:root {
  --bg: #f6f4ee;
  --card: #fffdf8;
  --ink: #2b2721;
  --muted: #8b8476;
  --accent: #0f6cac;
  --accent-dark: #0b5a91;
  --accent-soft: #e9f1f8;
  --line: #e8e4d8;
  --line-strong: #d3cdbd;
  --ok: #2f7a4d;
  --radius: 16px;
  --radius-sm: 10px;
  --shadow-sm: 0 1px 2px rgba(64, 55, 40, 0.05), 0 1px 3px rgba(64, 55, 40, 0.07);
  --shadow-md: 0 4px 14px rgba(64, 55, 40, 0.09), 0 2px 6px rgba(64, 55, 40, 0.06);
  --shadow-lg: 0 18px 44px rgba(64, 55, 40, 0.14), 0 6px 16px rgba(64, 55, 40, 0.09);
  --shadow-accent: 0 4px 16px rgba(15, 108, 172, 0.34);
  --ring: 0 0 0 4px rgba(15, 108, 172, 0.16);
  --ease: cubic-bezier(0.16, 1, 0.3, 1);
  --header-bg: rgba(255, 253, 248, 0.78);
  color-scheme: light;
}
html.dark {
  --bg: #1b1915;
  --card: #262219;
  --ink: #f1ebdf;
  --muted: #a49c8b;
  --accent: #58a7e6;
  --accent-dark: #7dbdf0;
  --accent-soft: #1d2b36;
  --line: #322e25;
  --line-strong: #443f33;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.5);
  --shadow-md: 0 4px 14px rgba(0, 0, 0, 0.55);
  --shadow-lg: 0 18px 44px rgba(0, 0, 0, 0.65), 0 6px 16px rgba(0, 0, 0, 0.45);
  --shadow-accent: 0 4px 16px rgba(88, 167, 230, 0.35);
  --ring: 0 0 0 4px rgba(88, 167, 230, 0.25);
  --header-bg: rgba(27, 25, 21, 0.74);
  color-scheme: dark;
}
html.theme-fade :not(.theme-toggle):not(.theme-toggle *) {
  transition: background-color 0.45s var(--ease), color 0.45s var(--ease), border-color 0.45s var(--ease), box-shadow 0.45s var(--ease), fill 0.45s var(--ease), stroke 0.45s var(--ease) !important;
}
* { box-sizing: border-box; }
html { background: var(--bg); -webkit-font-smoothing: antialiased; text-rendering: optimizeLegibility; scrollbar-width: thin; scrollbar-color: #c8c2b2 transparent; }
html.lenis, html.lenis body { height: auto; }
.lenis.lenis-smooth { scroll-behavior: auto !important; }
::-webkit-scrollbar { width: 10px; height: 10px; }
::-webkit-scrollbar-thumb { background: #c8c2b2; border-radius: 8px; border: 2px solid transparent; background-clip: padding-box; transition: background 0.25s var(--ease); }
::-webkit-scrollbar-thumb:hover { background-color: #aba394; }
::-webkit-scrollbar-track { background: transparent; }
html.dark { scrollbar-color: #4a463c transparent; }
html.dark ::-webkit-scrollbar-thumb { background: #4a463c; background-clip: padding-box; }
html.dark ::-webkit-scrollbar-thumb:hover { background-color: #615c50; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Text", "SF Pro Display", "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background: var(--bg);
  color: var(--ink);
  line-height: 1.6;
  font-size: 16px;
}
::selection { background: rgba(15, 108, 172, 0.2); }
:focus-visible { outline: 3px solid rgba(15, 108, 172, 0.45); outline-offset: 2px; border-radius: 4px; }
html.dark :focus-visible { outline-color: rgba(88, 167, 230, 0.55); }

