:root {
  --ink: #18221d;
  --muted: #637069;
  --paper: #f5f3ec;
  --card: #fffdf7;
  --line: #d9d8cf;
  --green: #235b46;
  --lime: #d9ff77;
  --orange: #ef8354;
  --blue: #2f6bff;
  --shadow: 0 18px 50px rgba(24, 34, 29, 0.08);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  color: var(--ink);
  background:
    radial-gradient(circle at 90% 5%, rgba(217,255,119,.45), transparent 25rem),
    var(--paper);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}
a { color: inherit; }
.shell { width: min(1180px, calc(100% - 32px)); margin: 0 auto; }
.topbar {
  position: sticky; top: 0; z-index: 10;
  background: rgba(245,243,236,.9); backdrop-filter: blur(16px);
  border-bottom: 1px solid rgba(217,216,207,.8);
}
.topbar .shell { min-height: 68px; display: flex; align-items: center; gap: 22px; }
.brand { font-weight: 900; letter-spacing: -.04em; text-decoration: none; font-size: 1.15rem; }
.brand span { color: var(--green); }
nav { display: flex; gap: 18px; margin-left: auto; }
nav a { text-decoration: none; color: var(--muted); font-size: .92rem; }
.lang-switch { display: flex; gap: 4px; padding: 4px; border: 1px solid var(--line); border-radius: 999px; }
.lang-switch button { border: 0; background: transparent; padding: 7px 10px; border-radius: 999px; cursor: pointer; color: var(--muted); }
html[data-lang="en"] [data-lang="zh"], html[data-lang="zh"] [data-lang="en"] { display: none !important; }
html[data-lang="en"] .lang-switch [data-set-lang="en"], html[data-lang="zh"] .lang-switch [data-set-lang="zh"] { background: var(--ink); color: white; }

.hero { padding: 78px 0 48px; display: grid; grid-template-columns: 1.15fr .85fr; gap: 48px; align-items: end; }
.eyebrow { text-transform: uppercase; letter-spacing: .16em; font-size: .75rem; font-weight: 800; color: var(--green); }
h1 { font-size: clamp(3rem, 7vw, 6.8rem); line-height: .9; letter-spacing: -.07em; margin: 16px 0 24px; max-width: 9ch; }
.hero p { font-size: 1.15rem; line-height: 1.65; color: var(--muted); max-width: 62ch; }
.hero-note { border-left: 4px solid var(--orange); padding: 16px 20px; background: rgba(255,253,247,.65); }
.hero-note strong { display:block; margin-bottom: 6px; }
.meta-row { display:flex; gap:10px; flex-wrap:wrap; margin-top: 24px; }
.pill { border: 1px solid var(--line); border-radius: 999px; padding: 8px 12px; font-size:.82rem; background: rgba(255,255,255,.55); }

.planner { display: grid; grid-template-columns: minmax(0,1.05fr) minmax(340px,.95fr); gap: 24px; align-items: start; padding: 24px 0 64px; }
.mobile-summary { display:none; }
.panel { background: var(--card); border: 1px solid var(--line); border-radius: 24px; box-shadow: var(--shadow); overflow: hidden; }
.panel-head { padding: 24px 26px 18px; border-bottom: 1px solid var(--line); display:flex; justify-content:space-between; gap:12px; align-items:start; }
.panel-head h2 { margin: 0; font-size: 1.4rem; letter-spacing: -.03em; }
.panel-head p { margin: 5px 0 0; color: var(--muted); font-size: .9rem; }
.form-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; padding: 26px; }
.presets { padding:18px 26px 0; display:grid; grid-template-columns:repeat(3,1fr); gap:8px; }
.presets button { min-height:72px; border:1px solid var(--line); border-radius:14px; background:white; color:var(--ink); cursor:pointer; display:flex; flex-direction:column; align-items:flex-start; justify-content:center; padding:11px 12px; font:inherit; }
.presets button:hover, .presets button.active { border-color:var(--green); background:#eef4ef; box-shadow:inset 0 0 0 1px var(--green); }
.presets button strong { font-size:.88rem; }
.presets button small { color:var(--muted); margin-top:4px; }
.presets p { grid-column:1/-1; margin:2px 0 0; color:var(--muted); font-size:.75rem; }
.field { display:flex; flex-direction:column; gap:8px; }
.field.full { grid-column: 1 / -1; }
label { font-weight: 750; font-size: .9rem; }
.hint { color: var(--muted); font-size: .76rem; line-height:1.45; }
input, select { width:100%; border:1px solid var(--line); background:white; color:var(--ink); border-radius:12px; padding:12px 13px; font:inherit; }
input:focus, select:focus { outline: 3px solid rgba(47,107,255,.14); border-color: var(--blue); }
.results { position: sticky; top: 92px; }
.result-hero { padding: 26px; background: var(--ink); color:white; }
.result-hero .eyebrow { color: var(--lime); }
.big-number { margin-top: 8px; font-size: clamp(2.6rem, 5vw, 4.4rem); line-height: 1; font-weight:900; letter-spacing:-.055em; }
.big-number small { font-size: .34em; font-weight:700; color:#c8d0cc; letter-spacing:0; }
.capacity-breakdown { margin-top:10px; color:#c8d0cc; font-size:.9rem; }
.result-grid { display:grid; grid-template-columns:1fr 1fr; }
.metric { padding:20px 22px; border-right:1px solid var(--line); border-bottom:1px solid var(--line); }
.metric:nth-child(even) { border-right:0; }
.metric .label { font-size:.78rem; color:var(--muted); text-transform:uppercase; letter-spacing:.08em; }
.metric .value { font-size:1.55rem; font-weight:850; margin-top:6px; letter-spacing:-.035em; }
.metric .sub { font-size:.76rem; color:var(--muted); margin-top:4px; line-height:1.4; }
.verdict { margin:22px; border-radius:16px; padding:18px; background:#eef4ef; border:1px solid #cad9ce; line-height:1.55; }
.formula { padding: 0 22px 24px; color: var(--muted); font-size:.78rem; line-height:1.55; }
.formula code { background:#efeee7; color:var(--ink); padding:2px 5px; border-radius:5px; }
.result-actions { display:grid; grid-template-columns:1fr 1fr; gap:8px; padding:0 22px 18px; }
.result-actions button { border:1px solid var(--ink); border-radius:12px; padding:11px; cursor:pointer; font:inherit; font-weight:750; background:var(--ink); color:white; }
.result-actions button + button { background:white; color:var(--ink); }
.verified { margin:0 22px 18px; padding:14px 15px; border:1px solid #cad9ce; background:#f3f8f4; border-radius:14px; display:flex; flex-direction:column; gap:5px; color:var(--muted); font-size:.76rem; line-height:1.45; }
.verified strong { color:var(--green); }
.verified a { color:var(--blue); }
.print-only { display:none; }

