CSS UserStyle fixes for the latest Google Plus layout as of 2013 Q3. So far only the single column layout is being tweaked.

google_plus_single_column_layout_fixes-mozformat.user.css

@-moz-document domain("plus.google.com") {
#I_have_all_the_rules_prefixed_with_nonexisting_ids_to_describe_the_rules_and_to_enforce_correct_rule_orders_for_user_style_engines_that_strip_comments_and_sort_rules_alphabetically {}


}

@-moz-document domain("plus.google.com") {
#_Single_Column_Layout_Section_comment { /* The rules in this section apply to the single column layout */ }
#rule_1a_remove_fixed_width_on_content_columns, .ow > div, .ow .e4CL6 { width: inherit!important; }
#rule_1b_set_maximum_width_on_content_columns, .ow > div { max-width: /*[[max-column-width]]*/!important; }
#rule_1c_make_share_box_same_width_as_content_columns, .ow > div .EyKftc { max-width: inherit; }

#rule_2a_force_single_column_layout_on_profile_posts_page, .ow > div .hy8VRd { width: 100%!important; }
#rule_2b_force_single_column_layout_on_profile_posts_page_remove_indent_second_column, .ow > div .hy8VRd.XkmQbb+.XkmQbb { margin-left: inherit; }


#rule_3_force_single_column_layout_on_profile_about_page_comment {
  /* 
  Personally I think the default 2 column layout for this page looks better, 
  but I'll leave it in for those who want everything in the single column format 
  If you don't like it, feel free to remove all of the rule_3x lines, or comment out the entire block.
  */
}
#rule_3a_force_single_column_layout_on_profile_about_page_outer_column, .wz4dC { width: 100%; margin-left: inherit;}
#rule_3b_force_single_column_layout_on_profile_about_page_inner_column, .fNFtPe { width: inherit; }

#rule_4a_fix_individual_post_layout_set_maximum_width, .CZb {width: inherit; max-width: /*[[max-column-width]]*/;}
#rule_4b_fix_individual_post_layout_make_column_fill_to_max_width, .CZb .Vra {width: inherit;}
#rule_4c_fix_individual_post_layout_fix_post_width, .CZb .Vra .e4CL6 {width: inherit;}
#rule_4d_fix_individual_post_layout_force_profile_box_in_same_column, .CZb .Vra .wEiS3b {position: inherit; right: inherit; overflow: inherit; width: 100%;}

#rule_5_force_single_column_layout_on_events_page_comment {
  /* 
  Again I personally think the default 2 column layout for this page looks better, 
  but I'll leave it in for those who want everything in the single column format 
  If you don't like it, feel free to remove all of the rule_5x lines, or comment out the entire block.
  */
}
#rule_5a_force_single_column_layout_on_events_page_reserve_entire_width, .OT3k, .OT3k .Rae1q {width: 100%;}
#rule_5b_force_single_column_layout_on_events_page_center_posts, .U4 { margin-left: auto;margin-right: auto;}
#rule_5c_force_single_column_layout_on_events_page_center_section_titles, .OT3k .Rae1q {text-align: center;}
#rule_5d_force_single_column_layout_on_events_page_post_widths_and_remove_tiling, .U4 { width: inherit; max-width: /*[[max-column-width]]*/; display: block;}

#rule_6a_force_single_column_layout_on_hangouts_page, #contentPane.he .hy8VRd { width: 100%; }
}
#rule_6b_force_single_column_layout_on_hangouts_page_remove_index_from_second_column, #contentPane.he .hy8VRd.XkmQbb+.XkmQbb { margin-left: inherit; }

#rule_7a_remove_fixed_width_on_notifications_page_set_maximum_width, .c9 .e4CL6 { width: inherit!important; max-width: /*[[max-column-width]]*/; }
#rule_7b_remove_fixed_width_on_notifications_page_stretch_inner_column, .c9 .e4CL6 .dQ { width: inherit!important; }

google_plus_single_column_layout_fixes.user.css

#I_have_all_the_rules_prefixed_with_nonexisting_ids_to_describe_the_rules_and_to_enforce_correct_rule_orders_for_user_style_engines_that_strip_comments_and_sort_rules_alphabetically {}
#_Single_Column_Layout_Section_comment { /* The rules in this section apply to the single column layout */ }
#rule_1a_remove_fixed_width_on_content_columns, .ow > div, .ow .e4CL6 { width: inherit!important; }
#rule_1b_set_maximum_width_on_content_columns, .ow > div { max-width: 900px!important; }
#rule_1c_make_share_box_same_width_as_content_columns, .ow > div .EyKftc { max-width: inherit; }

