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

:root {
    --primary: #6366f1;
    --primary-dark: #4f46e5;
    --secondary: #8b5cf6;
    --success: #10b981;
    --danger: #ef4444;
    --warning: #f59e0b;
    --dark: #1e293b;
    --light: #f1f5f9;
    --white: #ffffff;
    --shadow: 0 4px 6px -1px rgba(0,0,0,0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.1);
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    color: var(--dark);
}

/* ============================================
   HAMBURGER MENU (Mobile Only)
   ============================================ */
.hamburger-btn {
    display: none; /* Hidden by default on desktop */
    position: fixed;
    top: 20px;
    left: 20px;
    z-index: 1001;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    border: none;
    border-radius: 12px;
    padding: 14px 16px;
    cursor: pointer;
    box-shadow: 0 4px 15px rgba(99, 102, 241, 0.4);
    transition: all 0.3s;
}

.hamburger-btn:hover {
    transform: scale(1.1);
}

.hamburger-icon {
    width: 25px;
    height: 20px;
    position: relative;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
}

.hamburger-icon span {
    display: block;
    height: 3px;
    background: var(--white);
    border-radius: 2px;
    transition: all 0.3s;
}

.hamburger-btn.active .hamburger-icon span:nth-child(1) {
    transform: translateY(8.5px) rotate(45deg);
}

.hamburger-btn.active .hamburger-icon span:nth-child(2) {
    opacity: 0;
}

.hamburger-btn.active .hamburger-icon span:nth-child(3) {
    transform: translateY(-8.5px) rotate(-45deg);
}

/* Overlay untuk mobile */
.sidebar-overlay {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    z-index: 999;
    opacity: 0;
    transition: opacity 0.3s;
}

.sidebar-overlay.active {
    display: block;
    opacity: 1;
}

/* Auth Pages */
.auth-container {
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    padding: 20px;
}

.auth-card {
    background: var(--white);
    border-radius: 20px;
    box-shadow: var(--shadow-lg);
    width: 100%;
    max-width: 450px;
    padding: 40px;
    animation: slideUp 0.5s ease;
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.auth-logo {
    text-align: center;
    margin-bottom: 30px;
}

.auth-logo h1 {
    font-size: 2.5rem;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    font-weight: 800;
}

.auth-logo p {
    color: #64748b;
    margin-top: 8px;
}

.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
    color: var(--dark);
}

.form-control {
    width: 100%;
    padding: 12px 16px;
    border: 2px solid #e2e8f0;
    border-radius: 10px;
    font-size: 1rem;
    transition: all 0.3s;
}

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

.form-check {
    display: flex;
    align-items: center;
    gap: 8px;
    margin: 15px 0;
}

.btn {
    padding: 12px 24px;
    border: none;
    border-radius: 10px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s;
    text-decoration: none;
    display: inline-block;
    text-align: center;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: var(--white);
    width: 100%;
}

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

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

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

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

.btn-sm {
    padding: 8px 16px;
    font-size: 0.875rem;
}

.auth-links {
    text-align: center;
    margin-top: 20px;
}

.auth-links a {
    color: var(--primary);
    text-decoration: none;
    font-weight: 600;
}

/* Dashboard Layout */
.dashboard {
    display: flex;
    min-height: 100vh;
}

.sidebar {
    width: 280px;
    background: var(--white);
    box-shadow: var(--shadow);
    position: fixed;
    height: 100vh;
    overflow-y: auto;
    transition: transform 0.3s;
    z-index: 1000;
}

.sidebar-header {
    padding: 30px 20px;
    text-align: center;
    border-bottom: 2px solid var(--light);
}

.sidebar-header h2 {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    font-size: 1.8rem;
}

.profile-section {
    padding: 20px;
    text-align: center;
    border-bottom: 2px solid var(--light);
}

.profile-avatar {
    width: 80px;
    height: 80px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 10px;
    font-size: 2rem;
    color: var(--white);
    font-weight: 700;
}

.nav-menu {
    padding: 20px 0;
}

.nav-item {
    padding: 15px 25px;
    display: flex;
    align-items: center;
    gap: 12px;
    color: var(--dark);
    text-decoration: none;
    transition: all 0.3s;
    border-left: 3px solid transparent;
}

.nav-item:hover,
.nav-item.active {
    background: var(--light);
    border-left-color: var(--primary);
    color: var(--primary);
}

.nav-icon {
    font-size: 1.2rem;
}

.main-content {
    flex: 1;
    margin-left: 280px;
    padding: 30px;
    transition: margin-left 0.3s;
}

.top-bar {
    background: var(--white);
    padding: 20px 30px;
    border-radius: 15px;
    box-shadow: var(--shadow);
    margin-bottom: 30px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 15px;
}

