:root{
  /* 4px base */
  --space-1:4px;  --space-2:8px;  --space-3:12px; --space-4:16px;
  --space-5:20px; --space-6:24px; --space-7:28px; --space-8:32px;
  --space-10:40px;--space-12:48px;--space-14:56px;--space-16:64px;
  --space-18:72px;--space-24:96px;

  /* the four that carry the layout */
  --space-inset:8px;   /* inside a pastille */
  --space-row:16px;    /* between list rows */
  --space-card:24px;   /* card padding */
  --space-block:48px;  /* between page blocks */

  /* layout constants */
  --sidebar-width:296px;
  --sidebar-inset:24px;  /* margin from content and from the window edge */
  --sidebar-pad:20px;
  --page-pad-x:64px;
  --content-max:1280px;
  --grid-gap:20px;
  --card-pad:26px;
  --stack:72px;          /* between spec sections */

  --control-h-sm:36px;
  --control-h-md:44px;
  --control-h-lg:48px;
  --nav-item-h:42px;
  --icon-size:20px;
  --icon-stroke:1.75;
}