How to perfectly vertical align navigation buttons with responsive image - html

Question

I want to make the button always aligns vertically on the middle of the image responsively. I can make the image responsive using .img-responsive, however I can't make the arrow to be always on the middle of the image. I suspect the issue is because I can't make the height of the arrow's div to be equal the height of the image. Any way to do so?
Here is my jsFiddle..
PS: for those who can come up with better words please change the title.. ^^

Answer 1

CSS only solution. Using the display table and table-cell combo, you can achieve what you are looking for. I had never really tried it before, as far as I know, but searched around a bit and found a solution which gave me a good starting point to achieve what I needed.
The trick is to have a container which will possess the display table property. Inside that wrapper, you will have all your other elements, which will possess the table-cell property, in order to have them behave properly and stack themselves next to each other, as table-cell would to do.
By giving your table-cells a 100% height, they will adapt themselves to the height of the wrapper, giving you the chance to use the handy little table property going by the name: vertical align. Use the middle vertical align property to center perfectly your nav buttons.
Give your image the max-width 100% property for proper responsive behavior. But don't use bootstrap's own image responsive class because it contains css properties we don't want and that messes up our layout.
I reworked the html a bit, so that each element align perfectly, in the correct order.
WORKING EXAMPLE JSFIDDLE
HTML:
<div class="row">
<div class="col-xs-12">
<div class="image-container">
<div class="prev-btn nav-btn"> < </div>
<div class="inner-container">
<img src="http://farm9.staticflickr.com/8072/8346734966_f9cd7d0941_z.jpg" class="center-block">
</div>
<div class="next-btn nav-btn"> > </div>
</div>
</div>
</div>
CSS:
.image-container{
display:table;
height: 100%;
text-align:center;
}
.inner-container{
display:table-cell;
width: 100%;
height: 100%;
padding: 0 15px;
vertical-align: middle;
text-align: center;
}
.inner-container img{
width: 100%;
height: auto;
max-width: 100%;
}
.nav-btn{
font-size:50px;
font-weight:700;
font-family: monospace;
color: #000;
cursor:pointer;
}
.nav-btn:hover{
color: #B6B6B6;
}
.prev-btn{
position: relative;
height: 100%;
display: table-cell;
vertical-align: middle;
}
.next-btn{
position: relative;
height: 100%;
display: table-cell;
vertical-align: middle;
}

Answer 2

Here's a simple solution in Javascript/Jquery. The trick is to adjust the position of each NAV buttons according to the height of the image each time the browser id resized. Dividing the image height by 2 will get you the center of the image, aka the position where you will want your buttons to be. Using only this value will no be enough, you also need to get the center value of your nav buttons. Substracting each values will give you the real position value for your buttons. The ScreenResize function will then update the position each time the image is scaled responsively.
$(function(){
//Call On Resize event on load
screenResize();
//Bind On Resize event to window
window.onresize = screenResize;
});
function screenResize() {
//Adjust Nav buttons position according to image height
$('.nav_btn').css({
'top': (($('.center-block').height() / 2)-($('.nav_btn').height() / 2))
});
}
Also, change the line-height of your buttons to this, it will help:
.nav_btn p{
line-height: 1.25;
}
Finally, use Media-Queries to change buttons font-size and line-height if necessary. Also, like user Valentin said, using images for the nav buttons could also be easier, you wouldn't have to use media-queries.
Example JSFIDDLE