body {
  margin: 0;
  font-family: 'Segoe UI', sans-serif;
  background-color: #fefefe;
  color: #222;
  padding: 10px;
}

header {
  text-align: center;
  background: linear-gradient(135deg, #74ebd5, #9face6);
  color: white;
  padding: 30px 20px;
  border-radius: 10px;
  margin-bottom: 20px;
}

.back-btn {
  display: inline-block;
  margin-top: 10px;
  padding: 6px 12px;
  background: white;
  color: #333;
  text-decoration: none;
  border-radius: 6px;
  font-weight: bold;
}

.subjects-grid {
  display: flex;
 justify-content: center;
  flex-direction: column;
}

.subjects-grid iframe {
 
  padding: 0px;
  border-radius: 8px;
 
  
  transition: 0.3s;
  
}

.video-box {
    display: flex;
    align-items: center;
    flex-direction: column;
    gap: 5px;
    background-color: #900baa;
 padding: 10px;
 color:white;
 text-align: center;
 margin-top: 20px;
 border-radius: 8px;
}
.title-box {
    display: flex;
    flex-direction: column;
   
    
}

footer {
  text-align: center;
  margin-top: 100px;
  color: #666;
  font-size: 14px;
}
nav {
  
    background-color:cadetblue;
   border-radius: 8px;
   padding: 0px;
   display: flex;
 justify-content: center;
  flex-direction: column;
  align-items: center;




}
ul{
    display: flex;
 justify-content: center;
   flex-direction: column;
    padding: 0px;
}
nav ul li {
     display: block;
  text-align: center;
  background: #e0f7fa;
  color: #00796b;
 padding: 15px;
  border-radius: 8px;
  font-weight: bold;
  text-decoration: none;
  transition: 0.3s;
 margin-top: 20px;
}
nav ul li a{
    text-decoration: none;
    color: #666;
}

@media only screen and (min-width:600px) {
    iframe {
        height: 315;
        width: 460px;
       
    }
    .video-box {
    display: flex;
    flex-direction: row;
    gap: 5px;
    background-color: #00796b;
 padding: 20px;
 color:white;
}
nav {
   padding: 5px;
    background-color:cadetblue;
   border-radius: 8px;
  display: block;
   
}
ul{
    display: flex;
    justify-content: space-around;
 flex-direction: row;

}
nav ul li {
   
  text-align: center;
  background: #e0f7fa;
  color: #00796b;
  
  border-radius: 8px;
  font-weight: bold;
  text-decoration: none;
  transition: 0.3s;
 margin-top: 0px;
}
}
iframe{
  border-radius: 10px;
}