.wrap { max-width: 1080px; margin: 0 auto; padding: 0 22px; }

/* ---------- Header ---------- */
header.site {
  position: sticky;
  top: 0;
  z-index: 50;
  background: var(--header-bg);
  backdrop-filter: blur(20px) saturate(1.8);
  -webkit-backdrop-filter: blur(20px) saturate(1.8);
  border-bottom: 1px solid rgba(90, 80, 60, 0.12);
}
html.dark header.site { border-bottom-color: rgba(255, 255, 255, 0.08); }
header.site .wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
  padding: 14px 22px;
}
.logo {
  font-weight: 700;
  font-size: 1.1rem;
  text-decoration: none;
  color: var(--ink);
  display: flex;
  align-items: center;
  gap: 10px;
  letter-spacing: -0.02em;
  transition: opacity 0.25s var(--ease), transform 0.25s var(--ease);
}
.logo:hover { opacity: 0.75; transform: scale(0.99); }
.logo .mark {
  width: 30px;
  height: 30px;
  border-radius: 8px;
  background: linear-gradient(180deg, #1680c9, #0a5690);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 15px;
  box-shadow: var(--shadow-accent);
}
nav.site { display: flex; align-items: center; gap: 6px; }
nav.site a {
  color: var(--muted);
  text-decoration: none;
  padding: 8px 14px;
  font-size: 0.92rem;
  border-radius: 8px;
  transition: color 0.28s var(--ease), background 0.28s var(--ease), transform 0.28s var(--ease);
}
nav.site a:hover { color: var(--ink); background: rgba(0, 0, 0, 0.05); }
nav.site a:active { transform: scale(0.96); }

/* ---------- Language switcher ---------- */
.lang-wrap { display: flex; align-items: center; gap: 8px; }
.lang-label { color: var(--muted); font-size: 0.82rem; white-space: nowrap; }
.lang-wrap select {
  appearance: none;
  -webkit-appearance: none;
  border: 1px solid var(--line-strong);
  background: var(--card) url("data:image/svg+xml;charset=utf-8,%3Csvg xmlns='http://www.w3.org/2000/svg' width='10' height='6' viewBox='0 0 10 6'%3E%3Cpath d='M1 1l4 4 4-4' stroke='%238b8476' stroke-width='1.5' fill='none' stroke-linecap='round'/%3E%3C/svg%3E") no-repeat right 12px center;
  color: var(--ink);
  font-size: 0.88rem;
  font-weight: 500;
  padding: 8px 32px 8px 14px;
  border-radius: 10px;
  cursor: pointer;
  transition: border-color 0.28s var(--ease), box-shadow 0.28s var(--ease);
}
.lang-wrap select:hover { border-color: #b8b1a0; box-shadow: 0 2px 8px rgba(64, 55, 40, 0.08); }
.lang-wrap select:focus { outline: none; border-color: var(--accent); box-shadow: var(--ring); }

/* ---------- Theme toggle ---------- */
.theme-toggle {
  flex: none;
  width: 38px;
  height: 38px;
  border-radius: 50%;
  border: 1px solid var(--line-strong);
  background: var(--card);
  color: var(--ink);
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0;
  overflow: hidden;
  transition: transform 0.28s var(--ease), border-color 0.28s var(--ease), background 0.28s var(--ease), box-shadow 0.28s var(--ease);
}
.theme-toggle:hover { transform: scale(1.07); border-color: var(--accent); box-shadow: 0 2px 10px rgba(64, 55, 40, 0.1); }
.theme-toggle:active { transform: scale(0.93); transition-duration: 0.12s; }
.theme-toggle:focus { outline: none; }
.theme-toggle:focus-visible { box-shadow: var(--ring); }
.tgl { position: relative; display: block; width: 22px; height: 22px; }
.sat { position: absolute; inset: 0; transform-origin: 11px 28px; transition: transform 0.6s ease-in-out; }
.sat .ic { display: block; width: 22px; height: 22px; transform-origin: 50% 50%; }
.sat-sun { transform: rotate(0deg); }
.sat-moon { transform: rotate(180deg); }
html.dark .sat-sun { transform: rotate(180deg); }
html.dark .sat-moon { transform: rotate(360deg); }
.sat-sun .ic { opacity: 1; transition: transform 0.6s ease-in-out, opacity 0.15s ease; }
.sat-moon .ic { opacity: 0; transform: rotate(-180deg); transition: transform 0.6s ease-in-out, opacity 0.15s ease 0.15s; }
html.dark .sat-sun .ic { opacity: 0; transition: transform 0.6s ease-in-out, opacity 0.15s ease 0.15s; }
html.dark .sat-moon .ic { opacity: 1; transform: rotate(-360deg); transition: transform 0.6s ease-in-out, opacity 0.15s ease; }

