a{
     -o-transition:color .2s ease-out, background 2s ease-in;
     -ms-transition:color .2s ease-out, background 2s ease-in;
     -moz-transition:color .2s ease-out, background 2s ease-in;
     -webkit-transition:color .2s ease-out, background 2s ease-in;
     transition:color .2s ease-out, background 2s ease-in;
}

کد فوق باید در a باشد