/* Import Inter font for modern typography */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&display=swap');

:root {
    /* Color System */
    --primary-50: #f0f9ff;
    --primary-100: #e0f2fe;
    --primary-200: #bae6fd;
    --primary-300: #7dd3fc;
    --primary-400: #38bdf8;
    --primary-500: #0ea5e9;
    --primary-600: #0284c7;
    --primary-700: #0369a1;
    --primary-800: #075985;
    --primary-900: #0c4a6e;
    
    --secondary-50: #fdf4ff;
    --secondary-100: #fae8ff;
    --secondary-200: #f5d0fe;
    --secondary-300: #f0abfc;
    --secondary-400: #e879f9;
    --secondary-500: #d946ef;
    --secondary-600: #c026d3;
    --secondary-700: #a21caf;
    --secondary-800: #86198f;
    --secondary-900: #701a75;
    
    --success-500: #10b981;
    --warning-500: #f59e0b;
    --error-500: #ef4444;
    
    /* Neutral Colors */
    --gray-50: #f9fafb;
    --gray-100: #f3f4f6;
    --gray-200: #e5e7eb;
    --gray-300: #d1d5db;
    --gray-400: #9ca3af;
    --gray-500: #6b7280;
    --gray-600: #4b5563;
    --gray-700: #374151;
    --gray-800: #1f2937;
    --gray-900: #111827;
    
    /* Theme Variables */
    --primary: var(--primary-600);
    --secondary: var(--secondary-600);
    --accent: var(--primary-500);
    --glass: rgba(255, 255, 255, 0.08);
    --glass-border: rgba(255, 255, 255, 0.12);
    --background: #0f172a;
    --background-secondary: #1e293b;
    --text-primary: #f8fafc;
    --text-secondary: #cbd5e1;
    --text-muted: #64748b;
    --card-bg: rgba(30, 41, 59, 0.6);
    --border-color: rgba(148, 163, 184, 0.1);
    
    /* Spacing System (8px base) */
    --space-1: 0.25rem;  /* 4px */
    --space-2: 0.5rem;   /* 8px */
    --space-3: 0.75rem;  /* 12px */
    --space-4: 1rem;     /* 16px */
    --space-5: 1.25rem;  /* 20px */
    --space-6: 1.5rem;   /* 24px */
    --space-8: 2rem;     /* 32px */
    --space-10: 2.5rem;  /* 40px */
    --space-12: 3rem;    /* 48px */
    --space-16: 4rem;    /* 64px */
    --space-20: 5rem;    /* 80px */
    
    /* Border Radius */
    --radius-sm: 0.375rem;
    --radius-md: 0.5rem;
    --radius-lg: 0.75rem;
    --radius-xl: 1rem;
    --radius-2xl: 1.5rem;
    
    /* Shadows */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
    --shadow-2xl: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
    
    /* Transitions */
    --transition-fast: 150ms ease-in-out;
    --transition-normal: 250ms ease-in-out;
    --transition-slow: 350ms ease-in-out;
}

/* Light theme overrides */
body.light {
    --background: #ffffff;
    --background-secondary: #f8fafc;
    --text-primary: #1e293b;
    --text-secondary: #475569;
    --text-muted: #64748b;
    --card-bg: rgba(255, 255, 255, 0.8);
    --glass: rgba(255, 255, 255, 0.6);
    --glass-border: rgba(148, 163, 184, 0.2);
    --border-color: rgba(148, 163, 184, 0.2);
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: linear-gradient(135deg, var(--background) 0%, var(--background-secondary) 100%);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    transition: all var(--transition-normal);
    overflow-x: hidden;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-weight: 600;
    line-height: 1.2;
    color: var(--text-primary);
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.5rem; }

p {
    color: var(--text-secondary);
    line-height: 1.6;
}

/* Authentication Section */
#auth-section {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: var(--space-8);
    position: relative;
}

#auth-section::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: 
        radial-gradient(circle at 20% 80%, rgba(120, 119, 198, 0.3) 0%, transparent 50%),
        radial-gradient(circle at 80% 20%, rgba(255, 119, 198, 0.3) 0%, transparent 50%),
        radial-gradient(circle at 40% 40%, rgba(120, 219, 255, 0.2) 0%, transparent 50%);
    pointer-events: none;
}

