header{
    background-color: lightgray;
    color: darkblue;
    position: fixed; 
    width:100%;
    top:0;
    grid-column: 1/span 2;
}
nav{
    width:100%;
    background-color: lightblue;
    top: 50px;             /* đặt ngay dưới header (header cao 50px) */
    grid-column: 1/span 2;
}
nav li {
    display: inline;
    margin-right: 50px;
    background-color: yellow;
}
body{
    display: grid;
    background-color: whitesmoke;
    grid-template-columns: 15% 85%;
    max-width: 1500px;
    margin: 0 auto;
    padding-top: 50px;
}
.sidebar{
    width: 150px;
    background-color: lightgreen;
    padding: 10px;
    grid-column: 1;
    word-wrap: break-word;
    line-height: 1.5;
    height: 100vh;
}
.list{
    width:70%;
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    padding: 10px;
    grid-column: 2;
}
.pic{
    width: 200px;   /* chiều rộng */
    height: 200px;  /* chiều cao */
}
.card{
    background-color: cyan;
    border: 1px solid blue;
    border-radius: 5px;
    text-align: center;
    padding: 10px;
    width: 70%;
    height: fit-content;
}
footer {
  background-color: darkgray; 
  color: white;
  text-align: center;
  padding: 20px; 
  margin-top: 20px;
  grid-column: 1 / -1;
}