body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  margin: 0;
  padding: 0;
  background: linear-gradient(to right, #0f2027, #203a43, #2c5364);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  animation: fadeIn 1.5s ease-in;
}

.container {
  background-color: rgba(255, 255, 255, 0.1);
  border-radius: 20px;
  padding: 30px;
  box-shadow: 0 10px 25px rgba(0, 0, 0, 0.4);
  max-width: 500px;
  width: 90%;
  animation: floatUp 0.8s ease-out;
}

.app-title {
  text-align: center;
  font-size: 2em;
  margin-bottom: 20px;
  color: #ffdd57;
  text-shadow: 1px 1px 2px #000;
}

label {
  display: block;
  margin-top: 10px;
  font-weight: bold;
}

input, select, button {
  width: 100%;
  padding: 10px;
  margin-top: 5px;
  border-radius: 8px;
  border: none;
  font-size: 1em;
}

button {
  background-color: #00c896;
  color: white;
  margin-top: 15px;
  cursor: pointer;
  transition: background-color 0.3s;
}

button:hover {
  background-color: #00a77f;
}

#planOutput {
  background: #ffffff20;
  padding: 20px;
  margin-top: 20px;
  border-radius: 12px;
  animation: fadeIn 1s ease;
}

#exerciseSession {
  margin-top: 30px;
}

.hidden {
  display: none;
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes floatUp {
  from { transform: translateY(40px); opacity: 0; }
  to { transform: translateY(0); opacity: 1; }
}