div.activity {
    border-left-color: rgba(246, 106, 10, 1);
    background-color: rgba(246, 106, 10, 0.1);;
}
div.activity .admonition-title {
    background-color: rgba(246, 106, 10, .1)
}

div.activity .admonition-title::after {
    color: rgba(246, 106, 10, 1);
    content: '\f19d';
}