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Pure CSS Fixed Header Variable Width Table

First
Second
Third
First First First
First Second Third
First Second Third
First Second Third
First Second Third
First Second Third
First Second Third
First Second Third
First Second Third
First Second Third
First Second Third
First Second Third
First Second Third
First Second Third
Last Last Last

Pure CSS Fixed Header Variable Width Table - different content

First
Second and Longer
Third
First First First
First Second Third
First Second this has longer content and so forth Third
First Second Third slightly longer

Pure CSS Fixed Header Variable Width Table with extra wrap div

First
Second and Longer
Third
First First First
First Second Third
First Second this has longer content and so forth Third
First Second Third slightly longer
First First First
First Second Third
First Second this has longer content and so forth Third
First Second Third slightly longer

Pure CSS Fixed Header etc. with hidden header for width calculation

First Column
Second and Longer than Content in the Column
Third
First Column
Second and Longer than Content in the Column
Third
First First First
First Second Third
First Second Third
First Second Third slightly longer
First First First
First Second Third
First Second Third

Pure CSS Fixed Header Variable Width Table - Center Aligned (Zupa style)

First
Second and Longer
Third
First First First
First Second Third
First Second this has longer content and so forth Third
First Second Third slightly longer
First First First
First Second Third
First Second this has longer content and so forth Third
First Second Third slightly longer

Pure CSS Fixed Header Variable Width Table - Center Aligned (Zupa style) with hidden header

First
Second and Longer than Content in the Column
Third
First Column
Second and Longer than Content in the Column
Third
First First First
First Second Third
First Second this has longer content and so forth Third
First Second Third slightly longer
First First First
First Second Third
First Second this has longer content and so forth Third
First Second Third slightly longer

Pure CSS Fixed Header with Complex Header Rows

First and Second
Third
First
Second
First First First
First Second Third
First Second Third
First Second Third
First Second Third
First Second Third
First Second Third
First Second Third
First Second Third
First Second Third
First Second Third
First Second Third
First Second Third
First Second Third
Last Last Last

Same table with header style for jQuery Table Sorter plugin

First Name  
Last Name  
Age  
Total  
Peter Parker 28 $9.99
John Hood 33 $19.99
Clark Kent 18 $15.89
Bruce Almighty 45 $153.19
Bruce Evans 22 $13.19
Bruce Evans 22 $13.19
Elizabeth Bennet 20 $132.19
Jack Bagthorpe 11 $10
Rosie Bagthorpe 9 $15

The sorting is from the jQuery plugin Table Sorter written by Christian Bach. Please see his site for documentation. This is just showing how the pure CSS fixed-header table headers can be styled to show sorting.