/* ============================================================
   AI for Math Workshop @ ICML 2026 — Stylesheet
   ============================================================ */

/* ---- CSS Variables ---- */
:root {
  --color-primary:       #2F6FED;   /* Apple-like blue */
  --color-primary-dark:  #1F4FB5;
  --color-primary-light: #AFC8FF;
  --color-link:          #2F6FED;
  --color-link-hover:    #1F4FB5;
  --color-accent:        #8EA3B8;
  --color-text:          #1F2324;
  --color-text-muted:    #66707A;
  --color-text-light:    #98A2AD;
  --color-bg:            #F5F7FA;
  --color-surface:       #FFFFFF;
  --color-bg-tinted:     #EEF3F8;
  --color-bg-light:      #F8FAFC;
  --color-border:        #D9E2EC;
  --color-border-light:  #E8EEF5;
  --color-hero-start:    #0F1720;
  --color-hero-mid:      #2F4357;
  --color-hero-end:      #9EB1C4;
  --radius-sm:           6px;
  --radius-md:           10px;
  --radius-lg:           16px;
  --shadow-sm:           0 10px 28px rgba(15, 23, 32, .06);
  --shadow-md:           0 18px 42px rgba(15, 23, 32, .10);
  --shadow-lg:           0 28px 72px rgba(15, 23, 32, .14);
  --font-sans:           'Source Sans 3', 'Helvetica Neue', Arial, sans-serif;
  --font-serif:          'Source Serif 4', Georgia, serif;
  --max-width:           1100px;
  --nav-height:          64px;
  --transition:          0.2s ease;
  --hero-content-shift:  0px;
  --hero-content-scale:  1;
  --hero-content-opacity: 1;
  --hero-overlay-shift:  0px;
  --hero-overlay-opacity: 1;
  --hero-bg-shift:       0px;
}

/* ---- Reset & Base ---- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--nav-height) + 12px);
}

body {
  font-family: var(--font-sans);
  font-size: 17px;
  line-height: 1.72;
  letter-spacing: 0.002em;
  color: var(--color-text);
  background:
    linear-gradient(180deg, #ffffff 0%, var(--color-bg) 40%, #f1f5f9 100%);
}

img { max-width: 100%; display: block; }
a { color: var(--color-link); text-decoration: none; transition: color var(--transition); }
a:hover { color: var(--color-link-hover); text-decoration: underline; }
ul { list-style: none; }

::selection {
  background: rgba(47, 111, 237, 0.16);
  color: var(--color-text);
}

/* ============================================================
   Motion
   ============================================================ */
.motion-ready [data-reveal] {
  opacity: 0;
  filter: blur(8px);
  transform: translate3d(0, 18px, 0) scale(0.993);
  transition:
    opacity 0.58s cubic-bezier(0.22, 1, 0.36, 1),
    transform 0.68s cubic-bezier(0.22, 1, 0.36, 1),
    filter 0.58s cubic-bezier(0.22, 1, 0.36, 1);
  transition-delay: var(--reveal-delay, 0ms);
  will-change: opacity, transform, filter;
}

.motion-ready [data-reveal="soft"] {
  transform: translate3d(0, 12px, 0) scale(0.996);
}

.motion-ready [data-reveal="card"] {
  transform: translate3d(0, 20px, 0) scale(0.988);
}

.motion-ready [data-reveal="left"] {
  transform: translate3d(-16px, 12px, 0) scale(0.992);
}

.motion-ready [data-reveal="right"] {
  transform: translate3d(16px, 12px, 0) scale(0.992);
}

.motion-ready [data-reveal="hero"] {
  transform: translate3d(0, 16px, 0) scale(0.995);
}

.motion-ready [data-reveal].is-visible {
  opacity: 1;
  filter: blur(0);
  transform: translate3d(0, 0, 0) scale(1);
}

@keyframes heroGlowDrift {
  0% {
    transform: translate3d(-4%, -2%, 0) scale(1);
    opacity: 0.34;
  }
  50% {
    transform: translate3d(3%, 2%, 0) scale(1.08);
    opacity: 0.48;
  }
  100% {
    transform: translate3d(6%, -1%, 0) scale(1.03);
    opacity: 0.38;
  }
}

@keyframes heroShimmer {
  0% {
    transform: translate3d(-8%, 0, 0) scale(1);
    opacity: 0.18;
  }
  100% {
    transform: translate3d(8%, -3%, 0) scale(1.06);
    opacity: 0.28;
  }
}

/* ============================================================
   Navigation
   ============================================================ */
.navbar {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: var(--nav-height);
  background: rgba(248, 250, 252, 0.9);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
  z-index: 1000;
  transition: box-shadow var(--transition);
}
.navbar::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--color-primary) 0%, var(--color-accent) 60%, rgba(142,163,184,0) 100%);
}
.navbar.scrolled { box-shadow: var(--shadow-md); }

