:root {
    --color-primary: #3A3B92;
    --color-secondary: #5D5FB6;
    --color-accent: #20408E;
    --color-bg: #F4F5F6;
    --color-surface: #FFFFFF;
    --color-text: #25264D;
    --color-text-alt: #6E6E7E;
    --color-divider: #D1D1E0;
    --color-success: #28A745;
    --color-warning: #FFC107;
    --color-error: #DC3545;
}

/* Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background: linear-gradient(135deg, var(--color-bg) 0%, #e0e1f0 100%);
    min-height: 100vh;
    color: var(--color-text);
    line-height: 1.6;
    position: relative;
    overflow-x: hidden;
    padding-bottom: 40px;
}

/* Background decorative elements */
body::before,
body::after {
    content: "";
    position: absolute;
    border-radius: 50%;
    z-index: -1;
}

body::before {
    width: 300px;
    height: 300px;
    background: radial-gradient(circle, var(--color-secondary) 0%, transparent 70%);
    opacity: 0.3;
    top: -100px;
    right: -100px;
}

body::after {
    width: 250px;
    height: 250px;
    background: radial-gradient(circle, var(--color-accent) 0%, transparent 70%);
    opacity: 0.2;
    bottom: -100px;
    left: -50px;
}

.bg-shape {
    position: absolute;
    z-index: -1;
    opacity: 0.1;
}

.shape-1 {
    top: 20%;
    left: 10%;
    width: 100px;
    height: 100px;
    background-color: var(--color-primary);
    border-radius: 20px;
    transform: rotate(45deg);
}

.shape-2 {
    bottom: 15%;
    right: 10%;
    width: 120px;
    height: 120px;
    background-color: var(--color-secondary);
    border-radius: 50%;
}

/* Header */
.header {
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-accent) 100%);
    color: white;
    padding: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    margin-bottom: 2rem;
}

.header-logo {
    display: flex;
    align-items: center;
}

.logo {
    width: 40px;
    height: 40px;
    background: white;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: bold;
    color: var(--color-primary);
    margin-right: 10px;
    font-size: 16px;
}

/* Main container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
}

/* Page title */
.page-title {
    margin-bottom: 1.5rem;
    color: var(--color-text);
    font-size: 1.5rem;
    position: relative;
    padding-bottom: 0.5rem;
}

.page-title::after {
    content: "";
    position: absolute;
    bottom: 0;
    left: 0;
    width: 50px;
    height: 3px;
    background: var(--color-accent);
    border-radius: 3px;
}

/* Card styles */
.card {
    background-color: rgba(255, 255, 255, 0.95);
    border-radius: 12px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.05);
    overflow: hidden;
    margin-bottom: 2rem;
    transition: transform 0.3s, box-shadow 0.3s;
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.1);
}

.card-header {
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-accent) 100%);
    color: white;
    padding: 1.2rem;
    font-size: 1.2rem;
    font-weight: 500;
}

.card-body {
    padding: 1.5rem;
}

/* Form styles */
.form-group {
    margin-bottom: 1.2rem;
}

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

.form-control {
    width: 100%;
    padding: 0.8rem 1rem;
    border: 1px solid var(--color-divider);
    border-radius: 6px;
    font-size: 1rem;
    transition: border-color 0.3s, box-shadow 0.3s;
}

.form-control:focus {
    border-color: var(--color-secondary);
    box-shadow: 0 0 0 3px rgba(93, 95, 182, 0.2);
    outline: none;
}

select.form-control {
    appearance: none;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' fill='%236E6E7E' viewBox='0 0 16 16'%3E%3Cpath d='M7.247 11.14 2.451 5.658C1.885 5.013 2.345 4 3.204 4h9.592a1 1 0 0 1 .753 1.659l-4.796 5.48a1 1 0 0 1-1.506 0z'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 1rem center;
    background-size: 16px 12px;
    padding-right: 2.5rem;
}

/* Button styles */
.btn {
    display: inline-block;
    padding: 0.8rem 1.5rem;
    background-color: var(--color-primary);
    color: white;
    border: none;
    border-radius: 6px;
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    text-decoration: none;
    text-align: center;
    transition: background-color 0.3s, transform 0.1s;
}

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

.btn:active {
    transform: scale(0.98);
}

.btn-block {
    display: block;
    width: 100%;
}

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

.btn-secondary:hover {
    background-color: #5a5a69;
}

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

.btn-success:hover {
    background-color: #218838;
}

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

.btn-error:hover {
    background-color: #c82333;
}

/* Alert messages */
.alert {
    padding: 1rem;
    border-radius: 6px;
    margin-bottom: 1.2rem;
    font-size: 0.95rem;
}

.alert-success {
    background-color: rgba(40, 167, 69, 0.1);
    border-left: 4px solid var(--color-success);
    color: var(--color-success);
}

.alert-error {
    background-color: rgba(220, 53, 69, 0.1);
    border-left: 4px solid var(--color-error);
    color: var(--color-error);
}

.alert-warning {
    background-color: rgba(255, 193, 7, 0.1);
    border-left: 4px solid var(--color-warning);
    color: #856404;
}

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

.course-card {
    background-color: rgba(255, 255, 255, 0.95);
    border-radius: 12px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.05);
    overflow: hidden;
    transition: transform 0.3s, box-shadow 0.3s;
    height: 100%;
    display: flex;
    flex-direction: column;
}

.course-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.1);
}

.course-header {
    padding: 1.2rem;
    background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-accent) 100%);
    color: white;
}

.course-title {
    font-size: 1.2rem;
    margin-bottom: 0.5rem;
}

.course-body {
    padding: 1.2rem;
    flex-grow: 1;
    display: flex;
    flex-direction: column;
}

.course-description {
    color: var(--color-text-alt);
    margin-bottom: 1rem;
    flex-grow: 1;
}

.course-price {
    font-size: 1.3rem;
    font-weight: 600;
    color: var(--color-text);
    margin-bottom: 1rem;
}

/* Navigation */
.nav-link {
    display: inline-block;
    color: var(--color-accent);
    text-decoration: none;
    margin: 0 1rem 1rem 0;
    transition: color 0.2s;
}

.nav-link:hover {
    color: var(--color-secondary);
    text-decoration: underline;
}

/* Footer */
footer {
    text-align: center;
    padding: 1.5rem;
    color: var(--color-text-alt);
    font-size: 0.9rem;
    margin-top: 3rem;
    border-top: 1px solid var(--color-divider);
}

/* Tables */
.data-table {
    width: 100%;
    border-collapse: collapse;
    background-color: rgba(255, 255, 255, 0.95);
    border-radius: 8px;
    overflow: hidden;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.05);
}

.data-table th,
.data-table td {
    padding: 0.8rem 1rem;
    text-align: left;
    border-bottom: 1px solid var(--color-divider);
}

.data-table th {
    background-color: rgba(93, 95, 182, 0.1);
    color: var(--color-text);
    font-weight: 600;
}

.data-table tbody tr:hover {
    background-color: rgba(93, 95, 182, 0.05);
}

/* Responsive */
@media (max-width: 768px) {
    .header {
        padding: 0.8rem;
        flex-direction: column;
    }
    
    .header-logo {
        margin-bottom: 0.5rem;
    }
    
    .course-grid {
        grid-template-columns: 1fr;
    }
    
    .data-table {
        display: block;
        overflow-x: auto;
    }
    
    .card-header, .card-body {
        padding: 1rem;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 0 0.8rem;
    }
    
    .btn {
        display: block;
        width: 100%;
        margin-bottom: 0.5rem;
    }
}