/* Calcaholic — global stylesheet */
:root {
  --ink: #1a2333;
  --ink-soft: #4b5670;
  --ink-faint: #8a93a8;
  --bg: #f6f8fb;
  --card: #ffffff;
  --line: #e3e8f0;
  --accent: #4f46e5;
  --accent-dark: #4338ca;
  --accent-soft: #eef2ff;
  --good: #059669;
  --warn: #d97706;
  --bad: #dc2626;
  --radius: 14px;
  --shadow: 0 1px 3px rgba(26, 35, 51, 0.07), 0 8px 24px rgba(26, 35, 51, 0.06);
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  font-size: 17px;
  line-height: 1.6;
  color: var(--ink);
  background: var(--bg);
}

/* ---------- Header ---------- */
.site-header {
  background: var(--card);
  border-bottom: 1px solid var(--line);
}
.site-header .wrap {
  max-width: 1080px;
  margin: 0 auto;
  padding: 14px 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
}
.logo {
  font-size: 1.45rem;
  font-weight: 800;
  text-decoration: none;
  color: var(--ink);
  letter-spacing: -0.02em;
}
.logo span { color: var(--accent); }
.site-nav { display: flex; gap: 4px; flex-wrap: wrap; }
.site-nav a {
  text-decoration: none;
  color: var(--ink-soft);
  font-size: 0.95rem;
  font-weight: 600;
  padding: 6px 12px;
  border-radius: 8px;
}
.site-nav a:hover { background: var(--accent-soft); color: var(--accent-dark); }

/* ---------- Layout ---------- */
.page {
  max-width: 760px;
  margin: 0 auto;
  padding: 28px 20px 64px;
}
.breadcrumb {
  font-size: 0.85rem;
  color: var(--ink-faint);
  margin-bottom: 14px;
}
.breadcrumb a { color: var(--ink-faint); text-decoration: none; }
.breadcrumb a:hover { color: var(--accent); }

h1 {
  font-size: 2rem;
  line-height: 1.2;
  letter-spacing: -0.02em;
  margin: 0 0 10px;
}
.intro { font-size: 1.05rem; color: var(--ink-soft); margin: 0 0 24px; }

h2 { font-size: 1.4rem; margin: 40px 0 12px; letter-spacing: -0.01em; }
h3 { font-size: 1.1rem; margin: 24px 0 8px; }

a { color: var(--accent); }

/* ---------- Calculator card ---------- */
.calc-card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 24px;
}
.calc-form .field { margin-bottom: 16px; }
.calc-form label {
  display: block;
  font-weight: 600;
  font-size: 0.92rem;
  margin-bottom: 5px;
}
.calc-form .hint {
  font-weight: 400;
  color: var(--ink-faint);
  font-size: 0.85rem;
}
.calc-form input[type="number"],
.calc-form input[type="text"],
.calc-form select {
  width: 100%;
  padding: 11px 13px;
  font-size: 1.05rem;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: #fbfcfe;
  color: var(--ink);
}
.calc-form input:focus, .calc-form select:focus {
  outline: 2px solid var(--accent);
  outline-offset: 0;
  border-color: var(--accent);
}
.field-row { display: flex; gap: 12px; }
.field-row .field { flex: 1; }

.mode-toggle { display: flex; gap: 8px; margin-bottom: 18px; flex-wrap: wrap; }
.mode-toggle label {
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 7px 14px;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--ink-soft);
  cursor: pointer;
  user-select: none;
}
.mode-toggle input { position: absolute; opacity: 0; pointer-events: none; }
.mode-toggle label:has(input:checked) {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}

.btn {
  display: inline-block;
  border: 0;
  border-radius: 10px;
  padding: 12px 22px;
  font-size: 1.05rem;
  font-weight: 700;
  cursor: pointer;
  text-decoration: none;
  text-align: center;
}
.btn-primary { background: var(--accent); color: #fff; width: 100%; }
.btn-primary:hover { background: var(--accent-dark); }
.btn-ghost {
  background: transparent;
  color: var(--ink-soft);
  border: 1px solid var(--line);
  font-size: 0.88rem;
  font-weight: 600;
  padding: 8px 14px;
}
.btn-ghost:hover { border-color: var(--accent); color: var(--accent); }

/* ---------- Result ---------- */
.result {
  margin-top: 20px;
  padding: 20px;
  border-radius: 12px;
  background: var(--accent-soft);
  border: 1px solid #dfe3fb;
  display: none;
}
.result.show { display: block; }
.result .big {
  font-size: 2.2rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.15;
  color: var(--accent-dark);
}
.result .big.good { color: var(--good); }
.result .big.warn { color: var(--warn); }
.result .big.bad { color: var(--bad); }
.result .note { color: var(--ink-soft); font-size: 0.95rem; margin-top: 6px; }
.result table { width: 100%; border-collapse: collapse; margin-top: 12px; font-size: 0.92rem; }
.result th, .result td { text-align: right; padding: 6px 8px; border-bottom: 1px solid #dfe3fb; }
.result th:first-child, .result td:first-child { text-align: left; }

/* ---------- Share / embed row ---------- */
.share-row {
  display: flex;
  gap: 8px;
  margin-top: 16px;
  flex-wrap: wrap;
  align-items: center;
}
.share-row .spacer { flex: 1; }