.nav-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

.nav-logo {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-serif);
  font-weight: 700;
  font-size: 17px;
  color: #314252;
  letter-spacing: 0.01em;
  white-space: nowrap;
  text-decoration: none;
}
.nav-logo img {
  width: 30px;
  height: 30px;
  object-fit: contain;
  border-radius: 8px;
  background: rgba(255,255,255,0.86);
  box-shadow: 0 6px 16px rgba(18, 30, 43, 0.08);
}
.nav-logo span {
  display: inline-block;
}
.nav-logo:hover {
  color: #213446;
  text-decoration: none;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 4px;
  flex-wrap: nowrap;
}
.nav-links li a {
  display: block;
  padding: 7px 12px;
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-weight: 500;
  color: var(--color-text);
  text-decoration: none;
  transition: background var(--transition), color var(--transition);
}
.nav-links li a:hover {
  background: rgba(47, 111, 237, 0.08);
  color: var(--color-primary-dark);
}
.nav-links li a.active {
  color: var(--color-primary-dark);
  background: rgba(47, 111, 237, 0.12);
}

/* Hamburger */
.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}
.nav-toggle span {
  display: block;
  width: 22px; height: 2px;
  background: var(--color-text);
  border-radius: 2px;
  transition: all var(--transition);
}

/* ============================================================
   Hero
   ============================================================ */
.hero {
  min-height: 100vh;
  background-image: url('../images/background.png');
  background-size: cover;
  background-position: center calc(50% + var(--hero-bg-shift));
  background-repeat: no-repeat;
  background-color: var(--color-hero-start);
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: calc(var(--nav-height) + 40px) 24px 80px;
  position: relative;
  overflow: hidden;
}

.hero-overlay {
  position: absolute;
  inset: 0;
  background: transparent;
  pointer-events: none;
}

.hero::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0; bottom: 0;
  pointer-events: none;
  background: transparent;
}

.hero::after {
  content: '';
  position: absolute;
  inset: -10%;
  pointer-events: none;
  background: transparent;
}

.motion-ready .hero-overlay {
  background:
    linear-gradient(180deg, rgba(12, 18, 28, 0.22) 0%, rgba(12, 18, 28, 0.12) 26%, rgba(12, 18, 28, 0.24) 100%);
  opacity: var(--hero-overlay-opacity);
  transform: translate3d(0, var(--hero-overlay-shift), 0);
}

.motion-ready .hero::before {
  background:
    radial-gradient(circle at 18% 26%, rgba(211, 227, 255, 0.32) 0%, rgba(211, 227, 255, 0) 34%),
    radial-gradient(circle at 80% 18%, rgba(167, 198, 255, 0.24) 0%, rgba(167, 198, 255, 0) 30%);
  animation: heroGlowDrift 18s ease-in-out infinite alternate;
}

.motion-ready .hero::after {
  background:
    linear-gradient(115deg, rgba(255, 255, 255, 0) 20%, rgba(236, 244, 255, 0.18) 50%, rgba(255, 255, 255, 0) 78%);
  animation: heroShimmer 14s ease-in-out infinite alternate;
}

.hero-content {
  max-width: 840px;
  position: relative;
  z-index: 1;
}

.motion-ready .hero-content {
  opacity: var(--hero-content-opacity);
  transform: translate3d(0, var(--hero-content-shift), 0) scale(var(--hero-content-scale));
  will-change: transform, opacity;
}

.hero-badge {
  display: inline-block;
  background: rgba(247, 240, 230, 0.12);
  border: 1px solid rgba(247, 240, 230, 0.26);
  color: rgba(251, 245, 237, 0.92);
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  padding: 6px 16px;
  border-radius: 100px;
  margin-bottom: 24px;
}

.hero-title {
  font-family: var(--font-serif);
  font-size: clamp(30px, 5.3vw, 58px);
  font-weight: 700;
  color: #fff;
  line-height: 1.08;
  letter-spacing: -0.02em;
  margin-bottom: 12px;
  text-shadow: 0 10px 30px rgba(0,0,0,0.18);
}

.hero-subtitle-text {
  font-family: var(--font-sans);
  font-weight: 400;
  font-size: clamp(18px, 2.6vw, 26px);
  color: rgba(241, 246, 252, 0.84);
  display: block;
  margin-top: 8px;
  line-height: 1.4;
}

.hero-meta {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 24px;
  margin: 28px 0 34px;
}

.hero-meta-item {
  display: flex;
  align-items: center;
  gap: 8px;
  color: rgba(241, 246, 252, 0.88);
  font-size: 16px;
  font-weight: 500;
}
.hero-meta-item svg {
  width: 20px; height: 20px;
  opacity: 0.8;
}

.hero-actions {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 12px;
}

/* ============================================================
   Buttons
   ============================================================ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 24px;
  border-radius: 999px;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  text-decoration: none;
  transition: all var(--transition);
  border: 2px solid transparent;
  line-height: 1;
}

.btn-primary {
  background: var(--color-primary);
  color: #fff;
  border-color: transparent;
  box-shadow: 0 14px 28px rgba(47, 111, 237, 0.18);
}
.btn-primary:hover {
  background: var(--color-primary-dark);
  color: #fff;
  text-decoration: none;
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

/* Primary outside hero */
.hero .btn-primary {
  background: var(--color-bg);
  color: var(--color-primary-dark);
  box-shadow: 0 14px 28px rgba(0, 0, 0, 0.18);
}
.hero .btn-primary:hover {
  background: #F1F6FF;
  color: var(--color-primary-dark);
}

.btn-secondary {
  background: rgba(255, 255, 255, 0.1);
  color: #fff;
  border-color: rgba(255, 255, 255, 0.36);
}
.btn-secondary:hover {
  background: rgba(255, 255, 255, 0.18);
  color: #fff;
  text-decoration: none;
  transform: translateY(-1px);
}

