* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Poppins', sans-serif;
}

:root {
    --primary-color: #6366f1;
    --primary-light: #818cf8;
    --primary-dark: #4f46e5;
    --success-color: #10b981;
    --danger-color: #ef4444;
    --warning-color: #f59e0b;
}

/* Light Mode Variables */
.light-mode {
    --bg-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --bg-color: #f3f4f6;
    --text-color: #1f2937;
    --text-secondary: #4b5563;
    --card-bg: rgba(255, 255, 255, 0.25);
    --card-border: rgba(255, 255, 255, 0.18);
    --glass-bg: rgba(255, 255, 255, 0.25);
    --glass-border: rgba(255, 255, 255, 0.18);
    --shadow-color: rgba(0, 0, 0, 0.1);
    --nav-bg: rgba(255, 255, 255, 0.8);
    --input-bg: white;
    --input-border: #e5e7eb;
    --hover-color: #f9fafb;
}

/* Dark Mode Variables */
.dark-mode {
    --bg-gradient: linear-gradient(135deg, #1a1a2e 0%, #16213e 100%);
    --bg-color: #0f172a;
    --text-color: #f3f4f6;
    --text-secondary: #cbd5e1;
    --card-bg: rgba(15, 23, 42, 0.7);
    --card-border: rgba(255, 255, 255, 0.08);
    --glass-bg: rgba(15, 23, 42, 0.7);
    --glass-border: rgba(255, 255, 255, 0.08);
    --shadow-color: rgba(0, 0, 0, 0.3);
    --nav-bg: rgba(15, 23, 42, 0.9);
    --input-bg: #1e293b;
    --input-border: #334155;
    --hover-color: #1e293b;
}

body {
    background: var(--bg-gradient);
    color: var(--text-color);
    min-height: 100vh;
    transition: all 0.3s ease;
}

/* Navbar Styles */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: var(--nav-bg);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--glass-border);
    z-index: 1000;
    animation: slideDown 0.5s ease;
}

@keyframes slideDown {
    from {
        transform: translateY(-100%);
    }
    to {
        transform: translateY(0);
    }
}

.nav-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    font-size: 1.5rem;
    font-weight: 700;
}

.logo i {
    color: var(--primary-color);
    font-size: 2rem;
}

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

.nav-right {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.theme-btn {
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: 50%;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    color: var(--text-color);
    font-size: 1.2rem;
    transition: all 0.3s ease;
}

.theme-btn:hover {
    transform: rotate(45deg);
    background: var(--primary-color);
    color: white;
}

.user-menu {
    display: flex;
    align-items: center;
    gap: 1rem;
    background: var(--glass-bg);
    padding: 0.5rem 1rem;
    border-radius: 50px;
    border: 1px solid var(--glass-border);
}

.user-name {
    font-weight: 500;
}

.logout-btn {
    background: none;
    border: none;
    color: var(--danger-color);
    font-size: 1.2rem;
    cursor: pointer;
    padding: 0.5rem;
    border-radius: 50%;
    transition: all 0.3s ease;
}

.logout-btn:hover {
    background: var(--danger-color);
    color: white;
}

/* Auth Container */
.auth-container {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 2rem;
    margin-top: 60px;
    animation: fadeIn 0.5s ease;
}

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

.auth-card {
    max-width: 500px;
    width: 100%;
    padding: 2.5rem;
    border-radius: 20px;
    background: var(--glass-bg);
    backdrop-filter: blur(10px);
    border: 1px solid var(--glass-border);
    box-shadow: 0 8px 32px var(--shadow-color);
}

.auth-header {
    text-align: center;
    margin-bottom: 2rem;
}

.auth-header h2 {
    font-size: 2rem;
    margin-bottom: 0.5rem;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

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

.auth-tabs {
    display: flex;
    gap: 1rem;
    margin-bottom: 2rem;
    background: var(--input-bg);
    padding: 0.5rem;
    border-radius: 10px;
}

.tab-btn {
    flex: 1;
    padding: 0.75rem;
    border: none;
    background: none;
    color: var(--text-secondary);
    font-weight: 500;
    cursor: pointer;
    border-radius: 8px;
    transition: all 0.3s ease;
}

.tab-btn.active {
    background: var(--primary-color);
    color: white;
}

.auth-form {
    display: none;
}

.auth-form.active {
    display: block;
    animation: slideUp 0.5s ease;
}

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

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

.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.form-group label i {
    margin-right: 0.5rem;
    color: var(--primary-color);
}

.form-group input,
.form-group select {
    width: 100%;
    padding: 0.75rem 1rem;
    border: 2px solid var(--input-border);
    border-radius: 10px;
    background: var(--input-bg);
    color: var(--text-color);
    font-size: 1rem;
    transition: all 0.3s ease;
}

.form-group input:focus,
.form-group select:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.auth-submit-btn {
    width: 100%;
    padding: 1rem;
    border: none;
    border-radius: 10px;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
    color: white;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    transition: all 0.3s ease;
}

.auth-submit-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 20px rgba(99, 102, 241, 0.4);
}

/* App Container */
.app-container {
    margin-top: 80px;
    padding: 2rem;
    min-height: calc(100vh - 80px);
}

.dashboard {
    display: grid;
    grid-template-columns: 280px 1fr;
    gap: 2rem;
    max-width: 1400px;
    margin: 0 auto;
}

/* Sidebar */
.sidebar {
    padding: 2rem;
    border-radius: 20px;
    background: var(--glass-bg);
    backdrop-filter: blur(10px);
    border: 1px solid var(--glass-border);
    height: fit-content;
    position: sticky;
    top: 100px;
    animation: slideLeft 0.5s ease;
}

