style.css

.main {
    background-color:black; /* You can change the color to your preference */
    color:white
}

/* Change the background color of the sidebar */
.sidebar .block-container {
    background-color: black; /* You can change the color to your preference */
}

.footer {
    position: fixed;
    left: 0;
    bottom: 0;
    width: 100%;
    background-color:black;
    color: white;
    text-align: right;
}

h1, h2, h3, h4, h5, h6, p, label, .stMarkdown, .sidebar .block-container {
    color: white;
}