:root {
    --primary-color: #667eea;
    --primary-dark: #5568d3;
    --secondary-color: #764ba2;
    --accent-color: #f093fb;
    --success-color: #10b981;
    --danger-color: #ef4444;
    --warning-color: #f59e0b;
    --dark: #1f2937;
    --gray-50: #f9fafb;
    --gray-100: #f3f4f6;
    --gray-200: #e5e7eb;
    --gray-300: #d1d5db;
    --gray-600: #4b5563;
    --gray-700: #374151;
    --gray-800: #1f2937;
    --gray-900: #111827;
    --white: #ffffff;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
    --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);
    --border-radius: 12px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    color: var(--gray-900);
    line-height: 1.6;
    padding: 0;
    margin: 0;
}

/* Modern Navbar */
.navbar {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    box-shadow: var(--shadow-md);
    padding: 1rem 2rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    position: sticky;
    top: 0;
    z-index: 1000;
    border-bottom: 1px solid var(--gray-200);
}

.navbar a {
    color: var(--gray-700);
    text-decoration: none;
    padding: 0.75rem 1.5rem;
    margin: 0 0.25rem;
    border-radius: 8px;
    font-weight: 500;
    transition: var(--transition);
    display: inline-block;
}

.navbar a:hover {
    background: var(--primary-color);
    color: var(--white);
    transform: translateY(-2px);
}

.navbar a:active {
    transform: translateY(0);
}

/* Container */
.container {
    max-width: 1200px;
    margin: 2rem auto;
    background: var(--white);
    padding: 2.5rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-xl);
    animation: fadeIn 0.5s ease-in-out;
}

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

/* Typography */
h1 {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--gray-900);
    margin-bottom: 1.5rem;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

h2 {
    font-size: 1.875rem;
    font-weight: 600;
    color: var(--gray-800);
    margin-bottom: 1rem;
    margin-top: 2rem;
}

h3 {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--gray-700);
    margin-bottom: 0.75rem;
}

h4 {
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--gray-700);
    margin-bottom: 0.5rem;
}

p {
    color: var(--gray-600);
    margin-bottom: 1rem;
}

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

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

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

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    color: var(--gray-700);
    font-size: 0.95rem;
}

.form-group input,
.form-group textarea,
.form-control {
    width: 100%;
    padding: 0.875rem 1rem;
    border: 2px solid var(--gray-200);
    border-radius: 8px;
    font-size: 1rem;
    transition: var(--transition);
    background: var(--white);
    color: var(--gray-900);
    font-family: inherit;
}

.form-group input:focus,
.form-group textarea:focus,
.form-control:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

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

/* Modern Buttons */
.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    font-size: 1rem;
    font-weight: 500;
    text-align: center;
    text-decoration: none;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    transition: var(--transition);
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: var(--white);
    box-shadow: var(--shadow-md);
    margin-right: 0.5rem;
    margin-bottom: 0.5rem;
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
    text-decoration: none;
    color: var(--white);
}

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

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

.btn-danger {
    background: linear-gradient(135deg, #ef4444, #dc2626);
}

.btn-success {
    background: linear-gradient(135deg, var(--success-color), #059669);
}

.btn-secondary {
    background: var(--gray-600);
}

/* Alert Styles */
.alert {
    padding: 1rem 1.25rem;
    margin-bottom: 1.5rem;
    border-radius: 8px;
    border-left: 4px solid;
    animation: slideIn 0.3s ease-out;
}

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

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

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

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

/* Modern Table */
.table {
    width: 100%;
    border-collapse: separate;
    border-spacing: 0;
    margin-top: 1.5rem;
    background: var(--white);
    border-radius: 8px;
    overflow: hidden;
    box-shadow: var(--shadow);
}

.table thead {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
}

.table thead th {
    padding: 1rem;
    text-align: left;
    font-weight: 600;
    color: var(--white);
    font-size: 0.875rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.table tbody tr {
    border-bottom: 1px solid var(--gray-200);
    transition: var(--transition);
}

.table tbody tr:hover {
    background: var(--gray-50);
    transform: scale(1.01);
}

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

.chat-header p {
    color: white;
}

.table tbody td {
    padding: 1rem;
    color: var(--gray-700);
}

/* Card Component */
.card {
    background: var(--white);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    margin-bottom: 1.5rem;
    box-shadow: var(--shadow);
    transition: var(--transition);
    border: 1px solid var(--gray-200);
}

.card:hover {
    box-shadow: var(--shadow-lg);
    transform: translateY(-4px);
}

.card h2, .card h3 {
    margin-top: 0;
}

/* Section */
.section {
    background: var(--gray-50);
    border-radius: var(--border-radius);
    padding: 2rem;
    margin-bottom: 2rem;
    border: 1px solid var(--gray-200);
}

.section h2 {
    margin-top: 0;
    color: var(--gray-800);
    border-bottom: 2px solid var(--primary-color);
    padding-bottom: 0.5rem;
    display: inline-block;
}

/* List Styles */
ul {
    list-style: none;
    padding: 0;
}

ul li {
    padding: 1rem;
    margin-bottom: 0.75rem;
    background: var(--white);
    border-radius: 8px;
    border-left: 4px solid var(--primary-color);
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
}

ul li:hover {
    box-shadow: var(--shadow-md);
    transform: translateX(4px);
}

ul li strong {
    color: var(--gray-900);
    font-size: 1.1rem;
    display: block;
    margin-bottom: 0.25rem;
}

/* Badge */
.badge {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    font-size: 0.875rem;
    font-weight: 500;
    border-radius: 9999px;
    background: var(--primary-color);
    color: var(--white);
}

/* Course Grid */
.course-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1.5rem;
    margin-top: 2rem;
}

.course-card {
    background: var(--white);
    border-radius: var(--border-radius);
    padding: 1.5rem;
    box-shadow: var(--shadow);
    transition: var(--transition);
    border: 1px solid var(--gray-200);
    display: flex;
    flex-direction: column;
}

.course-card:hover {
    box-shadow: var(--shadow-xl);
    transform: translateY(-8px);
    border-color: var(--primary-color);
}

.course-card h2 {
    margin-top: 0;
    font-size: 1.5rem;
    margin-bottom: 0.75rem;
}

.course-card h2 a {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    text-decoration: none;
}

.course-card p {
    flex-grow: 1;
    margin-bottom: 1rem;
}

/* Utilities */
.text-center {
    text-align: center;
}

.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mt-4 { margin-top: 2rem; }

.mb-1 { margin-bottom: 0.5rem; }
.mb-2 { margin-bottom: 1rem; }
.mb-3 { margin-bottom: 1.5rem; }
.mb-4 { margin-bottom: 2rem; }

.flex {
    display: flex;
}

.justify-between {
    justify-content: space-between;
}

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

.gap-2 {
    gap: 1rem;
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        margin: 1rem;
        padding: 1.5rem;
    }

    .navbar {
        flex-direction: column;
        padding: 1rem;
    }

    .navbar a {
        margin: 0.25rem 0;
    }

    h1 {
        font-size: 2rem;
    }

    .course-grid {
        grid-template-columns: 1fr;
    }
}

/* Loading Animation */
.loading {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 3px solid rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    border-top-color: var(--white);
    animation: spin 1s ease-in-out infinite;
}

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