.auth-header {
    text-align: center;
    margin-bottom: var(--space-12);
    z-index: 1;
    position: relative;
}

.logo-container {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-4);
    margin-bottom: var(--space-4);
}

.logo-icon {
    font-size: 3rem;
    color: var(--primary);
    filter: drop-shadow(0 0 20px rgba(59, 130, 246, 0.5));
}

.auth-header h1 {
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    font-size: 3.5rem;
    font-weight: 700;
    margin: 0;
}

.tagline {
    color: var(--text-muted);
    font-size: 1.125rem;
    font-weight: 400;
    margin-top: var(--space-2);
}

.auth-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: var(--space-8);
    width: 100%;
    max-width: 800px;
    z-index: 1;
    position: relative;
}

/* Glass Effect */
.glass {
    background: var(--glass);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-radius: var(--radius-2xl);
    border: 1px solid var(--glass-border);
    box-shadow: var(--shadow-2xl);
    transition: all var(--transition-normal);
}

.glass:hover {
    transform: translateY(-4px);
    box-shadow: 0 32px 64px -12px rgba(0, 0, 0, 0.4);
    border-color: rgba(255, 255, 255, 0.2);
}

/* Auth Cards */
.auth-card {
    padding: var(--space-8);
    position: relative;
    overflow: hidden;
}

.auth-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--primary) 0%, var(--secondary) 100%);
}

.card-header {
    text-align: center;
    margin-bottom: var(--space-8);
}

.card-icon {
    font-size: 2.5rem;
    color: var(--primary);
    margin-bottom: var(--space-4);
    display: block;
}

.card-header h2 {
    color: var(--text-primary);
    font-weight: 600;
    margin: 0;
}

/* Form Styles */
.auth-form {
    display: flex;
    flex-direction: column;
    gap: var(--space-5);
}

.input-group {
    position: relative;
    display: flex;
    align-items: center;
}

.input-icon {
    position: absolute;
    left: var(--space-4);
    color: var(--text-muted);
    z-index: 2;
    transition: color var(--transition-fast);
}

.input-group:focus-within .input-icon {
    color: var(--primary);
}

input {
    width: 100%;
    padding: var(--space-4) var(--space-4) var(--space-4) var(--space-12);
    background: var(--glass);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    color: var(--text-primary);
    font-size: 1rem;
    font-weight: 400;
    transition: all var(--transition-fast);
    outline: none;
}

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

input:focus {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
    background: rgba(255, 255, 255, 0.05);
}

input:invalid {
    border-color: var(--error-500);
}

/* Button Styles */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-2);
    padding: var(--space-4) var(--space-6);
    border: none;
    border-radius: var(--radius-lg);
    font-size: 1rem;
    font-weight: 500;
    text-decoration: none;
    cursor: pointer;
    transition: all var(--transition-fast);
    position: relative;
    overflow: hidden;
    min-height: 48px;
}

.btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: left var(--transition-slow);
}

.btn:hover::before {
    left: 100%;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-700) 100%);
    color: white;
    box-shadow: var(--shadow-md);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
    background: linear-gradient(135deg, var(--primary-500) 0%, var(--primary-600) 100%);
}

.btn-primary:active {
    transform: translateY(0);
}

.btn-success {
    background: linear-gradient(135deg, var(--success-500) 0%, #059669 100%);
    color: white;
    box-shadow: var(--shadow-md);
}

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

.btn-outline {
    background: transparent;
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

.btn-outline:hover {
    background: var(--glass);
    border-color: var(--primary);
    color: var(--primary);
}

.btn-link {
    background: none;
    border: none;
    color: var(--primary);
    cursor: pointer;
    text-decoration: none;
    font-weight: 500;
    padding: var(--space-1) var(--space-2);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
    display: inline-flex;
    align-items: center;
    gap: var(--space-1);
}

.btn-link:hover {
    background: rgba(59, 130, 246, 0.1);
    color: var(--primary-400);
}

