/* ===================================================
   NTC-R 2026 — styles.css
   Navy + Amber palette · Inter typeface · Mobile-first
=================================================== */

/* --------------------------------------------------
   1. CUSTOM PROPERTIES
-------------------------------------------------- */
:root {
  --navy:        #0f1f3d;
  --navy-mid:    #1a3258;
  --navy-light:  #243d6b;
  --amber:       #f59e0b;
  --amber-dark:  #d97706;
  --amber-light: #fffbeb;
  --body-bg:     #f8f9fb;
  --white:       #ffffff;
  --text:        #1a1a2e;
  --text-muted:  #64748b;
  --text-dark:   #e8edf5;
  --border:      #e2e8f0;
  --section-alt: #f0f4f8;

  --font: 'Inter', system-ui, -apple-system, sans-serif;

  --section-py:    clamp(3.5rem, 7vw, 6rem);
  --container-max: 1100px;
  --container-px:  clamp(1.25rem, 5vw, 2.5rem);

  --radius:    0.5rem;
  --radius-lg: 1rem;
  --shadow:    0 1px 3px rgba(15,31,61,.08), 0 4px 12px rgba(15,31,61,.06);
  --shadow-lg: 0 8px 30px rgba(15,31,61,.14);
  --transition: .2s ease;
}

/* --------------------------------------------------
   2. RESET & BASE
-------------------------------------------------- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html {
  scroll-behavior: smooth;
  scroll-padding-top: 3.75rem; /* sticky nav height */
}

body {
  font-family: var(--font);
  background: var(--body-bg);
  color: var(--text);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

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

a { color: var(--amber-dark); text-decoration: none; transition: color var(--transition); }
a:hover { color: var(--navy); }

ul { list-style: none; }

/* --------------------------------------------------
   3. TYPOGRAPHY
-------------------------------------------------- */
h1, h2, h3, h4 { font-weight: 700; line-height: 1.2; color: var(--navy); }

h1 { font-size: clamp(2.2rem, 5.5vw, 4rem); }
h2 { font-size: clamp(1.6rem, 3.5vw, 2.25rem); }
h3 { font-size: clamp(1rem,  2.5vw, 1.25rem); }

p { text-align: justify; hyphens: auto; }
p + p { margin-top: 1rem; }
.hero p { text-align: center; }

/* --------------------------------------------------
   4. LAYOUT
-------------------------------------------------- */
.container {
  max-width: var(--container-max);
  margin-inline: auto;
  padding-inline: var(--container-px);
}

.section {
  padding-block: var(--section-py);
  background: var(--white);
}
.section--alt  { background: var(--section-alt); }
.section--dark {
  background: var(--navy);
  color: var(--text-dark);
}
.section--dark h2,
.section--dark h3 { color: var(--text-dark); }

.section__header { margin-bottom: clamp(1.25rem, 2.5vw, 1.75rem); }

.section__label {
  display: inline-block;
  font-size: .75rem;
  font-weight: 600;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--amber-dark);
  margin-bottom: .5rem;
}
.section--dark .section__label { color: var(--amber); }

.section__title { margin-bottom: .75rem; }

.section__lead {
  font-size: clamp(1rem, 2vw, 1.1rem);
  color: var(--text-muted);
}
.section--dark .section__lead { color: var(--text-dark); opacity: .8; }

/* --------------------------------------------------
   5. BUTTONS
-------------------------------------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: .4rem;
  padding: .75rem 1.75rem;
  border-radius: var(--radius);
  font-family: var(--font);
  font-size: .9375rem;
  font-weight: 600;
  cursor: pointer;
  border: 2px solid transparent;
  transition: transform var(--transition), box-shadow var(--transition),
              background var(--transition), border-color var(--transition), color var(--transition);
  text-decoration: none;
  white-space: nowrap;
}
.btn:hover { transform: translateY(-2px); box-shadow: var(--shadow-lg); }

