3 column layout with inline block not working- the divs aren't lining up correctly - css

Question

I have a div which contains three child div's, and for some reason the first child div is properly positioned within its parent, but the other two children are positioned lower from the first child. The more content I add to the first child the lower the other children become positioned relative to the top of the container parent.
Heres a jfiddle showing you my problem: http://jsfiddle.net/gY72a/7/
the three children arent on the same line here but you can see the problem when you look at how high the first child is positioned compared to the second one.
Code is already in the jfiddle, but here is the css I am using:
/*Parent div in which all three children are nested*/
#main {
width: 80%;
min-width: 1000px;
background-color: #FFFFFF;
margin: 1% auto;
border-radius: 1px;
border: 0px solid rgba(0, 0, 0, 0.15);
box-shadow: 2px 2px 2px 0px rgba(0, 0, 0, 0.2);
}
/*First child*/
#leftside {
display: inline-block;
width: 18%;
margin: 10px 1% 8px;
padding: 1em;
background-color: rgba(0, 0, 0, 0.1);
}
/*Second Child*/
#innermain {
display: inline-block;
width: 50%;
margin: 10px 1% 8px;
padding:1em;
background-color: #eaeaea;
border-radius: 1px;
border: 0px solid rgba(0, 0, 0, 0.15);
box-shadow: 2px 2px 2px 0px rgba(0, 0, 0, 0.2);
}
/*Third child*/
#rightside {
width: 20%;
min-width: 320px;
padding: 1em 0px;
display: inline-block;
background: #FFFFFF;
margin: 10px 1% 8px ;
border-radius: 1px;
border: 1px solid rgba(0, 0, 0, 0.15);
}

Answer 1

The main problem here is that you are using `display:inline-block" and also that you are using a combination of percentages and margins with ems. Now, theoretically, you could have 3 blocks, and add their widths and the padding, and the margin - to all equal 100, but even if you wanted to go that route, you are using the inline-block method - which by default leaves a little unwanted space between each block, and throws off that number. Beyond that, padding and margins add to the size of the box, so if you have a box that is 20% wide, and has a padding of 1em and a margin of 1% - then it's 20%+2%+2em (+total border width) - and what does that equal? Well, I don't know - and the browser isn't going to love dealing with that either, because depending on window size, that number is going to be different. So, if you want to know the problem, those are the factors leading to the problems.
If you want a solution, then you have a few routes, but they depend on what you need to do. It doesn't appear as though you are building this site responsively. So in that case, you are working with a 1000px wide canvas. - and in that case, then there is no reason why you cant just use px to add up margin/padding/box size etc to equal 100. leave the boxes as display: block; and float them left.
If you want to come into the present, and start using a bit of modern stuff - you should read about box-sizing: border-box - What that does is change the box model so that the padding and borders of boxes moves inside the box and therefore doesn't add to it's size. It's really great and makes working with css a pleasure. Then you don't have to add stuff up to determine the box's size. - so - unless you need to support IE 7 - I would suggest you make it standard in your overall approach to CSS from now on. http://www.paulirish.com/2012/box-sizing-border-box-ftw/
If you are going to float the columns in their "wrapper" thing - then that wrapper thing is no longer going to regognize them in the same way, so you are going to have to look up clearfixing the div, or use overflow:hidden; (which has some issues) or float that wrapper itself to get them to live in the same world again, because floating takes the elements out of the regular flow.
In the case that you can go with box-sizing, then you still have to worry about margins(they don't move inside the box). So, you'll need to have those in percentages, or get another fancy way of making consistent gutter widths, but since you have a static sized site - I'm not going to go into that.
Here is a fiddle without all of your styles - to show how it works.
HTML
<div class="content-wrapper">
<div class="column what">
<h2>What We do</h2>
<p>Bla bla bla</p>
</div>
<div class="column main-content">
<h2>Latest News and Events</h2>
</div>
<div class="column where">
<h2>Where To Find Us</h2>
</div>
</div> <!-- .content-wrapper -->
CSS
*, *:before, *:after {
-moz-box-sizing: border-box;
-webkit-box-sizing: border-box;
box-sizing: border-box;
}
.content-wrapper {
width: 1000px;
margin-right: auto;
margin-left: auto;
border: 1px solid red;
overflow: hidden; /* should be clearfix instead */
}
.column { /* what the columns have in common */
float: left;
padding: 1em;
}
.what {
width: 25%;
margin-right: 1%;
background-color: orange;
}
.main-content {
width: 48%;
margin-right: 1%;
background-color: yellow;
}
.where {
width: 25%;
background: red;
}

Answer 2

You have specified display:inline-block for the divs below which should align them properly in a row with the widths given. But the width is taken by the content section of the div and the div adds the margins given to them with the width. This is why the blocks are jumping below one another.
When you apply box-sizing: border-box; to the divs, the width of the div will be calculated including the margins given to the corresponding divs.
Hope this helps you.
#main, #leftside, #innermain{
-webkit-box-sizing: border-box; /* Safari/Chrome, other WebKit */
-moz-box-sizing: border-box; /* Firefox, other Gecko */
box-sizing: border-box; /* Opera/IE 8+ */
}

Answer 3

This should do what you want:
#main div {
float: left;
}