.class-id-badge {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: var(--white);
    padding: 10px 20px;
    border-radius: 10px;
    font-weight: 600;
    display: inline-flex;
    align-items: center;
    gap: 10px;
}

/* Cards Grid */
.cards-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 25px;
    margin-top: 20px;
}

.card {
    background: var(--white);
    border-radius: 15px;
    padding: 25px;
    box-shadow: var(--shadow);
    transition: all 0.3s;
    position: relative;
    overflow: hidden;
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

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

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: start;
    margin-bottom: 15px;
}

.card-title {
    font-size: 1.3rem;
    font-weight: 700;
    color: var(--dark);
}

.card-subtitle {
    color: #64748b;
    margin-top: 5px;
    font-size: 0.9rem;
}

.card-actions {
    display: flex;
    gap: 10px;
}

.icon-btn {
    width: 35px;
    height: 35px;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.3s;
    border: none;
    background: var(--light);
}

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

.add-card {
    border: 2px dashed #cbd5e1;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    min-height: 200px;
    cursor: pointer;
    transition: all 0.3s;
}

.add-card:hover {
    border-color: var(--primary);
    background: rgba(99, 102, 241, 0.05);
}

.add-icon {
    font-size: 3rem;
    color: var(--primary);
    margin-bottom: 10px;
}

/* Groups */
.groups-container {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 20px;
}

.group-card {
    background: var(--white);
    border-radius: 12px;
    padding: 20px;
    box-shadow: var(--shadow);
    position: relative;
}

.group-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 15px;
    padding-bottom: 15px;
    border-bottom: 2px solid var(--light);
}

.group-number {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: var(--white);
    width: 40px;
    height: 40px;
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 700;
    font-size: 1.2rem;
}

.members-list {
    margin: 15px 0;
}

.member-item {
    background: var(--light);
    padding: 10px;
    border-radius: 8px;
    margin-bottom: 8px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.member-info h4 {
    font-size: 0.95rem;
    margin-bottom: 3px;
}

.member-info p {
    font-size: 0.8rem;
    color: #64748b;
}

/* Modal */
.modal {
    display: none;
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background: rgba(0,0,0,0.5);
    animation: fadeIn 0.3s;
}

.modal.show {
    display: flex;
    align-items: center;
    justify-content: center;
}

.modal-content {
    background: var(--white);
    border-radius: 15px;
    padding: 30px;
    width: 90%;
    max-width: 500px;
    max-height: 90vh;
    overflow-y: auto;
    animation: slideUp 0.3s;
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
    padding-bottom: 15px;
    border-bottom: 2px solid var(--light);
}

.close-btn {
    font-size: 1.5rem;
    cursor: pointer;
    color: #64748b;
    background: none;
    border: none;
}

/* Alert */
.alert {
    padding: 15px 20px;
    border-radius: 10px;
    margin-bottom: 20px;
    display: flex;
    align-items: center;
    gap: 10px;
}

.alert-success {
    background: #d1fae5;
    color: #065f46;
    border-left: 4px solid var(--success);
}

.alert-danger {
    background: #fee2e2;
    color: #991b1b;
    border-left: 4px solid var(--danger);
}

.alert-warning {
    background: #fef3c7;
    color: #92400e;
    border-left: 4px solid var(--warning);
}

/* Badge */
.badge {
    display: inline-block;
    padding: 5px 12px;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 600;
}

.badge-primary {
    background: var(--primary);
    color: var(--white);
}

.badge-success {
    background: var(--success);
    color: var(--white);
}

/* ============================================
   RESPONSIVE - MOBILE
   ============================================ */
@media (max-width: 768px) {
    /* CRITICAL: Show hamburger button on mobile */
    .hamburger-btn {
        display: block !important; /* Force display */
    }
    
    /* Hide sidebar by default */
    .sidebar {
        transform: translateX(-100%);
    }
    
    /* Show sidebar when active */
    .sidebar.active {
        transform: translateX(0);
    }
    
    /* Adjust main content */
    .main-content {
        margin-left: 0;
        padding: 80px 15px 20px 15px; /* Extra padding top for hamburger */
    }
    
    /* Cards grid - single column */
    .cards-grid {
        grid-template-columns: 1fr;
    }
    
    /* Groups grid - single column */
    .groups-container {
        grid-template-columns: 1fr;
    }
    
    /* Top bar responsive */
    .top-bar {
        flex-direction: column;
        align-items: flex-start;
        padding: 15px 20px;
    }
    
    .top-bar h1 {
        font-size: 1.5rem;
    }
    
    /* Auth card mobile */
    .auth-card {
        padding: 25px;
    }
    
    .auth-logo h1 {
        font-size: 2rem;
    }
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}