.btn-outline {
  background: transparent;
  color: var(--color-primary-dark);
  border-color: rgba(47, 111, 237, 0.38);
}
.btn-outline:hover {
  background: rgba(47, 111, 237, 0.08);
  text-decoration: none;
}

.btn-small {
  padding: 9px 16px;
  font-size: 13px;
}

/* ============================================================
   Sections
   ============================================================ */
.section {
  padding: 80px 24px;
  position: relative;
  isolation: isolate;
  overflow: hidden;
  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.5),
    inset 0 -1px 0 rgba(217, 226, 236, 0.36);
}
.section-white  {
  background:
    linear-gradient(90deg, rgba(47, 111, 237, 0.028) 0%, rgba(255, 255, 255, 0) 18%, rgba(255, 255, 255, 0) 80%, rgba(142, 163, 184, 0.035) 100%),
    linear-gradient(180deg, rgba(255, 255, 255, 0.94) 0%, rgba(249, 251, 254, 0.96) 100%);
}
.section-light  {
  background:
    linear-gradient(90deg, rgba(47, 111, 237, 0.03) 0%, rgba(255, 255, 255, 0) 22%, rgba(255, 255, 255, 0) 82%, rgba(142, 163, 184, 0.04) 100%),
    linear-gradient(180deg, rgba(248,250,252,0.97) 0%, rgba(244,247,250,0.99) 100%);
}
.section-tinted {
  background:
    linear-gradient(90deg, rgba(255, 255, 255, 0.18) 0%, rgba(255, 255, 255, 0) 24%, rgba(255, 255, 255, 0) 76%, rgba(47, 111, 237, 0.035) 100%),
    linear-gradient(180deg, rgba(238,243,248,0.98) 0%, rgba(247,250,253,0.99) 100%);
}
.section + .section { border-top: 1px solid rgba(217, 208, 195, 0.45); }

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  position: relative;
  z-index: 1;
}

.section::before,
.section::after {
  content: '';
  position: absolute;
  pointer-events: none;
  z-index: 0;
}

.section::before {
  top: -210px;
  right: -180px;
  width: min(38vw, 500px);
  height: min(38vw, 500px);
  border-radius: 50%;
  background:
    radial-gradient(circle at 34% 34%, rgba(47, 111, 237, 0.14) 0%, rgba(47, 111, 237, 0.07) 18%, rgba(47, 111, 237, 0) 46%),
    radial-gradient(circle at 52% 52%, transparent 54%, rgba(47, 111, 237, 0.12) 54.4%, rgba(47, 111, 237, 0.12) 55%, transparent 55.6%),
    radial-gradient(circle at 52% 52%, transparent 66%, rgba(142, 163, 184, 0.10) 66.4%, rgba(142, 163, 184, 0.10) 67%, transparent 67.6%),
    radial-gradient(circle at 52% 52%, transparent 78%, rgba(255, 255, 255, 0.48) 78.2%, rgba(255, 255, 255, 0.48) 78.8%, transparent 79.4%),
    linear-gradient(135deg, rgba(255, 255, 255, 0.16) 0%, rgba(255, 255, 255, 0) 58%);
  opacity: 0.92;
}

.section::after {
  left: -170px;
  bottom: -180px;
  width: min(35vw, 420px);
  height: min(35vw, 420px);
  border-radius: 50%;
  background:
    radial-gradient(circle at 60% 40%, rgba(142, 163, 184, 0.15) 0%, rgba(142, 163, 184, 0.07) 20%, rgba(142, 163, 184, 0) 48%),
    radial-gradient(circle at 48% 48%, transparent 52%, rgba(142, 163, 184, 0.11) 52.4%, rgba(142, 163, 184, 0.11) 53%, transparent 53.6%),
    radial-gradient(circle at 48% 48%, transparent 64%, rgba(47, 111, 237, 0.08) 64.4%, rgba(47, 111, 237, 0.08) 65%, transparent 65.6%),
    radial-gradient(circle at 48% 48%, transparent 76%, rgba(255, 255, 255, 0.44) 76.2%, rgba(255, 255, 255, 0.44) 76.8%, transparent 77.4%),
    linear-gradient(140deg, rgba(255, 255, 255, 0.18) 0%, rgba(255, 255, 255, 0) 54%);
  opacity: 0.88;
}

.section-light::before {
  background:
    radial-gradient(circle at 34% 34%, rgba(47, 111, 237, 0.12) 0%, rgba(47, 111, 237, 0.05) 18%, rgba(47, 111, 237, 0) 46%),
    radial-gradient(circle at 52% 52%, transparent 54%, rgba(47, 111, 237, 0.10) 54.4%, rgba(47, 111, 237, 0.10) 55%, transparent 55.6%),
    radial-gradient(circle at 52% 52%, transparent 66%, rgba(142, 163, 184, 0.08) 66.4%, rgba(142, 163, 184, 0.08) 67%, transparent 67.6%),
    radial-gradient(circle at 52% 52%, transparent 78%, rgba(255, 255, 255, 0.42) 78.2%, rgba(255, 255, 255, 0.42) 78.8%, transparent 79.4%),
    linear-gradient(135deg, rgba(255, 255, 255, 0.14) 0%, rgba(255, 255, 255, 0) 56%);
}

