How to stop button from moving - html

Question

I have a button that, when pressed, is supposed to expand the element behind it (.nav which contains .work and .contact) out in both directions. However, I can't seem to keep the button in the center.
$(function() {
var nav = $('.nav');
var button = $('.nav button');
button.on('click', function(){
nav.toggleClass('active');
if(nav.hasClass('active'))
button.text('');
else
button.text('');
});
});
html {
background: #f1f1f1;
}
.nav {
display: block;
margin: auto;
margin-top: 80px;
margin-bottom: 200px;
background: #ccc;
color: black;
text-align: center;
width: 350px;
height: 330px;
transition: width 0.5s;
}
.nav.active {
width: 1000px;
transition: width 0.5s;
}
.navigation button {
position: absolute;
width: 350px;
Height: 350px;
margin: 0 auto;
display: block;
background-color: #2e0513!important;
background: url(TransplantAltFontbackgroundvector.png) 12px 15px;
background-repeat: no-repeat;
background-size: 325px 325px;
border: none;
transition: 0.5s ease-in-out;
}
.navigation.active button {
transform: scale(1.1);
transition: 0.5s ease-in-out;
}
.navigation:hover button {
box-shadow: 0px 0px 20px black;
transform: scale(1.01);
transition: 0.1s ease-in-out;
}
.navigation.active:hover button {
box-shadow: none!important;
transform: scale(1.1)!important;
transition: 0.5s ease-in-out;
}
.navigation button img {
position: relative;
right: 30px;
bottom: 40px;
}
.work,
.contact {
position: relative;
visibility: hidden;
}
.work a {
font-family: arapey;
font-size: 30px;
font-style: italic;
text-decoration: none;
}
.contact a {
font-family: arapey;
font-size: 30px;
font-style: italic;
text-decoration: none;
}
.nav.active > .work {
visibility: visible!important;
display: table;
margin: auto;
position: relative;
float: left;
left: 125px;
top: 150px;
}
.nav.active > .contact {
visibility: visible!important;
display: table;
margin: auto;
position: relative;
float: right;
right: 125px;
top: 150px;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="navigation">
<div class="nav">
<button>
</button>
<div class="work">
work
</div>
<div class="contact">
contact
</div>
</div>
</div>

Answer 1

Give the nav a style of position: relative. Then, toggle a class (or just add the styling, should work as well) to the button on click that does the following:
button.my-pressed-class {
position: absolute;
left: 50%;
transform: translateX(-50%);
}
This should keep it in the middle.
Edit: Keep in mind you already have a transform set on the button on hover. Just, add the translateX to hover when the button has the aforementioned class, to avoid it from moving around on hover.

Answer 2

add postion relative to .navigation and position absolute to .nav with left value
$(function() {
var nav = $('.nav');
var button = $('.nav button');
button.on('click', function(){
nav.toggleClass('active');
if(nav.hasClass('active'))
button.text('');
else
button.text('');
});
});
html {
background: #f1f1f1;
}
.navigation {
position: relative;
}
.nav {
display: block;
margin: auto;
margin-top: 80px;
margin-bottom: 200px;
background: #ccc;
color: black;
text-align: center;
width: 350px;
height: 330px;
transition: width 0.5s;
position: absolute;
left: 100px;
}
.nav.active {
width: 1000px;
transition: width 0.5s;
}
.navigation button {
position: absolute;
width: 350px;
Height: 350px;
margin: 0 auto;
display: block;
background-color: #2e0513!important;
background: url(TransplantAltFontbackgroundvector.png) 12px 15px;
background-repeat: no-repeat;
background-size: 325px 325px;
border: none;
transition: 0.5s ease-in-out;
}
.navigation.active button {
transform: scale(1.1);
transition: 0.5s ease-in-out;
}
.navigation:hover button {
box-shadow: 0px 0px 20px black;
transform: scale(1.01);
transition: 0.1s ease-in-out;
}
.navigation.active:hover button {
box-shadow: none!important;
transform: scale(1.1)!important;
transition: 0.5s ease-in-out;
}
.navigation button img {
position: relative;
right: 30px;
bottom: 40px;
}
.work,
.contact {
position: relative;
visibility: hidden;
}
.work a {
font-family: arapey;
font-size: 30px;
font-style: italic;
text-decoration: none;
}
.contact a {
font-family: arapey;
font-size: 30px;
font-style: italic;
text-decoration: none;
}
.nav.active > .work {
visibility: visible!important;
display: table;
margin: auto;
position: relative;
float: left;
left: 125px;
top: 150px;
}
.nav.active > .contact {
visibility: visible!important;
display: table;
margin: auto;
position: relative;
float: right;
right: 125px;
top: 150px;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="navigation">
<div class="nav">
<button>
</button>
<div class="work">
work
</div>
<div class="contact">
contact
</div>
</div>
</div>