<img class="logo" src="http://www.torxmedia.com/images/torx-logo.png">

<div class="logo-btn">Make my Logo Bigger!</div>

.logo-btn{
  background: #333;
  padding: 20px; 
  width: 200px;
  display: block;
  border-radius: 20px;
  color: #bada55;
  font-family: arial;
  text-transform: uppercase;
  margin: 0 auto;
  cursor: pointer;
}

.logo{
  position: relative;
  width: 200px;
  margin: 20px auto;
  display: block;
}

$( ".logo-btn" ).click(function() {
    $('.logo').css({"width":"100%"});
});