/* =====================================================================
   THE KNOBS — this is the only block you need to edit to retheme.
   Every colour, space and column width used anywhere on the site is
   defined here. Nothing below this block hard-codes a colour or a size.
   ===================================================================== */
:root {
  /* Colours */
  --color-bg:      #fcfcfa;   /* page background */
  --color-text:    #191a18;   /* body text */
  --color-muted:   #5c5e59;   /* metadata, captions, minor sections */
  --color-rule:    #dedfd8;   /* hairlines and borders */
  --color-panel:   #f1f3ed;   /* tinted feature panel */
  --color-accent:  #24578c;   /* links and the feature panel's edge */
  --color-focus:   #b8651b;   /* keyboard focus ring, kept distinct from links */

  /* Type */
  --font-body: "Iowan Old Style", "Palatino Linotype", Palatino, "Book Antiqua", Georgia, "Times New Roman", serif;
  --font-meta: ui-sans-serif, system-ui, -apple-system, "Segoe UI", Helvetica, Arial, sans-serif;
  --size-base: 1.0625rem;
  --leading: 1.65;

  /* Spacing scale */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.875rem;
  --space-4: 1.5rem;
  --space-5: 2.5rem;
  --space-6: 4rem;

  /* Layout */
  --measure: 70ch;          /* prose column: index, research, writing */
  --measure-narrow: 62ch;   /* prose column: exposition.html */
  --gutter: 1.25rem;        /* left/right page padding */
}

/* Dark mode overrides the knobs and nothing else. */
@media (prefers-color-scheme: dark) {
  :root {
    --color-bg:     #16181a;
    --color-text:   #e7e8e4;
    --color-muted:  #a0a39c;
    --color-rule:   #2e3134;
    --color-panel:  #1e2124;
    --color-accent: #8fb8e8;
    --color-focus:  #e2a05a;
  }
}

/* ============================ BASE ================================== */
*, *::before, *::after { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--color-bg);
  color: var(--color-text);
  font: var(--size-base)/var(--leading) var(--font-body);
  -webkit-text-size-adjust: 100%;
}

img { max-width: 100%; height: auto; display: block; }

h1, h2, h3 { line-height: 1.25; font-weight: 600; }
h1 { font-size: 1.9rem;  margin: 0 0 var(--space-3); }
h2 { font-size: 1.3rem;  margin: 0 0 var(--space-3); }
h3 { font-size: 1.05rem; margin: var(--space-4) 0 var(--space-2); }
p  { margin: 0 0 var(--space-3); }
p:last-child { margin-bottom: 0; }

/* ======================= LINKS AND FOCUS ============================ */
a {
  color: var(--color-accent);
  text-decoration: underline;
  text-underline-offset: 0.15em;
  text-decoration-thickness: 1px;
}
a:hover { text-decoration-thickness: 2px; }

:focus-visible {
  outline: 2px solid var(--color-focus);
  outline-offset: 3px;
  border-radius: 2px;
}

.skip-link { position: absolute; left: -9999px; font-family: var(--font-meta); }
.skip-link:focus {
  position: static;
  display: inline-block;
  margin: var(--space-2) var(--gutter);
}

/* ===================== LAYOUT CONTAINERS ============================ */
.page {
  max-width: var(--measure);
  margin: 0 auto;
  padding: 0 var(--gutter);
}
.page--narrow { max-width: var(--measure-narrow); }

main { padding: var(--space-5) 0 var(--space-6); }
main > section { margin-top: var(--space-6); }
main > section:first-child { margin-top: 0; }
article > section { margin-top: var(--space-5); }

/* ========================= NAVIGATION =============================== */
.site-header { border-bottom: 1px solid var(--color-rule); }

.nav {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: baseline;
  gap: var(--space-2) var(--space-4);
  padding-top: var(--space-3);
  padding-bottom: var(--space-3);
}
.nav__name {
  color: var(--color-text);
  text-decoration: none;
  font-size: 1.05rem;
}
.nav__links {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2) var(--space-4);
  list-style: none;
  margin: 0;
  padding: 0;
  font-family: var(--font-meta);
  font-size: 0.9rem;
}
.nav__links [aria-current="page"] { color: var(--color-text); }

/* ================== MASTHEAD (photo + identity) ===================== */
/* Wraps on its own: below ~600px the photo lands above the text. */
.masthead {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-4) var(--space-5);
  align-items: flex-start;
}
.masthead__photo { flex: 0 0 auto; width: 280px; }
.masthead__id { flex: 1 1 12rem; min-width: 0; }
.masthead__meta {
  font-family: var(--font-meta);
  font-size: 0.95rem;
  line-height: 1.5;
  color: var(--color-muted);
}

/* ======================= FEATURE PANEL ============================== */
.feature {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-4);
  align-items: flex-start;
  padding: var(--space-4);
  background: var(--color-panel);
  border: 1px solid var(--color-rule);
  border-left: 3px solid var(--color-accent);
}
.feature:hover { border-color: var(--color-accent); }
.feature__figure { flex: 0 1 40%; min-width: 11rem; margin: 0; }
.feature__body { flex: 1 1 15rem; min-width: 0; }
.feature__more { font-family: var(--font-meta); font-size: 0.9rem; }

/* ============ ENTRY LISTS (papers, talks, notes, courses) =========== */
.entries { list-style: none; margin: 0; padding: 0; }
.entry {
  padding: var(--space-3) 0;
  border-top: 1px solid var(--color-rule);
}
.entry:first-child { border-top: 0; padding-top: 0; }
.entry__title { margin-bottom: var(--space-1); font-weight: 600; }
.entry__meta {
  margin-bottom: var(--space-1);
  font-family: var(--font-meta);
  font-size: 0.9rem;
  color: var(--color-muted);
}
.keywords { font-family: var(--font-meta); font-size: 0.9rem; color: var(--color-muted); }

/* ============ MINOR SECTIONS (teaching, service, elsewhere) ========= */
.minor { font-size: 0.95rem; color: var(--color-muted); }
.minor h2 { font-size: 1.05rem; color: var(--color-text); }
.minor ul { margin: 0; padding-left: 1.1rem; }
.minor li { margin-bottom: var(--space-1); }
main > .minor { margin-top: var(--space-5); }

/* ==================== ARTICLE AND FIGURES =========================== */
.standfirst { font-size: 1.15rem; color: var(--color-muted); margin-bottom: var(--space-5); }
figure { margin: var(--space-5) 0; }
figcaption {
  margin-top: var(--space-2);
  font-family: var(--font-meta);
  font-size: 0.85rem;
  line-height: 1.5;
  color: var(--color-muted);
}
.back-link { margin-top: var(--space-5); font-family: var(--font-meta); font-size: 0.9rem; }
/* Long display equations scroll inside their own box, not the page. */
.katex-display { overflow-x: auto; overflow-y: hidden; padding: 0.2em 0; }

/* ============================ FOOTER ================================ */
.site-footer {
  border-top: 1px solid var(--color-rule);
  padding: var(--space-4) 0 var(--space-5);
  font-family: var(--font-meta);
  font-size: 0.85rem;
  color: var(--color-muted);
}

/* ========================== NARROW SCREENS ========================== */
@media (max-width: 600px) {
  :root { --gutter: 1rem; }
  h1 { font-size: 1.6rem; }
  h2 { font-size: 1.2rem; }
  .nav { gap: var(--space-1) var(--space-3); }
  .nav__links { gap: var(--space-1) var(--space-3); }
  .masthead__photo { width: 100%; max-width: 280px; }
  .masthead__id { flex-basis: 100%; }
  .feature__figure, .feature__body { flex-basis: 100%; }
}