/* ============================================
   ARC AI SYMPOSIUM — DESIGN TOKENS & STYLES
   Custom dark-themed palette: deep navy + cyan
   ============================================ */

/* --- Google Fonts loaded in HTML --- */

:root {
  /* --- Font families --- */
  --font-display: 'Plus Jakarta Sans', 'Helvetica Neue', sans-serif;
  --font-body: 'Inter', 'Helvetica Neue', sans-serif;

  /* --- Type Scale (fluid) --- */
  --text-xs:   clamp(0.75rem,  0.7rem  + 0.25vw, 0.875rem);
  --text-sm:   clamp(0.875rem, 0.8rem  + 0.35vw, 1rem);
  --text-base: clamp(1rem,     0.9rem  + 0.5vw,  1.125rem);
  --text-lg:   clamp(1.125rem, 0.95rem + 0.85vw, 1.5rem);
  --text-xl:   clamp(1.5rem,   1rem    + 1.5vw,  2.25rem);
  --text-2xl:  clamp(2rem,     1.2rem  + 2.5vw,  3.5rem);
  --text-3xl:  clamp(2.5rem,   1rem    + 4vw,    5rem);
  --text-hero: clamp(3rem,     0.5rem  + 7vw,    8rem);

  /* --- 4px Spacing System --- */
  --space-1:  0.25rem;
  --space-2:  0.5rem;
  --space-3:  0.75rem;
  --space-4:  1rem;
  --space-5:  1.25rem;
  --space-6:  1.5rem;
  --space-8:  2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;
  --space-32: 8rem;

  /* --- Radius --- */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-full: 9999px;

  /* --- Transitions --- */
  --transition-interactive: 180ms cubic-bezier(0.16, 1, 0.3, 1);

  /* --- Content widths --- */
  --content-narrow: 640px;
  --content-default: 960px;
  --content-wide: 1200px;
  --content-full: 100%;
}

/* ============================================
   DARK MODE (Default)
   Deep navy circuit-board aesthetic
   ============================================ */
:root, [data-theme="dark"] {
  /* ARC Official: Primary Blue #003058 — used for deep backgrounds */
  --color-bg:             #001a33;
  --color-surface:        #002244;
  --color-surface-2:      #003058;
  --color-surface-offset: #001e3a;
  --color-surface-offset-2: #002545;
  --color-surface-dynamic: #003a6b;
  --color-divider:        rgba(255, 255, 255, 0.08);
  --color-border:         rgba(255, 255, 255, 0.1);

  --color-text:           #ffffff;
  --color-text-muted:     #c8d6e5;
  --color-text-faint:     #7b8fa3;
  --color-text-inverse:   #003058;

  /* ARC Official: Secondary Red #BA0C2F — used as accent/primary CTA */
  --color-primary:        #BA0C2F;
  --color-primary-hover:  #d41038;
  --color-primary-active: #9a0a27;
  --color-primary-highlight: rgba(186, 12, 47, 0.15);

  --color-accent-blue:    #547b96;
  --color-accent-purple:   #886488;
  --color-accent-pink:     #993955;

  --color-error:          #ff6b6b;
  --color-success:        #51cf66;
  --color-warning:        #ffd43b;

  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 12px 40px rgba(0, 0, 0, 0.5);

  --circuit-color: rgba(186, 12, 47, 0.08);
  --circuit-node: rgba(136, 100, 136, 0.14);
  --glow: rgba(136, 100, 136, 0.15);
}

/* ============================================
   LIGHT MODE
   Clean white/navy reverse
   ============================================ */
[data-theme="light"] {
  --color-bg:             #f5f7fa;
  --color-surface:        #ffffff;
  --color-surface-2:      #eef2f7;
  --color-surface-offset: #e8ecf2;
  --color-surface-offset-2: #dfe4ec;
  --color-surface-dynamic: #d5dbe5;
  --color-divider:        rgba(0, 48, 88, 0.1);
  --color-border:         rgba(0, 48, 88, 0.12);