.section-light::after {
  opacity: 0.78;
}

.section-tinted::after {
  background:
    radial-gradient(circle at 60% 40%, rgba(255, 255, 255, 0.68) 0%, rgba(255, 255, 255, 0.22) 18%, rgba(255, 255, 255, 0) 44%),
    radial-gradient(circle at 48% 48%, transparent 52%, rgba(47, 111, 237, 0.10) 52.4%, rgba(47, 111, 237, 0.10) 53%, transparent 53.6%),
    radial-gradient(circle at 48% 48%, transparent 64%, rgba(142, 163, 184, 0.10) 64.4%, rgba(142, 163, 184, 0.10) 65%, transparent 65.6%),
    radial-gradient(circle at 48% 48%, transparent 76%, rgba(255, 255, 255, 0.40) 76.2%, rgba(255, 255, 255, 0.40) 76.8%, transparent 77.4%),
    linear-gradient(140deg, rgba(255, 255, 255, 0.2) 0%, rgba(255, 255, 255, 0) 54%);
}

.section-tinted::before {
  opacity: 0.98;
}

#news::before {
  top: auto;
  bottom: -220px;
  right: -120px;
}

#news::after {
  top: 12%;
  bottom: auto;
  left: -200px;
}

#about::after {
  bottom: auto;
  top: 24%;
  left: -190px;
}

#about::before {
  top: -190px;
  right: -160px;
}

#speakers::before {
  top: -170px;
  right: -120px;
}

#speakers::after {
  left: -180px;
  bottom: -160px;
}

#schedule::after {
  top: 18%;
  bottom: auto;
  left: auto;
  right: -170px;
}

#schedule::before {
  top: auto;
  bottom: -220px;
  right: auto;
  left: -180px;
}

#cfp::before {
  top: 12%;
  right: -170px;
}

#cfp::after {
  left: -200px;
  bottom: -170px;
}

#challenge::after {
  left: -170px;
  bottom: -180px;
}

#challenge::before {
  top: -180px;
  right: -150px;
}

#organizers::before {
  top: auto;
  bottom: -220px;
  right: -130px;
}

#organizers::after {
  top: 16%;
  bottom: auto;
  left: -190px;
}

#sponsors::after {
  left: -180px;
  bottom: -180px;
}

#sponsors::before {
  top: 8%;
  right: -170px;
}

.section-title {
  font-family: var(--font-serif);
  font-size: clamp(26px, 3.5vw, 36px);
  font-weight: 700;
  color: var(--color-text);
  letter-spacing: -0.015em;
  margin-bottom: 10px;
  text-align: center;
}
.section-title::after {
  content: '';
  display: block;
  width: 64px;
  height: 3px;
  background: linear-gradient(90deg, var(--color-primary) 0%, var(--color-accent) 100%);
  border-radius: 2px;
  margin: 14px auto 0;
}

.motion-ready .section-title::after {
  opacity: 0.72;
  transform: scaleX(0.72);
  transform-origin: center;
  transition:
    transform 0.62s cubic-bezier(0.22, 1, 0.36, 1),
    opacity 0.42s ease;
}

.motion-ready .section-title.is-visible::after {
  opacity: 1;
  transform: scaleX(1);
}

.section-subtitle {
  text-align: center;
  color: var(--color-text-muted);
  font-size: 17px;
  line-height: 1.65;
  margin-bottom: 44px;
  margin-top: 12px;
  max-width: 760px;
  margin-left: auto;
  margin-right: auto;
}
.section-subtitle a { color: var(--color-primary); }

.subsection-title {
  font-family: var(--font-serif);
  font-size: 23px;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: 22px;
  margin-top: 48px;
  padding-bottom: 10px;
  border-bottom: 2px solid var(--color-border);
}

/* ============================================================
   News
   ============================================================ */
.news-list {
  max-width: 780px;
  margin: 0 auto;
}
.news-item {
  display: flex;
  gap: 16px;
  padding: 17px 20px;
  margin-bottom: 14px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-left: 4px solid rgba(47, 111, 237, 0.45);
  border-radius: 14px;
  align-items: flex-start;
  box-shadow: var(--shadow-sm);
}
.news-item:last-child { margin-bottom: 0; }
.news-date {
  flex-shrink: 0;
  width: 132px;
  font-size: 13px;
  color: var(--color-text-muted);
  font-weight: 500;
  padding-top: 2px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}
.news-text {
  font-size: 15px;
  line-height: 1.65;
}

/* ============================================================
   About
   ============================================================ */
.about-grid {
  display: grid;
  grid-template-columns: 1fr 320px;
  gap: 44px;
  margin-top: 44px;
}

.about-text {
  max-width: 720px;
}

.about-lead {
  font-family: var(--font-serif);
  font-size: 19px;
  line-height: 1.75;
  color: var(--color-text);
  margin-bottom: 18px;
  font-weight: 300;
}

.about-text p {
  margin-bottom: 16px;
  font-size: 16px;
  line-height: 1.78;
}

.about-panels {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
  margin: 18px 0 20px;
}

.about-panel {
  padding: 16px 18px;
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-md);
  background: linear-gradient(180deg, rgba(255,255,255,0.98) 0%, rgba(245,248,251,0.95) 100%);
}