@keyframes slideLeft {
    from {
        opacity: 0;
        transform: translateX(-20px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

.user-profile {
    text-align: center;
    padding-bottom: 2rem;
    border-bottom: 1px solid var(--glass-border);
    margin-bottom: 2rem;
}

.user-avatar {
    width: 100px;
    height: 100px;
    margin: 0 auto 1rem;
    background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 3rem;
    color: white;
}

.user-profile h3 {
    margin-bottom: 0.5rem;
}

.user-class {
    color: var(--text-secondary);
    font-size: 0.9rem;
}

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

.menu-item {
    padding: 1rem;
    border: none;
    background: none;
    color: var(--text-secondary);
    font-size: 1rem;
    font-weight: 500;
    text-align: left;
    border-radius: 10px;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 1rem;
    transition: all 0.3s ease;
}

.menu-item i {
    width: 20px;
    color: var(--primary-color);
}

.menu-item:hover,
.menu-item.active {
    background: var(--hover-color);
    color: var(--text-color);
}

/* Main Content */
.main-content {
    animation: fadeIn 0.5s ease;
}

.schedule-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
    padding: 1rem;
    background: var(--glass-bg);
    backdrop-filter: blur(10px);
    border-radius: 15px;
    border: 1px solid var(--glass-border);
}

.schedule-header h1 {
    font-size: 1.8rem;
    display: flex;
    align-items: center;
    gap: 1rem;
}

.schedule-header h1 i {
    color: var(--primary-color);
}

.class-badge {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
    color: white;
    padding: 0.5rem 1.5rem;
    border-radius: 50px;
    font-weight: 600;
}

/* Add Lesson Form */
.add-lesson-form {
    margin-bottom: 2rem;
    padding: 2rem;
    border-radius: 15px;
    background: var(--glass-bg);
    backdrop-filter: blur(10px);
    border: 1px solid var(--glass-border);
}

.add-lesson-form h3 {
    margin-bottom: 1.5rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--primary-color);
}

.form-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.form-actions {
    display: flex;
    gap: 1rem;
    justify-content: flex-end;
}

.btn-primary,
.btn-secondary {
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 8px;
    font-weight: 500;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    transition: all 0.3s ease;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
    color: white;
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 20px rgba(99, 102, 241, 0.4);
}

.btn-secondary {
    background: var(--input-bg);
    color: var(--text-secondary);
    border: 1px solid var(--glass-border);
}

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

/* Schedule Grid */
.schedule-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
}

.day-card {
    background: var(--glass-bg);
    backdrop-filter: blur(10px);
    border: 1px solid var(--glass-border);
    border-radius: 15px;
    padding: 1.5rem;
    animation: cardAppear 0.5s ease;
    transition: all 0.3s ease;
}

@keyframes cardAppear {
    from {
        opacity: 0;
        transform: scale(0.9);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}

.day-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 30px var(--shadow-color);
}

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

.day-header h3 {
    font-size: 1.2rem;
    text-transform: capitalize;
}

.day-header i {
    color: var(--primary-color);
    font-size: 1.2rem;
}

.lesson-item {
    background: var(--input-bg);
    padding: 1rem;
    border-radius: 10px;
    margin-bottom: 0.75rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    animation: slideIn 0.3s ease;
    border: 1px solid var(--glass-border);
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateX(-10px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

.lesson-info {
    flex: 1;
}

.lesson-name {
    font-weight: 600;
    margin-bottom: 0.25rem;
}

.lesson-details {
    font-size: 0.85rem;
    color: var(--text-secondary);
    display: flex;
    gap: 1rem;
}

.lesson-details i {
    color: var(--primary-color);
    margin-right: 0.25rem;
}

.lesson-actions {
    display: flex;
    gap: 0.5rem;
}

.edit-btn,
.delete-btn {
    padding: 0.4rem;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.3s ease;
}

.edit-btn {
    background: var(--warning-color);
    color: white;
}

.delete-btn {
    background: var(--danger-color);
    color: white;
}

.edit-btn:hover,
.delete-btn:hover {
    transform: scale(1.1);
}

.no-lessons {
    text-align: center;
    color: var(--text-secondary);
    padding: 2rem;
    font-style: italic;
}

/* Responsive Design */
@media (max-width: 1024px) {
    .dashboard {
        grid-template-columns: 1fr;
    }
    
    .sidebar {
        position: static;
    }
}

@media (max-width: 768px) {
    .nav-container {
        padding: 1rem;
    }
    
    .logo span {
        display: none;
    }
    
    .form-row {
        grid-template-columns: 1fr;
    }
    
    .schedule-grid {
        grid-template-columns: 1fr;
    }
    
    .schedule-header {
        flex-direction: column;
        gap: 1rem;
        text-align: center;
    }
    
    .form-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .auth-card {
        padding: 1.5rem;
    }
    
    .user-name {
        display: none;
    }
    
    .lesson-item {
        flex-direction: column;
        gap: 0.5rem;
        text-align: center;
    }
    
    .lesson-actions {
        width: 100%;
        justify-content: center;
    }
}

/* Glassmorphism Class */
.glass {
    background: var(--glass-bg);
    backdrop-filter: blur(10px);
    border: 1px solid var(--glass-border);
}

/* Animations */
.fade-in {
    animation: fadeIn 0.5s ease;
}

.slide-up {
    animation: slideUp 0.5s ease;
}