/* ============================================
   5th TUK International Conference — Styles
   Colors: Gold, Green, Navy Blue
   ============================================ */

:root {
  --gold: #C5A028;
  --gold-light: #E8C84A;
  --gold-dark: #9A7B1A;
  --green: #1B7A3D;
  --green-light: #2DA55A;
  --green-dark: #0F5A2A;
  --navy: #0A1F44;
  --navy-light: #1A3A6B;
  --navy-dark: #060F22;
  --white: #FFFFFF;
  --off-white: #F7F8FA;
  --gray-100: #E8ECF1;
  --gray-200: #C5CDD8;
  --gray-400: #8896A6;
  --gray-600: #4A5568;
  --gray-800: #2D3748;
  --shadow-sm: 0 1px 3px rgba(10, 31, 68, 0.08);
  --shadow-md: 0 4px 16px rgba(10, 31, 68, 0.12);
  --shadow-lg: 0 8px 32px rgba(10, 31, 68, 0.16);
  --radius: 12px;
  --radius-lg: 20px;
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-display: 'Playfair Display', Georgia, serif;
  --header-height: 96px;
}

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

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

body {
  font-family: var(--font-body);
  color: var(--gray-800);
  background: var(--white);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

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

a {
  text-decoration: none;
  color: inherit;
}

ul {
  list-style: none;
}

.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

/* ---- Header / Nav ---- */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: var(--white);
  border-bottom: 3px solid var(--gold);
  box-shadow: var(--shadow-md);
  transition: box-shadow var(--transition);
}

.header--scrolled {
  box-shadow: var(--shadow-lg);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: var(--header-height);
}

.nav__logo {
  display: flex;
  align-items: center;
  padding: 8px 0;
}

.nav__logo img {
  height: 72px;
  width: auto;
}

.nav__menu {
  display: flex;
  align-items: center;
  gap: 4px;
}

.nav__link {
  color: var(--navy);
  font-size: 0.92rem;
  font-weight: 600;
  padding: 10px 18px;
  border-radius: 8px;
  transition: color var(--transition), background var(--transition);
}

.nav__link:hover {
  color: var(--green);
  background: rgba(27, 122, 61, 0.06);
}

.nav__link--cta {
  background: var(--gold);
  color: var(--navy-dark) !important;
  margin-left: 8px;
}

.nav__link--cta:hover {
  background: var(--gold-light);
  color: var(--navy-dark) !important;
}

.nav__toggle {
  display: none;
  flex-direction: column;
  gap: 6px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 6px;
}

.nav__toggle span {
  display: block;
  width: 28px;
  height: 3px;
  background: var(--navy);
  border-radius: 2px;
  transition: var(--transition);
}

/* ---- Hero (Light Theme) ---- */
.hero {
  position: relative;
  background: linear-gradient(160deg, #ffffff 0%, #f4faf6 40%, #fffbf0 75%, #f6f8fc 100%);
  padding-top: var(--header-height);
  overflow: hidden;
}

.hero__bg {
  position: absolute;
  inset: 0;
  top: var(--header-height);
  pointer-events: none;
  overflow: hidden;
}

.hero__blob {
  position: absolute;
  border-radius: 50%;
  filter: blur(60px);
  opacity: 0.55;
}

.hero__blob--gold {
  width: 420px;
  height: 420px;
  top: -80px;
  right: -60px;
  background: radial-gradient(circle, rgba(232, 200, 74, 0.45) 0%, rgba(197, 160, 40, 0.15) 50%, transparent 70%);
}

.hero__blob--green {
  width: 380px;
  height: 380px;
  bottom: -40px;
  left: -80px;
  background: radial-gradient(circle, rgba(45, 165, 90, 0.35) 0%, rgba(27, 122, 61, 0.12) 50%, transparent 70%);
}

.hero__blob--navy {
  width: 300px;
  height: 300px;
  top: 40%;
  left: 50%;
  transform: translateX(-50%);
  background: radial-gradient(circle, rgba(26, 58, 107, 0.12) 0%, transparent 70%);
}

.hero__pattern {
  position: absolute;
  inset: 0;
  background-image: radial-gradient(rgba(10, 31, 68, 0.07) 1px, transparent 1px);
  background-size: 28px 28px;
  mask-image: linear-gradient(180deg, rgba(0, 0, 0, 0.5) 0%, transparent 85%);
  -webkit-mask-image: linear-gradient(180deg, rgba(0, 0, 0, 0.5) 0%, transparent 85%);
}