.about-panel h3 {
  font-size: 15px;
  font-weight: 700;
  margin-bottom: 6px;
  color: var(--color-primary-dark);
}

.about-panel p {
  margin-bottom: 0;
  font-size: 15px;
  line-height: 1.7;
}

.about-bridge {
  margin-bottom: 12px !important;
  font-weight: 600;
  color: var(--color-text);
}

.about-footnote {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 10px 14px;
  align-items: start;
  margin-top: 18px;
  padding: 14px 16px;
  border-top: 1px solid var(--color-border);
  color: var(--color-text-muted);
}

.about-footnote span {
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-primary-dark);
}

.about-footnote p {
  margin: 0;
  font-size: 14px;
  line-height: 1.7;
}

.topic-list {
  list-style: none;
  margin: 20px 0;
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.topic-list li {
  padding: 15px 18px;
  background: linear-gradient(180deg, rgba(255,255,255,0.98) 0%, rgba(245,248,251,0.96) 100%);
  border: 1px solid var(--color-border-light);
  border-left: 3px solid var(--color-primary);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  font-size: 15px;
  line-height: 1.7;
  box-shadow: var(--shadow-sm);
}

/* ============================================================
   Info Cards
   ============================================================ */
.info-card {
  background: linear-gradient(180deg, rgba(255,255,255,0.98) 0%, rgba(247,250,252,0.96) 100%);
  border: 1px solid var(--color-border);
  border-top: 3px solid rgba(47, 111, 237, 0.32);
  border-radius: var(--radius-lg);
  padding: 22px;
  margin-bottom: 20px;
  box-shadow: var(--shadow-sm);
}
.info-card h3 {
  font-size: 18px;
  font-weight: 700;
  margin-bottom: 14px;
  color: var(--color-text);
  padding-bottom: 10px;
  border-bottom: 1px solid var(--color-border);
}
.dates-note {
  font-size: 12px;
  font-weight: 600;
  color: var(--color-text-muted);
  white-space: nowrap;
}
.info-card.accent {
  border-color: rgba(47, 111, 237, 0.24);
  background: linear-gradient(135deg, rgba(243,248,255,0.98) 0%, rgba(255,255,255,0.98) 100%);
}

.dates-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.dates-list li {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  font-size: 14px;
}
.date-label { color: var(--color-text-muted); }
.date-value { font-weight: 600; text-align: right; }
.date-value.highlight { color: var(--color-primary-dark); }

.history-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.history-list li {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 8px;
  font-size: 14px;
}
.history-list li span { color: var(--color-text-muted); font-size: 12px; }

.mt-sm { margin-top: 12px; }
.mt-lg { margin-top: 56px; }

/* ============================================================
   People Cards (Speakers & Organizers)
   ============================================================ */
.people-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 22px;
  margin-top: 16px;
}

.organizers-grid {
  grid-template-columns: repeat(4, 1fr);
}

.volunteers-grid {
  grid-template-columns: repeat(5, 1fr);
}

.competition-grid {
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 14px;
}

.competition-grid .person-card {
  min-width: 0;
}

.competition-grid .person-card.compact {
  padding: 10px 12px 8px;
}

.competition-grid .person-card.compact .person-avatar {
  width: 76px;
  height: 76px;
  margin-bottom: 8px;
}

.competition-grid .person-name {
  font-size: 15px;
  line-height: 1.3;
  margin-bottom: 4px;
}

.competition-grid .person-role,
.competition-grid .person-affil {
  font-size: 12px;
  line-height: 1.4;
}

.competition-grid .person-affil {
  min-height: 2.8em;
}

.person-card {
  background: linear-gradient(180deg, rgba(255,255,255,0.98) 0%, rgba(247,250,252,0.96) 100%);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 22px;
  display: flex;
  gap: 16px;
  transition: box-shadow var(--transition), transform var(--transition);
  box-shadow: var(--shadow-sm);
}
.person-card:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
  border-color: rgba(47, 111, 237, 0.22);
}
.person-card.compact {
  flex-direction: column;
  align-items: center;
  text-align: center;
  padding: 14px 14px 14px;
  gap: 4px;
}
.person-card.compact .person-info {
  display: flex;
  flex-direction: column;
  align-items: center;
}
.person-card.compact .person-bio {
  margin-top: 6px;
}

.person-avatar {
  flex-shrink: 0;
  width: 72px; height: 72px;
  border-radius: 50%;
  overflow: hidden;
  background: linear-gradient(135deg, #243241 0%, #7E96AE 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
}
.person-card.compact .person-avatar {
  width: 110px; height: 110px;
  margin: 0 auto 0;
}
.person-avatar img {
  width: 100%; height: 100%;
  object-fit: cover;
}
.person-avatar .initials {
  color: #fff;
  font-weight: 700;
  font-size: 20px;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100%; height: 100%;
}

.person-info { flex: 1; min-width: 0; }
.person-name {
  font-size: 18px;
  font-weight: 700;
  margin-bottom: 2px;
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}
.person-name a { color: var(--color-text); text-decoration: none; }
.person-name a:hover { color: var(--color-link); }

.contact-badge {
  font-size: 10px;
  font-weight: 700;
  background: #D9E8FF;
  color: #173B77;
  border: 1px solid #BDD3F5;
  padding: 3px 9px;
  border-radius: 100px;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  text-decoration: none;
}
.person-name .contact-badge {
  color: #173B77;
}
.person-name .contact-badge:hover {
  color: #0E2D63;
  background: #CFE1FF;
}