.btn--amber {
  background: var(--amber);
  color: var(--navy);
  border-color: var(--amber);
}
.btn--amber:hover { background: var(--amber-dark); border-color: var(--amber-dark); color: var(--navy); }

.btn--outline {
  background: transparent;
  color: var(--text-dark);
  border-color: rgba(255,255,255,.35);
}
.btn--outline:hover { border-color: var(--amber); color: var(--amber); }

.btn--outline-navy {
  background: transparent;
  color: var(--navy);
  border-color: var(--navy);
}
.btn--outline-navy:hover { background: var(--navy); color: var(--white); }

/* --------------------------------------------------
   6. HEADER / STICKY NAV
-------------------------------------------------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(15,31,61,.97);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border-bottom: 1px solid rgba(255,255,255,.06);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  max-width: var(--container-max);
  margin-inline: auto;
  padding-inline: var(--container-px);
  height: 3.5rem;
}

.nav__brand {
  font-size: 1.125rem;
  font-weight: 800;
  color: var(--text-dark);
  letter-spacing: -.01em;
}
.nav__brand span { color: var(--amber); }
.nav__brand:hover { color: var(--text-dark); }

.nav__menu {
  display: flex;
  align-items: center;
  gap: .125rem;
}
.nav__menu a {
  font-size: .875rem;
  font-weight: 500;
  color: rgba(232,237,245,.7);
  padding: .375rem .625rem;
  border-radius: var(--radius);
  transition: color var(--transition), background var(--transition);
}
.nav__menu a:hover,
.nav__menu a.is-active { color: var(--text-dark); background: rgba(255,255,255,.07); }
.nav__menu a.is-active { color: var(--amber); }

.nav__toggle {
  display: none;
  flex-direction: column;
  justify-content: space-between;
  width: 1.5rem;
  height: 1.125rem;
  background: transparent;
  border: none;
  cursor: pointer;
  padding: 0;
  flex-shrink: 0;
}
.nav__toggle span {
  display: block;
  height: 2px;
  background: var(--text-dark);
  border-radius: 2px;
  transition: transform var(--transition), opacity var(--transition);
}
.nav__toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(8px) rotate(45deg); }
.nav__toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.nav__toggle[aria-expanded="true"] span:nth-child(3) { transform: translateY(-8px) rotate(-45deg); }

/* --------------------------------------------------
   7. HERO
-------------------------------------------------- */
.hero {
  position: relative;
  background: var(--navy);
  background-image:
    radial-gradient(ellipse 70% 55% at 65% 35%, rgba(245,158,11,.08) 0%, transparent 65%),
    radial-gradient(ellipse 45% 50% at 5%  85%, rgba(36,61,107,.9)  0%, transparent 55%);
  padding-block: clamp(2.75rem, 6vw, 5rem);
  overflow: hidden;
  text-align: center;
}

/* Network-constellation backdrop */
.hero__bg {
  position: absolute;
  inset: -24px;          /* bleed so the drift never exposes an edge */
  width: calc(100% + 48px);
  height: calc(100% + 48px);
  z-index: 0;
  pointer-events: none;
  opacity: .85;
  animation: hero-drift 24s ease-in-out infinite;
}
.hero > .container { position: relative; z-index: 1; }

.hero__bg-edges line { stroke: rgba(245,158,11,.16); stroke-width: 1; }
.hero__bg-edges--faint line { stroke: rgba(232,237,245,.07); }
.hero__bg-nodes circle { fill: rgba(245,158,11,.55); }
.hero__bg-node--hub { fill: rgba(245,158,11,.85); }
.hero__bg-glow { fill: rgba(245,158,11,.10); }

/* Portrait constellation only on narrow screens */
.hero__bg--portrait { display: none; }

/* Bottom fade so the constellation dissolves into the page */
.hero::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 42%;
  background: linear-gradient(to bottom, transparent, var(--navy));
  z-index: 0;
  pointer-events: none;
}

