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

nav {
  background-color: #151d42;
  /*????? tap ??????? ??? logo */
  box-shadow: 0 2px 5px rgba(0,0,0,0.1);
  position: sticky;
  top: 0;
  z-index: 1000;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 10px 20px;
}

.logo {
  font-size: 24px;
  font-weight: bold;
  color: #007BFF;
}

nav ul {
  list-style: none;
  display: flex;
}

nav ul li a {
  text-decoration: none;
  color: #ffffff;
  /*?????? 333  ??????????????? menu front */
   font-size: 18px;
 /*???? */
  padding: 10px 15px;
 
  display: block;
}

nav ul li:hover {
  background-color: #1b2657;
  
  /*????? ?????????? mouse ???? menu */
}

/* Dropdown */
nav ul li ul {
  position: absolute;
  background-color: #151d42;
   /*?????  dropdown menu ?????????? mouse ???? menu ???? white*/
  box-shadow: 0 2px 5px rgba(0,0,0,0.1);
  display: none;
  min-width: 200px;
}

nav ul li:hover ul {
  display: block;
}

.checkbtn {
  font-size: 22px;
   /*???? 20px*/
  cursor: pointer;
  display: none;
}

/* Responsive */
@media screen and (max-width: 768px) {
  .checkbtn {
    display: block;
  }

  nav ul {
    position: fixed;
    top: 60px;
    left: -100%;
    background-color: white;
    flex-direction: column;
    width: 100%;
    height: 100vh;
    transition: all 0.3s ease;
  }

  nav ul li {
    text-align: center;
    padding: 15px 0;
  }

  nav ul li ul {
    position: relative;
    background: #f9f9f9;
    box-shadow: none;
    display: none;
  }

  nav ul li:hover ul {
    display: block;
  }

  #check:checked ~ ul {
    left: 0;
  }
}