.person-role {
  font-size: 13px;
  color: var(--color-text);
  font-weight: 600;
  margin-bottom: 1px;
}

.person-affil {
  font-size: 14px;
  color: var(--color-text-muted);
  font-weight: 500;
  margin-bottom: 6px;
  line-height: 1.5;
}
.person-bio {
  font-size: 14px;
  color: var(--color-text-muted);
  line-height: 1.65;
  display: -webkit-box;
  -webkit-box-orient: vertical;
  -webkit-line-clamp: 5;
  overflow: hidden;
  min-height: calc(1.65em * 5);
}
.person-card.compact .person-bio {
  -webkit-line-clamp: 3;
  min-height: calc(1.6em * 3);
}

#speakers .people-grid {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 22px;
}

#speakers .person-card {
  flex-direction: column;
  align-items: center;
  text-align: left;
  gap: 16px;
  flex: 0 1 calc(25% - 17px);
  max-width: calc(25% - 17px);
  min-width: 250px;
}

#speakers .person-info {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  width: 100%;
}

#speakers .person-name {
  justify-content: flex-start;
}

#speakers .person-avatar {
  width: 112px;
  height: 112px;
  margin: 0 auto;
}

#speakers .person-affil,
#speakers .person-bio {
  text-align: left;
}

#speakers .person-bio {
  -webkit-line-clamp: 5;
  overflow: hidden;
  min-height: calc(1.65em * 5);
  cursor: pointer;
  position: relative;
}

#speakers .person-bio.is-expanded {
  display: block;
  -webkit-line-clamp: unset;
  overflow: visible;
  min-height: 0;
}

#speakers .person-bio.is-static {
  cursor: default;
}

.speaker-bio-toggle {
  margin-top: 10px;
  padding: 0;
  border: 0;
  background: none;
  color: var(--color-primary-dark);
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.01em;
  cursor: pointer;
}

.speaker-bio-toggle:hover {
  color: var(--color-link-hover);
  text-decoration: underline;
}

.speaker-bio-toggle[hidden] {
  display: none;
}

/* ============================================================
   Schedule
   ============================================================ */
.schedule-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
  margin-top: 34px;
}

.schedule-column {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.schedule-phase {
  display: flex;
  align-items: center;
  gap: 10px;
  margin: 2px 0 6px;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-text-muted);
}

.schedule-phase::after {
  content: "";
  flex: 1;
  height: 1px;
  background: linear-gradient(90deg, rgba(104, 125, 152, 0.26) 0%, rgba(104, 125, 152, 0.08) 100%);
}

.schedule-cluster {
  grid-column: 1 / -1;
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin-top: 6px;
  padding: 16px;
  border-radius: calc(var(--radius-md) + 6px);
  background: linear-gradient(180deg, rgba(246, 249, 252, 0.95) 0%, rgba(242, 246, 250, 0.9) 100%);
  border: 1px solid rgba(201, 212, 225, 0.88);
}

.schedule-cluster-row {
  display: grid;
  grid-template-columns: minmax(0, 1.6fr) minmax(280px, 0.9fr);
  gap: 12px;
  align-items: stretch;
}

.schedule-cluster-row .schedule-item {
  height: 100%;
}

.schedule-cluster .schedule-item.closing {
  width: 100%;
}

.schedule-item {
  display: flex;
  gap: 12px;
  align-items: flex-start;
  padding: 13px 15px;
  border-radius: var(--radius-md);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  transition: background var(--transition);
  box-shadow: var(--shadow-sm);
}

.schedule-item.talk { background: #F3F7FF; border-color: #D6E2F7; }
.schedule-item.break { background: #F7F9FB; border-color: #E0E8F0; }
.schedule-item.poster { background: #F7F8FA; border-color: #DCE4EC; }
.schedule-item.panel { background: #EEF5FF; border-color: #D2E0F3; }
.schedule-item.contributed { background: #F3F8F6; border-color: #D6E6DF; }
.schedule-item.closing { background: #F1F5FA; border-color: #D6E0EB; }

.schedule-time {
  flex-shrink: 0;
  width: 104px;
  font-size: 13px;
  font-weight: 600;
  color: var(--color-text-muted);
  padding-top: 3px;
  font-variant-numeric: tabular-nums;
}

.schedule-content {
  display: flex;
  flex-direction: column;
  gap: 3px;
}

.schedule-tag {
  display: inline-block;
  font-size: 11px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  padding: 2px 8px;
  border-radius: 100px;
}
.schedule-tag.invited  { background: #DCE8FF; color: #1F4FB5; }
.schedule-tag.opening  { background: #E6EEFF; color: #1F4FB5; }
.schedule-tag.coffee   { background: #EAF0F5; color: #4A6075; }
.schedule-tag.lunch    { background: #E1F0E9; color: #336154; }
.schedule-tag.poster-tag { background: #EAF0F5; color: #4A6075; }
.schedule-tag.panel-tag  { background: #DCEBFF; color: #2A5E9C; }
.schedule-tag.contrib    { background: #E1F0E9; color: #336154; }

.schedule-title {
  font-size: 14px;
  font-weight: 500;
  color: var(--color-text);
  line-height: 1.6;
}

