.download-section {
    display: flex;
    align-items: center;
    justify-content: center;
    flex-direction: column;
    width: 100vw;
}
.section-download-section {
    align-self: center;
    margin-bottom: 20px;
    width: 45%;
    margin-top: 5vh;
}

.section-header-download-section {
    background-color: #8c8c8c;
    color: white;
    border-radius: 15px;
    padding: 12px 20px;
    font-weight: 600;
    cursor: pointer;
    user-select: none;
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-size: 16px;
    width: 80%;
}

.arrow {
    border: solid white;
    border-width: 0 3px 3px 0;
    display: inline-block;
    padding: 5px;
    transform: rotate(45deg);
    transition: transform 0.3s ease;
    margin-left: 10px;
}

.arrow.open {
    transform: rotate(-135deg);
}

.chapters {
    margin-top: 15px;
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    width: 85%;
}

.download-section + .section-3 { margin-top: 4vh; }

@media (max-width: 1200px) {
    .section-download-section { width: 70%; }
    .section-header-download-section { width: 100%; }
    .chapters { width: 100%; }
}

/* prevent overlap with banner below on narrow widths */
@media (max-width: 900px) {
    .download-section { padding-bottom: 24px; }
}

.chapter {
    background-color: #8c8c8c;
    color: white;
    border-radius: 20px;
    padding: 8px 15px;
    font-size: 13px;
    cursor: pointer;
    text-decoration: none;
    user-select: none;
    display: inline-block;
    white-space: nowrap;
    transition: background-color 0.2s ease;
}

.chapter:hover {
    background-color: #6b6b6b;
}

@media (max-width: 768px) {
    .section-download-section { width: 90%; }
    .section-header-download-section { width: 100%; font-size: 14px; padding: 10px 14px; }
    .chapters { width: 100%; gap: 8px; }
    .chapter { font-size: 12px; padding: 8px 12px; }
}