findbar.css

/* Move findbar to top right */
.browserContainer > findbar {
    position: absolute;
    top: -1px;
    right: 0px;
    contain: content;
    border-radius: 0 0 var(--toolbarbutton-border-radius) var(--toolbarbutton-border-radius);
}

/* Hide status */
findbar .findbar-find-status {
    display: none;
}

/* Replace checkboxes with buttons */
findbar .checkbox-check {
    display: none !important;
}
findbar checkbox {
    border: 1px solid var(--input-border-color);
    border-radius: var(--toolbarbutton-border-radius);
    padding: 2px 4px;
    margin: -2px 4px !important;
    transition: 0.1s ease-in-out;
}
findbar checkbox[checked="true"] {
    background: var(--button-active-bgcolor);
    transition: 0.1s ease-in-out;
}