:root {
  color-scheme: light;
  font-family: 'Noto Sans JP', 'Helvetica Neue', Arial, sans-serif;
  --bg: #f8fafc;
  --panel: #ffffff;
  --primary: #2563eb;
  --border: #dbe2ea;
  --text: #0f172a;
  --muted: #6b7280;
}

* { box-sizing: border-box; }
body {
  margin: 0;
  padding: 24px;
  background: var(--bg);
  color: var(--text);
}

header, main, footer {
  max-width: 760px;
  margin: 0 auto;
}

.card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 20px;
  margin-bottom: 16px;
  box-shadow: 0 4px 10px rgba(15, 23, 42, 0.06);
}

h1, h2, h3 {
  margin: 0 0 12px;
}

p { margin: 0 0 10px; color: var(--muted); }

nav a {
  margin-right: 12px;
  color: var(--primary);
  text-decoration: none;
  font-weight: 600;
}

form label {
  display: block;
  margin-bottom: 4px;
  font-weight: 600;
}

form input {
  width: 100%;
  padding: 10px;
  margin-bottom: 12px;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 14px;
}

button {
  background: var(--primary);
  color: white;
  border: none;
  padding: 10px 16px;
  border-radius: 8px;
  cursor: pointer;
  font-weight: 700;
}

.result { margin-top: 8px; font-size: 14px; color: var(--muted); }