/* Auth Footer */
.auth-footer {
    text-align: center;
    margin-top: var(--space-6);
    padding-top: var(--space-6);
    border-top: 1px solid var(--border-color);
}

.auth-footer p {
    color: var(--text-secondary);
    font-size: 0.875rem;
}

/* Registration Forms */
.register-form {
    margin-top: var(--space-8);
    padding: var(--space-8);
    max-width: 400px;
    width: 100%;
}

.form-header {
    text-align: center;
    margin-bottom: var(--space-6);
}

.form-header i {
    font-size: 2rem;
    color: var(--primary);
    margin-bottom: var(--space-2);
    display: block;
}

.form-header h3 {
    color: var(--text-primary);
    margin: 0;
}

/* Dashboard Styles */
.dashboard {
    min-height: 100vh;
    background: var(--background);
}

.dashboard-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--space-6) var(--space-8);
    background: var(--glass);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-left .logo-container {
    gap: var(--space-3);
}

.header-left .logo-icon {
    font-size: 2rem;
}

.header-left h1 {
    font-size: 1.75rem;
    margin: 0;
}

.header-actions {
    display: flex;
    gap: var(--space-4);
}

.dashboard-content {
    padding: var(--space-8);
    max-width: 1200px;
    margin: 0 auto;
}

/* Section Styles */
.section-header {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    margin-bottom: var(--space-6);
}

.section-icon {
    font-size: 1.5rem;
    color: var(--primary);
}

.section-header h2 {
    margin: 0;
    color: var(--text-primary);
}

/* Create Class Section */
.create-class-section {
    margin-bottom: var(--space-8);
    padding: var(--space-8);
}

.create-class-form {
    max-width: 600px;
}

.form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--space-4);
    margin-bottom: var(--space-6);
}

/* Classes Grid */
.classes-section {
    padding: var(--space-8);
}

.classes-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: var(--space-6);
    margin-top: var(--space-6);
}

.class-card {
    background: var(--card-bg);
    border-radius: var(--radius-xl);
    padding: var(--space-6);
    border: 1px solid var(--border-color);
    transition: all var(--transition-normal);
    position: relative;
    overflow: hidden;
}

.class-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(90deg, var(--primary) 0%, var(--secondary) 100%);
}

.class-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary);
}

.class-card h3 {
    color: var(--text-primary);
    margin-bottom: var(--space-3);
    font-size: 1.25rem;
}

.class-card p {
    color: var(--text-secondary);
    margin-bottom: var(--space-2);
    font-size: 0.875rem;
}

.class-code {
    display: inline-flex;
    align-items: center;
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-700) 100%);
    color: white;
    padding: var(--space-2) var(--space-3);
    border-radius: var(--radius-md);
    font-family: 'Monaco', 'Menlo', monospace;
    font-size: 0.875rem;
    font-weight: 600;
    margin: var(--space-3) 0;
    letter-spacing: 0.5px;
}

/* Class View */
.class-view {
    padding: var(--space-8);
    margin-top: var(--space-6);
}

.back-button {
    margin-bottom: var(--space-6);
    background: var(--glass);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

.back-button:hover {
    background: var(--primary);
    color: white;
    border-color: var(--primary);
}

/* Assignments Section */
.assignments-section {
    margin-top: var(--space-8);
}

.upload-assignment {
    display: flex;
    align-items: center;
    gap: var(--space-4);
    padding: var(--space-6);
    background: var(--glass);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
    margin: var(--space-6) 0;
}

#selected-file-name {
    flex: 1;
    color: var(--text-secondary);
    font-size: 0.875rem;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.assignments-list {
    margin-top: var(--space-6);
}

.assignment-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--space-4);
    background: var(--glass);
    border-radius: var(--radius-lg);
    border: 1px solid var(--border-color);
    margin-bottom: var(--space-3);
    transition: all var(--transition-fast);
}

.assignment-item:hover {
    background: rgba(255, 255, 255, 0.05);
    border-color: var(--primary);
}

.assignment-name {
    flex: 1;
    color: var(--text-primary);
    font-weight: 500;
    margin-right: var(--space-4);
}