.hero::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, rgba(197, 160, 40, 0.35), rgba(27, 122, 61, 0.35), transparent);
}

.hero__content {
  position: relative;
  z-index: 1;
  text-align: center;
  padding: 64px 24px 72px;
  max-width: 920px;
  margin: 0 auto;
}

.hero__badge {
  display: inline-block;
  background: rgba(27, 122, 61, 0.08);
  border: 1px solid rgba(27, 122, 61, 0.2);
  color: var(--green);
  font-size: 0.85rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 8px 20px;
  border-radius: 100px;
  margin-bottom: 28px;
}

.hero__title {
  font-family: var(--font-display);
  font-size: clamp(2.2rem, 5vw, 3.4rem);
  font-weight: 700;
  color: var(--navy);
  line-height: 1.15;
  margin-bottom: 24px;
}

.hero__theme {
  font-family: var(--font-display);
  font-size: clamp(1.15rem, 2.4vw, 1.5rem);
  color: var(--navy);
  font-style: normal;
  font-weight: 600;
  line-height: 1.5;
  max-width: 780px;
  margin: 0 auto 32px;
}

.hero__date {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--navy);
  font-size: 1.05rem;
  font-weight: 700;
  margin-bottom: 12px;
}

.hero__date svg {
  width: 22px;
  height: 22px;
  color: var(--green);
  flex-shrink: 0;
}

.hero__actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 6px 4px;
  margin-top: 28px;
  padding: 16px 24px;
  background: var(--white);
  border: 1px solid var(--gray-100);
  border-radius: 100px;
  box-shadow: var(--shadow-sm);
  max-width: 100%;
}

.hero__action {
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--navy);
  padding: 6px 12px;
  border-radius: 6px;
  transition: color var(--transition), background var(--transition);
  white-space: nowrap;
}

.hero__action:hover {
  color: var(--green);
  background: rgba(27, 122, 61, 0.06);
}

.hero__action--primary {
  color: var(--gold-dark);
}

.hero__action--primary:hover {
  color: var(--navy);
  background: rgba(197, 160, 40, 0.12);
}

.hero__action-divider {
  color: var(--gray-200);
  font-weight: 300;
  user-select: none;
  padding: 0 2px;
}

.hero__location {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--gray-600);
  font-size: 0.95rem;
  font-weight: 600;
  margin-bottom: 0;
}

.hero__location svg {
  width: 18px;
  height: 18px;
  color: var(--green);
  flex-shrink: 0;
}

/* ---- Buttons ---- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 16px 36px;
  font-size: 1rem;
  font-weight: 700;
  border-radius: 10px;
  border: 2px solid transparent;
  cursor: pointer;
  transition: all var(--transition);
}

.btn--primary {
  background: var(--gold);
  color: var(--navy-dark);
  border-color: var(--gold);
}

.btn--primary:hover {
  background: var(--gold-light);
  border-color: var(--gold-light);
  transform: translateY(-2px);
  box-shadow: 0 6px 24px rgba(197, 160, 40, 0.35);
}

.btn--outline-dark {
  background: transparent;
  color: var(--navy);
  border-color: var(--gray-200);
}

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

.btn:disabled {
  opacity: 0.65;
  cursor: not-allowed;
  transform: none;
  box-shadow: none;
}

/* ---- Sections ---- */
.section {
  padding: 80px 0;
}

.section__header {
  text-align: center;
  margin-bottom: 48px;
}

.section__label {
  display: inline-block;
  color: var(--green);
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  margin-bottom: 12px;
}

.section__title {
  font-family: var(--font-display);
  font-size: clamp(1.8rem, 3.5vw, 2.4rem);
  font-weight: 700;
  color: var(--navy);
  margin-bottom: 12px;
}

.section__title--theme {
  font-size: clamp(1.25rem, 2.6vw, 1.75rem);
  font-style: italic;
  font-weight: 600;
  line-height: 1.45;
  max-width: 900px;
  margin-left: auto;
  margin-right: auto;
  color: var(--navy);
}

.section__subtitle {
  color: var(--gray-400);
  font-size: 1.05rem;
  max-width: 560px;
  margin: 0 auto;
}

