/* Mean Calculator — light theme, indigo + amber brand. Vanilla CSS, mobile-first. */
:root{
  --bg:#f6f8fc; --card:#ffffff; --ink:#17233f; --muted:#54648a; --line:#d9e1ef;
  --brand:#2456c8; --brand-dark:#173a7d; --header:#101f3c; --accent:#f0a22e; --accent-dark:#c77f1a;
  --soft:#eaf0fb; --good:#157347; --radius:14px;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;background:var(--bg);color:var(--ink);font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;font-size:17px;line-height:1.65}
.wrap{max-width:1060px;margin:0 auto;padding:0 18px}
.skip-link{position:absolute;left:-9999px;top:0;background:var(--brand-dark);color:#fff;padding:10px 16px;z-index:50}
.skip-link:focus{left:8px;top:8px}
a{color:var(--brand)}
a:hover{color:var(--brand-dark)}
h1{font-size:2rem;line-height:1.2;margin:.35em 0 .3em}
h2{font-size:1.45rem;line-height:1.3;margin:1.6em 0 .5em;color:var(--brand-dark)}
h3{font-size:1.12rem;margin:1.2em 0 .4em}
p{margin:.55em 0}
ul,ol{margin:.5em 0 .8em;padding-left:1.35em}
li{margin:.28em 0}
strong{color:var(--ink)}
.muted{color:var(--muted)}
.small{font-size:.9rem}

/* Header */
.site-header{background:var(--header);color:#fff;position:relative}
.header-inner{display:flex;flex-wrap:wrap;align-items:center;gap:6px 14px;padding-top:10px;padding-bottom:10px}
.brand{display:flex;align-items:center;gap:10px;text-decoration:none;color:#fff;font-weight:700;font-size:1.12rem;letter-spacing:.2px;min-height:48px}
.brand em{font-style:normal;color:var(--accent)}
.brand svg{flex:none}
.menu-btn{margin-left:auto;background:rgba(255,255,255,.08);border:1px solid rgba(255,255,255,.25);color:#fff;border-radius:10px;padding:0 15px;min-height:48px;font-size:1.25rem;cursor:pointer}
.main-nav{display:none;width:100%}
.main-nav.open{display:block}
.main-nav ul{list-style:none;margin:0;padding:6px 0 10px;display:flex;flex-direction:column;gap:2px}
.main-nav a{display:block;color:#cfdaf2;text-decoration:none;padding:12px 10px;border-radius:10px;font-size:1rem}
.main-nav a:hover{background:rgba(255,255,255,.09);color:#fff}
@media (min-width:900px){
  .menu-btn{display:none}
  .main-nav{display:block;width:auto;margin-left:auto}
  .main-nav ul{flex-direction:row;padding:0;gap:2px}
  .main-nav a{padding:10px 12px}
}

/* Breadcrumb + byline */
.breadcrumb{font-size:.88rem;color:var(--muted);padding:14px 0 0}
.breadcrumb a{color:var(--muted)}
.byline{font-size:.9rem;color:var(--muted);margin:2px 0 14px}
.byline a{color:var(--muted);text-decoration:underline}

/* Hero */
.hero{padding:10px 0 4px}
.hero .sub{font-size:1.12rem;color:var(--muted);max-width:44em;margin-top:0}

