);
    font-size: var(--font-size-xl);
    font-weight: 700;
}

.sidebar-nav {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-2);
}

.sidebar-link {
    display: flex;
    align-items: center;
    gap: var(--spacing-3);
    padding: var(--spacing-3) var(--spacing-4);
    border-radius: var(--radius-lg);
    color: var(--color-text-secondary);
    transition: all var(--transition-base);
}

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

.sidebar-link.active {
    background: var(--color-accent-gradient);
    color: white;
}

.sidebar-link svg {
    width: 20px;
    height: 20px;
}

.main-content {
    margin-left: 260px;
    padding: var(--spacing-8);
    min-height: 100vh;
}

/* ===================================
   Badges & Tags
   =================================== */
.badge {
    display: inline-flex;
    align-items: center;
    padding: var(--spacing-1) var(--spacing-3);
    font-size: var(--font-size-xs);
    font-weight: 600;
    border-radius: var(--radius-full);
}

.badge-success {
    background: rgba(16, 185, 129, 0.2);
    color: var(--color-success);
}

.badge-warning {
    background: rgba(245, 158, 11, 0.2);
    color: var(--color-warning);
}

.badge-error {
    background: rgba(239, 68, 68, 0.2);
    color: var(--color-error);
}

.badge-info {
    background: rgba(59, 130, 246, 0.2);
    color: var(--color-info);
}

.badge-pro {
    background: var(--color-accent-gradient);
    color: white;
}

/* ===================================
   Alerts
   =================================== */
.alert {
    padding: var(--spacing-4);
    border-radius: var(--radius-lg);
    margin-bottom: var(--spacing-4);
}

.alert-success {
    background: rgba(16, 185, 129, 0.1);
    border: 1px solid rgba(16, 185, 129, 0.3);
    color: var(--color-success);
}

.alert-error {
    background: rgba(239, 68, 68, 0.1);
    border: 1px solid rgba(239, 68, 68, 0.3);
    color: var(--color-error);
}

.alert-warning {
    background: rgba(245, 158, 11, 0.1);
    border: 1px solid rgba(245, 158, 11, 0.3);
    color: var(--color-warning);
}

.alert-info {
    background: rgba(59, 130, 246, 0.1);
    border: 1px solid rgba(59, 130, 246, 0.3);
    color: var(--color-info);
}

/* ===================================
   Upload Zone
   =================================== */
.upload-zone {
    border: 2px dashed var(--color-border);
    border-radius: var(--radius-xl);
    padding: var(--spacing-12);
    text-align: center;
    cursor: pointer;
    transition: all var(--transition-base);
}

.upload-zone:hover {
    border-color: var(--color-accent-primary);
    background: rgba(124, 58, 237, 0.05);
}

.upload-zone.dragover {
    border-color: var(--color-accent-primary);
    background: rgba(124, 58, 237, 0.1);
}

.upload-icon {
    width: 64px;
    height: 64px;
    margin: 0 auto var(--spacing-4);
    color: var(--color-text-muted);
}

/* ===================================
   Avatar
   =================================== */
.avatar {
    width: 40px;
    height: 40px;
    border-radius: var(--radius-full);
    object-fit: cover;
    border: 2px solid var(--color-border);
}

.avatar-lg {
    width: 80px;
    height: 80px;
}

.avatar-xl {
    width: 120px;
    height: 120px;
}

.avatar-placeholder {
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--color-bg-tertiary);
    color: var(--color-text-muted);
    font-weight: 600;
}

/* ===================================
   Stats Cards
   =================================== */
.stat-card {
    background: var(--color-bg-card);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-xl);
    padding: var(--spacing-6);
}

.stat-icon {
    width: 48px;
    height: 48px;
    border-radius: var(--radius-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: var(--spacing-4);
    background: rgba(124, 58, 237, 0.2);
    color: var(--color-accent-primary);
}

.stat-value {
    font-size: var(--font-size-3xl);
    font-weight: 700;
    margin-bottom: var(--spacing-1);
}

.stat-label {
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
}

/* ===================================
   Dropdown
   =================================== */
.dropdown {
    position: relative;
}