  --color-text:           #003058;
  --color-text-muted:     #374049;
  --color-text-faint:     #73777d;
  --color-text-inverse:   #ffffff;

  /* ARC Red as primary in light mode too */
  --color-primary:        #BA0C2F;
  --color-primary-hover:  #9a0a27;
  --color-primary-active: #7a0820;
  --color-primary-highlight: rgba(186, 12, 47, 0.08);

  --color-accent-blue:    #003058;
  --color-accent-purple:   #886488;
  --color-accent-pink:     #993955;

  --color-error:          #e53e3e;
  --color-success:        #38a169;
  --color-warning:        #d69e2e;

  --shadow-sm: 0 1px 2px rgba(0, 48, 88, 0.06);
  --shadow-md: 0 4px 16px rgba(0, 48, 88, 0.08);
  --shadow-lg: 0 12px 40px rgba(0, 48, 88, 0.12);

  --circuit-color: rgba(186, 12, 47, 0.04);
  --circuit-node: rgba(136, 100, 136, 0.08);
  --glow: rgba(136, 100, 136, 0.04);
}


/* ============================================
   GLOBAL STYLES
   ============================================ */

body {
  font-family: var(--font-body);
  overflow-x: hidden;
}

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color var(--transition-interactive);
}

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

/* ============================================
   SKIP LINK
   ============================================ */
.skip-link {
  position: absolute;
  top: -100%;
  left: var(--space-4);
  padding: var(--space-2) var(--space-4);
  background: var(--color-primary);
  color: var(--color-bg);
  border-radius: var(--radius-md);
  z-index: 1000;
  font-weight: 600;
  font-size: var(--text-sm);
}

.skip-link:focus {
  top: var(--space-2);
}

/* ============================================
   NAV / HEADER
   ============================================ */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  padding: var(--space-4) var(--space-6);
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: rgba(0, 26, 51, 0.8);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--color-divider);
  transition: background var(--transition-interactive);
}

[data-theme="light"] .site-header {
  background: rgba(245, 247, 250, 0.85);
}

.site-header__brand {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: var(--text-sm);
  color: var(--color-text);
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.site-header__actions {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

/* Desktop Navigation */
.site-nav {
  display: none;
}

@media (min-width: 768px) {
  .site-nav {
    display: flex;
  }
}

.site-nav__list {
  display: flex;
  gap: var(--space-8);
  list-style: none;
}

.site-nav__link {
  font-family: var(--font-display);
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  padding: var(--space-2) 0;
  transition: color var(--transition-interactive);
}

.site-nav__link:hover {
  color: var(--color-primary);
}

/* Hamburger Button */
.hamburger {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  width: 44px;
  height: 44px;
  gap: 5px;
  border-radius: var(--radius-md);
  transition: background var(--transition-interactive);
}

.hamburger:hover {
  background: var(--color-primary-highlight);
}

.hamburger__line {
  display: block;
  width: 20px;
  height: 2px;
  background: var(--color-text-muted);
  border-radius: var(--radius-full);
  transition: transform var(--transition-interactive),
              opacity var(--transition-interactive);
}

.hamburger[aria-expanded="true"] .hamburger__line:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}

.hamburger[aria-expanded="true"] .hamburger__line:nth-child(2) {
  opacity: 0;
}

.hamburger[aria-expanded="true"] .hamburger__line:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

@media (min-width: 768px) {
  .hamburger {
    display: none;
  }
}

/* Mobile Menu Overlay */
.mobile-menu {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 99;
  background: rgba(0, 26, 51, 0.95);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  visibility: hidden;
  transition: opacity 300ms cubic-bezier(0.16, 1, 0.3, 1),
              visibility 300ms cubic-bezier(0.16, 1, 0.3, 1);
}

[data-theme="light"] .mobile-menu {
  background: rgba(245, 247, 250, 0.95);
}

.mobile-menu.is-open {
  opacity: 1;
  visibility: visible;
}

.mobile-menu__list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--space-8);
  text-align: center;
}

.mobile-menu__link {
  font-family: var(--font-display);
  font-size: var(--text-xl);
  font-weight: 700;
  color: var(--color-text);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  padding: var(--space-3) var(--space-6);
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  transition: color var(--transition-interactive);
}

