/* Base reset and layout */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
body {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  background: linear-gradient(135deg, #e0eafc, #cfdef3);
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}
.container {
  background: #ffffff;
  padding: 2rem;
  width: 90%;
  max-width: 400px;
  border-radius: 0.5rem;
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
  text-align: center;
  animation: fadeIn 0.6s ease-out;
}
header h1 {
  font-size: 1.75rem;
  color: #333333;
}
header p {
  margin: 0.5rem 0 1.5rem;
  color: #666666;
}
.tracker-form {
  display: flex;
  gap: 0.5rem;
}
.tracker-form input {
  flex: 1;
  padding: 0.75rem 1rem;
  border: 2px solid #ddd;
  border-radius: 0.5rem;
  font-size: 1rem;
  transition: border-color 0.3s;
}
.tracker-form input:focus {
  outline: none;
  border-color: #007bff;
}
.tracker-form button {
  padding: 0.75rem 1rem;
  border: none;
  background: #007bff;
  color: #fff;
  font-size: 1rem;
  border-radius: 0.5rem;
  cursor: pointer;
  transition: background 0.3s, transform 0.2s;
}
.tracker-form button:hover {
  background: #0056b3;
  transform: translateY(-2px);
}
@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(-20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}
@keyframes shake {
  0% {
    transform: translateX(0);
  }
  25% {
    transform: translateX(-5px);
  }
  50% {
    transform: translateX(5px);
  }
  75% {
    transform: translateX(-5px);
  }
  100% {
    transform: translateX(0);
  }
}
.tracker-form input.shake {
  animation: shake 0.3s ease-in-out;
  border-color: #dc3545;
}
@media (max-width: 480px) {
  .container {
    padding: 1.5rem;
  }
  header h1 {
    font-size: 1.5rem;
  }
  .tracker-form {
    flex-direction: column;
  }
  .tracker-form button {
    width: 100%;
  }
}