/* ---- Themes (Three Columns) ---- */
.themes {
  background: var(--white);
  border-top: 1px solid var(--gray-100);
  padding-top: 64px;
  padding-bottom: 80px;
}

.themes__grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
  align-items: stretch;
}

.themes__column {
  --track-accent: var(--green);
  --track-soft: rgba(27, 122, 61, 0.1);
  --track-glow: rgba(27, 122, 61, 0.22);
  position: relative;
  display: flex;
  flex-direction: column;
  background: var(--white);
  border: 1px solid var(--gray-100);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-md);
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
}

.themes__column::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 5px;
  background: var(--track-accent);
}

.themes__column--green {
  --track-accent: var(--green);
  --track-soft: rgba(27, 122, 61, 0.1);
  --track-glow: rgba(27, 122, 61, 0.22);
}

.themes__column--gold {
  --track-accent: var(--gold);
  --track-soft: rgba(197, 160, 40, 0.14);
  --track-glow: rgba(197, 160, 40, 0.3);
}

.themes__column--navy {
  --track-accent: var(--navy);
  --track-soft: rgba(10, 31, 68, 0.08);
  --track-glow: rgba(10, 31, 68, 0.2);
}

.themes__column:hover {
  transform: translateY(-8px);
  box-shadow: 0 18px 40px var(--track-glow);
  border-color: transparent;
}

.themes__column-header {
  padding: 28px 24px 20px;
  background:
    linear-gradient(180deg, var(--track-soft) 0%, transparent 100%);
  border-bottom: 1px solid var(--gray-100);
}

.themes__column-meta {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 12px;
  margin-bottom: 14px;
}

.themes__count {
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--track-accent);
  background: var(--white);
  border: 1px solid var(--gray-100);
  padding: 6px 12px;
  border-radius: 100px;
}

.themes__column--green .themes__count {
  border-color: rgba(27, 122, 61, 0.25);
}

.themes__column--gold .themes__count {
  border-color: rgba(197, 160, 40, 0.35);
}

.themes__column--navy .themes__count {
  border-color: rgba(10, 31, 68, 0.2);
}

.themes__column-header h3 {
  font-family: var(--font-display);
  font-size: 1.2rem;
  color: var(--navy);
  font-weight: 700;
  line-height: 1.35;
}

.themes__list {
  display: flex;
  flex-direction: column;
  gap: 10px;
  padding: 20px 20px 24px;
  flex: 1;
}

.themes__list li {
  position: relative;
  padding: 14px 14px 14px 36px;
  background: var(--off-white);
  border-radius: 10px;
  color: var(--gray-600);
  font-size: 0.9rem;
  line-height: 1.55;
  border: 1px solid transparent;
  transition: background var(--transition), border-color var(--transition), transform var(--transition);
}

.themes__list li:hover {
  background: var(--white);
  border-color: var(--gray-200);
  transform: translateX(4px);
}

.themes__column--green .themes__list li:hover {
  border-color: rgba(27, 122, 61, 0.35);
}

.themes__column--gold .themes__list li:hover {
  border-color: rgba(197, 160, 40, 0.4);
}

.themes__column--navy .themes__list li:hover {
  border-color: rgba(10, 31, 68, 0.3);
}

.themes__list li::before {
  content: '';
  position: absolute;
  left: 14px;
  top: 20px;
  width: 10px;
  height: 10px;
  background: var(--track-accent);
  border-radius: 50%;
  box-shadow: 0 0 0 3px var(--track-soft);
}

/* ---- About ---- */
.about {
  background: var(--off-white);
  border-top: 1px solid var(--gray-100);
}

.about__intro {
  max-width: 820px;
  margin: 0 auto 48px;
  text-align: center;
}

.about__intro p {
  font-size: 1.05rem;
  color: var(--gray-600);
  line-height: 1.9;
}

.about__intro p + p {
  margin-top: 20px;
}

.about__lead {
  font-size: 1.12rem !important;
  color: var(--navy) !important;
  font-weight: 500;
}

.about__intro strong {
  color: var(--green);
  font-weight: 700;
}

.about__cards {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
}

.about__card {
  --card-accent: var(--green);
  --card-soft: rgba(27, 122, 61, 0.12);
  --card-glow: rgba(27, 122, 61, 0.2);
  position: relative;
  background: var(--white);
  border-radius: var(--radius-lg);
  padding: 32px 28px;
  border: 1px solid var(--gray-100);
  box-shadow: var(--shadow-md);
  overflow: hidden;
  transition: transform var(--transition), box-shadow var(--transition);
}

