:root {
    /* Colors */
    --primary: #1e40af;
    --primary-light: #3b82f6;
    --primary-dark: #1e3a8a;
    --secondary: #f59e0b;
    --success: #10b981;
    --danger: #ef4444;
    --warning: #f59e0b;
    --background: #f3f4f6;
    --surface: #ffffff;
    --text-main: #1f2937;
    --text-muted: #6b7280;
    --border: #e5e7eb;
    
    /* 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);
    
    /* Border Radius */
    --radius-md: 0.5rem;
    --radius-lg: 1rem;
    --radius-full: 9999px;
    
    /* Transitions */
    --transition: all 0.3s ease;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

body {
    background-color: var(--background);
    color: var(--text-main);
    line-height: 1.5;
    -webkit-font-smoothing: antialiased;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    color: var(--text-main);
    font-weight: 700;
}

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

a:hover {
    color: var(--primary-dark);
}

/* Layout */
.container {
    width: 100%;
    max-width: 480px; /* Mobile first approach for student app */
    margin: 0 auto;
    min-height: 100vh;
    background: var(--surface);
    position: relative;
    box-shadow: var(--shadow-lg);
    display: flex;
    flex-direction: column;
}

.admin-container {
    max-width: 1200px;
    padding: 2rem;
    background: transparent;
    box-shadow: none;
}

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

.form-label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
    font-size: 0.875rem;
    color: var(--text-main);
}

.form-control {
    width: 100%;
    padding: 0.75rem 1rem;
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    font-size: 1rem;
    transition: var(--transition);
    background-color: #f9fafb;
}

.form-control:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.25);
    background-color: var(--surface);
}

select.form-control {
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' fill='none' viewBox='0 0 24 24' stroke='%236b7280'%3E%3Cpath stroke-linecap='round' stroke-linejoin='round' stroke-width='2' d='M19 9l-7 7-7-7'%3E%3C/path%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 1rem center;
    background-size: 1.25rem;
}

textarea.form-control {
    min-height: 120px;
    resize: vertical;
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: var(--radius-md);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    text-align: center;
    width: 100%;
}

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

.btn-primary:hover {
    background-color: var(--primary-dark);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

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

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

/* Header */
.app-header {
    background: linear-gradient(135deg, var(--primary), var(--primary-light));
    color: white;
    padding: 2rem 1.5rem;
    border-bottom-left-radius: 1.5rem;
    border-bottom-right-radius: 1.5rem;
    box-shadow: var(--shadow-md);
}

.app-header.small {
    padding: 1.5rem;
    display: flex;
    align-items: center;
    gap: 1rem;
}

.app-header.small .back-btn {
    color: white;
    font-size: 1.5rem;
}

.header-title {
    font-size: 1.5rem;
    margin-bottom: 0.25rem;
}

.header-subtitle {
    font-size: 0.875rem;
    opacity: 0.9;
}

/* Login Page specific */
.login-content {
    flex: 1;
    padding: 2rem 1.5rem;
    display: flex;
    flex-direction: column;
    justify-content: center;
}

.logo-container {
    text-align: center;
    margin-bottom: 2rem;
}

.logo-circle {
    width: 80px;
    height: 80px;
    background: var(--primary-light);
    color: white;
    border-radius: var(--radius-full);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    font-size: 2.5rem;
    margin-bottom: 1rem;
    box-shadow: var(--shadow-md);
}

/* Menu Page */
.menu-content {
    padding: 1.5rem;
    flex: 1;
}

.welcome-card {
    background: white;
    padding: 1.5rem;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border);
    margin-bottom: 2rem;
    display: flex;
    align-items: center;
    gap: 1rem;
}

.avatar {
    width: 50px;
    height: 50px;
    background: var(--primary-light);
    color: white;
    border-radius: var(--radius-full);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.25rem;
    font-weight: 600;
}

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

.menu-item {
    background: white;
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    display: flex;
    align-items: center;
    gap: 1rem;
    transition: var(--transition);
    cursor: pointer;
    box-shadow: var(--shadow-sm);
}

.menu-item:hover {
    border-color: var(--primary);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.menu-icon {
    width: 48px;
    height: 48px;
    border-radius: var(--radius-md);
    background: rgba(59, 130, 246, 0.1);
    color: var(--primary);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
}