/* ---------- Hero ---------- */
.hero {
  text-align: center;
  padding: 72px 0 28px;
  max-width: 760px;
  margin: 0 auto;
}
.hero h1 {
  font-size: clamp(2.3rem, 5vw, 3.4rem);
  line-height: 1.08;
  margin: 0 0 14px;
  letter-spacing: -0.028em;
  font-weight: 700;
}
.hero p.lead {
  color: var(--muted);
  font-size: clamp(1.05rem, 2vw, 1.28rem);
  line-height: 1.5;
  margin: 0 auto;
  max-width: 640px;
  letter-spacing: -0.008em;
}

/* ---------- Typography ---------- */
h1 {
  font-size: 2.2rem;
  line-height: 1.14;
  margin: 0 0 10px;
  letter-spacing: -0.024em;
  font-weight: 700;
}
h2 {
  font-size: 1.5rem;
  margin: 44px 0 14px;
  letter-spacing: -0.02em;
  font-weight: 650;
}
h2#tools { scroll-margin-top: 80px; }
p.lead { color: var(--muted); margin: 0 0 22px; font-size: 1.1rem; }

/* ---------- Cards ---------- */
.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 30px;
  margin: 26px 0;
  box-shadow: var(--shadow-sm);
  transition: box-shadow 0.25s var(--ease), border-color 0.25s var(--ease);
}
.card:hover { box-shadow: var(--shadow-md); }

/* ---------- Form ---------- */
.calc-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 18px; }
.field { margin-bottom: 18px; }
.field label { display: block; font-weight: 600; font-size: 0.92rem; margin-bottom: 8px; color: var(--ink); }
.field .unit-hint { color: var(--muted); font-weight: 400; font-size: 0.82rem; }
.input-row { display: flex; align-items: center; gap: 10px; }
.input-row input, .input-row select {
  width: 100%;
  padding: 13px 16px;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius-sm);
  font-size: 1.02rem;
  font-family: inherit;
  background: var(--card);
  color: var(--ink);
  transition: border-color 0.28s var(--ease), box-shadow 0.28s var(--ease), background 0.28s var(--ease), transform 0.28s var(--ease);
}
.input-row input:hover, .input-row select:hover { border-color: #b3ac9b; box-shadow: 0 2px 10px rgba(64, 55, 40, 0.07); }
.input-row input:focus, .input-row select:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: var(--ring);
}
.input-row .unit { color: var(--muted); font-size: 0.92rem; white-space: nowrap; min-width: 3ch; }

/* ---------- Results ---------- */
.results { display: none; margin-top: 22px; border-top: 1px solid var(--line); padding-top: 20px; }
.results.show { display: block; animation: rise 0.32s var(--ease); }
@keyframes rise { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: none; } }
.result {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 12px;
  padding: 14px 18px;
  border-radius: var(--radius-sm);
  margin-bottom: 10px;
  background: var(--bg);
  border: 1px solid transparent;
  transition: background 0.28s var(--ease), border-color 0.28s var(--ease), transform 0.28s var(--ease);
}
.result:hover { background: var(--accent-soft); border-color: rgba(15, 108, 172, 0.18); }
.result .r-label { color: var(--muted); font-size: 0.94rem; }
.result .val {
  font-family: ui-monospace, "SF Mono", "Cascadia Mono", "Roboto Mono", Consolas, monospace;
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--ink);
  letter-spacing: -0.01em;
  font-variant-numeric: tabular-nums;
}
.result .unit-tag {
  font-family: ui-monospace, "SF Mono", "Cascadia Mono", "Roboto Mono", Consolas, monospace;
  font-size: 0.82rem;
  color: var(--muted);
  margin-left: 4px;
  font-weight: 500;
}
.result .note { font-size: 0.8rem; color: var(--muted); text-align: right; }