.mobile-menu__link:hover {
  color: var(--color-primary);
}

@media (min-width: 768px) {
  .mobile-menu {
    display: none !important;
  }
}

.theme-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  border-radius: var(--radius-md);
  color: var(--color-text-muted);
  transition: color var(--transition-interactive),
              background var(--transition-interactive);
}

.theme-toggle:hover {
  color: var(--color-text);
  background: var(--color-primary-highlight);
}

/* ============================================
   HERO SECTION
   ============================================ */
.hero {
  position: relative;
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: var(--space-24) var(--space-4) var(--space-16);
  overflow: hidden;
  background-image: url('./assets/poster-bg.jpg');
  background-size: cover;
  background-position: center top;
}

/* Dark overlay for readability over poster image */
.hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(to bottom, rgba(0,26,51,0.82) 0%, rgba(0,26,51,0.92) 60%, var(--color-bg) 100%);
  z-index: 0;
  pointer-events: none;
}

[data-theme="light"] .hero::before {
  background: linear-gradient(to bottom, rgba(245,247,250,0.85) 0%, rgba(245,247,250,0.95) 60%, var(--color-bg) 100%);
}

/* Subtle ambient glow behind hero content */
.hero__glow {
  position: absolute;
  top: 35%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 600px;
  height: 400px;
  background: radial-gradient(ellipse, var(--glow) 0%, transparent 70%);
  z-index: 1;
  pointer-events: none;
}

.hero__content {
  position: relative;
  z-index: 2;
  max-width: var(--content-default);
}

.hero__title {
  font-family: var(--font-display);
  font-size: var(--text-hero);
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--color-text);
  line-height: 1;
  margin-bottom: var(--space-4);
}

.hero__accent {
  display: block;
  width: 80px;
  height: 3px;
  background: linear-gradient(90deg, var(--color-primary), var(--color-accent-purple));
  margin: 0 auto var(--space-8);
  border-radius: var(--radius-full);
  opacity: 0.8;
}

.hero__date {
  font-family: var(--font-display);
  font-size: var(--text-xl);
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: var(--space-2);
}

.hero__time {
  font-family: var(--font-body);
  font-size: var(--text-lg);
  color: var(--color-text-muted);
  margin-bottom: var(--space-10);
}

.hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-4);
  justify-content: center;
}

/* ============================================
   BUTTONS
   ============================================ */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  font-family: var(--font-display);
  font-weight: 600;
  font-size: var(--text-sm);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  padding: var(--space-3) var(--space-8);
  border-radius: var(--radius-full);
  min-height: 48px;
  cursor: pointer;
  transition: background var(--transition-interactive),
              color var(--transition-interactive),
              box-shadow var(--transition-interactive),
              transform var(--transition-interactive);
}

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

.btn:active {
  transform: translateY(0);
}

.btn--primary {
  background: var(--color-primary);
  color: #ffffff;
  border: none;
}

.btn--primary:hover {
  background: var(--color-primary-hover);
  box-shadow: 0 4px 24px rgba(186, 12, 47, 0.3);
  color: #ffffff;
}

.btn--outline {
  background: transparent;
  color: var(--color-primary);
  border: 1px solid var(--color-primary);
}

.btn--outline:hover {
  background: var(--color-primary-highlight);
  color: var(--color-primary-hover);
}

/* ============================================
   SECTIONS
   ============================================ */
.section {
  padding: clamp(var(--space-12), 8vw, var(--space-24)) var(--space-4);
}

.section__inner {
  max-width: var(--content-default);
  margin-inline: auto;
}

.section__label {
  font-family: var(--font-display);
  font-size: var(--text-xs);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  color: var(--color-primary);
  margin-bottom: var(--space-4);
}

.section__heading {
  font-family: var(--font-display);
  font-size: var(--text-2xl);
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: var(--space-6);
}

.section__body {
  font-size: var(--text-base);
  color: var(--color-text-muted);
  line-height: 1.7;
  max-width: 65ch;
}

