/* ============================================
   AMI Workshop 2026
   University of Adelaide brand: Navy + Crimson
   ============================================ */

:root {
  /* ---- University of Adelaide brand colours ---- */
  --navy:        #0a2353;   /* primary deep navy */
  --navy-dark:   #06152e;   /* darkest navy */
  --navy-mid:    #122e65;
  --red:         #c8102e;   /* UA crimson red */
  --red-dim:     rgba(200,16,46,.13);
  --red-border:  rgba(200,16,46,.35);
  --red-bright:  #e81535;
  /* ---- neutrals ---- */
  --text:        #1a2133;
  --text-muted:  #5a6a8a;
  --border:      #dde3ee;
  --bg:          #ffffff;
  --bg-alt:      #f4f6fb;   /* cool-white with navy tinge */
  --radius:      8px;
  --shadow:      0 1px 4px rgba(10,35,83,.07), 0 4px 18px rgba(10,35,83,.07);
  --shadow-lg:   0 8px 36px rgba(10,35,83,.14);
}

/* ============================================================ RESET */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
  font-family: 'Inter', system-ui, sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.7;
  font-size: 16px;
}
h1, h2, h3, h4 {
  font-family: 'Merriweather', Georgia, serif;
  line-height: 1.25;
  color: var(--navy);
}
p { margin-bottom: 1rem; }
a { color: var(--navy); text-decoration: none; }
a:hover { color: var(--red); text-decoration: underline; }
.container { max-width: 1100px; margin: 0 auto; padding: 0 2rem; }

/* ============================================================ NAV */
#navbar {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  background: rgba(6,21,46,.97);
  backdrop-filter: blur(10px);
  border-bottom: 2px solid var(--red);
  transition: box-shadow .3s;
}
#navbar.scrolled { box-shadow: 0 2px 24px rgba(0,0,0,.5); }

.nav-container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 2rem;
  display: flex;
  align-items: center;
  height: 62px;
}
.nav-logo {
  font-family: 'Inter', sans-serif;
  font-weight: 800;
  font-size: .95rem;
  color: #fff;
  letter-spacing: .03em;
  white-space: nowrap;
}
.nav-logo .logo-ami { color: var(--red); }
.nav-links {
  display: flex;
  list-style: none;
  margin-left: auto;
}
.nav-links a {
  display: block;
  padding: .5rem 1rem;
  color: rgba(255,255,255,.75);
  font-size: .875rem;
  font-weight: 500;
  transition: color .2s;
  text-decoration: none;
}
.nav-links a:hover { color: #fff; }
.nav-toggle {
  display: none;
  background: none;
  border: none;
  color: #fff;
  font-size: 1.4rem;
  cursor: pointer;
  margin-left: auto;
}

/* ============================================================ HERO */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  background: var(--navy-dark);
  overflow: hidden;
}
/* Rio de Janeiro background image */
.hero-bg {
  position: absolute;
  inset: 0;
  background-image: url('https://images.unsplash.com/photo-1483729558449-99ef09a8c325?w=1920&q=85&fit=crop&auto=format&fm=jpg');
  background-size: cover;
  background-position: center 40%;
  background-repeat: no-repeat;
}
/* Dark gradient overlay for text readability */
.hero-overlay {
  position: absolute;
  inset: 0;
  background:
    linear-gradient(to right,
      rgba(6,21,46,.92) 0%,
      rgba(6,21,46,.75) 55%,
      rgba(6,21,46,.50) 100%),
    linear-gradient(to bottom,
      rgba(6,21,46,.3) 0%,
      transparent 40%,
      rgba(6,21,46,.5) 100%);
}

.hero-inner {
  position: relative;
  z-index: 2;
  width: 100%;
  max-width: 1100px;
  margin: 0 auto;
  padding: 9rem 2rem 6rem;
  display: grid;
  grid-template-columns: 1fr 380px;
  gap: 3.5rem;
  align-items: start;
}