@keyframes hero-drift {
  0%, 100% { transform: translate3d(0, 0, 0); }
  50%      { transform: translate3d(0, -14px, 0); }
}

/* Gentle twinkle on a few nodes */
@keyframes hero-twinkle {
  0%, 100% { opacity: 1; }
  50%      { opacity: .3; }
}
.hero__bg-node--twinkle { animation: hero-twinkle 5s ease-in-out infinite; }

@media (max-width: 600px) {
  .hero__bg--wide     { display: none; }
  .hero__bg--portrait { display: block; }
}

.hero__sponsor-logo {
  height: 3.75rem;
  width: auto;
  display: block;
  margin: 0 auto 1.25rem;
  opacity: .9;
}

.hero__badge {
  display: inline-flex;
  align-items: center;
  background: rgba(245,158,11,.14);
  border: 1px solid rgba(245,158,11,.3);
  color: var(--amber);
  font-size: .8125rem;
  font-weight: 500;
  letter-spacing: .025em;
  padding: .375rem 1rem;
  border-radius: 2rem;
  margin-bottom: 1.125rem;
}

.hero__title {
  color: var(--white);
  font-size: clamp(1.75rem, 3.8vw, 2.75rem);
  font-weight: 800;
  letter-spacing: -.025em;
  line-height: 1.08;
  margin-bottom: .5rem;
  text-align: center;
}
.hero__title span { color: var(--amber); }

.hero__acronym {
  font-size: clamp(.9rem, 2vw, 1.15rem);
  font-weight: 600;
  color: rgba(232,237,245,.45);
  letter-spacing: .1em;
  text-transform: uppercase;
  margin-bottom: .75rem;
}

.hero__tagline {
  font-size: clamp(1.125rem, 2.5vw, 1.5rem);
  font-weight: 700;
  color: var(--amber);
  margin-bottom: .5rem;
}

.hero__sub {
  font-size: clamp(.9375rem, 2vw, 1.0625rem);
  color: rgba(232,237,245,.72);
  max-width: 58ch;
  margin-inline: auto;
  margin-bottom: 1.5rem;
}

.hero__ctas { display: flex; flex-wrap: wrap; gap: .875rem; justify-content: center; }

/* --------------------------------------------------
   8. ABOUT
-------------------------------------------------- */
.about__grid {
  display: grid;
  grid-template-columns: 3fr 2fr;
  gap: 2.5rem 4rem;
  align-items: start;
}

.about__body { font-size: 1.0625rem; line-height: 1.78; }

.about__callout {
  background: linear-gradient(140deg, var(--navy) 0%, var(--navy-mid) 100%);
  border-radius: var(--radius-lg);
  padding: 2rem 2rem 2.25rem;
  color: var(--text-dark);
  position: sticky;
  top: 5.25rem; /* clears the 3.75rem sticky nav + breathing room */
}
.about__callout-label {
  font-size: .75rem;
  font-weight: 700;
  letter-spacing: .1em;
  text-transform: uppercase;
  color: var(--amber);
  margin-bottom: .875rem;
}
.about__callout p {
  font-size: 1.0625rem;
  line-height: 1.72;
  opacity: .85;
  max-width: none;
}

/* --------------------------------------------------
   9. TOPICS
-------------------------------------------------- */
.topics__grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: .75rem;
}

.topic-card {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: .9375rem 1.125rem;
  font-size: .9375rem;
  font-weight: 500;
  color: var(--text);
  display: flex;
  align-items: flex-start;
  gap: .75rem;
  transition: border-color var(--transition), box-shadow var(--transition), transform var(--transition);
}
.topic-card:hover {
  border-color: var(--amber);
  box-shadow: var(--shadow);
  transform: translateY(-2px);
}
.topic-card__dot {
  width: .3125rem;
  min-width: .3125rem;
  height: .3125rem;
  border-radius: 50%;
  background: var(--amber);
  margin-top: .45rem;
  flex-shrink: 0;
}