.menu-text {
    flex: 1;
}

.menu-text h3 {
    font-size: 1rem;
    margin-bottom: 0.25rem;
}

.menu-text p {
    font-size: 0.75rem;
    color: var(--text-muted);
}

/* File Upload custom */
.file-upload-wrapper {
    position: relative;
    border: 2px dashed var(--border);
    border-radius: var(--radius-md);
    padding: 2rem;
    text-align: center;
    transition: var(--transition);
    background-color: #f9fafb;
    cursor: pointer;
}

.file-upload-wrapper:hover {
    border-color: var(--primary);
    background-color: rgba(59, 130, 246, 0.05);
}

.file-upload-input {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    opacity: 0;
    cursor: pointer;
}

.file-upload-icon {
    font-size: 2rem;
    color: var(--primary-light);
    margin-bottom: 0.5rem;
}

#preview-container {
    margin-top: 1rem;
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.preview-img {
    width: 80px;
    height: 80px;
    object-fit: cover;
    border-radius: var(--radius-md);
    border: 1px solid var(--border);
}

/* Toggle Switch */
.switch-wrapper {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 1rem;
    background: #f9fafb;
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
}

.switch {
    position: relative;
    display: inline-block;
    width: 50px;
    height: 28px;
}

.switch input {
    opacity: 0;
    width: 0;
    height: 0;
}

.slider {
    position: absolute;
    cursor: pointer;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: #ccc;
    transition: .4s;
    border-radius: 34px;
}

.slider:before {
    position: absolute;
    content: "";
    height: 20px;
    width: 20px;
    left: 4px;
    bottom: 4px;
    background-color: white;
    transition: .4s;
    border-radius: 50%;
}

input:checked + .slider {
    background-color: var(--primary);
}

input:checked + .slider:before {
    transform: translateX(22px);
}

/* Admin Dashboard Specific */
.admin-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
}

.admin-header h1 {
    font-size: 1.875rem;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    margin-bottom: 2rem;
}

.stat-card {
    background: white;
    padding: 1.5rem;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border);
    display: flex;
    align-items: center;
    gap: 1.5rem;
}

.stat-icon {
    width: 60px;
    height: 60px;
    border-radius: var(--radius-full);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.75rem;
}

.stat-icon.all { background: rgba(59, 130, 246, 0.1); color: var(--primary); }
.stat-icon.processing { background: rgba(245, 158, 11, 0.1); color: var(--warning); }
.stat-icon.done { background: rgba(16, 185, 129, 0.1); color: var(--success); }

.stat-info h3 {
    font-size: 0.875rem;
    color: var(--text-muted);
    font-weight: 600;
}

.stat-info p {
    font-size: 1.875rem;
    font-weight: 700;
    color: var(--text-main);
    line-height: 1;
    margin-top: 0.25rem;
}

.table-container {
    background: white;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border);
    overflow: hidden;
}

.tabs {
    display: flex;
    border-bottom: 1px solid var(--border);
    background: #f9fafb;
}

.tab {
    padding: 1rem 1.5rem;
    font-weight: 600;
    color: var(--text-muted);
    cursor: pointer;
    border-bottom: 2px solid transparent;
    transition: var(--transition);
}

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

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

.table {
    width: 100%;
    border-collapse: collapse;
}

.table th, .table td {
    padding: 1rem 1.5rem;
    text-align: left;
    border-bottom: 1px solid var(--border);
}

.table th {
    font-weight: 600;
    color: var(--text-muted);
    font-size: 0.875rem;
    background: #f9fafb;
}

.table tr:last-child td {
    border-bottom: none;
}

.badge {
    padding: 0.25rem 0.75rem;
    border-radius: var(--radius-full);
    font-size: 0.75rem;
    font-weight: 600;
}

.badge-processing {
    background: rgba(245, 158, 11, 0.1);
    color: #d97706;
}

.badge-done {
    background: rgba(16, 185, 129, 0.1);
    color: #059669;
}

/* Responsive */
@media (max-width: 768px) {
    .admin-container {
        padding: 1rem;
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
    }
    
    .table-responsive {
        overflow-x: auto;
    }
}