/* Left */
.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: .45rem;
  padding: .35rem 1rem;
  background: var(--red-dim);
  border: 1px solid var(--red-border);
  color: #ff7a8a;
  font-size: .78rem;
  font-weight: 700;
  letter-spacing: .09em;
  text-transform: uppercase;
  border-radius: 100px;
  margin-bottom: 1.5rem;
}
.hero-badge::before {
  content: '';
  width: 7px; height: 7px;
  border-radius: 50%;
  background: var(--red);
  flex-shrink: 0;
}
.hero-title {
  font-size: clamp(1.8rem, 3.5vw, 2.9rem);
  color: #fff;
  margin-bottom: .75rem;
  line-height: 1.18;
}
.hero-title .accent { color: #ff8fa3; }
.hero-subtitle {
  font-size: clamp(.95rem, 1.8vw, 1.2rem);
  color: rgba(255,255,255,.62);
  margin-bottom: 1.75rem;
  font-family: 'Inter', sans-serif;
  font-weight: 300;
  letter-spacing: .025em;
}
.hero-meta {
  display: flex;
  flex-wrap: wrap;
  gap: .75rem;
  margin-bottom: 2.25rem;
}
.meta-chip {
  display: flex;
  align-items: center;
  gap: .4rem;
  padding: .38rem .85rem;
  background: rgba(255,255,255,.07);
  border: 1px solid rgba(255,255,255,.14);
  border-radius: 100px;
  color: rgba(255,255,255,.82);
  font-size: .82rem;
  font-weight: 500;
}
.meta-chip svg { width: 14px; height: 14px; flex-shrink: 0; opacity: .8; }
.hero-actions { display: flex; gap: 1rem; flex-wrap: wrap; }
.btn-primary {
  display: inline-block;
  padding: .8rem 2rem;
  background: var(--red);
  color: #fff;
  font-weight: 700;
  font-size: .9rem;
  border-radius: var(--radius);
  transition: transform .2s, box-shadow .2s, background .2s;
  text-decoration: none;
}
.btn-primary:hover {
  background: var(--red-bright);
  transform: translateY(-2px);
  box-shadow: 0 8px 28px rgba(200,16,46,.4);
  text-decoration: none;
  color: #fff;
}
.btn-secondary {
  display: inline-block;
  padding: .8rem 2rem;
  border: 1px solid rgba(255,255,255,.28);
  color: rgba(255,255,255,.9);
  font-weight: 500;
  font-size: .9rem;
  border-radius: var(--radius);
  transition: background .2s, border-color .2s;
  text-decoration: none;
}
.btn-secondary:hover {
  background: rgba(255,255,255,.1);
  border-color: rgba(255,255,255,.45);
  text-decoration: none;
  color: #fff;
}

/* Right — Latest News panel */
.hero-news {
  background: rgba(6,21,46,.82);
  border: 1px solid rgba(255,255,255,.14);
  border-top: 3px solid var(--red);
  border-radius: 10px;
  padding: 1.75rem;
  backdrop-filter: blur(8px);
}
.news-panel-title {
  font-family: 'Inter', sans-serif;
  font-size: .72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .12em;
  color: var(--red);
  margin-bottom: 1.25rem;
  display: flex;
  align-items: center;
  gap: .5rem;
}
.news-panel-title::after {
  content: '';
  flex: 1;
  height: 1px;
  background: rgba(255,255,255,.1);
}
.news-list { display: flex; flex-direction: column; gap: 0; }
.news-item {
  display: flex;
  gap: .85rem;
  padding: .9rem 0;
  border-bottom: 1px solid rgba(255,255,255,.07);
  align-items: flex-start;
}
.news-item:last-child { border-bottom: none; padding-bottom: 0; }
.news-dot {
  width: 8px; height: 8px;
  border-radius: 50%;
  background: var(--red);
  flex-shrink: 0;
  margin-top: .45rem;
}
.news-body {}
.news-date {
  font-size: .7rem;
  color: rgba(255,255,255,.38);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: .07em;
  margin-bottom: .15rem;
}
.news-text {
  font-size: .85rem;
  color: rgba(255,255,255,.82);
  line-height: 1.45;
  font-weight: 500;
}
.news-text a {
  color: rgba(255,255,255,.82);
  text-decoration: underline;
  text-decoration-color: rgba(255,255,255,.25);
}
.news-text a:hover { color: #fff; }

