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

:root {
  --primary: #005aa8;
  --background-light: #f5f7f8;
  --background-dark: #0f1a23;
  --text-dark: #0c151d;
  --slate-50: #f8fafc;
  --slate-200: #e2e8f0;
  --slate-300: #cbd5e1;
  --slate-400: #94a3b8;
  --slate-600: #475569;
  --slate-700: #334155;
  --slate-800: #1e293b;
}

body {
  font-family: 'Inter', sans-serif;
  background-color: var(--background-light);
  color: var(--text-dark);
  line-height: 1.5;
}

.material-symbols-outlined {
  font-variation-settings: 'FILL' 0, 'wght' 400, 'GRAD' 0, 'opsz' 24;
}

/* Header */
header {
  position: sticky;
  top: 0;
  z-index: 50;
  background-color: rgb(8 21 62);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--slate-200);
}

.header-container {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0.75rem 1rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo-section {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.logo-img {
  height: 60px;
  width: auto;
}

.nav-menu {
  display: none;
  gap: 2rem;
}

.nav-link {
  font-size: 1.15rem;
  font-weight: 500;
  color: #fff;
  text-decoration: none;
  transition: color 0.2s;
}

.nav-link:hover {
  color: rgb(34 211 238 / var(--tw-text-opacity, 1));
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.btn {
  cursor: pointer;
  border: none;
  border-radius: 0.5rem;
  font-weight: 700;
  transition: all 0.2s;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
}

.btn-icon {
  height: 2.5rem;
  padding: 0 0.625rem;
  background-color: var(--slate-200);
  color: var(--text-dark);
}

.btn-primary {
  height: 2.5rem;
  padding: 0 1rem;
  background-color: #012b50;
  color: white;
  font-size: 0.875rem;
}
.btn-whitee {
  line-height: 1;
  background-color: transparent;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.35em;
  padding: 0.75em 1em;
  padding-right: 1.25em;
  color: #fff;
  border: 1px solid transparent;
  font-weight: 700;
  border-radius: 2em;
  font-size: 1rem;
  box-shadow: 0 0.7em 1.5em -0.5em hsla(249, 62%, 51%, 0.745);
  transition: transform 0.3s;

  background: linear-gradient(
    90deg,
    rgba(77, 54, 208, 1) 0%,
    rgba(132, 116, 254, 1) 100%
  );
}
.btn-primary:hover {
  background-color: #004a8f;
}

.btn-menu {
  height: 2.5rem;
  padding: 0 0.625rem;
  background-color: var(--slate-200);
  color: var(--text-dark);
}
.btn-dangky {
  position: relative;
  z-index: 1;
  border-radius: 8px;
}
.btn-dangky:hover{
  transform: translateY(-3px) scale(1.05);
  box-shadow: 
    0 0 20px rgba(0, 245, 255, 0.6),
    0 0 40px rgba(255, 0, 128, 0.4),
    0 0 60px rgba(157, 0, 255, 0.3),
    0 10px 30px rgba(0, 0, 0, 0.3);
  background: linear-gradient(135deg, #764ba2 0%, #667eea 100%);
}

.btn-dangky::before {
  content: "";
  position: absolute;
  inset: -2px;
  border-radius: 8px;
  padding: 2px;
  
  /* Gradient chạy dọc theo viền */
  background: linear-gradient(-45deg, #e81cff 0%, #40c9ff 100% );
  background-size: 400% 100%; /* Tạo không gian để chạy */
  animation: borderSlide 5s linear infinite;

  -webkit-mask:
    linear-gradient(#fff 0 0) content-box,
    linear-gradient(#fff 0 0);
  -webkit-mask-composite: xor;
  mask-composite: exclude;

  z-index: -1;
}

@keyframes borderSlide {
  0% {
    background-position: 0% 50%;
  }
  50% {
    background-position: 100% 50%;
  }
  100% {
    background-position: 0% 50%;
  }
}

