This is the core Ttk theme 'clam' hacked up to look closer to the way I, personally, want it. This means somewhat red-shifted, in particular with text rendered black-on-#fef1e1, and with serif fonts where possible without changing TkDefaultFont. This still lets plenty of uses of TkDefaultFont slip through; for the full experience, try the following in ~/.config/fontconfig/fonts.conf:

<alias>
 <family>sans-serif</family>
  <prefer>
   <family>serif</family>
 </prefer>
</alias>

With the demo code at https://wiki.tcl-lang.org/page/List+of+ttk+Themes (bundled here as demottk.tcl, plumbed up to make test) you should see something like:

Unthemed widgets (in particular [text] and [canvas]) will still be black-on- white by default without further configuration. I recommend something like the following in ~/.Xresources (or otherwise added to the resource database):

*TkTheme: oyster
*background: #fef1e1

This will of course also affect many Xt and motif applications; I consider that a feature.