/* ============================================================ DATES BAR */
.dates-bar {
  background: var(--navy);
  padding: 1.75rem 0;
  border-top: none;
}
.dates-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1px;
  background: rgba(255,255,255,.1);
  border: 1px solid rgba(255,255,255,.08);
  border-radius: var(--radius);
  overflow: hidden;
}
.date-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 1.25rem 1rem;
  background: rgba(255,255,255,.02);
  text-align: center;
  gap: .3rem;
}
.date-label {
  font-size: .72rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: .09em;
  color: rgba(255,255,255,.45);
}
.date-value {
  font-size: 1rem;
  font-weight: 700;
  color: #ff8fa3;
  font-family: 'Inter', sans-serif;
}

/* ============================================================ SECTIONS */
.section { padding: 5.5rem 0; }
.section-alt { background: var(--bg-alt); }

.section-header { text-align: center; margin-bottom: 3rem; }
.section-tag {
  display: inline-block;
  font-size: .72rem;
  font-weight: 700;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--red);
  margin-bottom: .5rem;
}
.section-tag::before { content: '— '; }
.section-tag::after  { content: ' —'; }
.section-title {
  font-size: clamp(1.6rem, 3vw, 2.2rem);
  color: var(--navy);
}

/* ============================================================ ABOUT */
.about-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3.5rem;
  align-items: start;
}
.about-text p { color: var(--text); }
.about-text strong { color: var(--navy); }
.about-questions h3 {
  font-size: .82rem;
  margin-bottom: 1rem;
  color: var(--navy);
  font-family: 'Inter', sans-serif;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .08em;
}
.question-list { list-style: none; display: flex; flex-direction: column; gap: .7rem; }
.question-list li {
  padding: .75rem 1rem .75rem 1.25rem;
  border-left: 3px solid var(--red);
  background: #f8f0f2;
  border-radius: 0 var(--radius) var(--radius) 0;
  font-size: .88rem;
  color: var(--text);
  line-height: 1.55;
}

/* ============================================================ ORGANIZERS  (large cards, 2-column) */
.organizers-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.75rem;
}
.organizer-card {
  display: flex;
  gap: 1.5rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.75rem;
  box-shadow: var(--shadow);
  align-items: flex-start;
  transition: box-shadow .25s, border-color .25s;
}
.organizer-card:hover {
  box-shadow: var(--shadow-lg);
  border-color: var(--red);
}
.organizer-avatar {
  width: 150px; height: 150px;
  border-radius: 16px;
  background: linear-gradient(145deg, var(--navy), var(--navy-mid));
  border: 2px solid rgba(200,16,46,.4);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: 1.2rem;
  font-family: 'Inter', sans-serif;
  flex-shrink: 0;
  letter-spacing: .02em;
  overflow: hidden;
}
.organizer-avatar img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  border-radius: 10px;
  display: block;
}
.organizer-info h3 {
  font-size: 1.05rem;
  font-family: 'Inter', sans-serif;
  font-weight: 700;
  color: var(--navy);
  margin-bottom: .2rem;
}
.organizer-affil {
  font-size: .83rem;
  color: var(--red);
  font-weight: 600;
  margin-bottom: .5rem;
}
.organizer-email {
  font-size: .8rem;
  color: var(--text-muted);
  word-break: break-all;
  text-decoration: none;
  display: block;
  line-height: 1.4;
}
.organizer-email:hover { color: var(--navy); text-decoration: underline; }
/* Clickable name link */
.organizer-name-link {
  color: var(--navy);
  text-decoration: none;
  transition: color .2s;
}
.organizer-name-link:hover {
  color: var(--red);
  text-decoration: none;
}
.organizer-bio {
  font-size: .82rem;
  color: var(--text-muted);
  line-height: 1.58;
  margin-top: .5rem;
  margin-bottom: 0;
}

