{
  "title":"rem (root em) units",
  "description":"Type of unit similar to `em`, but relative only to the root element, not any parent element. Thus compounding does not occur as it does with `em` units.",
  "spec":"https://www.w3.org/TR/css3-values/#font-relative-lengths",
  "status":"cr",
  "links":[
    {
      "url":"http://snook.ca/archives/html_and_css/font-size-with-rem",
      "title":"Article on usage"
    },
    {
      "url":"https://github.com/chuckcarpenter/REM-unit-polyfill",
      "title":"REM Polyfill"
    }
  ],
  "bugs":[
    {
      "description":"IE 9, 10 and 11 do not support rem units when used in the \"line-height\" property when used on :before and :after pseudo elements (https://connect.microsoft.com/IE/feedback/details/776744)."
    },
    {
      "description":"Borders sized in \"rem\" disappear when the page is zoomed out in Chrome."
    },
    {
      "description":"Reportedly does not work on Android 4.3 browser for Samsung Note II or the Samsung Galaxy Tab 2 on Android 4.2."
    },
    {
      "description":"Chrome 31-34 & Chrome-based Android versions (like 4.4) [have a font size bug](https://code.google.com/p/chromium/issues/detail?id=319623) that occurs when the root element has a percentage-based size."
    },
    {
      "description":"Causes content display and scrolling issues on iPhone 4 which typically has Safari 5.1."
    }
  ],
  "categories":[
    "CSS3"
  ],
  "stats":{
    "ie":{
      "5.5":"n",
      "6":"n",
      "7":"n",
      "8":"n",
      "9":"a #1",
      "10":"a #1",
      "11":"y"
    },
    "edge":{
      "12":"y",
      "13":"y",
      "14":"y",
      "15":"y",
      "16":"y",
      "17":"y"
    },
    "firefox":{
      "2":"n",
      "3":"n",
      "3.5":"n",
      "3.6":"y",
      "4":"y",
      "5":"y",
      "6":"y",
      "7":"y",
      "8":"y",
      "9":"y",
      "10":"y",
      "11":"y",
      "12":"y",
      "13":"y",
      "14":"y",
      "15":"y",
      "16":"y",
      "17":"y",
      "18":"y",
      "19":"y",
      "20":"y",
      "21":"y",
      "22":"y",
      "23":"y",
      "24":"y",
      "25":"y",
      "26":"y",
      "27":"y",
      "28":"y",
      "29":"y",
      "30":"y",
      "31":"y",
      "32":"y",
      "33":"y",
      "34":"y",
      "35":"y",
      "36":"y",
      "37":"y",
      "38":"y",
      "39":"y",
      "40":"y",
      "41":"y",
      "42":"y",
      "43":"y",
      "44":"y",
      "45":"y",
      "46":"y",
      "47":"y",
      "48":"y",
      "49":"y",
      "50":"y",
      "51":"y",
      "52":"y",
      "53":"y",
      "54":"y",
      "55":"y",
      "56":"y",
      "57":"y",
      "58":"y",
      "59":"y",
      "60":"y",
      "61":"y"
    },
    "chrome":{
      "4":"y",
      "5":"y",
      "6":"y",
      "7":"y",
      "8":"y",
      "9":"y",
      "10":"y",
      "11":"y",
      "12":"y",
      "13":"y",
      "14":"y",
      "15":"y",
      "16":"y",
      "17":"y",
      "18":"y",
      "19":"y",
      "20":"y",
      "21":"y",
      "22":"y",
      "23":"y",
      "24":"y",
      "25":"y",
      "26":"y",
      "27":"y",
      "28":"y",
      "29":"y",
      "30":"y",
      "31":"y",
      "32":"y",
      "33":"y",
