:root {
  --bg: #f6f7fb;
  --surface: #ffffff;
  --text: #161a2b;
  --muted: #5d6478;
  --border: #e3e6ef;
  --accent: #2f5bea;
  --accent-soft: #eaf0ff;
  --danger: #d6455d;
  --ok: #1f9d63;
  --warn: #c98a12;
  --radius: 14px;
  --shadow: 0 1px 2px rgba(20, 30, 60, .04), 0 8px 24px rgba(20, 30, 60, .06);
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.6 -apple-system, BlinkMacSystemFont, "Segoe UI", Inter, Roboto, Helvetica, Arial, sans-serif;
}
.wrap { max-width: 880px; margin: 0 auto; padding: 0 16px; }
a { color: var(--accent); }
h1, h2, h3 { line-height: 1.25; margin: 0 0 .5em; }

/* Header */
.site-header { background: var(--surface); border-bottom: 1px solid var(--border); }
.header-inner { display: flex; align-items: center; justify-content: space-between; height: 56px; }
.logo { display: flex; align-items: center; gap: 8px; font-weight: 700; color: var(--text); text-decoration: none; font-size: 18px; }
.logo-mark { display: grid; place-items: center; width: 28px; height: 28px; border-radius: 8px; background: var(--accent); color: #fff; font-size: 15px; }
.nav { display: flex; gap: 18px; }
.nav a { color: var(--muted); text-decoration: none; font-size: 14px; }
.nav a:hover { color: var(--text); }

/* Hero */
.hero { padding-top: 24px; }
h1 { font-size: clamp(24px, 5vw, 34px); letter-spacing: -.01em; }
.subtitle { color: var(--muted); margin: 0 0 18px; }

/* Tabs */
.tabs { display: grid; grid-template-columns: 1fr 1fr; gap: 4px; background: #e9ecf4; padding: 4px; border-radius: 12px; margin-bottom: 14px; }
.tab { border: 0; background: transparent; padding: 10px 8px; border-radius: 9px; font: inherit; font-weight: 600; font-size: 15px; color: var(--muted); cursor: pointer; }
.tab.is-active { background: var(--surface); color: var(--accent); box-shadow: 0 1px 3px rgba(20, 30, 60, .1); }

/* Tool card */
.tool-card { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); box-shadow: var(--shadow); padding: 20px; }
.card-head { display: flex; flex-wrap: wrap; gap: 12px; justify-content: space-between; align-items: flex-start; margin-bottom: 14px; }
.card-head h2 { font-size: 19px; margin-bottom: 2px; }
.hint { color: var(--muted); font-size: 14px; margin: 0; }
.subject-name { flex: 1 1 220px; max-width: 300px; }

input[type=text], input[type=number] {
  width: 100%; min-width: 0;
  font: inherit; font-size: 16px; color: var(--text);
  padding: 9px 11px; border: 1px solid var(--border); border-radius: 9px; background: #fbfcfe;
  transition: border-color .15s, box-shadow .15s;
}
input:focus { outline: none; border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-soft); background: #fff; }
input.is-invalid { border-color: var(--danger); box-shadow: 0 0 0 3px rgba(214, 69, 93, .12); }
input[type=number] { -moz-appearance: textfield; }
input[type=number]::-webkit-inner-spin-button, input[type=number]::-webkit-outer-spin-button { -webkit-appearance: none; margin: 0; }

.rows-head, .row { display: grid; grid-template-columns: 1fr 92px 92px 36px; gap: 8px; align-items: center; }
.rows-head { font-size: 12px; font-weight: 600; color: var(--muted); text-transform: uppercase; letter-spacing: .04em; padding: 0 2px 6px; }
.rows { display: grid; gap: 8px; }
.row-del { width: 36px; height: 38px; border: 0; background: transparent; color: #9aa1b4; border-radius: 8px; cursor: pointer; font-size: 20px; line-height: 1; }
.row-del:hover { background: #fdecef; color: var(--danger); }

.actions { display: flex; gap: 8px; margin: 12px 0 16px; flex-wrap: wrap; }
.btn { font: inherit; font-weight: 600; font-size: 15px; border-radius: 10px; padding: 10px 16px; cursor: pointer; border: 1px solid transparent; transition: background .15s, border-color .15s, transform .05s; }
.btn:active { transform: translateY(1px); }
.btn-primary { background: var(--accent); color: #fff; }
.btn-primary:hover { background: #2549c6; }
.btn-primary:disabled { background: #b8c3e6; cursor: not-allowed; }
.btn-ghost { background: var(--surface); color: var(--accent); border-color: var(--border); }
.btn-ghost:hover { border-color: var(--accent); }
.btn-muted { color: var(--muted); }
.btn-block { width: 100%; }

