bulma (file, components): fix color fo icons: icons have no color specified anymore for a while, and use the color of parent elements. As they are often used in a `<a>` element (to work without javascript), they are often using a link color. This commit change a few icons to use a dark color instead.

#body {
    display: flex;
    align-items: center;
    justify-content: center;
}

#link_section {
    font-weight: bold;
    text-align: center;
    font-size: 1.5rem;
}

article p:last-child {
    text-align: center;
}