Telethon/client/doc/_static/custom.css

.underline {
    text-decoration: underline;
}

.strikethrough {
    text-decoration: line-through;
}

.spoiler {
    border-radius: 5%;
    padding: 0.1em;
    background-color: gray;
    color: gray;
    transition: all 200ms;
}

.spoiler:hover {
    background-color: unset;
    color: unset;
}

li {
    list-style: circle;
}