svg

IE9-Edge12, Safari 5.1-6, and UCWeb 11 do not support referencing external files via . 

not support

a

b

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a svg #facebook,
a svg #instagram { 
  transition: 200ms;
  transition-timing-function: ease-in-out;
  -webkit-transition: 200ms;
  -webkit-transition-timing-function: ease-in-out;
}