How to change button style on One Page

If you wan change button style (Button Block) on One Page, you can follow these.
#1. First, use this tool to find Page ID.
In my example, we will have: #collection-665d7b3947a3b1736246343b

#2. Next, use this code to Custom CSS box

#collection-665d7b3947a3b1736246343b div.button-block a {
    color: #f1f !important;
    background-color: #000 !important;
    font-size: 30px !important;
    border-radius: 10px;
}