:root {
  --bg: #ffffff; --panel: #f7f8fa; --border: #e3e6ea;
  --text: #1c2430; --muted: #6b7684; --accent: #2563eb;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: "Hiragino Sans", "Noto Sans JP", system-ui, sans-serif;
  color: var(--text); background: var(--panel);
  line-height: 1.7;
}
.page { max-width: 720px; margin: 0 auto; min-height: 100vh; background: var(--bg); }
.page-head {
  display: flex; justify-content: space-between; align-items: center;
  padding: 14px 20px; border-bottom: 1px solid var(--border);
  position: sticky; top: 0; background: var(--bg); z-index: 2;
}
.home { font-size: 18px; font-weight: 700; color: var(--text); text-decoration: none; }
.page-head select {
  border: 1px solid var(--border); border-radius: 8px; background: var(--bg);
  font-size: 13px; padding: 5px 8px; max-width: 150px;
}
.page-body { padding: 28px 24px 60px; }
.page-body h1 { font-size: 24px; margin: 0 0 20px; }
.page-body h2 { font-size: 17px; margin: 28px 0 8px; }
.page-body p { margin: 0 0 14px; }

/* フォーム */
form label { display: block; font-size: 13px; color: var(--muted); margin-bottom: 16px; }
form input, form textarea {
  display: block; width: 100%; margin-top: 5px; padding: 10px 12px;
  border: 1px solid var(--border); border-radius: 8px; font-size: 14px; font-family: inherit;
}
form .hp { position: absolute; left: -9999px; height: 0; width: 0; padding: 0; border: 0; }
form button[type="submit"] {
  width: 100%; padding: 12px; border: none; border-radius: 10px;
  background: var(--accent); color: #fff; font-size: 15px; cursor: pointer;
}
#submit-result { font-size: 13px; margin: 12px 0 0; }
#submit-result.ok { color: #16a34a; }
#submit-result.err { color: #dc2626; }
.back { margin-top: 28px; }
.back a { color: var(--accent); text-decoration: none; }

.feature-list { list-style: none; padding: 0; }
.feature-list li { padding: 8px 0; border-top: 1px dashed var(--border); font-size: 14px; }
.feature-list li b { display: block; }
.note { font-size: 12px; color: var(--muted); }
.madeby { font-size: 14px; }
.madeby a { color: var(--accent); text-decoration: none; }
.madeby a:hover { text-decoration: underline; }

@media (prefers-color-scheme: dark) {
  :root { --bg: #161a20; --panel: #0f1216; --border: #2a2f37; --text: #e6e9ee; --muted: #9aa4b0; }
}