/* ==========================================================================
   OASec 2026 — Light Theme + Teal Accent
   ========================================================================== */

/* --- CSS Custom Properties --- */
:root {
  --color-teal: #20c997;
  --color-teal-hover: #17a97e;

  --color-bg: #ffffff;
  --color-bg-elevated: #f7f7f7;
  --color-bg-card: #f0f0f0;
  --color-text: #111111;
  --color-text-muted: #666666;
  --color-accent: var(--color-teal);
  --color-accent-hover: var(--color-teal-hover);
  --color-border: #e0e0e0;

  --font-heading: 'Roboto Condensed', 'Inter', 'Noto Sans TC', 'Noto Sans CJK', sans-serif;
  --font-body: 'Inter', 'Roboto Condensed', 'Noto Sans TC', 'Noto Sans CJK', sans-serif;

  --max-width: 1200px;
  --nav-height: 64px;
}

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

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

body {
  background: var(--color-bg);
  color: var(--color-text);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--color-accent);
  text-decoration: none;
  transition: color 0.2s;
}

a:hover {
  color: var(--color-accent-hover);
}

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

/* --- Typography --- */
h1, h2, h3, h4 {
  font-family: var(--font-heading);
  font-weight: 700;
  line-height: 1.2;
}

h2 {
  font-size: 2rem;
  margin-bottom: 1rem;
}

.section-title {
  text-align: center;
  margin-bottom: 3rem;
}

.section-title h2 {
  display: inline-block;
  position: relative;
  padding-bottom: 0.5rem;
}

.section-title h2::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 60px;
  height: 3px;
  background: var(--color-accent);
}

.section-title p {
  color: var(--color-text-muted);
  margin-top: 0.75rem;
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

/* --- Layout --- */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
}

section {
  padding: 5rem 0;
}

section:nth-child(even) {
  background: var(--color-bg-elevated);
}

/* ==========================================================================
   Navigation
   ========================================================================== */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
  z-index: 1000;
  transition: background 0.3s;
}

.nav .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}

.nav-logo {
  font-family: var(--font-heading);
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--color-text);
  white-space: nowrap;
}

.nav-logo span {
  color: var(--color-accent);
}

.nav-links {
  display: flex;
  list-style: none;
  gap: 1.5rem;
  align-items: center;
}

.nav-links a {
  color: var(--color-text-muted);
  font-size: 0.9rem;
  font-weight: 500;
  padding: 0.25rem 0;
  position: relative;
  transition: color 0.2s;
}

.nav-links a.btn,
.nav-links a.btn:hover {
  color: #ffffff;
  text-decoration: none;
}

.nav-links a.btn::after {
  display: none;
}

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--color-accent);
  transition: width 0.2s;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--color-text);
}

.nav-links a:hover::after,
.nav-links a.active::after {
  width: 100%;
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  color: var(--color-text);
  font-size: 1.5rem;
  cursor: pointer;
  padding: 0.25rem;
}

/* ==========================================================================
   Hero
   ========================================================================== */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding-top: var(--nav-height);
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background:
    radial-gradient(ellipse at 50% 0%, rgba(32, 201, 151, 0.08) 0%, transparent 60%),
    radial-gradient(ellipse at 80% 80%, rgba(32, 201, 151, 0.05) 0%, transparent 50%);
  pointer-events: none;
}

.hero-content {
  position: relative;
  z-index: 1;
  max-width: 800px;
  padding: 2rem 1rem;
}

.hero-badge {
  display: inline-block;
  background: rgba(32, 201, 151, 0.1);
  border: 1px solid rgba(32, 201, 151, 0.3);
  color: var(--color-accent);
  padding: 0.4rem 1.2rem;
  border-radius: 100px;
  font-size: 0.85rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 1.5rem;
}

.hero h1 {
  font-size: clamp(2.5rem, 6vw, 4rem);
  margin-bottom: 1rem;
  letter-spacing: -0.02em;
}

.hero h1 span {
  color: var(--color-accent);
}

.hero-tagline {
  font-size: 1.2rem;
  color: var(--color-text-muted);
  margin-bottom: 2rem;
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