/* ---------- Disclaimer ---------- */
.disclaimer {
  margin: 18px 0 0;
  padding: 12px 16px;
  border: 1px solid var(--line);
  border-left: 4px solid var(--warn);
  border-radius: 0 10px 10px 0;
  background: var(--card);
  font-size: 0.85rem;
  color: var(--ink-soft);
}

/* ---------- Ad slot (reserved; house ads until AdSense) ---------- */
.ad-slot {
  margin: 28px 0;
  min-height: 120px;
  display: flex;
  align-items: center;
  justify-content: center;
}
.house-ad {
  width: 100%;
  border: 1px dashed #c7cff0;
  border-radius: var(--radius);
  background: linear-gradient(135deg, #eef2ff, #fdf4ff);
  padding: 22px;
  text-align: center;
}
.house-ad strong { display: block; font-size: 1.05rem; margin-bottom: 4px; }
.house-ad p { margin: 0 0 12px; color: var(--ink-soft); font-size: 0.92rem; }

/* ---------- Article content ---------- */
.content { margin-top: 8px; }
.content .formula {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 14px 18px;
  font-family: "Cambria Math", Georgia, serif;
  font-size: 1.12rem;
  overflow-x: auto;
}
.content .example {
  background: var(--card);
  border-left: 4px solid var(--accent);
  border-radius: 0 10px 10px 0;
  padding: 14px 18px;
  box-shadow: var(--shadow);
}

/* ---------- FAQ ---------- */
.faq details {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 0 18px;
  margin-bottom: 10px;
}
.faq summary {
  font-weight: 700;
  padding: 14px 0;
  cursor: pointer;
  list-style-position: outside;
}
.faq details p { margin-top: 0; color: var(--ink-soft); }

/* ---------- Related ---------- */
.related-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(210px, 1fr));
  gap: 12px;
  padding: 0;
  list-style: none;
}
.related-grid a {
  display: block;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 14px 16px;
  text-decoration: none;
  color: var(--ink);
  font-weight: 600;
  font-size: 0.95rem;
}
.related-grid a:hover { border-color: var(--accent); color: var(--accent-dark); }

/* ---------- Embed modal ---------- */
.modal-backdrop {
  position: fixed; inset: 0;
  background: rgba(20, 25, 40, 0.55);
  display: none;
  align-items: center;
  justify-content: center;
  padding: 20px;
  z-index: 50;
}
.modal-backdrop.show { display: flex; }
.modal {
  background: var(--card);
  border-radius: var(--radius);
  max-width: 560px;
  width: 100%;
  padding: 24px;
  box-shadow: 0 24px 64px rgba(0,0,0,0.25);
}
.modal h3 { margin: 0 0 8px; }
.modal p { color: var(--ink-soft); font-size: 0.92rem; margin: 0 0 12px; }
.modal textarea {
  width: 100%;
  height: 130px;
  font-family: Consolas, Menlo, monospace;
  font-size: 0.8rem;
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 12px;
  resize: vertical;
  color: var(--ink-soft);
  background: #fbfcfe;
}
.modal .modal-actions { display: flex; gap: 10px; margin-top: 12px; justify-content: flex-end; }

/* ---------- Homepage ---------- */
.hero { text-align: center; padding: 44px 20px 8px; }
.hero h1 { font-size: 2.5rem; }
.hero p { font-size: 1.15rem; color: var(--ink-soft); max-width: 560px; margin: 0 auto; }
.hero-search { max-width: 480px; margin: 22px auto 0; }
.hero-search input {
  width: 100%;
  padding: 14px 20px;
  font-size: 1.05rem;
  border: 2px solid var(--line);
  border-radius: 999px;
  background: var(--card);
  color: var(--ink);
  box-shadow: var(--shadow);
}
.hero-search input:focus { outline: none; border-color: var(--accent); }
.cat-icon { font-size: 1.15em; margin-right: 4px; }
.home-section { max-width: 1080px; margin: 0 auto; padding: 24px 20px; }
.home-section h2 { margin-top: 8px; }
.calc-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(230px, 1fr));
  gap: 14px;
  padding: 0;
  list-style: none;
}
.calc-grid a {
  display: block;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 18px;
  text-decoration: none;
  color: var(--ink);
  box-shadow: var(--shadow);
}
.calc-grid a:hover { border-color: var(--accent); transform: translateY(-1px); }
.calc-grid strong { display: block; margin-bottom: 4px; }
.calc-grid span { color: var(--ink-faint); font-size: 0.85rem; line-height: 1.4; display: block; }

/* ---------- Footer ---------- */
.site-footer {
  border-top: 1px solid var(--line);
  background: var(--card);
  margin-top: 48px;
}
.site-footer .wrap {
  max-width: 1080px;
  margin: 0 auto;
  padding: 28px 20px;
  display: flex;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
  font-size: 0.88rem;
  color: var(--ink-faint);
}
.site-footer a { color: var(--ink-soft); text-decoration: none; margin-right: 16px; }
.site-footer a:hover { color: var(--accent); }

/* ---------- Embed mode ---------- */
body.embed { background: transparent; }
body.embed .page { padding: 10px; max-width: none; }
.embed-footer {
  text-align: right;
  font-size: 0.78rem;
  margin-top: 10px;
  color: var(--ink-faint);
}
.embed-footer a { color: var(--accent); font-weight: 600; text-decoration: none; }

@media (max-width: 560px) {
  h1 { font-size: 1.6rem; }
  .hero h1 { font-size: 1.9rem; }
  .field-row { flex-direction: column; gap: 0; }
  .calc-card { padding: 18px; }
}