@keyframes borderRotate1 {
  0% {
    transform: rotate(0deg);
  }
  100% {
    transform: rotate(360deg);
  }
}

/* Hero Section */
.hero {
  min-height: 600px;
  background-image: linear-gradient(135deg, #03143fdc, #7a1b6c9f), 
                    url("./img/banner2.png");
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 2rem 1rem;
  text-align: center;
}

.hero-content {
  max-width: 56rem;
}

.hero-title {
  color: white;
  font-size: 2.25rem;
  font-weight: 900;
  line-height: 1.2;
  margin-bottom: 1rem;
  text-shadow: -1px -1px 0 #000, 1px -1px 0 #000, -1px 1px 0 #000, 1px 1px 0 #000;

}

.hero-subtitle {
  color: white;
  font-size: 1rem;
  margin-bottom: 2rem;
}

.hero-buttons {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  justify-content: center;
}

.btn-lg {
  height: 3rem;
  padding: 0 1.25rem;
  font-size: 1rem;
}

.btn-white {
  background-color: white;
  color: var(--primary);
}

.btn-outline {
  background-color: transparent;
  color: white;
  border: 1px solid white;
}

/* Timer Section */
.timer-section {
  background-color: #f1f5f9;
  padding: 40px;
}

.timer-container {
  max-width: 36rem;
  margin: 0 auto;
  padding: 0 1rem;
}

.timer-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1rem;
}

.timer-item {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.timer-box {
  height: 4rem;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: white;
  border-radius: 0.5rem;
}

.timer-number {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-dark);
}

.timer-label {
    text-align: center;
    font-size: 1.15rem;
    color: #012b50;
    font-weight: bold;
}

/* Introduction Section */
.intro-section {
  padding: 4rem 1rem;
}

.section-container {
  max-width: 80rem;
  margin: 0 auto;
}

.intro-grid {
  display: grid;
  gap: 3rem;
  align-items: center;
}

.section-title {
    font-size: 1.875rem;
    font-weight: 700;
    margin-bottom: 1.25rem;

    background: linear-gradient(to right, #ff00cc 0%, #333399  51%, #ff00cc  100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    position: relative;
}

.section-text {
  color: #012b50;
  line-height: 1.7;
  margin-bottom: 2rem;
}

.intro-features {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}

.feature-item {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.feature-icon {
  color: var(--primary);
  font-size: 1.5rem;
}

.intro-images {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1rem;
}

.intro-img {
  width: 100%;
  aspect-ratio: 1;
  object-fit: cover;
  border-radius: 0.5rem;
}

/* Topics Section */
.topics-section {
  padding: 4rem 1rem;
  background-color: #f1f5f9;
}

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

.section-description {
  max-width: 42rem;
  margin: 1rem auto 0;
  color: var(--slate-600);
  font-size: 1.15rem;
}

.topics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 2rem;
}

.topic-card {
  background-color: white;
  padding: 1.5rem;
  border-radius: 0.5rem;
  box-shadow: 0 1px 3px rgba(0,0,0,0.1);
}

.topic-icon-wrapper {
  width: 3rem;
  height: 3rem;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 0.5rem;
  background-color: rgba(0, 90, 168, 0.2);
  margin-bottom: 1rem;
}

.topic-icon {
  color: var(--primary);
  font-size: 1.875rem;
}

.topic-title {
  font-size: 1.125rem;
  font-weight: 700;
  color: var(--text-dark);
  margin-bottom: 0.5rem;
}

.topic-description {
  font-size: 0.875rem;
  color: var(--slate-600);
}

/* Important Dates Section */
.dates-section {
  padding: 4rem 1rem;
}

.dates-timeline {
  position: relative;
  padding-top: 2rem;
}

.timeline-line {
  display: none;
  position: absolute;
  top: -2px;
  left: 0;
  width: 100%;
  height: 2px;
  background-color: var(--slate-300);
}

