Css – How to add border radius on table row

You can apply this CSS to the inner <div>:

#inner {
  width: 50%;
  margin: 0 auto;
}

Of course, you don't have to set the width to 50%. Any width less than the containing <div> will work. The margin: 0 auto is what does the actual centering.

If you are targeting Internet Explorer 8 (and later), it might be better to have this instead:

#inner {
  display: table;
  margin: 0 auto;
}

It will make the inner element center horizontally and it works without setting a specific width.

Working example here:

#inner {
  display: table;
  margin: 0 auto;
  border: 1px solid black;
}

#outer {
  border: 1px solid red;
  width:100%
}

<div id="outer">
  <div id="inner">Foo foo</div>
</div>

EDIT

With flexbox it is very easy to style the div horizontally and vertically centered.

#inner {  
  border: 1px solid black;
}

#outer {
  border: 1px solid red;
  width:100%;
  display: flex;
  justify-content: center;
}

<div id="outer">
  <div id="inner">Foo foo</div>
</div>

To align the div vertically centered, use the property align-items: center.

I figured it out. You just have to use some special selectors.

The problem with rounding the corners of the table was that the td elements didn't also become rounded. You can solve that by doing something like this:

table tr:last-child td:first-child {
    border-bottom-left-radius: 10px;
}

table tr:last-child td:last-child {
    border-bottom-right-radius: 10px;
}

Now everything rounds properly, except that there's still the issue of border-collapse: collapse breaking everything.

A workaround is to add border-spacing: 0 and leave the default border-collapse: separate on the table.