/* ============================================
   ABOUT SECTION
   ============================================ */
.about {
  border-top: 1px solid var(--color-divider);
}

.about .section__body {
  font-size: var(--text-lg);
  line-height: 1.75;
}

/* ============================================
   SESSIONS SECTION
   ============================================ */
.sessions {
  border-top: 1px solid var(--color-divider);
}

.sessions-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-6);
  margin-top: var(--space-8);
}

.session-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: var(--space-8);
  position: relative;
  overflow: hidden;
  transition: border-color var(--transition-interactive),
              box-shadow var(--transition-interactive);
}

/* Frosted glass overlay effect */
.session-card::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(
    135deg,
    rgba(255, 255, 255, 0.03) 0%,
    rgba(255, 255, 255, 0) 100%
  );
  pointer-events: none;
}

[data-theme="light"] .session-card::before {
  background: linear-gradient(
    135deg,
    rgba(0, 48, 88, 0.02) 0%,
    rgba(0, 48, 88, 0) 100%
  );
}

.session-card__icon {
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-lg);
  background: var(--color-primary-highlight);
  color: var(--color-primary);
  margin-bottom: var(--space-5);
}

.session-card__icon svg {
  width: 24px;
  height: 24px;
}

.session-card__title {
  font-family: var(--font-display);
  font-size: var(--text-lg);
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: var(--space-3);
}

.session-card__desc {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  line-height: 1.7;
}

/* ============================================
   GET INVOLVED SECTION
   ============================================ */
.get-involved {
  border-top: 1px solid var(--color-divider);
}

/* ============================================
   DETAILS CARDS
   ============================================ */
.details {
  border-top: 1px solid var(--color-divider);
}

.details-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(min(260px, 100%), 1fr));
  gap: var(--space-6);
  margin-top: var(--space-8);
}

.detail-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: var(--space-8);
  position: relative;
  overflow: hidden;
  transition: border-color var(--transition-interactive),
              box-shadow var(--transition-interactive);
}

/* Frosted glass overlay effect */
.detail-card::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(
    135deg,
    rgba(255, 255, 255, 0.03) 0%,
    rgba(255, 255, 255, 0) 100%
  );
  pointer-events: none;
}

[data-theme="light"] .detail-card::before {
  background: linear-gradient(
    135deg,
    rgba(0, 48, 88, 0.02) 0%,
    rgba(0, 48, 88, 0) 100%
  );
}

.detail-card__icon {
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-lg);
  background: var(--color-primary-highlight);
  color: var(--color-primary);
  margin-bottom: var(--space-5);
}

.detail-card__icon svg {
  width: 24px;
  height: 24px;
}

.detail-card__label {
  font-family: var(--font-display);
  font-size: var(--text-xs);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-text-faint);
  margin-bottom: var(--space-2);
}

.detail-card__value {
  font-family: var(--font-display);
  font-size: var(--text-base);
  font-weight: 600;
  color: var(--color-text);
  line-height: 1.5;
}

/* ============================================
   VENDORS SECTION
   ============================================ */
.vendors {
  border-top: 1px solid var(--color-divider);
}

.vendors-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: var(--space-6);
  margin-top: var(--space-8);
}

.vendor-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: var(--space-6) var(--space-4);
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100px;
  position: relative;
  overflow: hidden;
  transition: border-color var(--transition-interactive),
              box-shadow var(--transition-interactive);
}

.vendor-card::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(
    135deg,
    rgba(255, 255, 255, 0.03) 0%,
    rgba(255, 255, 255, 0) 100%
  );
  pointer-events: none;
}

[data-theme="light"] .vendor-card::before {
  background: linear-gradient(
    135deg,
    rgba(0, 48, 88, 0.02) 0%,
    rgba(0, 48, 88, 0) 100%
  );
}

.vendor-card__logo {
  color: var(--color-text);
}

.vendor-card__logo svg {
  width: 100%;
  max-width: 180px;
  height: 48px;
}

/* ============================================
   REGISTRATION SECTION
   ============================================ */
.register {
  border-top: 1px solid var(--color-divider);
}

