body {
  background: linear-gradient(135deg, #6e8efb, #a777e3);
  font-family: 'Segoe UI', 'Roboto', Arial, sans-serif;
  margin: 0;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
}

.container {
  background: rgba(255,255,255,0.15);
  box-shadow: 0 8px 32px 0 rgba(31,38,135,0.37);
  border-radius: 20px;
  padding: 2rem 2.5rem;
  text-align: center;
  backdrop-filter: blur(8px);
}

h1 {
  color: #fff;
  margin-bottom: 1.5rem;
  letter-spacing: 2px;
}

.question {
  font-size: 1.5em;
  margin: 20px 0;
}

.numbers {
  font-size: 2.5rem;
  color: #fff;
  margin-bottom: 1rem;
  display: flex;
  justify-content: center;
  gap: 1rem;
  align-items: center;
}

.plus {
  font-weight: bold;
}

input[type="number"] {
  padding: 0.5rem;
  font-size: 1.2rem;
  border-radius: 8px;
  border: none;
  margin-bottom: 1rem;
  width: 120px;
  text-align: center;
}

input[type="number"]:focus {
  border-color: #007bff;
  outline: none;
}

button {
  background: #6e8efb;
  color: #fff;
  border: none;
  border-radius: 8px;
  padding: 0.7rem 1.5rem;
  font-size: 1rem;
  cursor: pointer;
  margin-top: 0.5rem;
  transition: background 0.2s;
}

button:hover {
  background: #a777e3;
}

.results {
  margin-top: 30px;
  font-size: 1.2em;
  display: none;
}

.restart {
  margin-top: 20px;
  display: none;
}

#progress {
  margin-top: 1rem;
  color: #fff;
  font-size: 1rem;
}

.hidden {
  display: none;
}

#result h2 {
  color: #fff;
}

#score {
  color: #fff;
  font-size: 1.2rem;
  margin-bottom: 1rem;
}