Issue With custom-style.css on WordPress Site

I bought a custom theme and am having issues with load time. The culprit is this custom-style.css. The code is:

[CODE]/* Custom Accent Colour */
a:hover,
.post_columns h4,
.post_grid h4,
.category_list h4,
#sidebar .widget h4,
#author h4,
#related h4,
.category_list h4 a,
.post_columns h3 a:hover,
#related .column h3 a:hover,
.category_list li .details h5 a:hover,
.tab li .details h5 a:hover,
.full_posts .details h5 a:hover,
#sidebar #twitter_update_list li a,
#sidebar a.twitter-link,
.widget li a:hover,
#content a,
#author a,
#comments .details .name span.author a:hover,
#comments .details .name span.date a:hover,
#respond a:hover,
ol.pinglist li a:hover { color: #D10000; }
.tz_tab_widget .tab_tags a:hover,
#slider .cats span,
.tab_tags a:hover { background: #D10000; }[/CODE]

These few lines of code should not be causing my site to take 20 seconds to load. When this file functions appropriately the load time is under 3 seconds.
I am not so versed in how WordPress functions. Some education on the role this file plays and perhaps so help on why the load keeps getting hung up here would be very beneficial.
Thanks!

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