body {
    margin: 0;
    font-family: "Segoe UI", Arial, sans-serif;
    background-color: #f4f6f8;
    color: #222;
}

/* Layout */
.container {
    display: flex;
}

/* LOCKED SIDEBAR */
.sidebar {
    position: fixed;
    top: 0;
    left: 0;
    width: 300px;
    height: 100vh;
    background-color: #0f172a;
    color: #fff;
    padding: 20px;
    box-sizing: border-box;
    overflow-y: auto;
}

.credentials {
    font-size: 14px;
    line-height: 1.5;
    margin-bottom: 15px;
}

.teacher-box {
    background-color: #1e293b;
    padding: 10px;
    border-radius: 8px;
    margin-bottom: 20px;
    font-size: 15px;
    font-weight: 500;
}

.nav-title {
    font-weight: bold;
    margin-bottom: 10px;
    font-size: 16px;
    border-bottom: 1px solid #334155;
    padding-bottom: 5px;
}

.nav-list {
    list-style: none;
    padding: 0;
    margin: 0;
}

.nav-list li {
    margin: 6px 0;
}

.nav-list a {
    color: #e5e7eb;
    text-decoration: none;
    display: block;
    padding: 6px 10px;
    border-radius: 6px;
    transition: background 0.2s;
}

.nav-list a:hover {
    background-color: #334155;
}

/* CONTENT */
.content {
    margin-left: 300px; /* space for fixed sidebar */
    padding: 40px;
    max-width: 1000px;
}

h1 {
    margin-top: 0;
    color: #0f172a;
}

p {
    text-align: justify;
    line-height: 1.6;
}

.image-section {
    margin-top: 40px;
    background-color: #ffffff;
    padding: 20px;
    border-radius: 12px;
    box-shadow: 0 4px 10px rgba(0,0,0,0.05);
}

.image-section h2 {
    margin-top: 0;
    color: #0f172a;
    font-size: 20px;
}

.image-container {
    margin-top: 15px;
    text-align: center;
}

.image-container img {
    max-width: 100%;
    height: auto;
    border-radius: 10px;
    border: 1px solid #e5e7eb;
}

.image-caption {
    margin-top: 8px;
    font-size: 17px;
    color: #555;
    font-style: italic;
}