/* ============================================================
   Call for Papers
   ============================================================ */
.cfp-grid {
  display: grid;
  grid-template-columns: 1fr 300px;
  gap: 48px;
  margin-top: 40px;
}

.cfp-intro {
  font-size: 17px;
  line-height: 1.7;
  margin-bottom: 24px;
}

.topics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 16px;
  margin-bottom: 36px;
}

.topic-card {
  background: linear-gradient(180deg, rgba(255,255,255,0.98) 0%, rgba(247,250,252,0.96) 100%);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 17px;
  box-shadow: var(--shadow-sm);
  transition: box-shadow var(--transition);
}
.topic-card:hover {
  box-shadow: var(--shadow-md);
  border-color: rgba(47, 111, 237, 0.22);
}
.topic-card h4 {
  font-size: 16px;
  font-weight: 700;
  color: var(--color-primary-dark);
  margin-bottom: 6px;
}
.topic-card p {
  font-size: 14px;
  color: var(--color-text-muted);
  line-height: 1.65;
}

.cfp-details { margin-top: 32px; }
.cfp-details h3 {
  font-size: 20px;
  font-weight: 700;
  margin-bottom: 16px;
}
.cfp-details ul {
  list-style: disc;
  padding-left: 22px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-bottom: 24px;
}
.cfp-details ul li {
  font-size: 15px;
  line-height: 1.7;
  color: var(--color-text);
}

.cfp-actions {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

/* ============================================================
   Challenge
   ============================================================ */
.challenge-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 22px;
  margin-top: 34px;
}

.challenge-card {
  background: linear-gradient(180deg, rgba(255,255,255,0.98) 0%, rgba(247,250,252,0.96) 100%);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  display: flex;
  flex-direction: column;
  box-shadow: var(--shadow-sm);
  transition: box-shadow var(--transition), transform var(--transition);
}
.challenge-card:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}

.challenge-header {
  padding: 18px 20px 16px;
  background: linear-gradient(135deg, #1F2D3B 0%, #6B8FBE 100%);
}

.challenge-number {
  display: inline-block;
  font-size: 11px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: rgba(255,255,255,0.7);
  background: rgba(255,255,255,0.15);
  padding: 3px 10px;
  border-radius: 100px;
  margin-bottom: 10px;
}

.challenge-title {
  font-size: 18px;
  font-weight: 700;
  color: #fff;
  line-height: 1.45;
}

.challenge-body {
  padding: 18px 20px;
  flex: 1;
}
.challenge-body p {
  font-size: 14px;
  color: var(--color-text-muted);
  line-height: 1.7;
  margin-bottom: 14px;
}

.challenge-lead {
  color: var(--color-text) !important;
  font-weight: 600;
  margin-bottom: 12px !important;
}

.challenge-highlights {
  display: flex;
  flex-direction: column;
  gap: 7px;
  margin-bottom: 14px;
  padding: 12px 14px;
  background: rgba(47, 111, 237, 0.05);
  border: 1px solid rgba(47, 111, 237, 0.12);
  border-radius: var(--radius-sm);
  list-style: none;
}

.challenge-highlights li {
  font-size: 13px;
  line-height: 1.6;
  color: var(--color-text-muted);
}
.challenge-body h4 {
  font-size: 14px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-text-muted);
  margin-bottom: 8px;
}
.challenge-tasks {
  padding-left: 18px;
  display: flex;
  flex-direction: column;
  gap: 6px;
  margin-bottom: 14px;
}
.challenge-body ol.challenge-tasks { list-style: decimal; }
.challenge-body ul.challenge-tasks { list-style: disc; }
.challenge-tasks li {
  font-size: 14px;
  line-height: 1.65;
  color: var(--color-text);
}

.challenge-metric {
  font-size: 13px !important;
  color: var(--color-text) !important;
  background: var(--color-bg-light);
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  margin-bottom: 8px !important;
  border: 1px solid var(--color-border-light);
}
.challenge-metric code {
  font-family: monospace;
  font-size: 12px;
  background: rgba(31, 35, 36, 0.06);
  padding: 2px 6px;
  border-radius: 4px;
}

.challenge-footer {
  padding: 16px 24px;
  border-top: 1px solid var(--color-border);
  background: rgba(245,248,252,0.88);
}

/* ============================================================
   Volunteers
   ============================================================ */
.volunteers-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 12px;
}

.volunteers-grid .person-card.compact {
  padding: 14px 14px 8px;
}

.volunteer-item {
  display: flex;
  flex-direction: column;
  gap: 2px;
  padding: 16px 18px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  font-size: 15px;
  transition: box-shadow var(--transition);
}
.volunteer-item:hover { box-shadow: var(--shadow-sm); }
.volunteer-item a { font-weight: 600; color: var(--color-text); }
.volunteer-item a:hover { color: var(--color-primary); }
.volunteer-item span { font-size: 14px; color: var(--color-text-muted); }

/* ============================================================
   Sponsors
   ============================================================ */
.sponsors-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 280px));
  justify-content: center;
  gap: 22px;
  margin-top: 40px;
}

.sponsor-card {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 138px;
  padding: 24px 28px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  background: linear-gradient(180deg, rgba(255,255,255,0.98) 0%, rgba(247,250,252,0.96) 100%);
  box-shadow: var(--shadow-sm);
}

