Div Attached to side of wrapper - html

Question

I am trying to add a div to the side of my wrapper. It will be a link / button.
I want it to be able to slide up and down, fixed to the right hand side border when scrolling.
The button is:
#booknow {
position: absolute;
right: 0;
margin-left:25px;
text-align:center;
font-family: 'Raleway',sans-serif;
font-size:22px;
color:#ffffff!important;
font-weight:700;
line-height:26px!important;
text-transform:uppercase;
}
And the inner wrapper (Where the border is), is:
.wrapper_inner{
position:relative;
z-index:10!important;
padding:30px!important;
background:#fff!important;
border:1px solid #D4D4D4!important; }
HTML:
<div class="wrapper">
<div class="wrapper_inner">
<div id="booknow">
Book <br> Now
</div>
</div>
</div>
At the minute I have this:
If I set it to fixed it slides up and down but it won't position perfectly to the outside of .wrapper_inner.

Answer 1

The HTML wasn't that helpful, so I just threw something together. The color scheme is to display the elements. I removed .inner_wrapper and added the surrounding layout so it would be possible to demonstrate that #booknow floats. If you click the #booknow it'll scroll down to a faux form at the bottom.
Demo: https://plnkr.co/edit/qACqW4O4rJn7YHoPRWLy?p=preview
Full screen: https://run.plnkr.co/njw73AIIIuHXEooM/
Relevant CSS
body {
position: relative;
overflow-y: scroll;
overflow-x:hidden;
font: 500 16px/1.4 'Arial';
min-height: 100vh;
}
.spacer {
position: absolute;
bottom: -200px;
height: 60%;
}
#booknow {
position: fixed;
top: 30px;
right: 0;
float: right;
margin-left: 25px;
text-align: center;
font-family: 'Raleway', sans-serif;
font-size: 22px;
color: #ffffff;
font-weight: 700;
line-height: 26px;
font-variant: small-caps;
z-index: 10;
background: #fc3;
padding: 10px;
width: 50px;
}
.wrapper {
position: absolute;
top: -110px;
margin: 25px;
padding: 5px 10px;
width: 100%;
border: 3px double grey;
min-height: 70px;
background: #eff999;
}