/* ==========================================================================
   Platform Research — shared stylesheet
   Clean academic: serif display, restrained slate/ink palette, generous space
   ========================================================================== */

:root {
  --ink:        #1b1b1f;
  --ink-soft:   #3a3a42;
  --muted:      #6b6b76;
  --line:       #e4e1da;
  --paper:      #fbfaf7;
  --paper-2:    #f4f2ec;
  --accent:     #2f4a6b;   /* muted academic navy/slate */
  --accent-ink: #22384f;
  --maxw:       72ch;
  --wide:       1080px;
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: "Newsreader", Georgia, "Times New Roman", serif;
  font-size: 1.125rem;
  line-height: 1.7;
  font-feature-settings: "kern" 1, "liga" 1;
  -webkit-font-smoothing: antialiased;
}

/* ---- Layout ------------------------------------------------------------- */
.wrap { width: 100%; max-width: var(--wide); margin: 0 auto; padding: 0 1.5rem; }
.prose { max-width: var(--maxw); }

section { padding: 4.5rem 0; }
section + section { border-top: 1px solid var(--line); }

/* ---- Typography --------------------------------------------------------- */
h1, h2, h3 { line-height: 1.15; font-weight: 600; color: var(--ink); letter-spacing: -0.01em; }
h1 { font-size: clamp(2.2rem, 5vw, 3.4rem); margin: 0 0 0.5rem; }
h2 { font-size: clamp(1.5rem, 3vw, 2rem); margin: 0 0 1rem; }
h3 { font-size: 1.25rem; margin: 0 0 0.4rem; }

p { margin: 0 0 1.1rem; color: var(--ink-soft); }
a { color: var(--accent); text-decoration: none; border-bottom: 1px solid rgba(47,74,107,0.25); transition: border-color .15s, color .15s; }
a:hover { color: var(--accent-ink); border-color: var(--accent); }

.eyebrow {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  font-size: 0.72rem; font-weight: 600; letter-spacing: 0.14em; text-transform: uppercase;
  color: var(--accent); margin: 0 0 1rem;
}
.lead { font-size: 1.3rem; color: var(--ink-soft); }
.muted { color: var(--muted); }

/* ---- Header / nav ------------------------------------------------------- */
.site-head { position: sticky; top: 0; z-index: 20; background: rgba(251,250,247,0.85); backdrop-filter: saturate(180%) blur(8px); border-bottom: 1px solid var(--line); }
.nav { display: flex; align-items: center; justify-content: space-between; gap: 1rem; padding: 1rem 1.5rem; max-width: var(--wide); margin: 0 auto; }
.brand { display: inline-flex; align-items: center; gap: 0.55rem; font-weight: 600; font-size: 1.15rem; letter-spacing: -0.01em; color: var(--ink); border: 0; }
.brand-mark { display: block; flex: none; width: 28px; height: 28px; }
.brand-name span { color: var(--accent); }
.nav-links { display: flex; gap: 1.6rem; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif; font-size: 0.92rem; }
.nav-links a { color: var(--ink-soft); border: 0; }
.nav-links a:hover { color: var(--accent); }
.nav-links a.active { color: var(--accent); font-weight: 600; }

/* ---- Hero --------------------------------------------------------------- */
.hero { padding: 6rem 0 4.5rem; }
.hero .lead { max-width: 60ch; }

/* ---- Buttons ------------------------------------------------------------ */
.btn-row { display: flex; flex-wrap: wrap; gap: 0.8rem; margin-top: 1.8rem; }
.btn {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  font-size: 0.95rem; font-weight: 500; padding: 0.65rem 1.25rem; border-radius: 6px; border: 1px solid var(--accent);
  background: var(--accent); color: #fff; cursor: pointer;
}
.btn:hover { background: var(--accent-ink); border-color: var(--accent-ink); color: #fff; }
.btn.ghost { background: transparent; color: var(--accent); }
.btn.ghost:hover { background: var(--paper-2); color: var(--accent-ink); }

