* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family:
    -apple-system, BlinkMacSystemFont, "Roboto", "Segoe UI", "Helvetica Neue",
    "Lucida Grande", Arial, sans-serif;
  font-size: 16px;
  color: #1e293b;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: 90px; /* Offset for sticky menu */
}

#header {
  top: 0;
  position: sticky;
}

header {
  height: 90px;
  font-weight: 400;
  background-color: #fcfcfc;
  /* background-color: rgba(250, 250, 250, 0.85); */
  box-shadow:
    0 2px 5px 0 rgba(0, 0, 0, 0.1),
    0 2px 10px 0 rgba(0, 0, 0, 0.1);
  display: flex;
  justify-content: space-around;
  align-items: center;
}

nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  min-width: 80%;
}

nav ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  align-items: center;
  flex-wrap: wrap;
}

nav ul li {
  position: relative; /* Required for dropdown positioning */
  margin: 0 10px;
}

nav ul li a {
  display: flex;
  text-decoration: none;
  padding: 10px 15px;
  border-radius: 5px;
  transition: background-color 0.3s;
}

nav ul li a:hover {
  background-color: #f2f2f2;
}

.link-btn {
  background-color: #2563eb;
  color: #fff;
  font-weight: bold;
  border-radius: 5px;
  padding: 10px 15px;
  text-decoration: none;
}

.link-btn:hover {
  background-color: #1d4ed8;
}

/* Dropdown Menu */
nav ul li ul.dropdown {
  display: none; /* Hide dropdown initially */
  position: absolute;
  top: 100%; /* Position below parent <li> */
  left: 0;
  background-color: white;
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
  border-radius: 5px;
  padding: 10px 0;
  z-index: 1000;
}

nav ul li ul.dropdown li {
  white-space: nowrap;
}

nav ul li ul.dropdown li a {
  padding: 10px 15px;
  display: block;
  text-align: left;
}

nav ul li ul.dropdown li a:hover {
  background-color: #f2f2f2;
}

/* Show Dropdown on Hover */
nav ul li:hover > ul.dropdown {
  display: block; /* Show dropdown when hovering over parent <li> */
}

footer {
  height: 40px;
  background: #0f172a;
  font-weight: 400;
  display: flex;
  justify-content: space-around;
  align-items: center;
}

footer a,
footer p {
  color: #eee;
  font-size: 12px;
  text-align: center;
}

.news {
  display: flex;
  flex-direction: column;
  list-style-type: none;
  line-height: 25px;

  /* Scroll */
  flex: 1;
  overflow-y: auto;
}

.news li {
  margin: 10px 0px;
  text-decoration: none;
  border-bottom: 1px solid #e5e7eb;
  padding-bottom: 10px;
}

.news a,
.text-page a {
  color: #2563eb;
}

main {
  display: flex;
  flex-direction: column;
  align-items: center;
  min-height: calc(
    100vh - 90px - 40px
  ); /* Subtracts header and footer heights */
}

.cover {
  display: flex;
  height: 50vh;
  align-items: center;
  justify-content: center;
  padding: 25px;
  background-image: url("https://vinuni.edu.vn/wp-content/uploads/2023/12/img_introduction-2.png");
  background-position: center;
  background-size: cover;
  width: 100%;
}

.cover-content {
  max-width: 70%;
  padding: 30px 35px;
  background-color: rgba(255, 255, 255, 0.88);
  border-radius: 5px;

  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
}

.cover-content .link-btn {
  margin-top: 1.2rem;
}

.cover-date {
  font-size: 28px;
  font-weight: 700;
  color: #dc2626;
  margin-bottom: 4px;
}

.cover-location {
  font-size: 20px;
  font-weight: 500;
  color: #1e3a5f;
  margin-bottom: 10px;
}

.content {
  background-color: #f0f4ff;
  display: flex;
  align-items: flex-start;
  justify-content: center;
  height: auto;
  padding: 45px 0px;
}

.content-left {
  height: auto;
  display: flex;
  width: 55%;
  margin-right: 20px;
}

.content-right {
  height: auto;
  display: flex;
  width: 30%;
}

.content-text {
  display: flex;
  flex-direction: column;
  width: 100%;
  padding: 22px 22px;
  background-color: #fff;
  box-shadow:
    0 2px 5px 0 rgba(0, 0, 0, 0.1),
    0 2px 10px 0 rgba(0, 0, 0, 0.1);
  border-radius: 5px;

  flex: 1;
  overflow-y: visible;
}

.content-text h3,
.content-text h4 {
  border-bottom: 2px solid #2563eb;
  padding-bottom: 6px;
  margin-bottom: 10px;
}