.register-layout {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: var(--space-12);
  align-items: start;
  margin-top: var(--space-8);
}

.register-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: var(--space-8);
  position: relative;
  overflow: hidden;
}

.register-card::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(
    135deg,
    rgba(255, 255, 255, 0.03) 0%,
    rgba(255, 255, 255, 0) 100%
  );
  pointer-events: none;
}

[data-theme="light"] .register-card::before {
  background: linear-gradient(
    135deg,
    rgba(0, 48, 88, 0.02) 0%,
    rgba(0, 48, 88, 0) 100%
  );
}

.register-form {
  display: flex;
  flex-direction: column;
  gap: var(--space-6);
  position: relative;
  z-index: 1;
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-6);
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}

.form-label {
  font-family: var(--font-display);
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--color-text);
}

.form-required {
  color: var(--color-primary);
}

.form-input {
  background: var(--color-surface-offset);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-3) var(--space-4);
  color: var(--color-text);
  font-size: var(--text-base);
  font-family: var(--font-body);
  min-height: 48px;
  transition: border-color var(--transition-interactive),
              box-shadow var(--transition-interactive);
  width: 100%;
}

.form-input::placeholder {
  color: var(--color-text-faint);
}

.form-input:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px var(--color-primary-highlight);
}

.form-input.is-invalid {
  border-color: var(--color-error);
  box-shadow: 0 0 0 3px rgba(255, 107, 107, 0.15);
}

.form-select {
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' viewBox='0 0 24 24' fill='none' stroke='%237b8fa3' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='6 9 12 15 18 9'%3E%3C/polyline%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right var(--space-4) center;
  padding-right: var(--space-12);
}

.form-select option {
  background: var(--color-surface);
  color: var(--color-text);
}

.form-textarea {
  resize: vertical;
  min-height: 80px;
}

.form-helper {
  font-size: var(--text-xs);
  color: var(--color-text-faint);
  line-height: 1.5;
  max-width: none;
}

/* Form messages */
.form-message {
  border-radius: var(--radius-md);
  padding: 0;
  font-size: var(--text-sm);
  line-height: 1.5;
  display: none;
}

.form-message.is-visible {
  display: block;
  padding: var(--space-4);
}

.form-message--success {
  background: rgba(81, 207, 102, 0.1);
  border: 1px solid rgba(81, 207, 102, 0.3);
  color: var(--color-success);
}

.form-message--error {
  background: rgba(255, 107, 107, 0.1);
  border: 1px solid rgba(255, 107, 107, 0.3);
  color: var(--color-error);
}

[data-theme="light"] .form-message--success {
  background: rgba(56, 161, 105, 0.08);
  border-color: rgba(56, 161, 105, 0.25);
  color: var(--color-success);
}

[data-theme="light"] .form-message--error {
  background: rgba(229, 62, 62, 0.08);
  border-color: rgba(229, 62, 62, 0.25);
  color: var(--color-error);
}

/* Submit button loading state */
.register-form__submit {
  align-self: flex-start;
  min-width: 180px;
  justify-content: center;
}

.submit-loading {
  display: none;
  align-items: center;
  gap: var(--space-2);
}

.register-form__submit.is-loading .submit-text {
  display: none;
}

.register-form__submit.is-loading .submit-loading {
  display: inline-flex;
  align-items: center;
}

.register-form__submit.is-loading {
  pointer-events: none;
  opacity: 0.7;
}

.spinner {
  animation: spin 1s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* ============================================
   QR CODE SECTION
   ============================================ */
.qr-section {
  display: flex;
  align-items: flex-start;
  justify-content: center;
}

.qr-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: var(--space-8);
  text-align: center;
  position: relative;
  overflow: hidden;
}

.qr-card::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(
    135deg,
    rgba(255, 255, 255, 0.03) 0%,
    rgba(255, 255, 255, 0) 100%
  );
  pointer-events: none;
}

