body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background-color: #efece4;
  margin: 0;
  padding: 2em;
  display: flex;
  flex-direction: column;
  align-items: center;
}

h1 {
  color: #333;
  margin-bottom: 1em;
}

.controls {
  display: flex;
  flex-wrap: wrap;
  gap: 1em;
  justify-content: center;
  margin-bottom: 1.5em;
}

label {
  font-weight: bold;
  margin-right: 0.5em;
}

select {
  font-size: 1em;
  padding: 0.4em;
  border-radius: 5px;
  border: 1px solid #ccc;
}

button {
  font-size: 1em;
  padding: 0.6em 1.2em;
  border: none;
  border-radius: 5px;
  background-color: #0078d4;
  color: white;
  cursor: pointer;
  transition: background-color 0.3s ease;
}

button:hover {
  background-color: #005fa3;
}

.problem {
  font-size: 2em;
  margin: 1em 0;
  color: #222;
}

input[type="number"] {
  font-size: 1.5em;
  padding: 0.5em;
  width: 120px;
  text-align: center;
  border: 2px solid #ccc;
  border-radius: 5px;
}

.feedback {
  font-size: 1.2em;
  margin-top: 1em;
  color: #444;
}

.scoreboard {
  margin-top: 2em;
  text-align: center;
}

.scoreboard h2 {
  font-size: 1.5em;
  color: #0078d4;
}

.scoreboard h3 {
  font-size: 1.2em;
  color: #28a745;
  margin-top: 0.5em;
}

.logo {
  display: block;
  margin: 2rem auto 1rem auto;
  max-width: 200px;
  width: 80vw;
  height: auto;
}

.controls, .scoreboard {
  width: 100%;
  max-width: 500px;
  margin-left: auto;
  margin-right: auto;
}

.problem, .feedback {
  width: 100%;
  max-width: 500px;
  margin-left: auto;
  margin-right: auto;
  text-align: center;
}

input[type="number"] {
  width: 100%;
  max-width: 200px;
  box-sizing: border-box;
  margin-bottom: 1em;
}

button {
  width: auto;
  min-width: 120px;
  margin: 0.5em 0.2em;
}

@media (max-width: 600px) {
  h1 {
    font-size: 1.5em;
  }
  .controls, .scoreboard, .problem, .feedback {
    max-width: 98vw;
    padding-left: 2vw;
    padding-right: 2vw;
  }
  .logo {
    max-width: 90vw;
    margin: 1.2rem auto 0.5rem auto;
  }
  input[type="number"] {
    font-size: 1.1em;
    max-width: 98vw;
  }
  button {
    min-width: 90px;
    font-size: 1em;
  }
}