/* --------------------------------------------------
   10. IMPORTANT DATES — TIMELINE
-------------------------------------------------- */
.dates-timeline {
  display: flex;
  flex-direction: column;
}

.dates-timeline__item {
  display: flex;
  gap: 1.375rem;
  align-items: flex-start;
  position: relative;
}
.dates-timeline__item:not(:last-child)::after {
  content: '';
  position: absolute;
  left: .875rem; /* centre of dot (dot width 1.75rem / 2) */
  top: 1.875rem;
  height: calc(100% - .75rem);
  width: 2px;
  background: var(--border);
}

.dates-timeline__dot-col {
  width: 1.75rem;
  flex-shrink: 0;
  display: flex;
  justify-content: center;
  padding-top: .1875rem;
}
.dates-timeline__dot {
  width: 1.75rem;
  height: 1.75rem;
  border-radius: 50%;
  background: var(--amber);
  border: 3px solid var(--body-bg);
  box-shadow: 0 0 0 2px var(--amber);
  flex-shrink: 0;
}
.dates-timeline__dot--tba {
  background: var(--border);
  box-shadow: 0 0 0 2px var(--border);
}

.dates-timeline__body { padding-bottom: 2rem; flex: 1; }
.dates-timeline__item:last-child .dates-timeline__body { padding-bottom: 0; }

.dates-timeline__date {
  font-size: .8125rem;
  font-weight: 700;
  color: var(--amber-dark);
  letter-spacing: .04em;
  text-transform: uppercase;
  margin-bottom: .2rem;
}
.dates-timeline__date--tba { color: var(--text-muted); }

.dates-timeline__label {
  font-size: 1rem;
  font-weight: 700;
  color: var(--navy);
  margin-bottom: .125rem;
}
.dates-timeline__label--tba { color: var(--text-muted); }

.dates-timeline__note {
  font-size: .875rem;
  color: var(--text-muted);
  margin-top: .125rem;
}

/* --------------------------------------------------
   11. SUBMISSION
-------------------------------------------------- */
.submit__grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
}

.submit__card {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.75rem;
  box-shadow: var(--shadow);
}
.submit__card h3 {
  font-size: 1.0625rem;
  margin-bottom: 1rem;
  padding-bottom: .75rem;
  border-bottom: 2px solid var(--amber);
}
.submit__card ul { display: flex; flex-direction: column; gap: .5rem; }
.submit__card li {
  font-size: .9375rem;
  display: flex;
  align-items: flex-start;
  gap: .625rem;
}
.submit__card li::before {
  content: '→';
  color: var(--amber);
  font-weight: 700;
  flex-shrink: 0;
  margin-top: .05rem;
}
.submit__card .note {
  font-size: .875rem;
  color: var(--text-muted);
  margin-top: 1rem;
  line-height: 1.6;
}

.submit__pubs {
  margin-top: 1.5rem;
  font-size: .9375rem;
  color: var(--text-muted);
}
.submit__pubs a { color: var(--amber); font-weight: 600; }

.submit__portal {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
  flex-wrap: wrap;
  background: var(--amber-light);
  border: 1px solid rgba(245,158,11,.35);
  border-radius: var(--radius);
  padding: 1.25rem 1.5rem;
  margin-top: 1.5rem;
}
.submit__portal-text { font-size: .875rem; color: #78350f; max-width: 38rem; }
.submit__portal-text strong { display: block; margin-bottom: .25rem; font-size: .9375rem; }
.submit__portal .btn { white-space: nowrap; flex-shrink: 0; }

/* --------------------------------------------------
   12. PROGRAM / FORMAT
-------------------------------------------------- */
.program__sessions { display: grid; gap: .875rem; grid-template-columns: repeat(2, 1fr); }

.session {
  display: flex;
  gap: 1.25rem;
  align-items: flex-start;
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem 1.5rem;
  transition: border-color var(--transition), box-shadow var(--transition);
}
.session:hover { border-color: var(--amber); box-shadow: var(--shadow); }