[data-theme="light"] .qr-card::before {
  background: linear-gradient(
    135deg,
    rgba(0, 48, 88, 0.02) 0%,
    rgba(0, 48, 88, 0) 100%
  );
}

#qr-canvas {
  border-radius: var(--radius-md);
  margin: 0 auto var(--space-4);
  image-rendering: pixelated;
}

.qr-card__text {
  font-family: var(--font-display);
  font-size: var(--text-xs);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-text-faint);
}

/* ============================================
   ACCESSIBILITY SECTION
   ============================================ */
.accessibility {
  border-top: 1px solid var(--color-divider);
}

.accessibility-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: var(--space-8);
  margin-top: var(--space-6);
}

.accessibility-card p {
  color: var(--color-text-muted);
  line-height: 1.7;
}

/* ============================================
   FOOTER
   ============================================ */
.site-footer {
  border-top: 1px solid var(--color-divider);
  padding: var(--space-12) var(--space-4);
  text-align: center;
}

.site-footer__name {
  font-family: var(--font-display);
  font-size: var(--text-sm);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-text);
  margin-bottom: var(--space-2);
}

.site-footer__address {
  font-size: var(--text-sm);
  color: var(--color-text-faint);
  font-style: normal;
}

.site-footer__copyright {
  font-size: var(--text-xs);
  color: var(--color-text-faint);
  margin-top: var(--space-4);
}

.site-footer__admin-link {
  display: inline-block;
  margin-top: var(--space-4);
  font-size: var(--text-xs);
  color: var(--color-text-faint);
  opacity: 0.5;
  transition: opacity var(--transition-interactive);
}

.site-footer__admin-link:hover {
  opacity: 1;
  color: var(--color-text-muted);
}

/* ============================================
   SCROLL REVEAL ANIMATIONS
   ============================================ */
.fade-in {
  opacity: 1;
}

@supports (animation-timeline: scroll()) {
  .fade-in {
    opacity: 0;
    animation: reveal-fade linear both;
    animation-timeline: view();
    animation-range: entry 0% entry 100%;
  }
}

@keyframes reveal-fade {
  to { opacity: 1; }
}

/* Fallback for browsers without scroll-driven animations */
.fade-in.is-visible {
  opacity: 1;
  transition: opacity 0.6s cubic-bezier(0.16, 1, 0.3, 1);
}

/* ============================================
   HERO GRADIENT
   ============================================ */
.hero::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  height: 200px;
  background: linear-gradient(to top, var(--color-bg), transparent);
  z-index: 2;
  pointer-events: none;
}

/* ============================================
   RESPONSIVE
   ============================================ */
@media (max-width: 767px) {
  .site-header {
    padding: var(--space-3) var(--space-4);
  }

  .hero {
    padding: var(--space-20) var(--space-4) var(--space-12);
    min-height: 100dvh;
  }

  .hero__title {
    font-size: clamp(2.5rem, 10vw, 4rem);
  }

  .hero__actions {
    flex-direction: column;
    align-items: stretch;
  }

  .hero__actions .btn {
    justify-content: center;
  }

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

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

  .vendors-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .register-layout {
    grid-template-columns: 1fr;
    gap: var(--space-8);
  }

  .form-row {
    grid-template-columns: 1fr;
  }

  .register-form__submit {
    align-self: stretch;
  }

  .section {
    padding: var(--space-12) var(--space-4);
  }
}

@media (min-width: 768px) and (max-width: 1023px) {
  .sessions-grid {
    grid-template-columns: 1fr;
  }

  .details-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .vendors-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .register-layout {
    grid-template-columns: 1fr auto;
  }
}

@media (min-width: 1024px) {
  .sessions-grid {
    grid-template-columns: repeat(3, 1fr);
  }

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

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

/* Hover-less devices */
@media (hover: none) {
  .btn:hover {
    transform: none;
    box-shadow: none;
  }

  .btn:active {
    opacity: 0.85;
  }

  .theme-toggle:hover {
    color: var(--color-text-muted);
    background: none;
  }

  .theme-toggle:active {
    color: var(--color-text);
    background: var(--color-primary-highlight);
  }
}

