body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: #f8f9fa;
    color: #343a40;
}

.fixed-left {
    background-color: #ffffff;
    border-right: 2px solid #dee2e6;
    height: 100dvh; /* Uses dynamic viewport unit */
    position: sticky;
    top: 0;
    overflow-y: hidden; /* prevent scroll unless really necessary */
}



.scrollable-right {
    background-color: #ffffff;
    padding: 40px;
    box-shadow: -2px 0 10px rgba(0, 0, 0, 0.05);
}

.display-2 {
    font-size: 2.5rem;
    font-weight: 600;
    margin-bottom: 20px;
}

h2 {
    font-size: 1.75rem;
    border-bottom: 2px solid #dee2e6;
    padding-bottom: 5px;
    margin-top: 30px;
    margin-bottom: 20px;
}

ul {
    list-style-type: none;
    padding-left: 0;
}

ul li {
    margin-bottom: 10px;
}

a {
    color: #0d6efd;
}

a:hover {
    text-decoration: underline;
}

.section-title {
    font-size: 1.5rem;
    margin-top: 20px;
    margin-bottom: 10px;
    color: #0d6efd;
}

.border.img-thumbnail {
    margin-top: 20px;
    border-radius: 10px;
}

.scrollable-right ul li {
    padding-left: 20px;
    position: relative;
}

.scrollable-right ul li::before {
    content: '\2022';
    color: #0d6efd;
    font-weight: bold;
    display: inline-block;
    width: 1em;
    margin-left: -1em;
}

#mobile-scroll-message {
    display: none;
    font-size: 0.9rem;
    color: #6c757d;
    margin-top: 10px;
}

@media (max-width: 768px) {
    #mobile-scroll-message {
        display: block;
    }
}

@media (prefers-color-scheme: dark) {
    body {
        background: #121212;
        color: #e0e0e0;
    }
    .fixed-left {
        background-color: #1e1e1e;
        border-right: 2px solid #333;
        color: #e0e0e0;
    }
    .scrollable-right {
        background-color: #1e1e1e;
        box-shadow: -2px 0 10px rgba(0, 0, 0, 0.7);
        color: #e0e0e0;
    }
    a {
        color: #66aaff;
    }
    a:hover {
        text-decoration: underline;
    }
    .scrollable-right ul li::before {
        color: #66aaff;
    }
    h2, h4, h5 {
        color: #66aaff;
    }
    #mobile-scroll-message {
        color: #999;
    }
}