Reply To: Help.

Here is code for your questions.

.color-scheme-light .main-nav .menu>li:hover>a {
    color: red;
}

.added_to_cart, .btn, .button, button, input[type=submit] {
    border-radius: 10px;
}

.main-header.header-base {
    border-top: 10px solid white;
}

Regarding text font size on home page: currently you have h4 tag there, try to use h1 or h2.