Hum, table cells provide the max-width and images a min-with, heights are absolute (with table cells spilling over, as with CCS "overflow-y: visible"), aligns and maybe HSPACE and VSPACE attributes do the rest. As long as images heights exceed the effective line-height and there's no visible text, this should render pixel perfect on any browser then in use. In this case, there's also an absolute width set for the entire table, adding further constraints. Table layouts can be elastic, with constraints or without, but this one should be pretty stable.

(Fun fact, the most amazing layout foot-guns, then: Effective font sizes and line-heights are subject to platform and configuration (e.g., Win vs Mac); Netscape does paragraph spacing at 1.2em, IE at 1em (if this matters, prefer `<br>` over paragraphs); frames dimensions in Netscape are always calculated as integer percentages of window dimensions, even if you provide absolute dimensions in pixels, while IE does what it says on the tin (a rare example), so they will be the same only by chance and effective rounding errors. And, of course, screen gamma is different on Win and Mac, so your colors will always be messed up – aim for a happy medium.)