/* ============================================================ TOPICS (in About) */
.topics-compact {
  margin-top: 3rem;
}
.topics-compact h3 {
  font-size: .82rem;
  font-family: 'Inter', sans-serif;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .08em;
  color: var(--navy);
  margin-bottom: 1.25rem;
}
.topics-compact-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
}
.topic-compact-card {
  display: flex;
  align-items: flex-start;
  gap: .7rem;
  padding: .9rem 1rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-left: 3px solid var(--navy);
  border-radius: 0 var(--radius) var(--radius) 0;
  font-size: .85rem;
  color: var(--text);
  font-weight: 500;
  line-height: 1.4;
  transition: border-color .2s;
}
.topic-compact-card:hover { border-left-color: var(--red); }

/* ============================================================ CALL FOR PAPERS */
.cfp-intro {
  text-align: center;
  max-width: 700px;
  margin: 0 auto 2.5rem;
  color: var(--text-muted);
}
/* CfP requirements box */
.cfp-requirements {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
  margin-bottom: 2.5rem;
}
.req-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-top: 3px solid var(--navy);
  border-radius: var(--radius);
  padding: 1.5rem;
  box-shadow: var(--shadow);
}
.req-card h4 {
  font-family: 'Inter', sans-serif;
  font-size: .8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .09em;
  color: var(--navy);
  margin-bottom: .75rem;
}
.req-card ul { list-style: none; display: flex; flex-direction: column; gap: .45rem; }
.req-card ul li {
  font-size: .87rem;
  color: var(--text);
  padding-left: 1rem;
  position: relative;
  line-height: 1.5;
}
.req-card ul li::before {
  content: '›';
  position: absolute;
  left: 0;
  color: var(--red);
  font-weight: 700;
}
.cfp-submit-box {
  background: var(--navy);
  border-radius: var(--radius);
  padding: 2.5rem;
  text-align: center;
  border-top: 3px solid var(--red);
}
.cfp-submit-box h3 {
  color: #fff;
  font-size: 1.2rem;
  margin-bottom: .6rem;
}
.cfp-submit-box p {
  color: rgba(255,255,255,.65);
  font-size: .9rem;
  max-width: 560px;
  margin: 0 auto 1.75rem;
}
.btn-submit {
  display: inline-flex;
  align-items: center;
  gap: .5rem;
  padding: .85rem 2.25rem;
  background: var(--red);
  color: #fff;
  font-weight: 700;
  font-size: .95rem;
  border-radius: var(--radius);
  transition: background .2s, transform .2s, box-shadow .2s;
  text-decoration: none;
  cursor: not-allowed;
  opacity: .65;
}
.btn-submit.active {
  cursor: pointer;
  opacity: 1;
}
.btn-submit.active:hover {
  background: var(--red-bright);
  transform: translateY(-2px);
  box-shadow: 0 8px 28px rgba(200,16,46,.4);
}
.btn-submit-note {
  margin-top: 1rem;
  margin-bottom: 0;
  font-size: .8rem;
  color: rgba(255,255,255,.4);
}
.topics-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
  margin-bottom: 3rem;
}
.topic-card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.75rem;
  box-shadow: var(--shadow);
  transition: box-shadow .2s, transform .2s, border-color .2s;
}
.topic-card:hover {
  box-shadow: var(--shadow-lg);
  transform: translateY(-3px);
  border-color: var(--navy);
}
.topic-icon {
  width: 46px; height: 46px;
  display: flex; align-items: center; justify-content: center;
  background: #edf0f8;
  border-radius: 10px;
  margin-bottom: 1rem;
  color: var(--navy);
}
.topic-icon svg { width: 22px; height: 22px; }
.topic-card h3 {
  font-size: .92rem;
  font-family: 'Inter', sans-serif;
  font-weight: 700;
  color: var(--navy);
  margin-bottom: .75rem;
  line-height: 1.35;
}
.topic-card ul { list-style: none; display: flex; flex-direction: column; gap: .4rem; }
.topic-card ul li {
  font-size: .82rem;
  color: var(--text-muted);
  padding-left: .9rem;
  position: relative;
  line-height: 1.45;
}
.topic-card ul li::before {
  content: '·';
  position: absolute;
  left: 0;
  color: var(--red);
  font-weight: 700;
}
.submission-info {
  background: var(--navy);
  border-radius: var(--radius);
  padding: 2rem 2.5rem;
  color: #fff;
  border-top: 3px solid var(--red);
}
.submission-info h3 {
  color: #fff;
  font-size: 1.05rem;
  margin-bottom: 1.25rem;
  font-family: 'Inter', sans-serif;
  font-weight: 600;
}
.submission-details {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.25rem;
}
.submission-item { display: flex; flex-direction: column; gap: .2rem; }
.submission-item strong {
  font-size: .72rem;
  text-transform: uppercase;
  letter-spacing: .09em;
  color: #ff8fa3;
  font-weight: 700;
}
.submission-item span { font-size: .9rem; color: rgba(255,255,255,.78); }

