:root{
  /* 4px base. Whitespace is generous by doctrine — prefer the next step up. */
  --space-0:0;
  --space-1:4px;
  --space-2:8px;
  --space-3:12px;
  --space-4:16px;
  --space-5:20px;
  --space-6:24px;
  --space-8:32px;
  --space-10:40px;
  --space-12:48px;
  --space-16:64px;
  --space-20:80px;
  --space-24:96px;
  --space-32:128px;
  --space-40:160px;

  /* Layout */
  --container-max:1200px;
  --container-narrow:720px;
  --container-prose:64ch;
  --gutter-mobile:20px;
  --gutter-desktop:40px;
  --section-y-mobile:var(--space-16);
  --section-y-desktop:var(--space-24);

  /* Controls — 44px minimum touch target */
  --control-h-sm:36px;
  --control-h-md:44px;
  --control-h-lg:54px;
  --control-px-sm:16px;
  --control-px-md:24px;
  --control-px-lg:32px;
}