I can't see the HTML, I don't know the class and id names to use in the CSS. As I understand it, this would not be a problem if I was just using wordpress.org.
Just to clarify, that statement is not true. You can see the HTML and CSS for any site on the internet regardless of whether it is setup as a WordPress.org site or a WordPress.com site, however, WordPress.com does not offer the option to modify theme HTML which is probably what you're thinking of.
To match the footer navigation styling in the Able theme to the top navigation on the same page, I would start by copying the =Navigation Menu section of the theme's CSS and then adjusting the selectors so they apply to the footer instead of the header.
Here is a direct link to your site's CSS which I got from the Appearance → Custom Design → CSS → Mode: Add-on section of your dashboard:
https://s1.wp.com/wp-content/themes/pub/able/style.css?m=1359464150g&minify=false
Here is an example. To get the following, I copied the =Navigation Menu section from your theme's CSS, stripped out anything that applied to submenus since you don't have those, replaced ".main-navigation" with "#colophon .footer-navigation", and added two rules to the top to make the footer area full width just like it is for the top navigation;
#colophon {
padding: 0;
}
.site-info {
padding: 0 26px;
}
#colophon .footer-navigation {
background-color: rgb( 240, 240, 240 ); /* #f0f0f0 */
background-image: -webkit-gradient( linear, left top, left bottom, from( rgba( 240, 240, 240, 0.8 ) ), to( rgba( 210, 210, 210, 0.8 ) ) );
background-image: -webkit-linear-gradient( rgba( 240, 240, 240, 0.8 ), rgba( 210, 210, 210, 0.8 ) );
background-image: -moz-linear-gradient( rgba( 240, 240, 240, 0.8 ), rgba( 210, 210, 210, 0.8 ) );
background-image: -ms-linear-gradient( rgba( 240, 240, 240, 0.8 ), rgba( 210, 210, 210, 0.8 ) );
background-image: -o-linear-gradient( rgba( 240, 240, 240, 0.8 ), rgba( 210, 210, 210, 0.8 ) );
background-image: linear-gradient( rgba( 240, 240, 240, 0.8 ), rgba( 210, 210, 210, 0.8 ) );
filter: progid:DXImageTransform.Microsoft.gradient( GradientType=0, startColorstr='#f0f0f0', endColorstr='#d2d2d2' );
-webkit-border-radius: 3px 3px 0 0;
border-radius: 3px 3px 0 0;
/* box-shadow values: #e6e6e6, #fafafa, #c8c8c8, #000 */
-webkit-box-shadow: inset 0 1px 0 rgba( 230, 230, 230, 0.8 ), inset 0 2px 0 rgba( 250, 250, 250, 0.8 ), inset 0 -1px 0 rgba( 200, 200, 200, 0.6 ), 0 0 1px rgba( 0, 0, 0, .1 );
-moz-box-shadow: inset 0 1px 0 rgba( 230, 230, 230, 0.8 ), inset 0 2px 0 rgba( 250, 250, 250, 0.8 ), inset 0 -1px 0 rgba( 200, 200, 200, 0.6 ), 0 0 1px rgba( 0, 0, 0, .1 );
-ms-box-shadow: inset 0 1px 0 rgba( 230, 230, 230, 0.8 ), inset 0 2px 0 rgba( 250, 250, 250, 0.8 ), inset 0 -1px 0 rgba( 200, 200, 200, 0.6 ), 0 0 1px rgba( 0, 0, 0, .1 );
-o-box-shadow: inset 0 1px 0 rgba( 230, 230, 230, 0.8 ), inset 0 2px 0 rgba( 250, 250, 250, 0.8 ), inset 0 -1px 0 rgba( 200, 200, 200, 0.6 ), 0 0 1px rgba( 0, 0, 0, .1 );