.hero-countdown {
  display: flex;
  justify-content: center;
  gap: 1.5rem;
  margin-bottom: 2.5rem;
}

.countdown-item {
  text-align: center;
}

.countdown-value {
  display: block;
  font-family: var(--font-heading);
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--color-accent);
  line-height: 1;
}

.countdown-label {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-text-muted);
  margin-top: 0.25rem;
}

.hero-ctas {
  display: flex;
  gap: 1rem;
  justify-content: center;
  flex-wrap: wrap;
}

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 2rem;
  border-radius: 6px;
  font-family: var(--font-heading);
  font-size: 1rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.03em;
  cursor: pointer;
  border: none;
  transition: transform 0.15s, box-shadow 0.2s, background 0.2s;
}

.btn:hover {
  transform: translateY(-1px);
}

.btn-primary {
  background: var(--color-accent);
  color: #ffffff;
}

.btn-primary:hover {
  background: var(--color-accent-hover);
  color: #ffffff;
  box-shadow: 0 4px 20px rgba(32, 201, 151, 0.3);
}

.btn-outline {
  background: transparent;
  color: var(--color-accent);
  border: 2px solid var(--color-accent);
}

.btn-outline:hover {
  background: rgba(32, 201, 151, 0.1);
  color: var(--color-accent-hover);
}

.btn-disabled {
  opacity: 0.45;
  cursor: not-allowed;
  pointer-events: none;
}

/* ==========================================================================
   About
   ========================================================================== */
.about-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  align-items: center;
}

.about-text p {
  color: var(--color-text-muted);
  margin-bottom: 1rem;
}

.about-text p:first-of-type {
  font-size: 1.1rem;
  color: var(--color-text);
}

.about-stats {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
}

.stat-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: 1.5rem;
  text-align: center;
}

.stat-value {
  font-family: var(--font-heading);
  font-size: 2rem;
  font-weight: 700;
  color: var(--color-accent);
  display: block;
}

.stat-label {
  font-size: 0.85rem;
  color: var(--color-text-muted);
  margin-top: 0.25rem;
}

/* ==========================================================================
   Tracks
   ========================================================================== */
.tracks-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1.5rem;
}

.track-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: 2rem 1.5rem;
  text-align: center;
  transition: transform 0.2s, border-color 0.2s, box-shadow 0.2s;
}

.track-card:hover {
  transform: translateY(-4px);
  border-color: var(--color-accent);
  box-shadow: 0 8px 30px rgba(32, 201, 151, 0.1);
}

.track-icon {
  font-size: 2.5rem;
  margin-bottom: 1rem;
}

.track-card h3 {
  font-size: 1.2rem;
  margin-bottom: 0.75rem;
  color: var(--color-accent);
}

.track-card p {
  font-size: 0.9rem;
  color: var(--color-text-muted);
  line-height: 1.5;
}

/* ==========================================================================
   CFP
   ========================================================================== */
.cfp-content {
  max-width: 900px;
  margin: 0 auto;
}

.cfp-dates {
  width: 100%;
  border-collapse: collapse;
  margin-bottom: 2rem;
}

.cfp-dates th,
.cfp-dates td {
  padding: 0.75rem 1rem;
  text-align: left;
  border-bottom: 1px solid var(--color-border);
}

.cfp-dates th {
  font-family: var(--font-heading);
  color: var(--color-accent);
  font-weight: 600;
  text-transform: uppercase;
  font-size: 0.8rem;
  letter-spacing: 0.05em;
}

.cfp-dates td:first-child {
  font-weight: 500;
}

.cfp-dates td:last-child {
  color: var(--color-text-muted);
}

.cfp-dates tr.highlight td {
  color: var(--color-accent);
  font-weight: 600;
}

.cfp-info {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2rem;
  margin-bottom: 2.5rem;
}

.cfp-info-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: 1.5rem;
}

.cfp-info-card h3 {
  font-size: 1rem;
  color: var(--color-accent);
  margin-bottom: 0.75rem;
}

