Is there a way to put a black border around buttons or even a css code to change the colour?

Find the selector for the buttons you would like to change and then apply a rule such as:

border-color: #000;

To learn about how CSS selectors work, read this help page:
http://www.htmldog.com/guides/css/beginner/selectors/

To find selectors on your blog, right click the button element you want to change, select the "Inspect Element" option, and look in the panel on the right to see all the current CSS being used. You can usually find the exact right selector that you need in there.

If you need further help, reply back here and include a link to a page on your blog that has the buttons and include a description of where to find them on the page.

I also just posted another question about changing my subhead colors in the CSS page. I'd love either of your help with that as well.

http://en.forums.wordpress.com/topic/subhead-text-color-change?replies=1#post-1298037

Thank you!
Jenni

.entry-content table, .entry-content tr, .entry-content th, .entry-content td, .entry-content tbody, .entry-content thead, .entry-content tfoot {
    border: 0 none;
}

This will take care of any table on any post or page.
(If you'd rather target only the table in question, that's also possible.)

edit to say this thread is now in the css forum: note that i'm not being pedantic or ocd about where threads are posted; it just makes it easier for other readers who want css help to find the topics in future…

Thanks so much again for your help. It worked perfectly.

And, do you or don't you have the Custom Design upgrade?

I'm not seeing supernu's suggestion in the sourcecode of your page, I'm seeing this:
<table style="background-color:#ffffff;" width="100%" border="0 !important" cellspacing="0" cellpadding="0">
These are all useless. Tables on Adelle don't have a bg color, so specifying white over the white bg of the site is superfluous. The rest are outdated coding that doesn't work (and 100% width is the default on Adelle anyway).
For more on table coding see my tutorial:
http://wpbtips.wordpress.com/2013/04/09/table-coding-for-wordpress-com-users/

So:
If you don't have the Custom Design upgrade, you need supernu's suggestion for each opening td tag, and for the opening table tag as well:
<table style="border:none;">
<td style="border:none;">

If you do have the upgrade you don't need any of this in the Text editor, but you need to post in the CSS forum, not the Support forum.

<td style="border:none;">TEXT</td>

Forgot to explain no.3. Modularity Lite happens to have a div with the ID "top": it's the div that encloses the blog title, tagline and top menu. So your link links to that div instead of the top of the browser window.

As for no.2, yes, I can see the line now. It's a stupid hr tag in the HTML of the theme (separates posts on category and archive pages). Add this:

.archive hr {
height: 0;
}

Problems 1 and 3 solved!

2) In Safari this is a non-issue (everything looks good). But in Firefox, I still see the horizontal lines that want to show up between posts on the category pages (e.g. http://ocdstyle.com/category/obsessed-w/). Those dividing lines are causing small spacing issues, and I want to get rid of them. I've made the images more transparent to help you see the lines running through the images.

2) I'm not seeing any line in Firefox or Safari.

3) Try adding this:

#top {
    margin-top: -5em;
    padding-top: 5em;
}

1) For some reason, the post preview images (.home . post img) on the home page are being clipped at the bottom by 1 px. Then on the category and post pages they are back to their normal height. It's not really noticeable, but it still bugs me.

2) The post preview images on the category page (.category .post img) have an annoying line running through them that you can see when the opacity effect is applied. Using border-bottom commands won't get rid of it. Might be a h2 or h3 issue?

3) No idea why using the #top url doesn't bring you to the tippy top when clicked; it brings you to the almost top (example in bottom right footer image). Maybe using a text widget and html is the answer and not the image widget?

Save me CSS wizards!

Do you know why is the right border cut off?