Styling Sortable Portfolio Filter

I´m using the code below. How can I:

1. Align the sortable filter in center above the portfolio items?
2. Give the category items a rectangular border with some colour change for active category etc.

I realy tried reading the forum but cant find anything that works.

The code I´m using:

#top .isotope-item {
padding-bottom: 10px;
padding-right: 10px;
}

#js_sort_items a { font-size: 16px; }
.sort_by_cat a > span {
padding: 4px 10px;
display: inline-block;
}
.sort_by_cat .text-sep {
display: none;
}

.sort_by_cat a.active_sort span {
font-size: 16px;
}

Kind regards
Micke