.dates-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1r));
  gap: 2rem;
}

.date-item {
  position: relative;
  text-align: center;
}

.date-marker {
  display: none;
  position: absolute;
  top: -2.75rem;
  left: 50%;
  transform: translateX(-50%);
  width: 1.25rem;
  height: 1.25rem;
  background-color: var(--primary);
  border-radius: 50%;
  align-items: center;
  justify-content: center;
  z-index: 1;
}

.date-marker-inner {
  width: 0.5rem;
  height: 0.5rem;
  background-color: white;
  border-radius: 50%;
}

.date-value {
  font-size: 0.875rem;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 0.5rem;
}

.date-label {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-dark);
}

/* Speakers Section */
.speakers-section {
  padding: 4rem 1rem;
  background-color: #f1f5f9;
}

.speakers-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 2rem;
}

.speaker-card {
  background-color: white;
  padding: 1.5rem;
  border-radius: 0.5rem;
  box-shadow: 0 1px 3px rgba(0,0,0,0.1);
  text-align: center;
}

.speaker-img {
  width: 7rem;
  height: 7rem;
  border-radius: 50%;
  margin: 0 auto 1rem;
  object-fit: cover;
}

.speaker-name {
  font-size: 1.125rem;
  font-weight: 700;
  color: var(--text-dark);
  margin-bottom: 0.25rem;
}

.speaker-affiliation {
  font-size: 0.875rem;
  color: var(--primary);
}

/* Responsive Design */
@media (min-width: 640px) {
  .header-container {
    padding: 0.75rem 1.5rem;
  }
  
  .btn-register-mobile {
    display: inline-flex;
  }
  
  .hero-title {
    font-size: 3rem;
    text-shadow:
        0 0 4px #00f2ff,
        0 0 4px #00f2ff,
        0 0 8px #ff00ff,
        0 0 16px rgba(255, 0, 255, 0.8);
  }
  
  .hero-subtitle {
    font-size: 1.25rem;
  }
  
  .intro-section, .topics-section, .dates-section, .speakers-section {
    padding: 6rem 1.5rem;
  }
  
  .section-title {
    font-size: 2.25rem;
  }
}

@media (min-width: 768px) {
  .nav-menu {
    display: flex;
  }
  
  .btn-menu {
    display: none;
  }
  
  .intro-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  
  
  .timeline-line {
    display: block;
  }
  
  .date-marker {
    display: flex;
  }
}

@media (min-width: 1024px) {
  .header-container {
    padding: 0.75rem 2rem;
  }
  
  .topics-grid {
    grid-template-columns: repeat(3, 1fr);
  }
  
  .dates-grid {
    grid-template-columns: repeat(5, 1fr);
  }
}

.hidden-mobile {
  display: none;
}

@media (min-width: 640px) {
  .hidden-mobile {
    display: inline-flex;
  }
}
/* MOBILE MENU */
/* MOBILE MENU */
.mobile-menu {
  position: absolute;
  top: 100%;          /* nằm NGAY DƯỚI header */
  left: 0;
  width: 100%;
  background: #000000e0;
  display: none;
  flex-direction: column;
  z-index: 999;
  box-shadow: 0 8px 20px rgba(0,0,0,0.15);
}

.mobile-menu.active {
  display: flex;
}

.mobile-menu a {
  padding: 1rem 1.25rem;
  font-size: 1rem;
  font-weight: 600;
  color: #fff;
  text-decoration: none;
  border-bottom: 1px solid #e5e7eb;
}

.mobile-menu a:last-child {
  border-bottom: none;
}
/*CSS popup*/
/* Popup overlay */
.popup-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.6);
  z-index: 9999;
  justify-content: center;
  align-items: center;
}

.popup-content {
  background: #fff;
  width: 90%;
  max-width: 900px;
  height: 90%;
  border-radius: 12px;
  position: relative;
  overflow: hidden;
}

