change navigation bar color with caret-browse mode in keysnail

gistfile1.js

key.setViewKey(['C-c', 'C-a'], function (ev) {
    children = document.getElementById("nav-bar").children;
    for(i=0; i<children.length; i++){
        children[i].style.backgroundColor = "pink";
    }
    util.setBoolPref("accessibility.browsewithcaret", true);
}, "Start Caret-Browse Mode");

key.setCaretKey(['C-c', 'C-a'], function (ev) {
    children = document.getElementById("nav-bar").children;
    for(i=0; i<children.length; i++){
        children[i].style.backgroundColor = "transparent";
    }
    util.setBoolPref("accessibility.browsewithcaret", false);
}, "Exit Caret-Browse Mode");