IE flexible box model not working

Question

Im trying to implement the flexible box model into my website, and while its working for the -webkit-browsers like chrome and safari, other browsers like mozilla and opera,

Answer 1

IE doesn't use the deprecated 2009 Flexbox properties, it uses the ones from the deprecated March 2012 draft. Opera supports the Flexbox standard properties without prefixes and the 2009 properties under the -webkit- prefix.

.holder {
  width: 100%;
  margin: auto;
  display: -webkit-box;
  display: -moz-box;
  display: -ms-flexbox;
  display: -webkit-flex;
  display: flex;
  -webkit-box-orient: vertical;
  -moz-box-orient: vertical;
  -webkit-box-direction: normal;
  -moz-box-direction: normal;
  -webkit-flex-direction: column;
  -ms-flex-direction: column;
  flex-direction: column;
  -webkit-box-flex: 1;
  -moz-box-flex: 1;
  -webkit-flex: 1;
  -ms-flex: 1;
  flex: 1;
  -webkit-box-pack: center;
  -moz-box-pack: center;
  -ms-flex-pack: center;
  -webkit-justify-content: center;
  justify-content: center;
  text-align: center;
}

.holder #new_div {
  width: 940px;
}

.holder div {
  /* justify-content does nothing here since this element isn't a flex container */
  -webkit-box-pack: center;
  -moz-box-pack: center;
  -ms-flex-pack: center;
  -webkit-justify-content: center;
  justify-content: center;
}

#new_div {
  margin: auto;
  display: -webkit-box;
  display: -moz-box;
  display: -ms-flexbox;
  display: -webkit-flex;
  display: flex;
  text-align: left;
  -webkit-box-flex: 1;
  -moz-box-flex: 1;
  -webkit-flex: 1;
  -ms-flex: 1;
  flex: 1;
  -webkit-box-pack: center;
  -moz-box-pack: center;
  -ms-flex-pack: center;
  -webkit-justify-content: center;
  justify-content: center;
  /* this shouldn't be necessary, as the default direction is `row` */
  -webkit-box-orient: horizontal;
  -moz-box-orient: horizontal;
  -webkit-box-direction: normal;
  -moz-box-direction: normal;
  -webkit-flex-direction: row;
  -ms-flex-direction: row;
  flex-direction: row;
  min-width: 940px;
  padding: 20px;
}

Also worth noting, this requires IE10+