.popup-content iframe {
  width: 100%;
  height: 100%;
}

.popup-close {
  position: absolute;
  top: 10px;
  right: 14px;
  font-size: 28px;
  background: none;
  border: none;
  cursor: pointer;
}

/*CSS ban lãnh đạo*/
.organizing-committee {
  background: #f8fafc;
  padding: 60px 0;
  font-family: system-ui, -apple-system, BlinkMacSystemFont;
}

.container {
  width: min(1100px, 90%);
  margin: auto;
}

.section-header {
  text-align: center;
  margin-bottom: 40px;
}

.section-header h2 {
  font-size: 2rem;
  margin-bottom: 10px;
}

.section-header p {
  color: #000000;
}

.committee-block {
  margin-bottom: 40px;
}

.block-title {
  font-size: 20px;
  margin-bottom: 20px;
  color: #0f172a;
}

/* ===== Executive Cards ===== */
.executive-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 16px;
}

.person-card {
  background: #fff;
  border-radius: 14px;
  padding: 16px;
  display: flex;
  gap: 14px;
  box-shadow: 0 6px 20px rgba(0,0,0,.05);
}

.avatar {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: #2563eb;
  color: #fff;
  display: grid;
  place-items: center;
  font-weight: 600;
  font-size: 14px;
}

.person-card h4 {
  margin: 0;
  font-size: 16px;
}

.person-card p {
  margin: 4px 0;
  font-weight: 500;
}

.person-card span {
  font-size: 13px;
  color: #64748b;
}

/* ===== Accordion ===== */
.accordion {
  background: #fff;
  border-radius: 12px;
  margin-bottom: 14px;
  box-shadow: 0 4px 16px rgba(0,0,0,.04);
  padding: 10px 16px;
}

.accordion summary {
  cursor: pointer;
  font-weight: 600;
  list-style: none;
}

.accordion ul {
  padding-left: 16px;
  margin-top: 12px;
}

.accordion li {
  margin-bottom: 12px;
  font-size: 14px;
}

.accordion a {
  color: #2563eb;
  text-decoration: none;
}
/*thu gọn hàng*/
/* ============================= */
/*  TOGGLE BAN CHUYÊN MÔN        */
/* ============================= */

/* Mặc định: ẩn toàn bộ card */
.executive-grid.limited .person-card {
  display: none;
}

/* Mobile: 1 cột → 2 hàng = 4 card */
@media (max-width: 767px) {
  .executive-grid.limited .person-card:nth-child(-n+4) {
    display: flex;
  }
}

/* Tablet: 2 cột → 2 hàng = 4 card */
@media (min-width: 768px) and (max-width: 1023px) {
  .executive-grid.limited .person-card:nth-child(-n+4) {
    display: flex;
  }
}

/* Desktop: 3 cột → 2 hàng = 6 card */
@media (min-width: 1024px) {
  .executive-grid.limited .person-card:nth-child(-n+6) {
    display: flex;
  }
}

/* ============================= */
/*  BUTTON XEM THÊM              */
/* ============================= */
.show-more-wrapper {
  text-align: center;
  margin-top: 20px;
}

.show-more-btn {
  padding: 15px 30px;
  font-size: 18px;
  color: white;
  background: linear-gradient(to right, #ff00cc 0%, #333399  51%, #ff00cc  100%);
  border: none;
  border-radius: 8px;
  cursor: pointer;
  outline: none;
  transition: all 0.8s ease;
  background-size: 200% 200%;
  animation: backgroundGradient 8s ease infinite;
}