.conference-title {
  color: #2563eb;
}

.content-text ul {
  padding-left: 2rem;
}

.content-text li {
  line-height: 25px;
  padding: 2px 0;
}

.about-host {
  display: flex;
  justify-content: center;
  padding: 45px 0px;
  background-color: #f0f4ff;
}

.about-host-content {
  width: 87%;
  padding: 22px;
  background-color: #fff;
  box-shadow:
    0 2px 5px 0 rgba(0, 0, 0, 0.1),
    0 2px 10px 0 rgba(0, 0, 0, 0.1);
  border-radius: 5px;
}

.about-host-content h3 {
  border-bottom: 2px solid #2563eb;
  padding-bottom: 6px;
  margin-bottom: 10px;
}

.about-host-content a {
  color: #2563eb;
}

.about-host-links {
  display: flex;
  gap: 20px;
  margin-top: 12px !important;
}

.about-host-links a {
  display: flex;
  align-items: center;
  gap: 4px;
  text-decoration: none;
  font-weight: 500;
}

.about-host-links a:hover {
  text-decoration: underline;
}

.sponsors {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  height: auto;
  padding: 45px 0px;
}

.sponsors div {
  display: flex;
  justify-content: center;
  align-items: center;
  flex-wrap: nowrap;
  gap: 40px;
  width: auto;
}

.sponsors h3 {
  font-size: 35px;
  padding: 20px 0px;
}

.sponsors img {
  width: 180px;
  height: 80px;
  margin: 20px 25px;
  object-fit: contain;
}

main h1 {
  font-size: 48px;
  color: #2563eb;
}

main h2 {
  font-size: 26px;
  color: #0f172a;
  font-weight: 800;
  margin: 8px 0px;
}

main h3 {
  font-size: 20px;
  color: #1e3a5f;
  font-weight: 600;
  margin: 8px 0px;
}

main h4 {
  font-size: 18px;
  font-weight: 500;
  margin: 3px 0;
}

main p {
  line-height: 25px;
  margin: 8px 0;
}

/* .action-btn a {
    text-decoration: none;
    font-weight: bold;
    color: #fff;
}

.action-btn:hover {
    background-color: #0073c0;

}

.action-btn {
    padding: 10px 15px;
    margin-top: 20px;
    margin-bottom: 8px;
    background: #2563eb;
    color: #fff;
    outline: none;
    border: none;
    font-weight: bold;
    border-radius: 5px;
    transition: background-color 0.3s;
} */

.text-page {
  width: 80%;
  margin: 40px 0px;
}

.text-page ul {
  margin-left: 30px;
}

.text-page li {
  padding: 5px 0px;
}

.text-page p {
  font-weight: 400;
  line-height: 25px;
  margin: 15px 0;
}

.text-page h1 {
  margin: 25px 0px;
  font-size: 32px;
  text-align: center;
}

.page-meta {
  text-align: center;
  font-size: 15px;
  font-weight: 600;
  color: #1e3a5f;
  background-color: #e8f0fe;
  border: 1px solid #bfcfea;
  border-radius: 6px;
  padding: 10px 20px;
  margin: 0 auto 20px auto;
}

.text-page h2 {
  font-size: 26px;
  margin: 25px 0px;
}

.text-page h3 {
  margin: 25px 0px;
}

.content-box {
  display: flex;
  flex-direction: column;
  width: 100%;
  padding: 0px 20px 20px 20px;
  background-color: #fff;
  box-shadow:
    0 2px 5px 0 rgba(0, 0, 0, 0.1),
    0 2px 10px 0 rgba(0, 0, 0, 0.1);
  border-radius: 5px;
  margin: 15px 0px;
}

.content-box ol {
  padding-left: 1.5rem;
  margin-left: 0.5rem;
}

.content-box h3,
.content-box h4 {
  border-bottom: 2px solid #2563eb;
  padding-bottom: 6px;
  margin-bottom: 10px;
}

.code-block {
  background-color: #1e293b;
  color: #e2e8f0;
  padding: 18px 22px;
  border-radius: 6px;
  font-family: "SF Mono", "Fira Code", "Fira Mono", Menlo, Consolas, monospace;
  font-size: 14px;
  line-height: 1.6;
  overflow-x: auto;
  margin: 10px 0;
}

.code-block code {
  color: inherit;
  font-family: inherit;
  font-size: inherit;
}

.table {
  border-collapse: collapse;
  width: 100%;
}
.table th,
.table td {
  text-align: left;
  padding: 0.5rem 1.5rem 0.5rem 0;
  white-space: nowrap;
}
.table tr {
  border-bottom: 1px solid #e5e5e5;
}
.table tr:last-child {
  border-bottom: 1px solid #e5e5e5;
}

.content-group {
  display: flex;
  justify-content: space-evenly;
  flex-wrap: wrap;
}