.cfp-info-card ul {
  list-style: none;
  color: var(--color-text-muted);
  font-size: 0.9rem;
}

.cfp-info-card li {
  padding: 0.25rem 0;
  padding-left: 1.2rem;
  position: relative;
}

.cfp-info-card li::before {
  content: '\2022';
  color: var(--color-accent);
  position: absolute;
  left: 0;
}

.cfp-ctas {
  display: flex;
  gap: 1rem;
  justify-content: center;
  flex-wrap: wrap;
}

.cfp-contact {
  text-align: center;
  margin-top: 1.5rem;
  color: var(--color-text-muted);
  font-size: 0.9rem;
}

/* ==========================================================================
   Schedule
   ========================================================================== */
.schedule-table-wrapper {
  overflow-x: auto;
}

.schedule-table {
  width: 100%;
  border-collapse: collapse;
  min-width: 700px;
}

.schedule-table th,
.schedule-table td {
  padding: 0.75rem 1rem;
  text-align: left;
  border-bottom: 1px solid var(--color-border);
  font-size: 0.9rem;
}

.schedule-table thead th {
  font-family: var(--font-heading);
  color: var(--color-accent);
  text-transform: uppercase;
  font-size: 0.8rem;
  letter-spacing: 0.05em;
  position: sticky;
  top: 0;
  background: var(--color-bg-elevated);
}

.schedule-table .time-col {
  white-space: nowrap;
  font-weight: 600;
  color: var(--color-accent);
  width: 140px;
}

.schedule-table .break-row td {
  color: var(--color-text-muted);
  font-style: italic;
  background: rgba(32, 201, 151, 0.03);
}

.schedule-table .keynote-row td {
  font-weight: 600;
}

/* ==========================================================================
   Speakers
   ========================================================================== */
.speakers-placeholder {
  text-align: center;
  padding: 3rem;
  background: var(--color-bg-card);
  border: 1px dashed var(--color-border);
  border-radius: 12px;
}

.speakers-placeholder p {
  color: var(--color-text-muted);
  font-size: 1.1rem;
  margin-bottom: 1.5rem;
}

.speakers-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 1.5rem;
}

.speaker-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: 1.5rem;
  text-align: center;
  transition: border-color 0.2s;
}

.speaker-card:hover {
  border-color: var(--color-accent);
}

.speaker-photo {
  width: 100px;
  height: 100px;
  border-radius: 50%;
  object-fit: cover;
  margin-bottom: 1rem;
  border: 2px solid var(--color-border);
}

.speaker-card h3 {
  font-size: 1rem;
  margin-bottom: 0.25rem;
}

.speaker-card .speaker-title {
  font-size: 0.85rem;
  color: var(--color-text-muted);
}

/* ==========================================================================
   Venue
   ========================================================================== */
.venue-content {
  text-align: center;
  max-width: 800px;
  margin: 0 auto;
}

.venue-placeholder {
  background: var(--color-bg-card);
  border: 1px dashed var(--color-border);
  border-radius: 12px;
  padding: 3rem;
}

.venue-placeholder p {
  color: var(--color-text-muted);
  font-size: 1.1rem;
}

.venue-placeholder .venue-city {
  font-size: 1.5rem;
  color: var(--color-text);
  font-family: var(--font-heading);
  font-weight: 700;
  margin-bottom: 0.5rem;
}

/* ==========================================================================
   Sponsors / Carousel
   ========================================================================== */

.carousel-section-title {
  margin-top: 4rem;
}

/* Logo carousel */
.logo-carousel {
  --items: 4;
  position: relative;
  padding: 0 2.75rem;
  margin-bottom: 1rem;
}

@media (max-width: 900px) {
  .logo-carousel { --items: 3; }
}

@media (max-width: 600px) {
  .logo-carousel { --items: 2; }
}

.carousel-viewport {
  overflow: hidden;
}

.carousel-track {
  display: flex;
  gap: 2rem;
  align-items: center;
  min-height: 88px;
  transition: transform 0.4s cubic-bezier(0.25, 0.46, 0.45, 0.94);
}