.session__icon {
  width: 2.5rem;
  height: 2.5rem;
  min-width: 2.5rem;
  background: rgba(245,158,11,.1);
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.125rem;
}
.session__body h3 { font-size: 1rem; margin-bottom: .25rem; }
.session__body p  { font-size: .875rem; color: var(--text-muted); max-width: none; }

.program__note {
  margin-top: 2rem;
  padding: 1.125rem 1.5rem;
  background: linear-gradient(135deg, var(--navy) 0%, var(--navy-mid) 100%);
  border-radius: var(--radius);
  color: var(--text-dark);
  font-size: .9375rem;
  opacity: .92;
}

/* --------------------------------------------------
   13. KEYNOTE
-------------------------------------------------- */
.keynote__tba {
  background: var(--white);
  border: 2px dashed var(--border);
  border-radius: var(--radius-lg);
  padding: 3rem 2.5rem;
  text-align: center;
  max-width: 520px;
}
.keynote__icon  { font-size: 2.75rem; margin-bottom: 1rem; opacity: .35; }
.keynote__tba h3 { font-size: 1.3rem; color: var(--text-muted); margin-bottom: .625rem; }
.keynote__tba p  { font-size: .9375rem; color: var(--text-muted); max-width: none; }

/* --------------------------------------------------
   14. ORGANIZERS
-------------------------------------------------- */
.org-group { margin-bottom: 2.5rem; }
.org-group:last-child { margin-bottom: 0; }

.org-group__label {
  font-size: .75rem;
  font-weight: 700;
  letter-spacing: .1em;
  text-transform: uppercase;
  color: var(--amber-dark);
  margin-bottom: .875rem;
  padding-bottom: .5rem;
  border-bottom: 1px solid var(--border);
}

.org-cards {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: .85rem 2.5rem;
}

/* Plain text rows, not boxes — kept understated on purpose */
.org-card { padding: 0; }
.org-card__name  { font-weight: 600; font-size: .9375rem; color: var(--navy); margin-bottom: .1rem; }
.org-card__affil { font-size: .8125rem; color: var(--text-muted); line-height: 1.45; }

.tpc-tba {
  font-size: .9375rem;
  color: var(--text-muted);
  font-style: italic;
}

/* --------------------------------------------------
   15. VENUE
-------------------------------------------------- */
.venue__content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  align-items: start;
}
.venue__text p { font-size: 1.0625rem; line-height: 1.75; }
.venue__text a { color: var(--amber-dark); text-decoration: underline; text-underline-offset: .2em; }
.venue__text a:hover { color: var(--navy); }
.venue__text .venue__link { margin-top: 1.75rem; }

.venue__map {
  border-radius: var(--radius-lg);
  overflow: hidden;
  aspect-ratio: 4/3;
}
.venue__map iframe {
  width: 100%;
  height: 100%;
  display: block;
  border: 0;
}

/* --------------------------------------------------
   16. REGISTRATION
-------------------------------------------------- */
.registration__body { font-size: 1.0625rem; line-height: 1.75; margin-bottom: 1.75rem; }

/* --------------------------------------------------
   17. CONTACT
-------------------------------------------------- */
.contact__chairs {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(230px, 1fr));
  gap: 1.125rem;
  margin-bottom: 2rem;
}

.contact-card {
  background: rgba(255,255,255,.05);
  border: 1px solid rgba(255,255,255,.1);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  transition: background var(--transition), border-color var(--transition);
}
.contact-card:hover {
  background: rgba(255,255,255,.08);
  border-color: rgba(245,158,11,.4);
}
.contact-card__name  { font-weight: 700; color: var(--white); font-size: 1rem; margin-bottom: .2rem; }
.contact-card__role  { font-size: .8125rem; color: var(--amber); font-weight: 600; margin-bottom: .5rem; }
.contact-card__affil { font-size: .8125rem; color: rgba(232,237,245,.55); margin-bottom: .875rem; }
.contact-card__email {
  display: inline-flex;
  align-items: center;
  gap: .375rem;
  font-size: .8125rem;
  color: rgba(232,237,245,.75);
  border-bottom: 1px solid rgba(232,237,245,.2);
  padding-bottom: .0625rem;
  transition: color var(--transition), border-color var(--transition);
}
.contact-card__email:hover { color: var(--amber); border-color: var(--amber); }