/* ============================================================ SPEAKERS */
.speakers-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 2rem;
}
.speaker-card {
  display: flex;
  gap: 1.5rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 2rem;
  box-shadow: var(--shadow);
  align-items: flex-start;
  transition: box-shadow .25s, border-color .25s;
}
.speaker-card:hover {
  box-shadow: var(--shadow-lg);
  border-color: var(--navy);
}
.speaker-avatar {
  width: 150px; height: 150px;
  border-radius: 16px;
  background: linear-gradient(135deg, var(--navy), var(--navy-mid));
  border: 2px solid rgba(200,16,46,.35);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: 1.35rem;
  font-family: 'Inter', sans-serif;
  flex-shrink: 0;
  overflow: hidden;
}
.speaker-avatar img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  border-radius: 10px;
  display: block;
}
/* TBD speaker card */
.speaker-card.tbd {
  opacity: .7;
  background: var(--bg-alt);
}
.speaker-card.tbd .speaker-avatar {
  background: #dde3ee;
  color: var(--text-muted);
  font-size: 1rem;
}
.speaker-card.tbd .speaker-info h3 { color: var(--text-muted); }
.speaker-card.tbd .speaker-affil { color: var(--text-muted); }
.speaker-info h3 {
  font-size: 1.1rem;
  font-family: 'Inter', sans-serif;
  font-weight: 700;
  color: var(--navy);
  margin-bottom: .2rem;
}
.speaker-affil {
  font-size: .83rem;
  color: var(--red);
  font-weight: 600;
  margin-bottom: .6rem;
}
.speaker-talk {
  font-size: .87rem;
  font-style: italic;
  color: var(--navy);
  margin-bottom: .7rem;
  font-weight: 500;
  line-height: 1.4;
}
.speaker-bio {
  font-size: .82rem;
  color: var(--text-muted);
  line-height: 1.6;
  margin-bottom: 0;
}

