Center relative element - css

Question

I have an relative button
button {
width: 305.4px;
height: 60px;
background: #E43B40;
margin-top: 109.5px;
margin-left: auto;
margin-right: auto;
display: inline-block;
cursor: pointer;
border: 0px;
outline: none;
font-family: Roboto Bold;
font-size: 16px;
color: #FFFFFF;
position: relative
}
I am trying to center it in the middle of screen. But it is stuck on the same place , the margins does not affect it. Parent element of this button is div with styles as follows:
parent {
width: 100%;
height: 100%;
margin-top: 504px;
background-repeat: no-repeat;
background-color: #F8F8F8;
padding-bottom: 250px;
overflow: auto;
display: block;
}
What could possibly cause this? Demo is here

Answer 1

html,
body {
height: 100%;
}
body {
margin: 0;
}
.button {
width: 305.4px;
height: 60px;
background: #E43B40;
display: inline-block;
cursor: pointer;
border: 0px;
outline: none;
font-family: Roboto Bold;
font-size: 16px;
color: #FFFFFF;
position: relative;
top: 50%;
transform: translateY(-50%);
}
.parent{
width: 100%;
height: 100%;
background-repeat: no-repeat;
background-color: #F8F8F8;
text-align: center;
}
<div class="parent">
<button class="button" type="button">Button</button>
</div>

Answer 2

button {
width: 305.4px;
height: 60px;
background: #E43B40;
margin-top: 109.5px;
margin-left: auto;
margin-right: auto;
display: inline-block;
cursor: pointer;
border: 0px;
outline: none;
font-family: Roboto Bold;
font-size: 16px;
color: #FFFFFF;
position: relative;
display:inline-block;
float:none;
}
parent{
width: 100%;
height: 100%;
margin-top: 504px;
background-repeat: no-repeat;
background-color: #F8F8F8;
padding-bottom: 250px;
overflow: auto;
display: block;
text-align:center;
}
i have updated both classes. apply it in your css.