How to get tiles centered and left-justified at the same time

FWIW: It’s now 2017 and the grid layout module does this out of the box (codepen demo). If the browser support suits you – then use grid. If not, then read on….

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As mentioned in @Skadi2k3’s answer, the best you can do with CSS is with a series of media queries.

That being said, if you are using a preprocessor such as LESS – this isn’t such a difficult or error-prone task. (although, yes, the CSS will still be long and ugly)

FIDDLE or CODEPEN (Supports LESS)

Here’s how to take advantage of LESS to set up the media queries:

Set up an iteration mixin like this: (You can paste this code into http://less2css.org)

@item-width:100px;
@item-height:100px;
@margin: 5px;
@min-cols:2;
@max-cols:12; //set an upper limit of how may columns you want to write the media queries for


.loopingClass (@index-width) when (@index-width <= @item-width * @max-cols) {
    @media (min-width:@index-width) {
        #content{
            width: @index-width;
        }
    }

    .loopingClass(@index-width + @item-width);
}

.loopingClass (@item-width * @min-cols);

The above mixin will spit out a series of media queries in the form:

@media (min-width: 200px) {
  #content {
    width: 200px;
  }
}
@media (min-width: 300px) {
  #content {
    width: 300px;
  }
}
@media (min-width: 400px) {
  #content {
    width: 400px;
  }
}
...
@media (min-width: 1200px) {
  #content {
    width: 1200px;
  }
}

So with a simple markup like:

<ul id="content">
    <li class="box"></li>
    <li class="box"></li>
    ...
    <li class="box"></li>
</ul>

With remaining CSS (LESS):

 #content {
    margin:0 auto;
    overflow: auto;
    min-width: @min-cols * @item-width;
    max-width: @max-cols * @item-width;
    display: block;
    list-style:none;
    background: aqua;
}
.box {
    float: left;
    height: @item-height - 2 *@margin;
    width: @item-width - 2*@margin;
    margin:@margin;
    background-color:blue;
}

… you get the desired result.

…and it’s super easy to customize the layout:

All I need to do is change the variables that I used in the LESS mixin according to my needs – I get the exact layout that I’m after.

So let’s say I have items 300px X 100px with a minimum of 2 columns and max 6 columns and a margin of 15px – I just modify the variables like so:

@item-width:300px;
@item-height:100px;
@margin: 15px;
@min-cols:2;
@max-cols:6;

…and voila, I get this CODEPEN