Nice work @Soly, as usual !
However I got one comment concerning the design : it is not compact enough. Gotta scroll between each modification and it's not really practical.
Here is some suggestions that I would do :
Align to the right of the "Max stat calculator" title, the class and level selectors (By the way, is the level selector really useful ? I mean, people anticipate their max plan with the level 200 in mind anyway so...)
Reduce the input width for materials and mag to something like 60-70 px
Reduce the line-height or spacing between each <tr> (not by a lot, because it's still need to be clear, but still 1-2px would not hurt)
Put two inputs of the "Mag" column on the same line. Like DEF & POW, DEX & MIND
Put the "Items" column under the "Mag" column
Also can you add something like this to your URL input ? (lazy user is lazy :p)
onclick="this.setSelectionRange(0, this.value.length)"