body {
  margin: 0;
  font-family: 'Segoe UI', sans-serif;
  background-color: #003322;
  color: #ffffff;
  background-image: radial-gradient(ellipse at center, #004d33 0%, #001a0d 100%);
}

header, footer {
  background-color: rgba(0, 128, 96, 0.6);
  text-align: center;
  padding: 1em;
  background-image: url('/css/organic-pattern.png');
  background-blend-mode: overlay;
}

.logo {
  font-size: 2em;
  font-family: 'Georgia', serif;
  text-shadow: 0 0 8px #00ffcc;
}

nav a {
  margin: 0 1em;
  text-decoration: none;
  color: #ccfff5;
}

nav a:hover {
  text-shadow: 0 0 5px #00ffaa;
}

main {
  padding: 2em;
}

.calculator {
  background: rgba(0, 255, 153, 0.05);
  padding: 2em;
  border-radius: 20px;
  box-shadow: 0 0 15px #00ffcc;
}

input {
  margin-top: 1em;
  width: 100%;
  padding: 0.7em;
  border: 2px solid #00ffaa;
  border-radius: 12px;
  background: #002218;
  color: #ffffff;
}

input:focus {
  outline: none;
  border-color: #33ffcc;
  box-shadow: 0 0 8px #33ffcc;
}

button {
  margin-top: 1em;
  padding: 0.9em 1.8em;
  background: #00cc99;
  border: none;
  border-radius: 30px;
  color: #001a0d;
  font-weight: bold;
  font-size: 1em;
  cursor: pointer;
  transition: background 0.3s ease;
}

button:hover {
  background: #00ffaa;
}

footer {
  position: fixed;
  bottom: 0;
  width: 100%;
  background-image: url('/css/cell-structure.png');
}

footer a {
  color: #99ffe6;
  text-decoration: none;
}

footer a:hover {
  text-shadow: 0 0 6px #00ffaa;
}