box-shadow: inset 0 1px 0 rgba( 230, 230, 230, 0.8 ), inset 0 2px 0 rgba( 250, 250, 250, 0.8 ), inset 0 -1px 0 rgba( 200, 200, 200, 0.6 ), 0 0 1px rgba( 0, 0, 0, .1 );
float: left;
font-size: 13px;
font-size: 1.3rem;
margin: 0;
}
#colophon .footer-navigation ul {
list-style: none;
margin: 0;
padding: 0 26px;
}
#colophon .footer-navigation a {
display: block;
padding: 6px 13px 7px;
text-decoration: none;
word-wrap: break-word;
border: 0;
}
#colophon .footer-navigation a:focus,
#colophon .footer-navigation li:hover > a,
#colophon .footer-navigation .current-menu-item > a,
#colophon .footer-navigation .current_page_item > a {
background-color: rgb( 215, 215, 215 ); /* #d7d7d7 */
background-image: -webkit-gradient( linear, left top, left bottom, from( rgba( 215, 215, 215, 0.8 ) ), to( rgba( 180, 180, 180, 0.8 ) ) );
background-image: -webkit-linear-gradient( rgba( 215, 215, 215, 0.8 ), rgba( 180, 180, 180, 0.8 ) );
background-image: -moz-linear-gradient( rgba( 215, 215, 215, 0.8 ), rgba( 180, 180, 180, 0.8 ) );
background-image: -ms-linear-gradient( rgba( 215, 215, 215, 0.8 ), rgba( 180, 180, 180, 0.8 ) );
background-image: -o-linear-gradient( rgba( 215, 215, 215, 0.8 ), rgba( 180, 180, 180, 0.8 ) );
background-image: linear-gradient( rgba( 215, 215, 215, 0.8 ), rgba( 180, 180, 180, 0.8 ) );
filter: progid:DXImageTransform.Microsoft.gradient( GradientType=0, startColorstr='#d7d7d7', endColorstr='#b4b4b4' );
/* box-shadow values: #c8c8c8, #f0f0f0, #a5a5a5, #000 */
-webkit-box-shadow: inset 0 1px 0 rgba( 200, 200, 200, 0.8 ), inset 0 2px 0 rgba( 240, 240, 240, 0.8 ), inset 0 -1px 0 rgba( 165, 165, 165, 0.6 ), 0 0 1px rgba( 0, 0, 0, 0.19 );
-moz-box-shadow: inset 0 1px 0 rgba( 200, 200, 200, 0.8 ), inset 0 2px 0 rgba( 240, 240, 240, 0.8 ), inset 0 -1px 0 rgba( 165, 165, 165, 0.6 ), 0 0 1px rgba( 0, 0, 0, 0.19 );
-ms-box-shadow: inset 0 1px 0 rgba( 200, 200, 200, 0.8 ), inset 0 2px 0 rgba( 240, 240, 240, 0.8 ), inset 0 -1px 0 rgba( 165, 165, 165, 0.6 ), 0 0 1px rgba( 0, 0, 0, 0.19 );
-o-box-shadow: inset 0 1px 0 rgba( 200, 200, 200, 0.8 ), inset 0 2px 0 rgba( 240, 240, 240, 0.8 ), inset 0 -1px 0 rgba( 165, 165, 165, 0.6 ), 0 0 1px rgba( 0, 0, 0, 0.19 );
box-shadow: inset 0 1px 0 rgba( 200, 200, 200, 0.8 ), inset 0 2px 0 rgba( 240, 240, 240, 0.8 ), inset 0 -1px 0 rgba( 165, 165, 165, 0.6 ), 0 0 1px rgba( 0, 0, 0, 0.19 );
}
#colophon .footer-navigation li .current-menu-item > a,
#colophon .footer-navigation li .current_page_item > a {
background: rgb( 230, 230, 230 ); /* #e6e6e6 */
background: rgba( 230, 230, 230, 0.9 );
box-shadow: none;
color: rgb( 13, 61, 155 ); /* #0d3d9b */
color: rgba( 13, 61, 155, 1 );
}
I used "#colophon" in front of ".footer-navigation" to make the rules more specific so I wouldn't have to use an !important tag on anything.
It looks scary because it's using soe nifty CSS3 stuff, but it's mostly a matter of cut/paste in this case.