.about__card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 5px;
  background: var(--card-accent);
}

.about__card::after {
  content: '';
  position: absolute;
  right: -40px;
  bottom: -40px;
  width: 140px;
  height: 140px;
  border-radius: 50%;
  background: var(--card-soft);
  pointer-events: none;
}

.about__card--green {
  --card-accent: var(--green);
  --card-soft: rgba(27, 122, 61, 0.12);
  --card-glow: rgba(27, 122, 61, 0.22);
}

.about__card--gold {
  --card-accent: var(--gold);
  --card-soft: rgba(197, 160, 40, 0.16);
  --card-glow: rgba(197, 160, 40, 0.28);
}

.about__card--navy {
  --card-accent: var(--navy);
  --card-soft: rgba(10, 31, 68, 0.1);
  --card-glow: rgba(10, 31, 68, 0.2);
}

.about__card:hover {
  transform: translateY(-8px);
  box-shadow: 0 18px 40px var(--card-glow);
}

.about__card-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 22px;
  position: relative;
  z-index: 1;
}

.about__card-icon {
  width: 64px;
  height: 64px;
  background: var(--card-accent);
  border-radius: 18px;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 8px 20px var(--card-glow);
}

.about__card--gold .about__card-icon {
  color: var(--navy-dark);
}

.about__card-icon svg {
  width: 30px;
  height: 30px;
  color: var(--white);
}

.about__card--gold .about__card-icon svg {
  color: var(--navy-dark);
}

.about__card-label {
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--card-accent);
  background: var(--card-soft);
  padding: 6px 12px;
  border-radius: 100px;
  white-space: nowrap;
}

.about__card h3 {
  position: relative;
  z-index: 1;
  font-family: var(--font-display);
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--navy);
  margin-bottom: 12px;
}

.about__card p {
  position: relative;
  z-index: 1;
  font-size: 0.95rem;
  color: var(--gray-600);
  line-height: 1.7;
}

/* ---- Registration Modal ---- */
.modal {
  position: fixed;
  inset: 0;
  z-index: 2000;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
  opacity: 0;
  visibility: hidden;
  transition: opacity var(--transition), visibility var(--transition);
}

.modal--open {
  opacity: 1;
  visibility: visible;
}

.modal__overlay {
  position: absolute;
  inset: 0;
  background: rgba(6, 15, 34, 0.65);
  backdrop-filter: blur(4px);
}

.modal__dialog {
  position: relative;
  width: 100%;
  max-width: 680px;
  max-height: 90vh;
  overflow-y: auto;
  background: var(--white);
  border-radius: var(--radius-lg);
  padding: 32px;
  box-shadow: var(--shadow-lg);
  border-top: 4px solid var(--gold);
  transform: translateY(16px);
  transition: transform var(--transition);
}

.modal--open .modal__dialog {
  transform: translateY(0);
}

.modal__close {
  position: absolute;
  top: 16px;
  right: 16px;
  width: 36px;
  height: 36px;
  border: none;
  background: var(--off-white);
  color: var(--navy);
  font-size: 1.5rem;
  line-height: 1;
  border-radius: 50%;
  cursor: pointer;
  transition: background var(--transition), color var(--transition);
}

.modal__close:hover {
  background: var(--navy);
  color: var(--white);
}

.modal__header {
  margin-bottom: 24px;
  padding-right: 40px;
}

.modal__header h2 {
  font-family: var(--font-display);
  font-size: 1.6rem;
  color: var(--navy);
  margin-bottom: 6px;
}

.modal__header p {
  color: var(--gray-400);
  font-size: 0.9rem;
}

.registration-form {
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.form-group label {
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--navy);
}

.required {
  color: var(--green);
}

.form-group input,
.form-group select {
  width: 100%;
  padding: 12px 14px;
  font-family: var(--font-body);
  font-size: 0.92rem;
  color: var(--gray-800);
  background: var(--off-white);
  border: 1px solid var(--gray-100);
  border-radius: 8px;
  transition: border-color var(--transition), box-shadow var(--transition);
}