.dropdown-menu {
    position: absolute;
    top: 100%;
    right: 0;
    min-width: 200px;
    margin-top: var(--spacing-2);
    padding: var(--spacing-2);
    background: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-xl);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: all var(--transition-base);
    z-index: var(--z-dropdown);
}

.dropdown.open .dropdown-menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.dropdown-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-3);
    padding: var(--spacing-3) var(--spacing-4);
    border-radius: var(--radius-md);
    color: var(--color-text-secondary);
    transition: all var(--transition-base);
}

.dropdown-item:hover {
    background: var(--color-bg-tertiary);
    color: var(--color-text-primary);
}

/* ===================================
   Tabs
   =================================== */
.tabs {
    display: flex;
    gap: var(--spacing-1);
    border-bottom: 1px solid var(--color-border);
    margin-bottom: var(--spacing-6);
}

.tab {
    padding: var(--spacing-3) var(--spacing-5);
    font-size: var(--font-size-sm);
    font-weight: 500;
    color: var(--color-text-secondary);
    border-bottom: 2px solid transparent;
    transition: all var(--transition-base);
    cursor: pointer;
}

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

.tab.active {
    color: var(--color-accent-primary);
    border-bottom-color: var(--color-accent-primary);
}

/* ===================================
   Modal
   =================================== */
.modal-overlay {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.7);
    backdrop-filter: blur(4px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: var(--z-modal);
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-base);
}

.modal-overlay.open {
    opacity: 1;
    visibility: visible;
}

.modal {
    background: var(--color-bg-secondary);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-2xl);
    width: 100%;
    max-width: 480px;
    max-height: 90vh;
    overflow-y: auto;
    transform: scale(0.9);
    transition: transform var(--transition-base);
}

.modal-overlay.open .modal {
    transform: scale(1);
}

.modal-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-5) var(--spacing-6);
    border-bottom: 1px solid var(--color-border);
}

.modal-title {
    font-size: var(--font-size-xl);
    font-weight: 600;
}

.modal-close {
    width: 32px;
    height: 32px;
    border-radius: var(--radius-md);
    background: transparent;
    border: none;
    color: var(--color-text-muted);
    cursor: pointer;
    transition: all var(--transition-base);
}

.modal-close:hover {
    background: var(--color-bg-tertiary);
    color: var(--color-text-primary);
}

.modal-body {
    padding: var(--spacing-6);
}

.modal-footer {
    display: flex;
    justify-content: flex-end;
    gap: var(--spacing-3);
    padding: var(--spacing-4) var(--spacing-6);
    border-top: 1px solid var(--color-border);
}

/* ===================================
   Animations
   =================================== */
@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

@keyframes slideUp {
    from { 
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.5; }
}

@keyframes spin {
    from { transform: rotate(0deg); }
    to { transform: rotate(360deg); }
}

.animate-fadeIn { animation: fadeIn 0.5s ease; }
.animate-slideUp { animation: slideUp 0.5s ease; }
.animate-pulse { animation: pulse 2s infinite; }
.animate-spin { animation: spin 1s linear infinite; }

/* Loading spinner */
.spinner {
    width: 24px;
    height: 24px;
    border: 2px solid var(--color-border);
    border-top-color: var(--color-accent-primary);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

/* ===================================
   Responsive
   =================================== */
@media (max-width: 768px) {
    :root {
        --font-size-5xl: 2.25rem;
        --font-size-4xl: 1.875rem;
        --font-size-3xl: 1.5rem;
    }
    
    .navbar-nav {
        display: none;
    }
    
    .sidebar {
        transform: translateX(-100%);
        transition: transform var(--transition-base);
    }
    
    .sidebar.open {
        transform: translateX(0);
    }
    
    .main-content {
        margin-left: 0;
    }
    
    .section {
        padding: var(--spacing-12) 0;
    }
}

/* ===================================
   Utilities
   =================================== */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.mt-4 { margin-top: var(--spacing-4); }
.mt-6 { margin-top: var(--spacing-6); }
.mt-8 { margin-top: var(--spacing-8); }
.mb-4 { margin-bottom: var(--spacing-4); }
.mb-6 { margin-bottom: var(--spacing-6); }
.mb-8 { margin-bottom: var(--spacing-8); }

.w-full { width: 100%; }
.h-full { height: 100%; }

.hidden { display: none; }
.visible { display: block; }