.content-box-small {
  display: flex;
  width: fit-content;
  max-width: 100%;
  flex-direction: column;
  padding: 0px 20px 20px 20px;
  background-color: #fff;
  box-shadow:
    0 2px 5px 0 rgba(0, 0, 0, 0.1),
    0 2px 10px 0 rgba(0, 0, 0, 0.1);
  border-radius: 5px;
  margin: 15px 0px;
}

.content-group img {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  margin: 10px 10px;
  height: 46vh;
  max-width: 100%;
  border-radius: 5px;
  box-shadow:
    0 2px 5px 0 rgba(0, 0, 0, 0.1),
    0 2px 10px 0 rgba(0, 0, 0, 0.1);
}

.bx-menu {
  font-size: 30px;
}

.box-icon {
  display: none;
}

/* Tablet and below */
@media only screen and (max-width: 1024px) {
  nav {
    position: relative;
    flex-direction: column;
  }

  .box-icon {
    display: flex;
    position: absolute;
    top: 50%;
    right: 20px;
    transform: translateY(-50%);
    cursor: pointer;
  }

  nav ul {
    background-color: #fcfcfc;
    display: none;
    position: absolute;
    top: 100%;
    right: 10px;
    width: 220px;
    padding: 8px 0;
    border-radius: 5px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
    z-index: 1000;
    flex-direction: column;
  }

  .showmenu {
    display: flex !important;
    flex-direction: column;
  }

  nav ul li {
    padding: 0;
    margin: 0;
  }

  nav ul li a {
    color: #222;
    padding: 10px 20px;
  }

  /* Make dropdowns work inline in mobile menu */
  nav ul li ul.dropdown {
    position: static;
    box-shadow: none;
    padding: 0;
    background-color: #f5f5f5;
    display: none;
  }

  nav ul li:hover > ul.dropdown,
  nav ul li:focus-within > ul.dropdown {
    display: block;
  }

  nav ul li ul.dropdown li {
    width: 100%;
  }

  nav ul li ul.dropdown li a {
    padding-left: 35px;
    font-size: 14px;
  }

  main h1 {
    font-size: 34px;
  }

  main h2 {
    font-size: 20px;
  }

  .cover {
    height: auto;
    min-height: 40vh;
    padding: 25px;
  }

  .cover-content {
    max-width: 90%;
  }

  .cover-date {
    font-size: 24px;
  }

  .cover-location {
    font-size: 18px;
  }

  .content-box-small {
    width: 100%;
  }

  .content {
    flex-direction: column;
    align-items: center;
    height: auto;
    padding: 25px 0;
  }

  .content-left {
    width: 90%;
    margin: 10px 0;
  }

  .content-right {
    width: 90%;
    margin: 10px 0;
  }

  .sponsors div {
    width: 90%;
  }

  .sponsors img {
    width: 30%;
  }

  .content-group img {
    height: 35vh;
  }

  .text-page {
    width: 90%;
  }

  /* Make tables scrollable */
  .table {
    display: block;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
  }

  footer {
    height: auto;
    padding: 10px 15px;
    flex-direction: column;
  }
}

/* Phone */
@media only screen and (max-width: 768px) {
  header {
    height: 70px;
  }

  html {
    scroll-padding-top: 70px;
  }

  main {
    min-height: calc(100vh - 70px - 40px);
  }

  main h1 {
    font-size: 26px;
  }

  main h2 {
    font-size: 18px;
  }

  main h3 {
    font-size: 17px;
  }

  .cover {
    padding: 20px 15px;
  }

  .cover-content {
    max-width: 100%;
    padding: 16px;
  }

  .cover-date {
    font-size: 20px;
  }

  .cover-location {
    font-size: 16px;
  }

  .content {
    padding: 20px 0;
  }

  .content-left,
  .content-right {
    width: 95%;
  }

  .sponsors h3 {
    font-size: 24px;
  }

  .sponsors div {
    width: 95%;
    justify-content: center;
  }

  .sponsors img {
    width: 40%;
    margin: 15px 10px;
  }

  .text-page {
    width: 95%;
    margin: 20px 0;
  }

  .text-page h1 {
    font-size: 24px;
  }

  .text-page h2 {
    font-size: 20px;
  }

  .content-group img {
    height: 30vh;
  }
}

/* Small phone */
@media only screen and (max-width: 480px) {
  main h1 {
    font-size: 22px;
  }

  main h2 {
    font-size: 16px;
  }

  nav ul li a {
    padding: 8px 12px;
    font-size: 14px;
  }

  .link-btn {
    font-size: 14px;
    padding: 8px 12px;
  }

  .sponsors img {
    width: 45%;
  }

  .content-group img {
    height: 25vh;
  }

  footer p,
  footer a {
    font-size: 10px;
  }
}