module.exports = {
  browsers: [
    //
    // Official browser support policy:
    // http://v4-alpha.getbootstrap.com/getting-started/browsers-devices/#supported-browsers
    //
    'Chrome >= 35', // Exact version number here is kinda arbitrary
    // Rather than using Autoprefixer's native "Firefox ESR" version specifier string,
    // we deliberately hardcode the number. This is to avoid unwittingly severely breaking the previous ESR in the event that:
    // (a) we happen to ship a new Bootstrap release soon after the release of a new ESR,
    //     such that folks haven't yet had a reasonable amount of time to upgrade; and
    // (b) the new ESR has unprefixed CSS properties/values whose absence would severely break webpages
    //     (e.g. `box-sizing`, as opposed to `background: linear-gradient(...)`).
    //     Since they've been unprefixed, Autoprefixer will stop prefixing them,
    //     thus causing them to not work in the previous ESR (where the prefixes were required).
    'Firefox >= 38', // Current Firefox Extended Support Release (ESR); https://www.mozilla.org/en-US/firefox/organizations/faq/
    // Note: Edge versions in Autoprefixer & Can I Use refer to the EdgeHTML rendering engine version,
    // NOT the Edge app version shown in Edge's "About" screen.
    // For example, at the time of writing, Edge 20 on an up-to-date system uses EdgeHTML 12.
    // See also https://github.com/Fyrd/caniuse/issues/1928
    'Edge >= 12',
    'Explorer >= 9',
    // Out of leniency, we prefix these 1 version further back than the official policy.
    'iOS >= 8',
    'Safari >= 8',
    // The following remain NOT officially supported, but we're lenient and include their prefixes to avoid severely breaking in them.
    'Android 2.3',
    'Android >= 4',
    'Opera >= 12'
  ]
}