.contact__note {
  font-size: .9375rem;
  color: rgba(232,237,245,.55);
}
.contact__note strong { color: rgba(232,237,245,.85); }

/* --------------------------------------------------
   18. FOOTER
-------------------------------------------------- */
.footer {
  background: #07101f;
  color: rgba(232,237,245,.45);
  padding-block: 2rem;
  font-size: .8125rem;
}
.footer__inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
}

.footer__logos {
  display: flex;
  align-items: center;
  gap: 1rem;
  flex-wrap: wrap;
}
.footer__logo-slot {
  height: 2rem;
  min-width: 5rem;
  background: rgba(255,255,255,.07);
  border-radius: .3125rem;
  display: flex;
  align-items: center;
  justify-content: center;
  padding-inline: .75rem;
  font-size: .625rem;
  font-weight: 600;
  letter-spacing: .06em;
  text-transform: uppercase;
  color: rgba(255,255,255,.28);
}

.footer__logo-img {
  height: 2rem;
  width: auto;
  opacity: .55;
  transition: opacity .2s ease;
}
.footer__logo-img:hover { opacity: .85; }

.footer__meta { text-align: right; line-height: 1.7; }
.footer__meta a { color: rgba(245,158,11,.55); }
.footer__meta a:hover { color: var(--amber); }

/* --------------------------------------------------
   19. REVEAL ANIMATION
-------------------------------------------------- */
.reveal {
  opacity: 0;
  transform: translateY(1.25rem);
  transition: opacity .55s ease, transform .55s ease;
}
.reveal.is-visible { opacity: 1; transform: none; }

/* --------------------------------------------------
   20. RESPONSIVE — 768 px breakpoint
-------------------------------------------------- */
@media (max-width: 768px) {
  .nav__toggle { display: flex; }

  .nav__menu {
    display: none;
    position: absolute;
    top: 3.5rem;
    left: 0;
    right: 0;
    background: rgba(15,31,61,.98);
    border-bottom: 1px solid rgba(255,255,255,.08);
    flex-direction: column;
    align-items: stretch;
    padding: .75rem .875rem;
    gap: .125rem;
  }
  .nav__menu.is-open { display: flex; }
  .nav__menu a { font-size: .9375rem; padding: .625rem .875rem; }

  .about__grid,
  .submit__grid,
  .venue__content,
  .program__sessions { grid-template-columns: 1fr; }

  /* single column: drop the sticky so the callout flows after the text */
  .about__callout { position: static; }

  .hero__ctas { flex-direction: column; align-items: center; }

  .footer__meta { text-align: left; }
}

/* --------------------------------------------------
   21. RESPONSIVE — 480 px breakpoint
-------------------------------------------------- */
@media (max-width: 480px) {
  .topics__grid { grid-template-columns: 1fr; }
  .org-cards    { grid-template-columns: 1fr 1fr; }
  .contact__chairs { grid-template-columns: 1fr; }

  .footer__logos { gap: .625rem; }
  .footer__logo-slot { font-size: .5625rem; min-width: 4rem; }
}

/* --------------------------------------------------
   22. REDUCED MOTION
-------------------------------------------------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }

  .hero__bg,
  .hero__bg-node--twinkle { animation: none; }

  .reveal {
    opacity: 1;
    transform: none;
    transition: none;
  }

  .btn,
  .topic-card,
  .org-card,
  .contact-card,
  .session { transition: none; }
}