There's a quiet frustration buried in this question, and it's one we've all felt at some point. You've built a table that looks exactly right, with the right fonts, the right sizes, the perfect diagonal line in that corner cell. Then you try to save it as a reusable style, and the options you need are grayed out. The font and size controls are right there, but they might as well be locked behind glass. The user who asked this isn't confused about how to format a table. They're confused about why the tool they're using won't let them do something that should be simple.
Here's what's actually happening, and it's worth being direct about it: table styles in Excel are designed to control the look of the table's structure, not the content's typography. That's why the font and size options are disabled in the New Table Style menu. The style system assumes you'll want consistent fonts across the whole table, so it locks those controls down to keep you from fragmenting the design. But that assumption doesn't match how people actually work. You don't want a uniform look. You want headers that read clearly at a glance, data that's easy to scan, and a top-left cell that stands apart because it's not really data at all. That's not a formatting quirk. That's a deliberate design choice, and the tool is fighting you on it.
The practical workaround isn't hidden in some obscure setting you accidentally triggered. It's just a different approach. Instead of trying to force the table style to carry your typography, you can set the fonts and sizes directly on the cells themselves, then create the table style to handle everything else: borders, fills, banding, and that diagonal line. Once the style is applied, the font settings you made manually will stick, because Excel doesn't override direct formatting when it applies a style. The grayed-out menu is a sign that you're trying to use the wrong layer of control. The cells are where your typography lives. The style is where your structure lives. Use them separately and you get what you actually want.
That's the real lesson here, and it applies beyond this one example. When a tool blocks you, it's worth asking whether the block is a bug or a boundary. In this case, it's a boundary, but it's one you can work around without losing any of the precision you're after. Set your fonts on the cells, build the style for the rest, and save yourself the headache of fighting a menu that was never meant to give you what you wanted in the first place. The table you're picturing is achievable. You just have to tell Excel where each piece belongs.