.guides { padding: 30px 0 90px; }
.section-kicker { color:var(--green); font-size:.78rem; font-weight:850; text-transform:uppercase; letter-spacing:.14em; }
.section-title { font-size:clamp(2rem,4vw,3.7rem); letter-spacing:-.055em; line-height:1; margin:12px 0 28px; max-width:14ch; }
.guide-grid { display:grid; grid-template-columns:repeat(3,1fr); gap:18px; }
.guide-card { min-height:260px; border:1px solid var(--line); border-radius:22px; background:var(--card); padding:24px; display:flex; flex-direction:column; text-decoration:none; transition:.2s ease; }
.guide-card:hover { transform:translateY(-4px); box-shadow:var(--shadow); }
.guide-card .num { font-size:.78rem; color:var(--muted); }
.guide-card h3 { font-size:1.55rem; letter-spacing:-.04em; margin:28px 0 12px; }
.guide-card p { color:var(--muted); line-height:1.55; }
.guide-card .arrow { margin-top:auto; font-weight:900; color:var(--green); }

.article { width:min(820px, calc(100% - 32px)); margin:0 auto; padding:70px 0 100px; }
.article h1 { max-width:13ch; font-size:clamp(2.8rem,7vw,5.8rem); }
.article h2 { margin-top:48px; font-size:2rem; letter-spacing:-.04em; }
.article h3 { margin-top:32px; }
.article p, .article li { color:#46514b; line-height:1.75; }
.article .lede { font-size:1.2rem; }
.callout { border-left:4px solid var(--orange); background:var(--card); padding:18px 22px; margin:28px 0; }
.source-list { border-top:1px solid var(--line); margin-top:54px; padding-top:22px; }
.source-list a { color:var(--blue); }
table { width:100%; border-collapse:collapse; margin:24px 0; background:var(--card); }
th,td { border:1px solid var(--line); padding:12px; text-align:left; vertical-align:top; }
th { background:#ecebe4; }
.footer { border-top:1px solid var(--line); padding:28px 0 42px; color:var(--muted); font-size:.82rem; }
.footer .shell { display:flex; flex-wrap:wrap; align-items:center; justify-content:space-between; gap:14px; }
.footer-links { display:flex; flex-wrap:wrap; gap:14px; }
.footer-links a { color:var(--muted); text-decoration:none; }
.footer-links a:hover { color:var(--ink); text-decoration:underline; }

@media (max-width: 880px) {
  nav { display:none; }
  .hero, .planner { grid-template-columns:1fr; }
  .hero { padding-top:48px; }
  .results { position:static; }
  .mobile-summary { grid-column:1/-1; position:sticky; top:68px; z-index:8; display:grid; grid-template-columns:1fr 1fr auto; align-items:center; gap:10px; padding:12px 14px; border-radius:16px; background:var(--ink); color:white; box-shadow:var(--shadow); }
  .mobile-summary div { display:flex; flex-direction:column; gap:2px; }
  .mobile-summary span { color:#c8d0cc; font-size:.7rem; }
  .mobile-summary strong { font-size:1.05rem; }
  .mobile-summary a { color:var(--lime); font-size:.75rem; text-decoration:none; font-weight:800; }
  .guide-grid { grid-template-columns:1fr; }
}
@media (max-width: 560px) {
  .shell { width:min(100% - 20px,1180px); }
  .topbar .shell { gap:10px; }
  .brand { font-size:1rem; }
  .form-grid { grid-template-columns:1fr; padding:18px; }
  .presets { padding:16px 18px 0; grid-template-columns:1fr; }
  .presets p { grid-column:auto; }
  .field.full { grid-column:auto; }
  .result-grid { grid-template-columns:1fr; }
  .metric { border-right:0; }
  h1 { font-size:3.2rem; }
}
@media print {
  body { background:white; }
  .topbar, .hero, #planner-form, .mobile-summary, .guides, .footer, .result-actions { display:none !important; }
  .shell, .planner { width:100%; display:block; padding:0; }
  .results { position:static; box-shadow:none; border:0; }
  .print-only { display:block; padding:0 22px 24px; color:var(--ink); font-size:.85rem; line-height:1.6; }
}