body {
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, "Hiragino Sans", "Noto Sans JP", sans-serif;
  line-height: 1.7;
  max-width: 800px;
  margin: 0 auto;
  padding: 20px;
  background: #f5f9ff;
}

.container {
  background: white;
  border-radius: 12px;
  padding: 30px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

h1 {
  color: #1e88e5;
  border-bottom: 3px solid #1e88e5;
  padding-bottom: 10px;
}

h2 {
  color: #2e7d32;
  margin-top: 30px;
  padding-left: 10px;
  border-left: 4px solid #2e7d32;
}

.problem {
  background: #fff3e0;
  border-left: 4px solid #ff9800;
  padding: 15px;
  margin: 20px 0;
}

.solution {
  background: #e8f5e9;
  border-left: 4px solid #4caf50;
  padding: 15px;
  margin: 20px 0;
}

.steps {
  counter-reset: step-counter;
  list-style: none;
  padding-left: 0;
}

.steps li {
  counter-increment: step-counter;
  margin: 15px 0;
  padding-left: 40px;
  position: relative;
}

.steps li::before {
  content: counter(step-counter);
  position: absolute;
  left: 0;
  top: 0;
  background: #1e88e5;
  color: white;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: bold;
}

.note {
  background: #e3f2fd;
  border-left: 4px solid #2196f3;
  padding: 15px;
  margin: 20px 0;
}

.warning {
  background: #ffebee;
  border-left: 4px solid #f44336;
  padding: 15px;
  margin: 20px 0;
}

code {
  background: #f5f5f5;
  padding: 2px 6px;
  border-radius: 3px;
  font-family: monospace;
}

.back-link {
  display: inline-block;
  margin-top: 30px;
  color: #1e88e5;
  text-decoration: none;
  font-weight: bold;
}

.back-link:hover {
  text-decoration: underline;
}