body {
    margin: 0;
    font-family: Arial;
    background: #f4f6f9;
}

/* TOP BAR */
.top-bar {
    background: #111;
    color: #fff;
    padding: 15px 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.top-bar a {
    color: #fff;
    margin-left: 10px;
    text-decoration: none;
}

/* GRID */
.grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px,1fr));
    gap: 20px;
    padding: 20px;
}

/* CARD */
.card {
    background: #fff;
    border-radius: 10px;
    overflow: hidden;
    box-shadow: 0 4px 10px rgba(0,0,0,0.1);
}

.course-img {
    width: 100%;
    height: 200px;
    object-fit: cover;
}

.card-body {
    padding: 15px;
}

.btn {
    display: block;
    text-align: center;
    background: #007bff;
    color: #fff;
    padding: 10px;
    border-radius: 6px;
    text-decoration: none;
}

/* COURSE PAGE */
.container {
    display: flex;
    height: calc(100vh - 60px);
}

.sidebar {
    width: 300px;
    background: #fff;
    overflow-y: auto;
    border-right: 1px solid #ddd;
}

.lesson {
    padding: 12px;
    border-bottom: 1px solid #eee;
    cursor: pointer;
}

.lesson:hover {
    background: #f0f0f0;
}

.main {
    flex: 1;
    padding: 20px;
}

.video iframe {
    width: 100%;
    height: 400px;
    border-radius: 10px;
}

#content {
    margin-top: 20px;
    background: #fff;
    padding: 15px;
    border-radius: 10px;
}