:root {
  --black: #0a0a0a;
  --dark: #1a1a1a;
  --gray: #666;
  --light-gray: #999;
  --border: #e0e0e0;
  --bg: #fafaf8;
  --white: #fff;
  --orange: #D85A30;
  --orange-light: #F0997B;
  --orange-dark: #993C1D;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

body {
  font-family: 'EB Garamond', 'Georgia', serif;
  font-size: 18px;
  line-height: 1.75;
  color: var(--dark);
  background: var(--bg);
}

a { color: var(--orange-dark); text-decoration: none; }
a:hover { color: var(--orange); }

.container { max-width: 900px; margin: 0 auto; padding: 0 2rem; }
.container-wide { max-width: 1100px; margin: 0 auto; padding: 0 2rem; }

/* Navigation */
nav {
  position: fixed; top: 0; width: 100%; z-index: 100;
  background: rgba(216,90,48,0.95);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid #c04828;
  padding: 1rem 0;
}
nav .container-wide {
  display: flex; align-items: center; justify-content: flex-start;
  flex-wrap: nowrap;
  gap: clamp(1.5rem, -0.5rem + 4vw, 4rem);
}
nav .mark { font-family: 'DM Sans', sans-serif; font-weight: 700; font-size: 1.1rem; color: var(--black); letter-spacing: 0.02em; flex-shrink: 0; }
nav .mark span { color: var(--orange); }
nav ul {
  list-style: none; display: flex;
  gap: clamp(0.75rem, 0rem + 1.5vw, 2rem);
  flex-wrap: nowrap;
}
nav ul a {
  font-family: 'DM Sans', sans-serif;
  font-size: clamp(0.7rem, 0.4rem + 0.5vw, 0.95rem);
  color: rgba(0,0,0,0.7);
  letter-spacing: clamp(0.02em, 0.01em + 0.05vw, 0.04em);
  text-transform: uppercase;
  white-space: nowrap;
}
nav ul a:hover { color: var(--black); }

/* Hamburger button — hidden by default, shown at narrow viewports */
.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.4rem;
  margin: -0.4rem 0;
  flex-shrink: 0;
}
.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: rgba(0,0,0,0.75);
  margin: 5px 0;
  transition: transform 0.2s ease, opacity 0.2s ease;
}
.nav-toggle[aria-expanded="true"] span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}
.nav-toggle[aria-expanded="true"] span:nth-child(2) {
  opacity: 0;
}
.nav-toggle[aria-expanded="true"] span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* Anchor links: leave space for sticky nav */
[id] { scroll-margin-top: 5rem; }

/* Hero */
.hero {
  padding: 10rem 0 6rem;
  border-bottom: 1px solid var(--border);
}

.hero h1 {
  font-family: 'DM Sans', sans-serif;
  font-size: 3.5rem; font-weight: 700;
  color: var(--black); line-height: 1.1;
  margin-bottom: 1.5rem;
}
.hero .tagline {
  font-size: 1.4rem; color: var(--gray);
  font-style: italic; margin-bottom: 2rem;
  max-width: 600px;
}
.hero .identity {
  font-size: 1.05rem; color: var(--dark);
  margin-bottom: 0.5rem;
}
.hero .built-with {
  font-family: 'DM Sans', sans-serif;
  font-size: 0.85rem; color: var(--light-gray);
  letter-spacing: 0.02em;
}

/* Sections */
section { padding: 5rem 0; border-bottom: 1px solid var(--border); }
section:last-child { border-bottom: none; }
section h2 {
  font-family: 'DM Sans', sans-serif;
  font-size: 1.8rem; font-weight: 700;
  color: var(--black); margin-bottom: 2rem;
}

section h3 {
  font-family: 'DM Sans', sans-serif;
  font-size: 1.2rem; font-weight: 600;
  color: var(--dark); margin-bottom: 0.75rem; margin-top: 2.5rem;
}
section p { margin-bottom: 1.25rem; }
.accent-line { width: 40px; height: 3px; background: var(--orange); margin-bottom: 2rem; }

/* Background network */
.bg-network {
  position: fixed; top: 0; left: 0; width: 100%; height: 100%;
  z-index: 0; pointer-events: none; overflow: hidden;
}
.bg-network svg { width: 100%; height: 100%; }
.hero, section, footer { position: relative; z-index: 1; }

/* Pillars grid */
.pillars { display: grid; grid-template-columns: repeat(3, 1fr); gap: 3rem; margin-top: 3rem; }
.pillar h3 { font-family: 'DM Sans', sans-serif; font-size: 1.1rem; font-weight: 700; color: var(--black); margin-bottom: 0.75rem; }
.pillar h3::before { content: ''; display: block; width: 24px; height: 2px; background: var(--orange); margin-bottom: 0.75rem; }
.pillar p { font-size: 0.95rem; color: var(--gray); }

