.Tong {
  position: relative;
  width: 100%;
}

.Tong img {
  width: 100%;
  height: 90vh;
  object-fit: cover;
  display: block;
}

.Tong .content {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  text-align: center;
  color: #173873;
  width: 90%;
  max-width: 1000px;
}

.Tong .content p {
  font-family: 'Times New Roman', Times, serif;
  font-size: 3vw;
  font-weight: 400;
  margin-bottom: 2rem;
}

.Tong .content button {
  padding: 1rem 2rem;
  font-size: 1.2vw;
  background-color: #cfe2ff;
  border: none;
  border-radius: 30px;
  color: #173873;
  font-weight: bold;
  cursor: pointer;
  box-shadow: 0 5px 10px rgba(0, 0, 0, 0.2);
  transition: all 0.3s ease;
}
.Tong a{
   text-decoration: none;
   font-size: 15px;
   color:#173873;
   font-family: Arial;
}

.introduction{
   display: flex;
   justify-content: center;
   gap: 5px;
 }
 .introduction .par1{
   width: 33%;
   height: 350px;
   border: 1px solid #ddd;
   padding: 10px;
   text-align: center;
   transition: all 0.3s ease-in;
   box-shadow: 0 4px 10px rgba(0,0,0,0.2);
   border-radius: 15px;
   background-color: #EFF9FF;
 }
 .introduction h2{
    font-size: 40px;
    color: #333399;
 }
 .introduction p{
    font-family: Arial, Helvetica, sans-serif;
    font-size: 17px;
    font-weight: bold;
 }
 .dacdiem{
    display: flex;
    justify-content: center;
    gap: 5px;
 }
 .dacdiem h1{
    text-align: center;
    color:#333399;
 }
 .part1{
    width: 25%;
    border: 1px solid #ddd;
    padding: 10px;
    text-align: center;
    transition: all 0.3s ease-in;
    border-radius: 0;
 }
 .part1 h2{
     color:#333399;
 }
 .part1 img{
    width: 100%;
    height: auto;
    display: block;
 }
 .part1:hover{
    border-radius: 15px;
    box-shadow: 0 4px 10px rgba(0,0,0,0.2);
    transform: translateY(-5px);
    cursor: pointer;
 }
.lydo h1{
    text-align: center;
    color:#333399;
}
.lydo .content{
   align-items: center;
   display: flex;
   justify-content: space-around;
   gap: 20px;
   width: 100%;
}
.lydo .part2{
  background-color:  #EFF9FF;
  width: 25%;
  border: 1px solid #ddd;
  padding: 10px;
  text-align: center;
  transition: all 0.3s ease-in;
  border-radius: 0;
}
.lydo .part2 img{
    width: 100%;
    height: auto;
    display: block;  
}
.lydo .part2 h2{
   color:#333399;
}
.lydo .part2:hover{
   border-radius: 15px;
   box-shadow: 0 4px 10px rgba(0,0,0,0.2);
   transform: translateY(-5px);
   cursor: pointer;  
}
.Camnhan h1{
   color:#333399;
   text-align: center;
}
.Camnhan .content{
  align-items: center;
  display: flex;
  justify-content: space-around;
  gap: 20px;
  width: 100%;
}
.Camnhan .left{
  background-color:  #EFF9FF;
  width: 35%;
  border: 1px solid #ddd;
  padding: 10px;
  text-align: center;
  transition: all 0.3s ease-in;
  border-radius: 0;
}
.Camnhan .left:hover{
  border-radius: 15px;
  box-shadow: 0 4px 10px rgba(0,0,0,0.2);
  transform: translateY(-5px);
  cursor: pointer;
}
.chiase{
  position: relative;
  width: 100%;
}
.chiase img{
  width: 100%;
  height: 80vh;
  object-fit: cover;
  display: block;
}
.chiase .noidung{
  background-color: #EFF9FF;
  border-radius: 8px;
  transition: all 0.3s ease-in;
  height: 30vh;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  text-align: center;
  color: #333399;
  width: 90%;
  max-width: 1000px;
}
.chiase button{
  padding: 1rem 2rem;
  font-size: 1.2vw;
  background-color: #EFF9FF;
  border: none;
  border-radius: 30px;
  color: #173873;
  font-weight: bold;
  cursor: pointer;
  box-shadow: 0 5px 10px rgba(0, 0, 0, 0.2);
  transition: all 0.3s ease;
}
.chiase a{
  text-decoration: none;
  color: #173873;
}
.chiase p{
  font-size: 18.5px;
  font-family: Arial, Helvetica, sans-serif;
}

.footer {
  background: #fff;
  border-top: 3px solid #333399;
  padding: 20px;
  font-family: Arial, sans-serif;
  font-size: 14px;
  color: #222;
}

.footer-container {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 30px;
}
.footer-left img{
    width: 150px;
    height: 150px;
}
.footer-left, .footer-middle, .footer-right {
  flex: 1;
  min-width: 250px;
}

.footer-middle h4,
.footer-right h4 {
  margin-bottom: 10px;
  color: #333;
}

.footer-middle a {
  color: black;
  text-decoration: none;
}

.footer-middle a:hover {
  text-decoration: underline;
}

.app-links img, .social-links img {
  height: 35px;
  margin-right: 10px;
  cursor: pointer;
}

.footer-bottom {
  margin-top: 20px;
  border-top: 1px solid #ccc;
  padding-top: 10px;
  text-align: center;
  font-size: 13px;
  color: #555;
}
.backToTop {
  position: fixed;
  bottom: 20px;
  right: 20px;
  z-index: 99;
  font-size: 18px;
  border: none;
  outline: none;
  background-color: #007bff;
  color: white;
  cursor: pointer;
  padding: 12px 16px;
  border-radius: 25%;
  display: none;
  transition: 0.3s;
}

.backToTop:hover {
  background-color: #0056b3;
}