/* Base */
:root{
  --bg:#ffffff;
  --text:#222;
  --muted:#555;
  --line:#e9e9ef;
  --brand:#0066cc; /* link/button */
  --brand-dark:#004a99;
  --accent:#ffcc00; /* badge accent */
}
*{box-sizing:border-box}
html{font-size:16px}
body{margin:0;font-family:system-ui,-apple-system,Segoe UI,Roboto,Arial,sans-serif;color:var(--text);background:var(--bg);line-height:1.65}
img{max-width:100%;height:auto;display:block}
a{color:var(--brand);text-decoration:none}
a:hover{text-decoration:underline}
.container{width:min(1120px, 92vw);margin-inline:auto}

/* Header */
.site-header{border-bottom:1px solid var(--line);background:#fff}
.header-flex{display:flex;align-items:center;justify-content:space-between;padding:.75rem 0}
.brand{font-weight:700}
.badge{background:var(--accent);color:#111;padding:.25rem .5rem;border-radius:.4rem;font-size:.78rem;font-weight:800}

/* Hero */
.hero{padding:1.25rem 0 0}
.hero h1{font-size:clamp(1.6rem,3.8vw,2.2rem);line-height:1.2;margin-bottom:.4rem}
.lede{color:var(--muted)}
.disclaimer{font-size:.85rem;color:#777;margin-top:.4rem}

/* Steps */
.step{padding:1.25rem 0;border-top:1px solid var(--line)}
.step h2{font-size:clamp(1.25rem,3.4vw,1.6rem);margin-bottom:.35rem}
.inline-note{margin:.4rem 0 .2rem}
.inline-aff{display:inline-block;background:var(--brand);color:#fff;padding:.15rem .45rem;border-radius:.35rem;font-weight:700}
.inline-aff:hover{background:var(--brand-dark);text-decoration:none}
.checklist, .steps, .tips{padding-left:1.1rem;margin:.4rem 0}
.fig{margin-top:.6rem;border:1px solid var(--line);border-radius:.6rem;overflow:hidden;background:#fafafa}
.fig figcaption{padding:.5rem .6rem;color:#666;font-size:.9rem}

/* Note block */
.note{padding:1rem 0;border-top:1px solid var(--line);background:#fcfdff}

/* Final CTA */
.final-cta{padding:1.4rem 0;border-top:1px solid var(--line);text-align:center;background:#f9fafb;margin-top:.5rem}
.final-cta .muted{color:#666;margin:.2rem 0 .9rem}
.btn{display:inline-block;padding:.7rem 1.2rem;border-radius:.55rem;font-weight:800}
.btn-primary{background:var(--brand);color:#fff}
.btn-primary:hover{background:var(--brand-dark);text-decoration:none}
.tiny{font-size:.8rem;color:#666;margin-top:.5rem}

/* Footer */
.site-footer{border-top:1px solid var(--line);padding:1rem 0;margin-top:1rem}
.foot-links{display:flex;gap:.75rem;justify-content:center;flex-wrap:wrap}
.copy{color:#777;font-size:.9rem;margin-top:.3rem}

/* Giảm kích thước ảnh Step 1 */
#s1 + .inline-note + .fig img {
  width: auto;
  max-width: 420px;   /* giới hạn chiều rộng */
  max-height: 260px;  /* giới hạn chiều cao */
  height: auto;
  display: block;
  margin-inline: auto; /* canh giữa */
}

.img-step1 {
  width: 100%;
  max-width: 380px;   /* giới hạn chiều ngang */
  height: auto;
  display: block;
  margin-inline: auto;
}