.show-more-btn:hover{
  background-position: right center;
  box-shadow: 0 0 20px #ff00cc,
              0 0 30px #333399,
              0 0 40px #ff00cc,
              0 0 50px #333399;
  animation: backgroundGradientHover 7s ease infinite;
}
@keyframes backgroundGradient{
  0%{background-position: 0% 50%;}
  50%{background-position: 100% 50%;}
  100%{background-position: 0% 50%;}
}
@keyframes backgroundGradientHover{
  0%{background-position: 0% 50%;}
  50%{background-position: 100% 50%;}
  100%{background-position: 0% 50%;}
}


/*end*/
/*Slider*/
.partners-slider {
  overflow: hidden;
  padding: 20px 0;
}

.partners-track {
  display: flex;
  width: max-content;
  animation: marquee 30s linear infinite;
}

@keyframes marquee {
  from {
    transform: translateX(0);
  }
  to {
    transform: translateX(-50%);
  }
}

/* pause khi hover */
.partners-slider:hover .partners-track {
  animation-play-state: paused;
}

/* Khung logo cố định */
.partner-item {
  width: 160px;          /* desktop */
  height: 80px;
  background: white;
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 12px;
  box-shadow: 0 4px 14px rgba(0,0,0,.06);
  margin-left: 20px;
}

/* Logo tự scale đúng tỉ lệ */
.partner-item img {
  max-width: 100%;
  max-height: 100%;
  object-fit: contain;
}
@media (max-width: 640px) {
  .partner-item {
    width: 120px;
    height: 60px;
    padding: 8px;
  }
}


/*end*/
/* ===== Thông tin liên hệ ===== */
/* ============================= */
/*  VENUE & CONTACT SECTION     */
/* ============================= */

.venue-section {
  background: #1e3769;
  padding: 60px 1rem;
}

.venue-grid {
  display: grid;
  gap: 32px;
  margin-top: 40px;
}

/* LEFT */
.venue-info {
  background: white;
  padding: 32px;
  border-radius: 16px;
  box-shadow: 0 10px 30px rgba(0,0,0,.06);
}

.venue-name {
  font-size: 28px;
  font-weight: 700;
  color: #243d6d;
  margin-bottom: 12px;
}

.venue-address {
  font-size: 18px;
  color: #000;
  line-height: 1.6;
  margin-bottom: 24px;
}

.venue-contact {
  list-style: none;
  padding: 0;
  margin: 0;
}

.venue-contact li {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 14px;
  font-size: 15px;
}

.venue-contact span {
  color: var(--primary);
  font-size: 22px;
}

.venue-contact a {
  color: var(--text-dark);
  text-decoration: none;
  font-size: 17px;
}

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

/* RIGHT */
.venue-map {
  border-radius: 16px;
  overflow: hidden;
  box-shadow: 0 10px 30px rgba(0,0,0,.06);
}

.venue-map iframe {
  width: 100%;
  height: 100%;
  min-height: 320px;
  border: 0;
}

/* RESPONSIVE */
@media (min-width: 768px) {
  .venue-grid {
    grid-template-columns: 1.1fr 1fr;
    align-items: stretch;
  }
}

/*end*/
/* ===== Desktop ===== */
@media (min-width: 768px) {
  .executive-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 1024px) {
  .executive-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}
.conference-acknowledgement {
  margin-top: 48px;
  padding-top: 24px;
  border-top: 1px solid #e5e7eb;
}

.acknowledgement-title {
  font-size: 1.35rem;
  font-weight: 600;
  margin-bottom: 8px;
  color: rgb(255, 255, 255);
}

.acknowledgement-text {
  font-size: 1.15rem;
  color: rgb(255, 255, 255);
  line-height: 1.6;
}
.section-footer {
  font-size: 2rem;
  margin-bottom: 10px;
  color: white;
  text-align: center;
}
.section-title-ft {
  font-size: 2rem;
  font-weight: 700;
  color: white;
  margin-bottom: 1rem;
}
.section-description-ft {
  max-width: 42rem;
  margin: 1rem auto 0;
  color: #fff;
  font-size: 1.15rem;
}
.partners-section{
  padding: 40px;
}