The captions used to illustrate the formulas are tables here:
in jdk 5/6 the table is centered nicely.
But with java7's javadocs (I think due to some css styles changes?),
the table is not centered but instead stretched.
I think we just need to center this table with a different technique?
Have a look at http://people.apache.org/~rmuir/java7-style-javadocs/org/apache/lucene/search/Similarity.html to see what I mean.
NOTE: these javadocs are under TFIDFSimilarity.java in trunk.