.assignment-actions {
    display: flex;
    gap: var(--space-2);
}

.download-btn {
    padding: var(--space-2) var(--space-4);
    font-size: 0.875rem;
    min-height: auto;
}

/* Notifications */
.notification {
    position: fixed;
    top: var(--space-6);
    right: var(--space-6);
    display: flex;
    align-items: center;
    gap: var(--space-3);
    padding: var(--space-4) var(--space-6);
    border-radius: var(--radius-lg);
    color: white;
    font-weight: 500;
    transform: translateX(calc(100% + var(--space-6)));
    transition: transform var(--transition-normal);
    z-index: 1000;
    max-width: 400px;
    box-shadow: var(--shadow-xl);
    backdrop-filter: blur(20px);
}

.notification.show {
    transform: translateX(0);
}

.notification.success {
    background: linear-gradient(135deg, var(--success-500) 0%, #059669 100%);
    border: 1px solid rgba(16, 185, 129, 0.3);
}

.notification.error {
    background: linear-gradient(135deg, var(--error-500) 0%, #dc2626 100%);
    border: 1px solid rgba(239, 68, 68, 0.3);
}

.notification-icon {
    font-size: 1.25rem;
    flex-shrink: 0;
}

.notification-text {
    flex: 1;
}

/* Loading Spinner */
.loading-spinner {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    background: rgba(0, 0, 0, 0.8);
    backdrop-filter: blur(10px);
    z-index: 9999;
}

.spinner {
    font-size: 3rem;
    color: var(--primary);
    margin-bottom: var(--space-4);
}

.loading-spinner p {
    color: var(--text-primary);
    font-size: 1.125rem;
}

/* Utility Classes */
.hidden {
    display: none !important;
}

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

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

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

/* Responsive Design */
@media (max-width: 768px) {
    .auth-container {
        grid-template-columns: 1fr;
        gap: var(--space-6);
    }
    
    .auth-header h1 {
        font-size: 2.5rem;
    }
    
    .logo-icon {
        font-size: 2.5rem;
    }
    
    .dashboard-header {
        padding: var(--space-4);
        flex-direction: column;
        gap: var(--space-4);
        text-align: center;
    }
    
    .header-actions .btn-text {
        display: none;
    }
    
    .header-actions .btn {
        width: 48px;
        height: 48px;
        padding: 0;
        border-radius: 50%;
    }
    
    .dashboard-content {
        padding: var(--space-4);
    }
    
    .form-row {
        grid-template-columns: 1fr;
    }
    
    .classes-grid {
        grid-template-columns: 1fr;
    }
    
    .upload-assignment {
        flex-direction: column;
        align-items: stretch;
    }
    
    .assignment-item {
        flex-direction: column;
        align-items: stretch;
        gap: var(--space-3);
    }
    
    .assignment-actions {
        justify-content: center;
    }
    
    .notification {
        top: var(--space-4);
        right: var(--space-4);
        left: var(--space-4);
        max-width: none;
        transform: translateY(-100vh);
    }
    
    .notification.show {
        transform: translateY(0);
    }
}

@media (max-width: 480px) {
    #auth-section {
        padding: var(--space-4);
    }
    
    .auth-header {
        margin-bottom: var(--space-8);
    }
    
    .auth-header h1 {
        font-size: 2rem;
    }
    
    .auth-card {
        padding: var(--space-6);
    }
    
    .register-form {
        padding: var(--space-6);
    }
}

/* Focus Styles for Accessibility */
.btn:focus-visible,
input:focus-visible {
    outline: 2px solid var(--primary);
    outline-offset: 2px;
}

/* Smooth Scrolling */
html {
    scroll-behavior: smooth;
}

/* Selection Styles */
::selection {
    background: var(--primary);
    color: white;
}

/* Scrollbar Styles */
::-webkit-scrollbar {
    width: 8px;
}

::-webkit-scrollbar-track {
    background: var(--background-secondary);
}

::-webkit-scrollbar-thumb {
    background: var(--primary);
    border-radius: var(--radius-md);
}

::-webkit-scrollbar-thumb:hover {
    background: var(--primary-600);
}