.sponsor-card img {
  max-width: 100%;
  max-height: 72px;
  width: auto;
  height: auto;
  object-fit: contain;
}

.sponsors-placeholder {
  text-align: center;
  padding: 48px 24px;
  border: 2px dashed var(--color-border);
  border-radius: var(--radius-lg);
  background: rgba(255,255,255,0.72);
  color: var(--color-text-muted);
  margin-top: 40px;
}

/* ============================================================
   Footer
   ============================================================ */
.footer {
  background: linear-gradient(180deg, #1E2426 0%, #161A1C 100%);
  color: rgba(255,255,255,0.7);
  padding: 56px 24px 32px;
  border-top: 4px solid var(--color-primary);
}

.footer-grid {
  max-width: var(--max-width);
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 40px;
  margin-bottom: 48px;
}

.footer-col h4 {
  font-size: 14px;
  font-weight: 700;
  color: #fff;
  margin-bottom: 16px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}
.footer-col p { font-size: 13px; line-height: 1.7; margin-bottom: 8px; }
.footer-col ul { display: flex; flex-direction: column; gap: 8px; }
.footer-col ul li a {
  font-size: 13px;
  color: rgba(255,255,255,0.6);
  text-decoration: none;
}
.footer-col ul li a:hover { color: #fff; }
.footer-col a { color: rgba(255,255,255,0.7); }
.footer-col a:hover { color: #fff; text-decoration: none; }

.social-links {
  display: flex;
  gap: 12px;
  margin-top: 12px;
}
.social-links a {
  font-size: 18px;
  color: rgba(255,255,255,0.6);
  text-decoration: none;
}
.social-links a:hover { color: #fff; }

.footer-bottom {
  max-width: var(--max-width);
  margin: 0 auto;
  padding-top: 24px;
  border-top: 1px solid rgba(255,255,255,0.1);
  text-align: center;
}
.footer-bottom p { font-size: 13px; }
.footer-bottom a { color: rgba(255,255,255,0.6); }
.footer-bottom a:hover { color: #fff; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    transition-delay: 0ms !important;
  }
}

/* ============================================================
   Responsive
   ============================================================ */
@media (max-width: 1180px) {
  #speakers .person-card {
    flex-basis: calc(33.333% - 15px);
    max-width: calc(33.333% - 15px);
  }
  .competition-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

@media (max-width: 900px) {
  .about-grid { grid-template-columns: 1fr; }
  .about-panels { grid-template-columns: 1fr; }
  .cfp-grid { grid-template-columns: 1fr; }
  .schedule-grid { grid-template-columns: 1fr 1fr; }
  .schedule-cluster-row { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: repeat(2, 1fr); }
  .section::before,
  .section::after {
    width: min(46vw, 300px);
    height: min(46vw, 300px);
  }
  .competition-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  #speakers .person-card {
    flex-basis: calc(50% - 11px);
    max-width: calc(50% - 11px);
  }
}

@media (max-width: 700px) {
  .nav-links {
    display: none;
    position: absolute;
    top: var(--nav-height);
    left: 0; right: 0;
    background: rgba(253, 251, 247, 0.98);
    flex-direction: column;
    align-items: stretch;
    padding: 12px 16px 20px;
    border-bottom: 1px solid var(--color-border);
    box-shadow: var(--shadow-md);
    gap: 2px;
  }
  .nav-links.open { display: flex; }
  .nav-links li a { padding: 10px 12px; font-size: 15px; }
  .nav-toggle { display: flex; }

  .section { padding: 58px 16px; }
  .hero { padding-top: calc(var(--nav-height) + 30px); }

  .people-grid { grid-template-columns: 1fr; }
  .organizers-grid { grid-template-columns: repeat(2, 1fr); }
  .competition-grid { grid-template-columns: 1fr; }
  .person-card { flex-direction: column; align-items: center; text-align: center; }
  .person-name { justify-content: center; }
  #speakers .person-card {
    flex-basis: calc(50% - 11px);
    max-width: calc(50% - 11px);
  }

  .footer-grid { grid-template-columns: 1fr 1fr; gap: 32px; }

  .nav-logo img { width: 26px; height: 26px; }
  .hero-title { font-size: 30px; }
  .hero-subtitle-text { font-size: 18px; }
}

@media (max-width: 480px) {
  .footer-grid { grid-template-columns: 1fr; }
  .organizers-grid { grid-template-columns: repeat(2, 1fr); }
  .volunteers-grid { grid-template-columns: repeat(2, 1fr); }
  .competition-grid { grid-template-columns: repeat(2, 1fr); }
  .schedule-time { width: auto; font-size: 11px; flex: 0 0 auto; }
  .schedule-item { flex-wrap: wrap; align-items: center; }
  .schedule-content { display: contents; }
  .schedule-tag { flex: 0 0 auto; margin-left: auto; font-size: 9px; padding: 1px 5px; letter-spacing: 0; white-space: nowrap; }
  .schedule-title { flex: 0 0 100%; margin-top: 4px; font-size: 13px; }
  .nav-logo { gap: 8px; font-size: 14px; }
  .nav-logo img { width: 24px; height: 24px; border-radius: 7px; }
  body { font-size: 16px; }
  .contact-badge { font-size: 8px; padding: 2px 6px; }
}