nav {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  padding: 10px 40px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  z-index: 12;
  /* background: rgba(10, 10, 10, 0.8);
  backdrop-filter: blur(10px);
  transition: background 0.3s ease; */
}
nav .logo {
  padding: 10px 10px 10px 0;
  position: relative;
}
nav .logo img {
  cursor: pointer;
  width: 30px;
  position: relative;
  z-index: 101;
  filter: brightness(1.2) contrast(1.2) drop-shadow(0 0 2px #fff);
  transition: all 0.3s ease;
  user-select: none;
}
nav .logo img.active {
  filter: brightness(1.4) contrast(1.4) drop-shadow(0 0 1px #fff);
}
nav .logo .logo_circle {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 0%;
  height: 0%;
  border-radius: 50%;
  overflow: hidden;
  background-color: #3d3d3d;
  transition: all 0.3s ease;
  z-index: 100;
}
nav .logo.active .logo_circle {
  width: 800px;
  height: 800px;
  background-color: #ff0000;
  transition: all 0.3s ease;
}
nav .menu {
  position: fixed;
  top: 100px;
  color: #fff;
  opacity: 0;
  transition: opacity 0.3s ease;
  width: 300px;
  display: none;
  z-index: 102;
}
nav .menu.active {
  opacity: 1;
  display: block;
}
nav .menu .menu_item {
  display: flex;
  flex-direction: column;
}
nav .menu .menu_item a {
  padding: 6px 0;
  font-size: 25px;
  cursor: pointer;
}
nav .menu .menu_item a.active {
  font-weight: 800;
}
nav .index_btn a img {
  width: 150px;
}

@media (max-width: 768px) {
  nav {
    padding: 10px 10px;
  }
  nav .index_btn a img {
    width: 100px;
  }
}