.o_recursive_expand_column {
    width: 30px;
}

.o_expand_button {
    border-color: transparent;
    background-color: transparent;
}

button.o_expand_button[data-depth="1"] {
    margin-left: 15px;
}

button.o_expand_button[data-depth="2"] {
    margin-left: 30px;
}

button.o_expand_button[data-depth="3"] {
    margin-left: 45px;
}

button.o_expand_button[data-depth="4"] {
    margin-left: 60px;
}

button.o_expand_button[data-depth="5"] {
    margin-left: 75px;
}