.carousel-slide {
  flex: 0 0 calc((100% - 2rem * (var(--items) - 1)) / var(--items));
  display: flex;
  align-items: center;
  justify-content: center;
}

/* Org/supporter logos */
.org-logo {
  height: 56px;
  width: auto;
  max-width: 100%;
  opacity: 0.8;
  transition: opacity 0.2s;
}

.org-logo:hover {
  opacity: 1;
}

.logo-row {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  align-items: center;
  gap: 2.5rem;
  padding: 1rem 0 2rem;
}

/* Empty state */
.carousel-empty {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 88px;
  color: var(--color-text-muted);
  font-size: 0.9rem;
  font-style: italic;
}

/* Arrow buttons */
.carousel-prev-btn,
.carousel-next-btn {
  position: absolute;
  top: 50%;
  transform: translateY(calc(-50% - 0.75rem)); /* account for dots space */
  width: 2.1rem;
  height: 2.1rem;
  border-radius: 50%;
  border: 1px solid var(--color-border);
  background: var(--color-bg-card);
  color: var(--color-text);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.85rem;
  transition: background 0.2s, color 0.2s, border-color 0.2s;
  z-index: 1;
}

.carousel-prev-btn { left: 0; }
.carousel-next-btn { right: 0; }

.carousel-prev-btn:hover,
.carousel-next-btn:hover {
  background: var(--color-accent);
  color: #fff;
  border-color: var(--color-accent);
}

.carousel-prev-btn:disabled,
.carousel-next-btn:disabled {
  opacity: 0.3;
  pointer-events: none;
}

.carousel-prev-btn.hidden,
.carousel-next-btn.hidden {
  display: none;
}

/* Dot indicators */
.carousel-dots {
  display: flex;
  justify-content: center;
  gap: 0.45rem;
  margin-top: 1.25rem;
  min-height: 1.25rem;
}

.carousel-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  border: none;
  background: var(--color-border);
  cursor: pointer;
  padding: 0;
  transition: background 0.2s;
}

.carousel-dot.active {
  background: var(--color-accent);
}

/* Founding Circle member grid */
.member-grid {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.65rem;
  padding: 0.5rem 0;
}

.member-chip {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.45rem 1rem;
  border-radius: 100px;
  border: 1px solid var(--color-border);
  background: var(--color-bg-card);
  color: var(--color-text);
  font-size: 0.9rem;
  font-weight: 500;
  text-decoration: none;
  transition: border-color 0.2s, background 0.2s, color 0.2s;
}

.member-chip i {
  color: var(--color-accent);
  font-size: 0.85rem;
  transition: color 0.2s;
}

.member-chip:hover {
  border-color: var(--color-accent);
  background: rgba(32, 201, 151, 0.07);
  color: var(--color-text);
}

.member-chip:hover i {
  color: var(--color-accent-hover);
}

.support-tiers {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 1.5rem;
  margin-top: 3rem;
}

.support-tier-card {
  flex: 0 1 calc(33.333% - 1rem);
  min-width: 260px;
}

@media (max-width: 900px) {
  .support-tiers {
    grid-template-columns: 1fr;
    max-width: 560px;
    margin-left: auto;
    margin-right: auto;
  }
}

.support-tier-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: 2rem 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

.support-tier-sponsor {
  border-color: var(--color-accent);
}

.support-tier-founding {
}

.support-tier-header {
  text-align: center;
}

.support-tier-icon {
  font-size: 1.8rem;
  color: var(--color-accent);
  margin-bottom: 0.75rem;
}

.support-tier-card h3 {
  font-family: var(--font-heading);
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: 0.4rem;
}

.support-tier-who {
  font-size: 0.85rem;
  color: var(--color-text-muted);
}

.support-tier-body {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

.support-tier-section h4 {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-text-muted);
  margin-bottom: 0.5rem;
}

.support-tier-section ul {
  list-style: none;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

.support-tier-section ul li {
  font-size: 0.9rem;
  padding-left: 1.1em;
  position: relative;
}

