How to center elements inside an element - html

Question

I was wondering how to center 3 divs inside a div.
Here is my code example
body {
position: fixed;
height: 100%;
width: 100%;
}
#container {
border: 3px solid black;
height: 90%;
width: 90%;
}
.plaatje {
width: 30%;
height: 70%;
border: 2px solid black;
float: left;
text-align: center;
}
#plaatje1 {
background-image: url("http://image.prntscr.com/image/c3d5dbc04f664a3386b372d8e4ceb4c7.png");
background-size: 100% 100%;
background-repeat: no-repeat;
}
#plaatje2 {
background-image: url("http://image.prntscr.com/image/2bcfd124f98a448cbae822337818ff4e.png");
background-size: 100% 100%;
background-repeat: no-repeat;
}
#plaatje3 {
background-image: url("http://image.prntscr.com/image/e1b7059d626f47cb94535bbba9887cc1.png");
background-size: 100% 100%;
background-repeat: no-repeat;
}
<div id="container">
<div id="plaatje1" class="plaatje">
</div>
<div id="plaatje2" class="plaatje">
</div>
<div id="plaatje3" class="plaatje">
</div>
</div>
The problem is, there is still a white space on the right hand-side of the picture, I have marked it so you know what i'm talking about.
It also needs to scale, so if I resize the window, that the third image doesn't pops below the first or that the space exists when I resize it fully.
Any help is appreciated.

Answer 1

I have created a jsFiddle which demonstrates how you can do this using flexbox. It doesn't require floating the elements and gives you with exactly what you're looking for.
I have added a wrapper around the images (.images) and given it the flex properties required to align its contents, then removed the floats and a few other unnecessary things.
Here is the browser support for flexbox: caniuse:flexbox
body {
position: fixed;
height: 100%;
width: 100%;
}
#container {
border: 3px solid black;
height: 90%;
width: 90%;
}
.images {
height: 90%;
display: flex;
justify-content: center;
}
.plaatje {
width: 30%;
height: 70%;
border: 2px solid black;
background-size: 100% 100%;
background-repeat: no-repeat;
}
#plaatje1 {
background-image: url("http://image.prntscr.com/image/c3d5dbc04f664a3386b372d8e4ceb4c7.png");
}
#plaatje2 {
background-image: url("http://image.prntscr.com/image/2bcfd124f98a448cbae822337818ff4e.png");
}
#plaatje3 {
background-image: url("http://image.prntscr.com/image/e1b7059d626f47cb94535bbba9887cc1.png");
}
<div id="container">
<div class="images">
<div id="plaatje1" class="plaatje"></div>
<div id="plaatje2" class="plaatje"></div>
<div id="plaatje3" class="plaatje"></div>
</div>
</div>

Answer 2

You could just simply try adding text-align:center; to your container div

Answer 3

There are many ways to do this, and you should probably start with http://www.w3schools.com/css/css_align.asp - this elementary level question often gets flagged as not appropriate for SO.
But! Welcome. Here's one way you could do this - I've added comments to explain what's going on. Basically your float: left by definition made the .plaatjes impossible to center; and the text-align: center needs to be on the containing element
body {
position: fixed; /* probably don't actually want */
height: 100%;
width: 100%;
margin: 0; /* add */
}
#container {
border: 3px solid black;
height: 90%;
width: 90%;
margin-left: 5%;
text-align: center; /* add */
}
.plaatje {
width: 30%;
height: 70%;
border: 2px solid black;
/* float: left; // remove
text-align: center;*/
display: inline-block; /* add */
}
#plaatje1 {
background-image: url("http://image.prntscr.com/image/c3d5dbc04f664a3386b372d8e4ceb4c7.png");
background-size: 100% 100%;
background-repeat: no-repeat;
}
#plaatje2 {
background-image: url("http://image.prntscr.com/image/2bcfd124f98a448cbae822337818ff4e.png");
background-size: 100% 100%;
background-repeat: no-repeat;
}
#plaatje3 {
background-image: url("http://image.prntscr.com/image/e1b7059d626f47cb94535bbba9887cc1.png");
background-size: 100% 100%;
background-repeat: no-repeat;
}
<div id="container">
<div id="plaatje1" class="plaatje">
</div><div id="plaatje2" class="plaatje">
</div><div id="plaatje3" class="plaatje">
</div>
</div>
<!-- removed spaces between the divs -->