/* Result */
.result { background: var(--accent-soft); border-radius: 12px; padding: 14px 16px; }
.result-main { display: flex; align-items: baseline; gap: 12px; flex-wrap: wrap; }
.result-label { font-weight: 600; color: var(--muted); }
.result-value { font-size: 40px; font-weight: 800; letter-spacing: -.02em; line-height: 1; font-variant-numeric: tabular-nums; }
.badge { font-size: 13px; font-weight: 700; padding: 4px 10px; border-radius: 999px; background: #fff; }
.badge:empty { display: none; }
.badge.b-fail { color: var(--danger); }
.badge.b-pass { color: var(--warn); }
.badge.b-good { color: var(--accent); }
.badge.b-great { color: var(--ok); }
.progress { height: 8px; background: rgba(47, 91, 234, .15); border-radius: 99px; margin: 12px 0 8px; overflow: hidden; }
.progress span { display: block; height: 100%; width: 0; background: var(--accent); border-radius: 99px; transition: width .3s ease; }
.result-detail { margin: 0; font-size: 14px; color: var(--muted); }
.result-detail strong { color: var(--text); }
.result-detail .warn { color: var(--warn); font-weight: 600; }

.card-foot { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 14px; }
.privacy { font-size: 14px; color: var(--muted); text-align: center; margin: 12px 0 0; }
.notice { background: #fff4e0; padding: 12px; border-radius: 10px; }

/* Ad slots: AdSense blocks pasted here show; empty slots take no space */
.ad-slot { text-align: center; }
.ad-slot:empty { display: none; }
.ad-leaderboard { margin: 28px 0; }
.ad-incontent { max-width: 640px; margin: 8px auto 32px; }

/* Content */
.content { padding-top: 12px; padding-bottom: 12px; }
.content > h2 { font-size: 24px; margin-top: 8px; }
.content > h3 { font-size: 18px; margin-top: 28px; }
.content p { color: #333a50; }
.steps { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; margin: 16px 0; }
.step { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 18px; }
.step h3 { font-size: 16px; }
.step p { font-size: 14px; margin: 0 0 8px; }
.step-icon { width: 40px; height: 40px; display: grid; place-items: center; border-radius: 10px; background: var(--accent-soft); color: var(--accent); margin-bottom: 10px; }
.formula { font-family: ui-monospace, SFMono-Regular, Consolas, monospace; font-size: 13px !important; background: #f3f5fa; padding: 6px 8px; border-radius: 6px; }
.example { color: var(--muted) !important; }

.faq { display: grid; gap: 8px; margin-bottom: 24px; }
.faq details { background: var(--surface); border: 1px solid var(--border); border-radius: 12px; padding: 0 16px; }
.faq summary { cursor: pointer; font-weight: 600; padding: 14px 0; list-style: none; position: relative; padding-right: 24px; }
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after { content: "+"; position: absolute; right: 0; top: 12px; font-size: 20px; color: var(--accent); }
.faq details[open] summary::after { content: "−"; }
.faq details p { margin: 0 0 14px; font-size: 15px; }

/* Footer */
.site-footer { border-top: 1px solid var(--border); background: var(--surface); margin-top: 24px; }
.footer-inner { display: flex; justify-content: space-between; flex-wrap: wrap; gap: 8px; padding-top: 18px; padding-bottom: 18px; font-size: 14px; color: var(--muted); }
.footer-inner nav { display: flex; gap: 16px; }
.footer-inner a { color: var(--muted); }


/* Responsive */
@media (max-width: 720px) {
  .steps { grid-template-columns: 1fr; }
}
@media (max-width: 560px) {
  .nav { display: none; }
  .tool-card { padding: 14px; }
  .subject-name { max-width: none; }
  .rows-head, .row { grid-template-columns: 1fr 64px 64px 30px; gap: 6px; }
  input[type=text], input[type=number] { padding: 9px 8px; }
  .row-del { width: 30px; }
  .result-value { font-size: 34px; }
  .card-foot .btn { flex: 1 1 100%; }
}
@media (prefers-reduced-motion: reduce) {
  .progress span { transition: none; }
}

/* Legal pages */
.legal h2 { font-size: 18px; margin-top: 28px; }
.legal .updated { color: var(--muted); font-size: 14px; }
.legal .data { display: grid; grid-template-columns: max-content 1fr; gap: 6px 16px; background: var(--surface); border: 1px solid var(--border); border-radius: 12px; padding: 14px 16px; }
.legal .data dt { font-weight: 600; }
.legal .data dd { margin: 0; overflow-wrap: anywhere; }
.legal .table-wrap { overflow-x: auto; }
.legal table { width: 100%; border-collapse: collapse; background: var(--surface); font-size: 14px; }
.legal th, .legal td { border: 1px solid var(--border); padding: 8px 10px; text-align: left; vertical-align: top; }
@media (max-width: 560px) { .legal .data { grid-template-columns: 1fr; } .legal .data dd { margin-bottom: 6px; } }