/* Tool card */
.tool-card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:20px;margin:16px 0 26px;box-shadow:0 2px 14px rgba(23,35,63,.06)}
.tool-card label{font-weight:700;display:block;margin-bottom:6px}
.tool-card textarea{width:100%;border:2px solid var(--line);border-radius:10px;padding:12px;font:inherit;font-size:1.05rem;resize:vertical;min-height:56px;background:#fbfcfe}
.tool-card textarea:focus{outline:none;border-color:var(--brand)}
.micro{font-size:.88rem;color:var(--muted);margin-top:6px}
.tool-actions{display:flex;flex-wrap:wrap;gap:10px;margin:14px 0 4px}
.btn{background:var(--brand);color:#fff;border:none;border-radius:10px;padding:0 20px;min-height:48px;font:inherit;font-weight:600;cursor:pointer;display:inline-flex;align-items:center;justify-content:center;text-decoration:none}
.btn:hover{background:var(--brand-dark);color:#fff}
.btn-ghost{background:var(--soft);color:var(--brand-dark)}
.btn-ghost:hover{background:#d7e3f8}
.btn-accent{background:var(--accent);color:#231600}
.btn-accent:hover{background:var(--accent-dark);color:#fff}
.toggle-row{display:flex;align-items:center;gap:8px;flex-wrap:wrap;margin:16px 0 4px;font-weight:600}
.toggle-group{display:inline-flex;border:2px solid var(--line);border-radius:10px;overflow:hidden}
.toggle-group button{background:#fff;border:none;padding:0 18px;min-height:48px;font:inherit;font-weight:600;cursor:pointer;color:var(--muted)}
.toggle-group button[aria-pressed="true"]{background:var(--brand);color:#fff}
.check-row{display:flex;align-items:center;gap:10px;margin:12px 0 0;font-weight:600}
.check-row input{width:22px;height:22px;accent-color:var(--brand)}

/* Results */
.results{margin-top:16px}
.results-headline{background:var(--soft);border:1px solid var(--line);border-radius:12px;padding:14px 18px;display:flex;flex-wrap:wrap;gap:8px 34px;align-items:baseline}
.results-headline .rh-item .rh-label{font-size:.85rem;color:var(--muted);text-transform:uppercase;letter-spacing:.06em}
.results-headline .rh-item .rh-value{font-size:1.7rem;font-weight:800;color:var(--brand-dark);line-height:1.15}
.results-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:10px;margin-top:10px}
.rg-item{background:#fbfcfe;border:1px solid var(--line);border-radius:10px;padding:10px 14px}
.rg-item .rg-label{font-size:.82rem;color:var(--muted);text-transform:uppercase;letter-spacing:.05em}
.rg-item .rg-value{font-size:1.22rem;font-weight:700}
@media (min-width:640px){.results-grid{grid-template-columns:repeat(4,1fr)}}
.results-empty{color:var(--muted);border:1px dashed var(--line);border-radius:10px;padding:14px 16px;margin-top:16px}

/* Steps */
.steps{margin-top:20px;border-top:1px solid var(--line);padding-top:14px}
.steps h3{margin-top:0;color:var(--brand-dark)}
.step{margin:.5em 0}
.step .step-n{display:inline-block;background:var(--brand);color:#fff;border-radius:50%;width:26px;height:26px;line-height:26px;text-align:center;font-size:.85rem;font-weight:700;margin-right:8px}
.step .answer{font-weight:800;color:var(--brand-dark)}
.sorted-line{font-family:ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;font-size:.95rem;background:#fbfcfe;border:1px solid var(--line);border-radius:8px;padding:8px 12px;overflow-x:auto;white-space:nowrap}
.sorted-line .mid{background:var(--accent);border-radius:4px;padding:0 4px;font-weight:700}

/* Tables */
.table-wrap{overflow-x:auto;margin:12px 0;border:1px solid var(--line);border-radius:10px}
table{border-collapse:collapse;width:100%;background:#fff}
th,td{padding:9px 12px;text-align:left;border-bottom:1px solid var(--line);font-size:.97rem}
th{background:var(--soft);color:var(--brand-dark)}
tr:last-child td{border-bottom:none}
td.num,th.num{text-align:right;font-variant-numeric:tabular-nums}

/* Row editors (weighted / frequency tools) */
.rows-editor{margin:10px 0}
.rows-head,.row-line{display:grid;grid-template-columns:1fr 1fr 52px;gap:8px;align-items:center;margin-bottom:8px}
.rows-head{font-weight:700;font-size:.9rem;color:var(--muted)}
.rows-head.freq,.row-line.freq{grid-template-columns:1fr 1fr 1fr 52px}
.row-line input{width:100%;border:2px solid var(--line);border-radius:8px;padding:10px;font:inherit;min-height:48px}
.row-line input:focus{outline:none;border-color:var(--brand)}
.row-del{background:#fdecec;color:#9c2222;border:1px solid #f3c2c2;border-radius:8px;min-height:48px;font-size:1.1rem;cursor:pointer}
.mode-tabs{display:flex;gap:8px;flex-wrap:wrap;margin:8px 0 4px}

