%table.condensed-table.span8
  %tr
    %th= t_attr :date, Activity
    %th.number= t_attr :working_hours, Activity
    %th.number= t_attr :overtime, Activity
    %th.number= t_attr :overall_overtime, Activity

  - WorkDay.create_or_update_upto(@employee, Date.today.end_of_month)
  - range = Date.today.beginning_of_month..Date.today.end_of_month
  - @employee.work_days.where(:date => range).each do |day|
    - tr_params = {:class => work_day_classes(day)}
    - tr_params.merge!(:rel => 'popover', 'data-content' => h(render 'timesheets/activities_popover', :activities => day.activities), 'data-original-title' => 'Aktivitäten', 'data-html' => 'true') unless day.activities.empty?
    %tr{tr_params}
      %td= link_to l(day.date, :format => '%a, %d.%m.%Y'), person_activities_path(@employee, :by_date => day.date.to_s(:db)), 'data-href-container' => 'tr'
      %td.number
        %span.strong= "%0.2f" % day.hours_worked
        = "(%0.2f)" % day.hours_due
      %td.number.overtime.strong= "%0.2f" % day.overtime
      %td.number.overall-overtime.strong= "%0.2f" % day.overall_overtime

%table.condensed-table.span8
  %tr
    %th= t_attr :date, Activity
    %th.right= t_attr :working_hours, Activity
    %th.right= t_attr :overtime, Activity
    %th.right= t_attr :overall_overtime, Activity

  - WorkDay.create_or_update_upto(@employee, Date.today.end_of_month)
  - range = Date.today.beginning_of_month..Date.today.end_of_month
  - @employee.work_days.where(:date => range).each do |day|
    - tr_params = {:class => work_day_classes(day)}
    - tr_params.merge!(:rel => 'popover', 'data-content' => h(render 'timesheets/activities_popover', :activities => day.activities), 'data-original-title' => 'Aktivitäten', 'data-html' => 'true') unless day.activities.empty?
    %tr{tr_params}
      %td= link_to l(day.date, :format => '%a, %d.%m.%Y'), person_activities_path(@employee, :by_date => day.date.to_s(:db)), 'data-href-container' => 'tr'
      %td.right
        %span.strong= "%0.2f" % day.hours_worked
        = "(%0.2f)" % day.hours_due
      %td.right.overtime.strong= "%0.2f" % day.overtime
      %td.right.overall-overtime.strong= "%0.2f" % day.overall_overtime

Use .right CSS class instead of .number.
Use .right CSS class instead of .number.
