body {
    font-family: Arial, Helvetica, sans-serif;
    background-color: #e9edf1;
    margin: 0;
    padding: 25px;
}
#pageWrapper {
    max-width: 1100px;
    margin: auto;
    background-color: #f7f9fb;
    border: 5px solid #4f6f8d;
    border-radius: 14px;
    padding: 25px;
    box-shadow: 0 0 18px rgba(0,0,0,0.12);
}
#topNav {
    background-color: #4f6f8d;
    border-radius: 10px;
    padding: 12px 0;
}
#topNav ul {
    list-style: none;
    display: flex;
    justify-content: center;
    gap: 35px;
    margin: 0;
    padding: 0;
}
#topNav a {
    text-decoration: none;
    color: white;
    font-size: 18px;
    font-weight: bold;
}
#topNav a:hover {
    color: #111111;
}
#pageHeader {
    text-align: center;
    margin: 25px 0;
}
#pageHeader h1 {
    color: #263f5c;
    font-size: 30px;
}
#pageHeader p {
    font-size: 18px;
}
.grade-page {
    display: grid;
    gap: 18px;
}
.chapter-card {
    background-color: #edf1f5;
    border: 3px solid #4f6f8d;
    border-left: 12px solid #4f6f8d;
    border-radius: 14px;
    padding: 20px 30px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.18);
}
.chapter-card h2 {
    color: #263f5c;
    font-size: 22px;
    margin: 0 0 10px 0;
}
.chapter-card p {
    font-size: 17px;
    line-height: 1.5;
    margin: 10px 0;
}
.chapter-card a {
    display: inline-block;
    background-color: #4f6f8d;
    color: white;
    text-decoration: none;
    font-size: 16px;
    font-weight: bold;
    padding: 10px 18px;
    margin-top: 10px;
    border-radius: 8px;
}
.chapter-card a:visited {
    color: white;
}
.chapter-card a:hover {
    background-color: #263f5c;
    color: white;
}