/* ============================================
   ARC OFFICIAL LOGO — DARK/LIGHT SWITCHING
   ============================================ */
.arc-logo {
  display: block;
  margin: 0 auto var(--space-6);
  width: clamp(200px, 30vw, 340px);
  height: auto;
}

/* Dark mode: show white logo, hide color logo */
[data-theme="dark"] .arc-logo--dark {
  display: block;
}
[data-theme="dark"] .arc-logo--light {
  display: none;
}

/* Light mode: show color logo, hide white logo */
[data-theme="light"] .arc-logo--dark {
  display: none;
}
[data-theme="light"] .arc-logo--light {
  display: block;
}

/* ============================================
   ABOUT SECTION — LAYOUT WITH LAPTOP ART
   ============================================ */
.about__layout {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-12);
  align-items: center;
  margin-top: var(--space-4);
}

.about__image-col {
  display: flex;
  justify-content: center;
}

.about__laptop {
  width: 100%;
  max-width: 550px;
  height: auto;
  border-radius: var(--radius-lg);
  opacity: 0.92;
  transition: opacity var(--transition-interactive);
}

.about__laptop:hover {
  opacity: 1;
}

@media (max-width: 767px) {
  .about__layout {
    grid-template-columns: 1fr;
    gap: var(--space-8);
  }

  .about__image-col {
    order: -1;
  }

  .about__laptop {
    max-width: 400px;
  }
}

/* ============================================
   NECTIR LOGO SIZING
   ============================================ */
.vendor-card__logo--grammarly {
  display: flex;
  align-items: center;
  justify-content: center;
}

.vendor-card__logo--grammarly svg {
  max-width: 240px;
  height: auto;
  max-height: 56px;
}

.vendor-card__logo--nectir {
  display: flex;
  align-items: center;
  justify-content: center;
}

.nectir-logo {
  width: 100%;
  max-width: 140px;
  height: auto;
}

.vendor-card__logo--ocelot {
  display: flex;
  align-items: center;
  justify-content: center;
}

.ocelot-logo {
  width: 100%;
  max-width: 180px;
  height: auto;
  filter: brightness(0) invert(1);
}

[data-theme="light"] .ocelot-logo {
  filter: none;
}

/* ============================================
   PURPLE ACCENT TOUCHES
   ============================================ */

/* Session icon backgrounds alternate: red, purple, pink */
.session-card:nth-child(2) .session-card__icon {
  background: rgba(136, 100, 136, 0.15);
  color: var(--color-accent-purple);
}

.session-card:nth-child(3) .session-card__icon {
  background: rgba(153, 57, 85, 0.15);
  color: var(--color-accent-pink);
}

/* Card hover: subtle purple glow */
@media (hover: hover) {
  .session-card:hover,
  .detail-card:hover,
  .vendor-card:hover {
    border-color: rgba(136, 100, 136, 0.3);
    box-shadow: 0 4px 24px rgba(136, 100, 136, 0.1);
  }
}

/* Section divider gradient stripe */
.sessions::before,
.vendors::before {
  content: '';
  display: block;
  width: 60px;
  height: 3px;
  background: linear-gradient(90deg, var(--color-primary), var(--color-accent-purple));
  border-radius: var(--radius-full);
  margin-bottom: var(--space-12);
}

/* Purple tinted frosted glass on session cards */
.session-card:nth-child(2)::before {
  background: linear-gradient(
    135deg,
    rgba(136, 100, 136, 0.04) 0%,
    rgba(136, 100, 136, 0) 100%
  );
}

/* Footer: subtle gradient border top */
.site-footer {
  border-image: linear-gradient(90deg, var(--color-primary), var(--color-accent-purple), transparent) 1;
}

/* ============================================
   INSTITUTION "OTHER" CONDITIONAL FIELD
   ============================================ */
.form-group--conditional {
  margin-top: var(--space-3);
  animation: slideDown 200ms cubic-bezier(0.16, 1, 0.3, 1);
}

@keyframes slideDown {
  from {
    opacity: 0;
    transform: translateY(-4px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}