      "34":"y",
      "35":"y",
      "36":"y",
      "37":"y",
      "38":"y",
      "39":"y",
      "40":"y",
      "41":"y",
      "42":"y",
      "43":"y",
      "44":"y",
      "45":"y",
      "46":"y",
      "47":"y",
      "48":"y",
      "49":"y",
      "50":"y",
      "51":"y",
      "52":"y",
      "53":"y",
      "54":"y",
      "55":"y",
      "56":"y",
      "57":"y",
      "58":"y",
      "59":"y",
      "60":"y",
      "61":"y",
      "62":"y",
      "63":"y",
      "64":"y",
      "65":"y",
      "66":"y",
      "67":"y"
    },
    "safari":{
      "3.1":"n",
      "3.2":"n",
      "4":"n",
      "5":"y",
      "5.1":"y",
      "6":"y",
      "6.1":"y",
      "7":"y",
      "7.1":"y",
      "8":"y",
      "9":"y",
      "9.1":"y",
      "10":"y",
      "10.1":"y",
      "11":"y",
      "11.1":"y",
      "TP":"y"
    },
    "opera":{
      "9":"n",
      "9.5-9.6":"n",
      "10.0-10.1":"n",
      "10.5":"n",
      "10.6":"n",
      "11":"n",
      "11.1":"n",
      "11.5":"n",
      "11.6":"y",
      "12":"y",
      "12.1":"y",
      "15":"y",
      "16":"y",
      "17":"y",
      "18":"y",
      "19":"y",
      "20":"y",
      "21":"y",
      "22":"y",
      "23":"y",
      "24":"y",
      "25":"y",
      "26":"y",
      "27":"y",
      "28":"y",
      "29":"y",
      "30":"y",
      "31":"y",
      "32":"y",
      "33":"y",
      "34":"y",
      "35":"y",
      "36":"y",
      "37":"y",
      "38":"y",
      "39":"y",
      "40":"y",
      "41":"y",
      "42":"y",
      "43":"y",
      "44":"y",
      "45":"y",
      "46":"y",
      "47":"y",
      "48":"y",
      "49":"y",
      "50":"y",
      "51":"y",
      "52":"y"
    },
    "ios_saf":{
      "3.2":"n",
      "4.0-4.1":"y",
      "4.2-4.3":"y",
      "5.0-5.1":"a #2",
      "6.0-6.1":"y",
      "7.0-7.1":"y",
      "8":"y",
      "8.1-8.4":"y",
      "9.0-9.2":"y",
      "9.3":"y",
      "10.0-10.2":"y",
      "10.3":"y",
      "11.0-11.2":"y",
      "11.3":"y"
    },
    "op_mini":{
      "all":"y"
    },
    "android":{
      "2.1":"y",
      "2.2":"y",
      "2.3":"y",
      "3":"y",
      "4":"y",
      "4.1":"y",
      "4.2-4.3":"y",
      "4.4":"y",
      "4.4.3-4.4.4":"y",
      "62":"y"
    },
    "bb":{
      "7":"y",
      "10":"y"
    },
    "op_mob":{
      "10":"n",
      "11":"n",
      "11.1":"n",
      "11.5":"n",
      "12":"y",
      "12.1":"y",
      "37":"y"
    },
    "and_chr":{
      "64":"y"
    },
    "and_ff":{
      "57":"y"
    },
    "ie_mob":{
      "10":"y",
      "11":"y"
    },
    "and_uc":{
      "11.8":"y"
    },
    "samsung":{
      "4":"y",
      "5":"y",
      "6.2":"y"
    },
    "and_qq":{
      "1.2":"y"
    },
    "baidu":{
      "7.12":"y"
    }
  },
  "notes":"",
  "notes_by_num":{
    "1":"IE 9 & IE 10 do not support `rem` units when used in the `font` shorthand property (the entire declaration is ignored) or when used on pseudo elements.",
    "2":"iOS Safari 5.0-5.1 support `rem` but not in combination with media queries."
  },
  "usage_perc_y":97.62,
  "usage_perc_a":0.27,
  "ucprefix":false,
  "parent":"",
  "keywords":"rems",
  "ie_id":"",
  "chrome_id":"",
  "firefox_id":"",
  "webkit_id":"",
  "shown":true
}