We support last two major versions, with following exceptions: IE is supported from version 11 upwards, and iOS from version 8. Our Browserslist string can be found here. At the time of writing it was 'last 2 versions', 'not ie < 11', 'not ie_mob < 11', 'ie >= 11', 'iOS >= 8', which evaluates to
[ 'chrome 51',
'chrome 50',
'edge 13',
'edge 12',
'firefox 47',
'firefox 46',
'ie 11',
'ie_mob 11',
'ios_saf 9.3',
'ios_saf 9.0-9.2',
'ios_saf 8.1-8.4',
'ios_saf 8',
'opera 37',
'opera 36',
'safari 9.1',
'safari 9' ]