.support-tier-section ul li::before {
  content: '—';
  position: absolute;
  left: 0;
  color: var(--color-accent);
  font-size: 0.75rem;
  line-height: 1.6;
}

.support-tier-note {
  font-size: 0.8rem;
  color: var(--color-text-muted);
  font-style: italic;
  margin-top: 0.5rem;
}

.support-tier-card .btn {
  display: block;
  text-align: center;
}

/* ==========================================================================
   Register
   ========================================================================== */
.register-content {
  max-width: 800px;
  margin: 0 auto;
  text-align: center;
}

.ticket-tiers {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1.5rem;
  margin-bottom: 2.5rem;
}

.ticket-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: 12px;
  padding: 2rem 1.5rem;
  text-align: center;
  transition: border-color 0.2s;
}

.ticket-card.featured {
  border-color: var(--color-accent);
}

.ticket-card h3 {
  font-size: 1.1rem;
  margin-bottom: 0.5rem;
}

.ticket-price {
  font-family: var(--font-heading);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-accent);
  margin-bottom: 0.5rem;
}

.ticket-desc {
  font-size: 0.85rem;
  color: var(--color-text-muted);
}

/* ==========================================================================
   FAQ
   ========================================================================== */
.faq-list {
  max-width: 800px;
  margin: 0 auto;
}

.faq-item {
  border-bottom: 1px solid var(--color-border);
}

.faq-question {
  width: 100%;
  background: none;
  border: none;
  color: var(--color-text);
  font-family: var(--font-heading);
  font-size: 1.05rem;
  font-weight: 600;
  text-align: left;
  padding: 1.25rem 0;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
}

.faq-question:hover {
  color: var(--color-accent);
}

.faq-icon {
  font-size: 1.2rem;
  transition: transform 0.3s;
  flex-shrink: 0;
}

.faq-item.open .faq-icon {
  transform: rotate(45deg);
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease;
}

.faq-answer-inner {
  padding-bottom: 1.25rem;
  color: var(--color-text-muted);
  line-height: 1.7;
  font-size: 0.95rem;
}

/* ==========================================================================
   Footer
   ========================================================================== */
.footer {
  background: var(--color-bg);
  border-top: 1px solid var(--color-border);
  padding: 3rem 0;
}

.footer-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1.5rem;
}

.footer-org {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.footer-org-logo {
  height: 32px;
}

.footer-links {
  display: flex;
  gap: 1.5rem;
  flex-wrap: wrap;
}

.footer-links a {
  color: var(--color-text-muted);
  font-size: 0.9rem;
}

.footer-links a:hover {
  color: var(--color-accent);
}

.footer-copy {
  width: 100%;
  text-align: center;
  color: var(--color-text-muted);
  font-size: 0.8rem;
  margin-top: 1.5rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--color-border);
}

/* ==========================================================================
   Responsive
   ========================================================================== */
@media (max-width: 1024px) {
  .tracks-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .about-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 768px) {
  :root {
    --nav-height: 56px;
  }

  section {
    padding: 3.5rem 0;
  }

  .nav-links {
    display: none;
    position: fixed;
    top: var(--nav-height);
    left: 0;
    right: 0;
    height: calc(100dvh - var(--nav-height));
    background: rgba(26, 26, 26, 0.98);
    flex-direction: column;
    align-items: center;
    justify-content: center;
    gap: 2rem;
  }

  .nav-links.open {
    display: flex;
  }

  .nav-links a {
    font-size: 1.2rem;
  }

  .nav-toggle {
    display: block;
  }

  .tracks-grid {
    grid-template-columns: 1fr;
  }

  .cfp-info {
    grid-template-columns: 1fr;
  }

  .hero h1 {
    font-size: 2rem;
  }

  .hero-countdown {
    gap: 1rem;
  }

  .countdown-value {
    font-size: 1.8rem;
  }

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

  .footer-content {
    flex-direction: column;
    text-align: center;
  }

  .footer-links {
    justify-content: center;
  }
}