* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
body {
  font-family: Arial, sans-serif;
  background-color: #ffffff;
  color: #333;
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  text-align: center;
}
main {
  flex: 1;
  padding: 20px;
  display: flex;
  flex-direction: column;
  align-items: center;
}
.logo {
  width: 280px;
  max-width: 100%;
  margin: 20px 0;
}
h1 {
  margin-bottom: 20px;
}
.intro {
  max-width: 600px;
  margin-bottom: 20px;
  background: #fff;
  padding: 15px;
  border: 1px solid #dcdcdc;
  box-shadow: 0 0 8px rgba(0, 0, 0, 0.1);
}
.intro p {
  font-size: 16px;
  margin-bottom: 15px;
}
.mode-controls {
  margin-bottom: 20px;
}
.mode-controls button {
  padding: 10px 20px;
  font-size: 16px;
  margin: 0 10px;
  background: #f2f2f2;
  border: 1px solid #dcdcdc;
  border-radius: 4px;
  cursor: pointer;
}
.mode-controls button:hover {
  background: #e6e6e6;
}
.question-container {
  margin-bottom: 20px;
  width: 100%;
  max-width: 800px;
  overflow-x: auto;
}
.binary-table {
  width: 100%;
  border-collapse: collapse;
  margin-bottom: 20px;
}
.binary-table td,
.binary-table th {
  border: 1px solid #ccc;
  padding: 8px;
  text-align: center;
  font-size: 18px;
  min-width: 40px;
}
.ip-container {
  margin-bottom: 20px;
}
.ip-table {
  width: 100%;
  border-collapse: collapse;
}
.ip-table th {
  background-color: #f7f7f7;
  font-size: 16px;
  padding: 8px;
}
.ip-table td {
  font-size: 16px;
  padding: 8px;
}
.ip-question {
  font-size: 20px;
  margin-top: 10px;
}
.hex-container {
  margin-bottom: 20px;
}
.input-area {
  margin-bottom: 20px;
}
.input-area input {
  padding: 10px;
  font-size: 16px;
  width: 60%;
  border: 1px solid #ccc;
  border-radius: 4px;
}
.input-area button {
  padding: 10px 20px;
  font-size: 16px;
  margin-left: 10px;
  background: #f2f2f2;
  border: 1px solid #dcdcdc;
  border-radius: 4px;
  cursor: pointer;
}
.input-area button:hover {
  background: #e6e6e6;
}
.controls {
  margin-bottom: 20px;
}
.controls button {
  padding: 10px 20px;
  font-size: 16px;
  margin: 0 10px;
  background: #f2f2f2;
  border: 1px solid #dcdcdc;
  border-radius: 4px;
  cursor: pointer;
}
.controls button:hover {
  background: #e6e6e6;
}
.score-timer {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-around;
  font-size: 18px;
  margin-bottom: 20px;
}
.score-timer span {
  margin: 5px 10px;
}
.result-message {
  font-size: 20px;
  font-weight: bold;
  margin-top: 10px;
}
footer {
  padding: 10px;
  background: #333;
  color: #ffffff;
  text-align: center;
}
@media (max-width: 768px) {
  .input-area input {
    width: 80%;
  }
  .mode-controls button,
  .controls button {
    padding: 8px 16px;
    font-size: 14px;
  }
  .binary-table td,
  .binary-table th {
    font-size: 16px;
    padding: 6px;
    min-width: 30px;
  }
  .score-timer {
    flex-direction: column;
    align-items: center;
  }
}
@media (max-width: 480px) {
  .intro,
  .question-container,
  .input-area,
  .controls,
  .score-timer {
    width: 100%;
    padding: 10px;
  }
  .input-area input {
    width: 90%;
  }
  .binary-table td,
  .binary-table th {
    font-size: 14px;
    padding: 4px;
    min-width: 28px;
  }
}