/* Paper cards */
.paper { padding: 2rem 0; border-bottom: 1px solid var(--border); }
.paper:last-child { border-bottom: none; }
.paper h3 { font-family: 'DM Sans', sans-serif; font-size: 1.15rem; font-weight: 700; color: var(--black); margin-top: 0; margin-bottom: 0.25rem; }
.paper .subtitle { font-style: italic; color: var(--gray); font-size: 0.95rem; margin-bottom: 0.5rem; }
.paper .meta { font-family: 'DM Sans', sans-serif; font-size: 0.8rem; color: var(--orange); margin-bottom: 1rem; }
.paper p { font-size: 0.95rem; }
.paper .pdf-link {
  display: inline-block; margin-top: 1rem;
  font-family: 'DM Sans', sans-serif; font-size: 0.85rem;
  color: var(--orange-dark); border: 1px solid var(--orange-light);
  padding: 0.4rem 1.2rem; border-radius: 4px;
}
.paper .pdf-link:hover { background: var(--orange); color: var(--white); border-color: var(--orange); }

/* Research directions */
.direction { margin-bottom: 2rem; }
.direction h4 {
  font-family: 'DM Sans', sans-serif;
  font-size: 1rem; font-weight: 600; color: var(--dark); margin-bottom: 0.4rem;
}
.direction p { font-size: 0.92rem; color: var(--gray); margin-bottom: 0; }

/* Sidebar layout — reusable two-column with sticky nav */
.page-layout {
  display: grid;
  grid-template-columns: 220px 1fr;
  gap: 3rem;
  max-width: 1100px;
  margin: 0 auto;
  padding: 8rem 2rem 4rem;
  position: relative;
  z-index: 1;
}
.page-sidebar {
  position: sticky;
  top: 8rem;
  align-self: start;
  max-height: calc(100vh - 9rem);
  overflow-y: auto;
  padding-right: 1rem;
}
.page-sidebar h4 {
  font-family: 'DM Sans', sans-serif;
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--black);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 0.75rem;
  margin-top: 1.5rem;
}
.page-sidebar h4:first-child { margin-top: 0; }
.page-sidebar ul {
  list-style: none;
  margin-bottom: 0.5rem;
}
.page-sidebar ul li {
  margin-bottom: 0.3rem;
}
.page-sidebar ul li a {
  font-family: 'DM Sans', sans-serif;
  font-size: 0.82rem;
  color: var(--gray);
  display: block;
  padding: 0.25rem 0;
  padding-left: 0.75rem;
  border-left: 2px solid transparent;
  transition: all 0.15s ease;
}
.page-sidebar ul li a:hover {
  color: var(--orange);
  border-left-color: var(--orange-light);
}
.page-sidebar ul li a.active {
  color: var(--orange-dark);
  border-left-color: var(--orange);
  font-weight: 500;
}
.page-content {
  min-width: 0;
}
.page-content h2 {
  font-family: 'DM Sans', sans-serif;
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--black);
  margin-bottom: 1.5rem;
  padding-top: 2rem;
}
.page-content h2:first-child { padding-top: 0; }
.page-content .section-divider {
  width: 100%;
  height: 1px;
  background: var(--border);
  margin: 3rem 0;
}

/* Footer */
footer {
  padding: 3rem 0;
  background: var(--black);
  color: var(--light-gray);
  font-family: 'DM Sans', sans-serif;
  font-size: 0.85rem;
}
footer a { color: var(--orange-light); }
footer .footer-grid { display: grid; grid-template-columns: 1fr 1fr 2fr; gap: 3rem; align-items: flex-start; }
footer .footer-col h4 { color: var(--white); font-size: 0.9rem; margin-bottom: 0.75rem; }
footer .footer-col p { margin-bottom: 0.25rem; line-height: 1.6; }

/* Responsive */

/* Hamburger menu kicks in when shrunk single-line labels still can't fit */
@media (max-width: 850px) {
  nav {
    background: #D85A30;
    backdrop-filter: none;
  }
  nav .container-wide {
    justify-content: flex-start;
    gap: 0.75rem;
  }
  .nav-toggle {
    display: block;
    order: -1;
  }
  nav .mark {
    order: 0;
  }
  nav ul {
    order: 99;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    width: 100%;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    background: #D85A30;
    border-bottom: 1px solid #c04828;
    box-shadow: 0 4px 12px rgba(0,0,0,0.15);
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.25s ease-out;
  }
  nav[data-menu-open="true"] {
    background: #D85A30;
    backdrop-filter: none;
  }
  nav[data-menu-open="true"] ul {
    max-height: 100vh;
  }
  nav ul li {
    width: 100%;
  }
  nav ul a {
    display: block;
    padding: 0.9rem 2rem;
    font-size: 0.85rem;
    letter-spacing: 0.04em;
    border-top: 1px solid rgba(0,0,0,0.08);
    white-space: normal;
  }
  nav ul li:first-child a { border-top: none; }
  .page-layout { padding-top: 6rem; }
}

@media (max-width: 768px) {
  .hero { padding: 9rem 0 4rem; }
  .hero h1 { font-size: 2.2rem; }
  .pillars { grid-template-columns: 1fr; gap: 2rem; }
  footer .footer-grid { grid-template-columns: 1fr; gap: 2rem; }
  .page-layout { grid-template-columns: 1fr; }
  .page-sidebar {
    position: relative; top: 0;
    max-height: none; overflow: visible;
    border-bottom: 1px solid var(--border);
    padding-bottom: 1.5rem; margin-bottom: 1rem;
  }
}