/* Content blocks */
.formula-box{background:var(--soft);border:1px solid var(--line);border-left:5px solid var(--accent);border-radius:10px;padding:14px 18px;margin:14px 0;font-size:1.08rem}
.formula-box .big{font-size:1.35rem;font-weight:800;color:var(--brand-dark)}
.note-box{background:#fff8ea;border:1px solid #f0dcb0;border-radius:10px;padding:12px 16px;margin:14px 0}
main img.content-img{max-width:100%;height:auto;border-radius:12px;border:1px solid var(--line);margin:10px 0;background:#fff}
figure{margin:14px 0}
figure img{max-width:100%;height:auto;border-radius:12px;border:1px solid var(--line);background:#fff}
figcaption{font-size:.88rem;color:var(--muted);margin-top:6px}
.boxplot-box{background:#fff;border:1px solid var(--line);border-radius:10px;padding:10px;margin:12px 0}

/* FAQ */
.faq{margin-top:8px}
.faq-item{border-bottom:1px solid var(--line);padding:6px 0 10px}
.faq-item h3{margin-bottom:.2em}

/* Cards */
.card-grid{display:grid;grid-template-columns:1fr;gap:12px;margin:14px 0}
@media (min-width:640px){.card-grid{grid-template-columns:repeat(2,1fr)}}
@media (min-width:960px){.card-grid{grid-template-columns:repeat(3,1fr)}}
.calc-card{background:#fff;border:1px solid var(--line);border-radius:12px;padding:16px 18px;text-decoration:none;color:var(--ink);display:block}
.calc-card:hover{border-color:var(--brand);box-shadow:0 3px 12px rgba(23,35,63,.09)}
.calc-card .cc-title{font-weight:700;color:var(--brand-dark);font-size:1.05rem}
.calc-card .cc-desc{color:var(--muted);font-size:.93rem;margin-top:4px}
.post-card{background:#fff;border:1px solid var(--line);border-radius:12px;padding:16px 18px;text-decoration:none;color:var(--ink);display:block}
.post-card:hover{border-color:var(--brand)}
.post-card .cc-title{font-weight:700;color:var(--brand-dark)}
.post-card .cc-desc{color:var(--muted);font-size:.93rem;margin-top:4px}

/* Footer */
.site-footer{background:var(--header);color:#cfdaf2;margin-top:48px;padding:34px 0 26px}
.footer-grid{display:grid;grid-template-columns:1fr;gap:22px}
@media (min-width:760px){.footer-grid{grid-template-columns:1.4fr 1fr 1fr 1fr}}
.site-footer h3{color:#fff;font-size:1rem;margin:0 0 8px}
.site-footer ul{list-style:none;margin:0;padding:0}
.site-footer li{margin:.35em 0}
.site-footer a{color:#cfdaf2;text-decoration:none}
.site-footer a:hover{color:#fff;text-decoration:underline}
.footer-brand{display:flex;align-items:center;gap:9px;color:#fff;font-weight:700;font-size:1.08rem}
.footer-brand em{font-style:normal;color:var(--accent)}
.footer-note{font-size:.9rem;color:#9fb2d8;max-width:36em}
.footer-bottom{border-top:1px solid rgba(255,255,255,.15);margin-top:24px;padding-top:16px;font-size:.88rem;color:#9fb2d8;display:flex;flex-wrap:wrap;gap:6px 20px}

/* 404 */
.notfound{padding:34px 0 10px;text-align:left}

@media print{
  .site-header,.site-footer,.tool-actions,.menu-btn,.breadcrumb{display:none}
  body{background:#fff}
  .tool-card{box-shadow:none;border:none;padding:0}
}