/* ---- Cards / grids ------------------------------------------------------ */
.grid { display: grid; gap: 1.5rem; }
.grid.cols-2 { grid-template-columns: repeat(2, 1fr); }
.grid.cols-3 { grid-template-columns: repeat(3, 1fr); }
.card { background: #fff; border: 1px solid var(--line); border-radius: 10px; padding: 1.6rem 1.5rem; }
.card h3 { margin-top: 0; }
.card p:last-child { margin-bottom: 0; }

/* ---- Sector strip (platforms we study) ---------------------------------- */
.sectors-label { font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif; font-size: 0.72rem; font-weight: 600; letter-spacing: 0.14em; text-transform: uppercase; color: var(--muted); margin: 3rem 0 1.25rem; }
.sectors { display: grid; grid-template-columns: repeat(6, 1fr); gap: 0.85rem; }
.sector { display: flex; flex-direction: column; align-items: center; gap: 0.75rem; text-align: center; padding: 1.5rem 0.6rem; background: #fff; border: 1px solid var(--line); border-radius: 14px; transition: border-color .15s, transform .15s, box-shadow .15s; }
.sector:hover { border-color: var(--accent); transform: translateY(-2px); box-shadow: 0 6px 18px rgba(34,56,79,0.08); }
.sector svg { width: 24px; height: 24px; padding: 13px; box-sizing: content-box; background: var(--paper-2); border-radius: 50%; display: block; }
.sector .name { font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif; font-weight: 600; font-size: 0.82rem; color: var(--ink); line-height: 1.25; }
@media (max-width: 1000px) { .sectors { grid-template-columns: repeat(3, 1fr); } }
@media (max-width: 560px) { .sectors { grid-template-columns: repeat(2, 1fr); gap: 0.7rem; } }

/* ---- Publications list -------------------------------------------------- */
.pub { padding: 1.4rem 0; border-bottom: 1px solid var(--line); }
.pub:last-child { border-bottom: 0; }
.pub .title { font-weight: 600; color: var(--ink); }
.pub .authors { color: var(--ink-soft); }
.pub .venue { font-style: italic; color: var(--muted); }
.pub .tags { margin-top: 0.5rem; display: flex; gap: 0.5rem; flex-wrap: wrap; }
.tag {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  font-size: 0.72rem; letter-spacing: 0.03em; color: var(--accent); background: var(--paper-2);
  border: 1px solid var(--line); border-radius: 999px; padding: 0.15rem 0.6rem;
}

/* ---- Contact ------------------------------------------------------------ */
.contact-list { list-style: none; padding: 0; margin: 1.5rem 0 0; }
.contact-list li { padding: 0.6rem 0; border-bottom: 1px solid var(--line); display: flex; gap: 1rem; }
.contact-list .k { font-family: -apple-system, BlinkMacSystemFont, sans-serif; font-size: 0.8rem; text-transform: uppercase; letter-spacing: 0.08em; color: var(--muted); min-width: 7rem; padding-top: 0.15rem; }

/* ---- Footer ------------------------------------------------------------- */
.site-foot { border-top: 1px solid var(--line); padding: 2.5rem 0; margin-top: 2rem; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif; font-size: 0.85rem; color: var(--muted); }
.site-foot .wrap { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 1rem; }
.site-foot a { color: var(--muted); border: 0; }
.site-foot a:hover { color: var(--accent); }

/* ---- Responsive --------------------------------------------------------- */
@media (max-width: 720px) {
  body { font-size: 1.05rem; }
  .grid.cols-2, .grid.cols-3 { grid-template-columns: 1fr; }
  .nav-links { gap: 1.1rem; }
  .nav { flex-wrap: wrap; }
  section { padding: 3rem 0; }
  .hero { padding: 3.5rem 0 2.5rem; }
}