#rule_2a_force_single_column_layout_on_profile_posts_page, .ow > div .hy8VRd { width: 100%!important; }
#rule_2b_force_single_column_layout_on_profile_posts_page_remove_indent_second_column, .ow > div .hy8VRd.XkmQbb+.XkmQbb { margin-left: inherit; }


#rule_3_force_single_column_layout_on_profile_about_page_comment {
  /* 
  Personally I think the default 2 column layout for this page looks better, 
  but I'll leave it in for those who want everything in the single column format 
  If you don't like it, feel free to remove all of the rule_3x lines, or comment out the entire block.
  */
}
#rule_3a_force_single_column_layout_on_profile_about_page_outer_column, .wz4dC { width: 100%; margin-left: inherit;}
#rule_3b_force_single_column_layout_on_profile_about_page_inner_column, .fNFtPe { width: inherit; }

#rule_4a_fix_individual_post_layout_set_maximum_width, .CZb {width: inherit; max-width: 900px;}
#rule_4b_fix_individual_post_layout_make_column_fill_to_max_width, .CZb .Vra {width: inherit;}
#rule_4c_fix_individual_post_layout_fix_post_width, .CZb .Vra .e4CL6 {width: inherit;}
#rule_4d_fix_individual_post_layout_force_profile_box_in_same_column, .CZb .Vra .wEiS3b {position: inherit; right: inherit; overflow: inherit; width: 100%;}

#rule_5_force_single_column_layout_on_events_page_comment {
  /* 
  Again I personally think the default 2 column layout for this page looks better, 
  but I'll leave it in for those who want everything in the single column format 
  If you don't like it, feel free to remove all of the rule_5x lines, or comment out the entire block.
  */
}
#rule_5a_force_single_column_layout_on_events_page_reserve_entire_width, .OT3k, .OT3k .Rae1q {width: 100%;}
#rule_5b_force_single_column_layout_on_events_page_center_posts, .U4 { margin-left: auto;margin-right: auto;}
#rule_5c_force_single_column_layout_on_events_page_center_section_titles, .OT3k .Rae1q {text-align: center;}
#rule_5d_force_single_column_layout_on_events_page_post_widths_and_remove_tiling, .U4 { width: inherit; max-width: 900px; display: block;}

#rule_6a_force_single_column_layout_on_hangouts_page, #contentPane.he .hy8VRd { width: 100%; }
#rule_6b_force_single_column_layout_on_hangouts_page_remove_index_from_second_column, #contentPane.he .hy8VRd.XkmQbb+.XkmQbb { margin-left: inherit; }

#rule_7a_remove_fixed_width_on_notifications_page_set_maximum_width, .c9 .e4CL6 { width: inherit!important; max-width: 900px; }
#rule_7b_remove_fixed_width_on_notifications_page_stretch_inner_column, .c9 .e4CL6 .dQ { width: inherit!important; }

google_plus_two_columns_layout_fixes.user.css

/* These rules are still a bit of work in progress */
#_Two_Column_Layout_Section_comment { /* The rules in this section apply to the 2-columns layout */ }


#rule_1a_remove_fixed_width_on_content_columns, .ow > div { width: inherit!important; }
#rule_1b_set_maximum_width_on_content_columns_container, .ow > div { max-width: 1280px!important; /* replace with your screen's resolution */}
#rule_1d_make_share_box_same_width_as_content_columns, .ow > div .EyKftc { max-width: inherit; }
#rule_1c_make_content_columns_half_width, .ow > div .hy8VRd {
  width: 48.8%!important; 
  -webkit-box-sizing: border-box; /* Safari/Chrome, other WebKit */
  -moz-box-sizing: border-box;    /* Firefox, other Gecko */
  box-sizing: border-box;         /* Opera/IE 8+ */
}


#rule_2_offset_circles_overlay, .gf.ir {margin-top: 15px;}
#rule_2_increase_height_circles_overlay_list, .ar {max-height: 400px;}

#rule_4a_fix_individual_post_layout_set_maximum_width, .CZb {width: inherit; max-width: 900px;}
#rule_4b_fix_individual_post_layout_make_column_fill_to_max_width, .CZb .Vra {width: inherit;}
#rule_4c_fix_individual_post_layout_fix_post_width, .CZb .Vra .e4CL6 {width: inherit;}
#rule_4d_fix_individual_post_layout_force_profile_box_in_same_column, .CZb .Vra .wEiS3b {position: inherit; right: inherit; overflow: inherit; width: 100%;}

#rule_7a_remove_fixed_width_on_notifications_page_set_maximum_width, .c9 .e4CL6 { width: inherit!important; max-width: 900px; }
#rule_7b_remove_fixed_width_on_notifications_page_stretch_inner_column, .c9 .e4CL6 .dQ { width: inherit!important; }