* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: "Montserrat", sans-serif;
}

body {
  background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 20px;
}
.back-button {
  position: fixed;
  top: 10px;
  left: 50%;
  transform: translateX(-50%);
  padding: 10px 20px;
  text-decoration: none;
  color: #fff;
  background: linear-gradient(90deg, #00d2ff, #3a7bd5);
  border-radius: 8px;
  font-weight: 600;
  z-index: 1000;
  transition: background 0.3s, transform 0.2s;
}

.back-button:hover {
  background: linear-gradient(90deg, #3a7bd5, #00d2ff);
  transform: translateX(-50%) translateY(-2px);
}

.menu-container {
  max-width: 1200px;
  width: 100%;
  margin: 0 auto;
}

.nav-menu {
  display: flex;
  list-style: none;
  background: linear-gradient(145deg, #2c3e50, #4a6491);
  border-radius: 12px;
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
  position: relative;
}

.nav-menu::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 3px;
  background: linear-gradient(
    90deg,
    #ff9a9e,
    #fad0c4,
    #fad0c4,
    #a18cd1,
    #fbc2eb,
    #ff9a9e
  );
  background-size: 600% 100%;
  animation: gradient 8s linear infinite;
}

@keyframes gradient {
  0% {
    background-position: 0% 50%;
  }
  100% {
    background-position: 100% 50%;
  }
}

.nav-item {
  position: relative;
  flex: 1;
  text-align: center;
  transition: all 0.4s cubic-bezier(0.165, 0.84, 0.44, 1);
}

.nav-item:hover {
  background: rgba(255, 255, 255, 0.05);
}

.nav-link {
  color: #fff;
  text-decoration: none;
  font-weight: 600;
  font-size: 16px;
  display: block;
  padding: 20px 25px;
  position: relative;
  transition: all 0.3s ease;
  letter-spacing: 0.5px;
}

.nav-link::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 0;
  height: 3px;
  background: linear-gradient(90deg, #00d2ff, #3a7bd5);
  transition: all 0.3s ease;
}

.nav-item:hover .nav-link::after {
  width: 80%;
}

.submenu {
  position: absolute;
  top: 100%;
  left: 0;
  width: 100%;
  background: linear-gradient(145deg, #ffffff, #f8f9ff);
  border-radius: 0 0 12px 12px;
  box-shadow: 0 10px 25px rgba(0, 0, 0, 0.15);
  list-style: none;
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
  transition: all 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
  z-index: 100;
  overflow: hidden;
}

.nav-item:hover .submenu {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.submenu::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 3px;
}

.sub-item {
  border-bottom: 1px solid rgba(0, 0, 0, 0.05);
  transition: all 0.3s ease;
}

.sub-item:last-child {
  border-bottom: none;
}

.sub-item:hover {
  background: rgba(52, 112, 255, 0.05);
}

.sub-link {
  color: #2c3e50;
  text-decoration: none;
  font-weight: 500;
  display: block;
  padding: 15px 20px;
  position: relative;
  transition: all 0.3s ease;
}

.sub-link::before {
  content: "";
  position: absolute;
  left: 10px;
  top: 50%;
  transform: translateY(-50%);
  width: 6px;
  height: 6px;
  background: #3a7bd5;
  border-radius: 50%;
  opacity: 0;
  transition: all 0.3s ease;
}

.sub-item:hover .sub-link {
  padding-left: 25px;
  color: #2563eb;
}

.sub-item:hover .sub-link::before {
  opacity: 1;
  left: 15px;
}

@media (max-width: 768px) {
  .nav-menu {
    flex-direction: column;
    border-radius: 8px;
  }

  .submenu {
    position: static;
    width: 100%;
    box-shadow: none;
    border-radius: 0;
    max-height: 0;
    overflow: hidden;
    transition: all 0.4s ease;
    opacity: 1;
    visibility: visible;
    transform: none;
    background: rgba(255, 255, 255, 0.1);
  }

  .nav-item:hover .submenu {
    max-height: 500px;
    transform: none;
  }

  .sub-link {
    color: #e2e8f0;
    padding-left: 40px;
  }

  .sub-item:hover .sub-link {
    padding-left: 50px;
    color: #25ebe1;
  }

  .sub-link::before {
    background: #e2e8f0;
  }
}

.nav-item:nth-child(2) .submenu {
  animation-delay: 0.1s;
}
.nav-item:nth-child(3) .submenu {
  animation-delay: 0.2s;
}

.nav-link:hover {
  text-shadow: 0 0 10px rgba(255, 255, 255, 0.5);
}

.sub-link[data-icon]::after {
  content: attr(data-icon);
  font-weight: 900;
  position: absolute;
  right: 15px;
  top: 50%;
  transform: translateY(-50%);
  opacity: 0.5;
  transition: all 0.3s ease;
}

.sub-item:hover .sub-link[data-icon]::after {
  opacity: 1;
  color: #3a7bd5;
}