:root{
  color-scheme:light;
  --ink:#1f2937;
  --muted:#5b6472;
  --line:#d8dee8;
  --accent:#075fb8;
  --panel:#ffffff;
  --bg:#f4f7fb;
}
*{box-sizing:border-box}
html,body{margin:0;padding:0}
body{
  background:var(--bg);
  color:var(--ink);
  font-family:"Helvetica Neue",Arial,"Hiragino Kaku Gothic ProN","Hiragino Sans",Meiryo,sans-serif;
  line-height:1.75;
}
main{max-width:760px;margin:0 auto;padding:28px 18px 48px}
article{
  background:var(--panel);
  border:1px solid var(--line);
  border-radius:16px;
  padding:24px;
  box-shadow:0 10px 30px rgba(15,23,42,.08);
}
h1{font-size:1.65rem;line-height:1.3;margin:0 0 8px}
h2{font-size:1.08rem;margin:26px 0 8px}
p,li{font-size:.96rem}
.meta{color:var(--muted);font-size:.84rem;margin-bottom:22px}
ul{padding-left:1.35rem}
.note{
  border-left:4px solid var(--accent);
  background:#f4f9ff;
  padding:12px 14px;
  margin:18px 0;
}
.back{display:inline-block;margin-top:24px;color:var(--accent);font-weight:700;text-decoration:none}
.back:hover{text-decoration:underline}
@media(max-width:520px){
  main{padding:16px 12px 32px}
  article{padding:20px 16px;border-radius:14px}
  h1{font-size:1.4rem}
}