* {
    box-sizing: border-box;
    font-family: Arial, sans-serif;
}

body {
    background-color: #f4f4f4;
    margin: 0;
    padding: 0;
}

nav {
    background-color: #333;
    color: white;
    padding: 15px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

nav a {
    color: white;
    text-decoration: none;
    margin-left: 15px;
}

nav a:hover {
    text-decoration: underline;
}

.container {
    max-width: 1000px;
    margin: 20px auto;
    padding: 20px;
    background: white;
    box-shadow: 0 0 10px rgba(0,0,0,0.1);
    border-radius: 5px;
}

h1, h2, h3 {
    color: #333;
}

.form-group {
    margin-bottom: 15px;
}

.form-group label {
    display: block;
    margin-bottom: 5px;
}

.form-group input, .form-group textarea, .form-group select {
    width: 100%;
    padding: 10px;
    border: 1px solid #ddd;
    border-radius: 4px;
}

button, .btn {
    background-color: #007bff;
    color: white;
    padding: 10px 15px;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    text-decoration: none;
    display: inline-block;
}

button:hover, .btn:hover {
    background-color: #0056b3;
}

.btn-success {
    background-color: #28a745;
}

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

.btn-warning {
    background-color: #ffc107;
    color: #333;
}

.error {
    color: red;
    background: #ffe6e6;
    padding: 10px;
    border: 1px solid red;
    border-radius: 4px;
}

.success {
    color: green;
    background: #e6ffe6;
    padding: 10px;
    border: 1px solid green;
    border-radius: 4px;
}

/* Course Cards */
.course-list {
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
}

.course-card {
    border: 1px solid #ddd;
    border-radius: 5px;
    padding: 15px;
    width: calc(33.333% - 20px);
    background: #fff;
    box-shadow: 0 2px 5px rgba(0,0,0,0.05);
}

@media (max-width: 768px) {
    .course-card {
        width: 100%;
    }
}

.lesson-card {
    background: #f9f9f9;
    padding: 15px;
    margin-bottom: 15px;
    border-left: 4px solid #007bff;
}

.payment-box {
    border: 2px dashed #333;
    padding: 20px;
    text-align: center;
    background: #fffbe6;
}

table {
    border-collapse: collapse;
}
table th {
    background: #f2f2f2;
}