/* ============================================================ SCHEDULE */
.schedule-note {
  text-align: center;
  color: var(--text-muted);
  margin-bottom: 2rem;
  font-size: .95rem;
}
.schedule-table-wrap {
  overflow-x: auto;
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  border: 1px solid var(--border);
}
.schedule-table {
  width: 100%;
  border-collapse: collapse;
  background: var(--bg);
  font-size: .9rem;
}
.schedule-table thead th {
  background: var(--navy);
  color: rgba(255,255,255,.9);
  padding: .9rem 1.25rem;
  text-align: left;
  font-family: 'Inter', sans-serif;
  font-weight: 600;
  font-size: .78rem;
  text-transform: uppercase;
  letter-spacing: .08em;
}
.schedule-table thead th:first-child { border-left: 3px solid var(--red); }
.schedule-table tbody tr { border-bottom: 1px solid var(--border); }
.schedule-table tbody tr:last-child { border-bottom: none; }
.schedule-table tbody td {
  padding: .9rem 1.25rem;
  color: var(--text);
  vertical-align: middle;
}
.schedule-table tbody tr:hover:not(.schedule-section-header):not(.schedule-break) {
  background: var(--bg-alt);
}
.schedule-section-header td {
  background: #edf0f8;
  color: var(--navy);
  font-weight: 700;
  font-size: .8rem;
  text-transform: uppercase;
  letter-spacing: .09em;
  padding: .6rem 1.25rem;
  border-left: 3px solid var(--red);
}
.schedule-break td {
  color: var(--text-muted);
  font-style: italic;
  background: #fafafa;
}

/* ============================================================ FOOTER */
.footer {
  background: var(--navy-dark);
  border-top: 3px solid var(--red);
  color: rgba(255,255,255,.65);
  padding: 3rem 0 1.5rem;
}
.footer-content {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 2rem;
  padding-bottom: 2rem;
  border-bottom: 1px solid rgba(255,255,255,.08);
  margin-bottom: 1.5rem;
}
.footer-logo {
  font-size: 1.3rem;
  font-weight: 800;
  color: #fff;
  margin-bottom: .5rem;
  font-family: 'Inter', sans-serif;
}
.footer-logo .logo-ami { color: #ff8fa3; }
.footer-brand p {
  font-size: .85rem;
  margin-bottom: .25rem;
  color: rgba(255,255,255,.5);
}
.footer-links { display: flex; gap: 1.5rem; align-items: center; flex-wrap: wrap; }
.footer-links a {
  color: rgba(255,255,255,.55);
  font-size: .875rem;
  transition: color .2s;
  text-decoration: none;
}
.footer-links a:hover { color: #fff; }
.footer-contact {
  display: flex;
  align-items: center;
  gap: .5rem;
  flex-wrap: wrap;
}
.footer-contact-label {
  font-size: .8rem;
  color: rgba(255,255,255,.35);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: .06em;
}
.footer-contact-sep { color: rgba(255,255,255,.25); }
.footer-bottom {
  text-align: center;
  font-size: .8rem;
  color: rgba(255,255,255,.28);
}

/* ============================================================ RESPONSIVE */
@media (max-width: 1000px) {
  .hero-inner { grid-template-columns: 1fr; }
  .hero-news { max-width: 520px; }
}
@media (max-width: 900px) {
  .topics-grid { grid-template-columns: repeat(2, 1fr); }
  .topics-compact-grid { grid-template-columns: repeat(2, 1fr); }
  .cfp-requirements { grid-template-columns: 1fr; }
  .speakers-grid { grid-template-columns: 1fr; }
  .organizers-grid { grid-template-columns: 1fr; }
  .dates-grid { grid-template-columns: repeat(2, 1fr); }
  .submission-details { grid-template-columns: 1fr; }
}
@media (max-width: 640px) {
  .topics-grid { grid-template-columns: 1fr; }
  .nav-links { display: none; }
  .nav-links.open {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: 62px; left: 0; right: 0;
    background: var(--navy-dark);
    padding: 1rem 0;
    border-bottom: 1px solid rgba(255,255,255,.08);
  }
  .nav-toggle { display: block; }
  .nav-container { position: relative; }
  .footer-content { flex-direction: column; }
  .speaker-card, .organizer-card { flex-direction: column; }
}