body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%); /* Blue → Purple gradient */
  margin: 0;
  height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
}

/* Main card */
.container {
  background: #ffffff;
  padding: 30px;
  border-radius: 15px;
  box-shadow: 0px 8px 20px rgba(0, 0, 0, 0.2);
  text-align: center;
  width: 100%;
  max-width: 400px;
}

h1 {
  margin-bottom: 10px;
  color: #222;
  font-size: 1.6rem;
}

p {
  font-size: 14px;
  margin-bottom: 20px;
  color: #555;
}

/* Input box */
input {
  width: 100%;
  padding: 12px;
  font-size: 16px;
  border: 2px solid #ddd;
  border-radius: 8px;
  outline: none;
  transition: 0.3s;
  box-sizing: border-box;
}

input:focus {
  border-color: #667eea; /* matches gradient */
}

/* Buttons container */
.buttons {
  margin-top: 15px;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  justify-content: center;
}

/* Buttons style */
button {
  flex: 1;
  min-width: 120px;
  padding: 12px;
  font-size: 16px;
  cursor: pointer;
  border: none;
  border-radius: 8px;
  transition: 0.3s;
  font-weight: bold;
}

#check-btn {
  background-color: #28a745;
  color: white;
}

#check-btn:hover {
  background-color: #218838;
}

#clear-btn {
  background-color: #dc3545;
  color: white;
}

#clear-btn:hover {
  background-color: #c82333;
}

/* Results message */
#results-div {
  margin-top: 20px;
  font-size: 18px;
  font-weight: bold;
  min-height: 24px;
  transition: 0.3s;
}

/* 📱 Mobile-friendly */
@media (max-width: 480px) {
  .container {
    padding: 20px;
  }

  h1 {
    font-size: 1.4rem;
  }

  input {
    font-size: 14px;
    padding: 10px;
  }

  button {
    font-size: 14px;
    padding: 10px;
    min-width: 100px;
  }

  #results-div {
    font-size: 16px;
  }
}