.form-group input:focus,
.form-group select:focus {
  outline: none;
  border-color: var(--green);
  box-shadow: 0 0 0 3px rgba(27, 122, 61, 0.12);
  background: var(--white);
}

.form-group input[type="file"] {
  padding: 10px;
  background: var(--white);
  cursor: pointer;
}

.form-group--checkbox {
  padding-top: 4px;
}

.checkbox-label {
  display: flex;
  align-items: center;
  gap: 10px;
  cursor: pointer;
  font-weight: 500;
  color: var(--gray-600);
}

.checkbox-label input[type="checkbox"] {
  width: 18px;
  height: 18px;
  accent-color: var(--green);
  cursor: pointer;
}

.paper-fields {
  display: none;
  flex-direction: column;
  gap: 18px;
  padding: 20px;
  background: var(--off-white);
  border: 1px solid var(--gray-100);
  border-radius: var(--radius);
  border-left: 4px solid var(--green);
}

.paper-fields.is-visible {
  display: flex;
}

.form-hint {
  font-size: 0.82rem;
  color: var(--gray-400);
  line-height: 1.5;
  margin-top: 4px;
}

.form-actions {
  display: flex;
  justify-content: flex-end;
  gap: 12px;
  padding-top: 8px;
}

.form-message {
  padding: 16px 18px;
  border-radius: 10px;
  font-size: 0.95rem;
  font-weight: 500;
  margin-bottom: 20px;
  line-height: 1.5;
  display: none;
}

.form-message--visible,
.form-message:not([hidden]) {
  display: block;
}

.form-message__title {
  display: block;
  font-size: 1rem;
  font-weight: 800;
  margin-bottom: 6px;
  letter-spacing: 0.01em;
}

.form-message__text {
  display: block;
}

.form-message--success {
  background: #e8f8ef;
  color: #0f5a2a;
  border: 2px solid #1b7a3d;
  box-shadow: 0 4px 16px rgba(27, 122, 61, 0.12);
}

.form-message--success .form-message__title {
  color: #0f5a2a;
}

.form-message--error {
  background: #fef2f2;
  color: #991b1b;
  border: 2px solid #dc2626;
  box-shadow: 0 4px 16px rgba(220, 38, 38, 0.12);
}

.form-message--error .form-message__title {
  color: #991b1b;
}

/* ---- Footer ---- */
.footer {
  background: var(--navy-dark);
  border-top: 3px solid var(--gold);
  padding: 28px 0;
}

.footer__inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
}

.footer p {
  color: rgba(255, 255, 255, 0.5);
  font-size: 0.85rem;
}

.footer a {
  color: var(--gold-light);
  transition: color var(--transition);
}

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

/* ---- Responsive ---- */
@media (max-width: 1024px) {
  .themes__grid {
    grid-template-columns: 1fr;
    max-width: 600px;
    margin: 0 auto;
  }

  .about__cards {
    grid-template-columns: 1fr;
    max-width: 480px;
    margin: 0 auto;
  }
}

@media (max-width: 768px) {
  :root {
    --header-height: 80px;
  }

  .nav__toggle {
    display: flex;
  }

  .nav__logo img {
    height: 56px;
  }

  .nav__menu {
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    background: var(--white);
    flex-direction: column;
    padding: 16px 24px 24px;
    gap: 4px;
    transform: translateY(-120%);
    opacity: 0;
    transition: transform var(--transition), opacity var(--transition);
    border-bottom: 3px solid var(--gold);
    box-shadow: var(--shadow-lg);
  }

  .nav__menu--open {
    transform: translateY(0);
    opacity: 1;
  }

  .nav__link {
    display: block;
    width: 100%;
    padding: 12px 16px;
  }

  .nav__link--cta {
    margin-left: 0;
    text-align: center;
  }

  .hero__content {
    padding: 48px 20px 56px;
  }

  .hero__actions {
    flex-direction: column;
    border-radius: var(--radius);
    padding: 20px;
    gap: 8px;
  }

  .hero__action-divider {
    display: none;
  }

  .hero__action {
    width: 100%;
    text-align: center;
    padding: 10px 16px;
    white-space: normal;
  }

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

  .modal__dialog {
    padding: 24px 20px;
  }

  .form-actions {
    flex-direction: column-reverse;
  }

  .form-actions .btn {
    width: 100%;
  }

  .section {
    padding: 64px 0;
  }

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