<style>
* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Arial, sans-serif;
  background: #f7f9fc;
  color: #222;
}

.container {
  max-width: 1200px;
  margin: auto;
  padding: 16px;
}

.header {
  text-align: center;
  padding: 12px 0;
}

.header img {
  height: 38px;
}

.layout {
  display: grid;
  grid-template-columns: minmax(0, 3fr) minmax(0, 1fr);
  gap: 20px;
}

.card {
  background: #fff;
  border-radius: 10px;
  padding: 20px;
  box-shadow: 0 4px 14px rgba(0,0,0,.05);
}

h1 {
  font-size: 28px;
  margin: 0 0 12px;
}

h2 {
  font-size: 20px;
  margin-top: 24px;
}

p {
  line-height: 1.6;
  margin: 10px 0;
}

.hero-img {
  width: 100%;
  max-width: 520px;
  aspect-ratio: 10 / 7;
  display: block;
  margin: 18px auto;
}

.result-box {
  font-size: 18px;
  background: #f1f6ff;
  border-left: 4px solid #2f6fed;
  padding: 12px;
  margin-top: 16px;
}

.sidebar h3 {
  margin-top: 0;
}

.sidebar ul {
  list-style: none;
  padding: 0;
  margin: 0;
}

.sidebar li {
  margin-bottom: 8px;
}

.sidebar a {
  text-decoration: none;
  color: #2f6fed;
}

.sidebar a:hover {
  text-decoration: underline;
}

.footer {
  text-align: center;
  font-size: 14px;
  color: #666;
  margin: 40px 0 10px;
}

@media (max-width: 768px) {
  .layout {
    grid-template-columns: 1fr;
  }
}
</style>