/* ---------- Share ---------- */
.share { margin-top: 16px; font-size: 0.88rem; color: var(--muted); }
.share-row { display: flex; gap: 10px; margin-top: 6px; }
.share-row input {
  flex: 1;
  padding: 11px 14px;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  font-family: inherit;
  color: var(--ink);
  background: var(--bg);
  min-width: 0;
}
.share-row input:focus { outline: none; border-color: var(--accent); box-shadow: var(--ring); }
.copy-url { position: relative; }
.copy-url > span { display: inline-block; transition: opacity 0.25s var(--ease), transform 0.25s var(--ease); }
.copy-url .alt { position: absolute; inset: 0; display: flex; align-items: center; justify-content: center; opacity: 0; transform: translateY(10px); }
.copy-url.copied > span[data-i18n] { opacity: 0; transform: translateY(-10px); }
.copy-url.copied .alt { opacity: 1; transform: translateY(0); }

/* ---------- Buttons ---------- */
.btn {
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: 10px;
  padding: 11px 24px;
  font-size: 0.94rem;
  font-weight: 600;
  font-family: inherit;
  cursor: pointer;
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  will-change: transform;
  transition: background 0.3s var(--ease), transform 0.3s var(--ease), box-shadow 0.3s var(--ease), filter 0.3s var(--ease);
}
.btn:hover {
  background: var(--accent-dark);
  transform: translateY(-1px) scale(1.02);
  box-shadow: var(--shadow-accent);
  filter: brightness(1.03);
}
.btn:active { transform: translateY(0) scale(0.97); box-shadow: none; transition-duration: 0.12s; }
.btn.ghost {
  background: var(--card);
  color: var(--accent);
  border: 1px solid var(--line-strong);
  box-shadow: none;
}
.btn.ghost:hover { background: var(--accent-soft); box-shadow: none; }

/* ---------- Ad slot ---------- */
.ad-slot {
  background: repeating-linear-gradient(45deg, #faf8f2, #faf8f2 10px, #f1eee4 10px, #f1eee4 20px);
  border: 1px dashed #d9d3c3;
  border-radius: var(--radius);
  color: var(--muted);
  font-size: 0.8rem;
  text-align: center;
  padding: 28px 12px;
  margin: 30px 0;
}
html.dark .ad-slot { background: repeating-linear-gradient(45deg, #201d17, #201d17 10px, #26231c 10px, #26231c 20px); border-color: #3d382d; }

/* ---------- Affiliate ---------- */
.affiliate-box {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 22px 26px;
  margin: 30px 0;
  box-shadow: var(--shadow-sm);
}
.affiliate-box h3 { margin: 0 0 10px; font-size: 1.02rem; color: var(--ink); }
.affiliate-box ul { margin: 0; padding-left: 18px; font-size: 0.94rem; }
.affiliate-box a { color: var(--accent); text-decoration: none; }
.affiliate-box a:hover { text-decoration: underline; }

/* ---------- Tool grid ---------- */
.tool-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 16px;
}
.tool-card {
  display: block;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 22px;
  text-decoration: none;
  color: var(--ink);
  box-shadow: var(--shadow-sm);
  will-change: transform;
  transition: transform 0.35s var(--ease), box-shadow 0.35s var(--ease), border-color 0.35s var(--ease);
}
.tool-card:hover {
  transform: translateY(-4px) scale(1.015);
  border-color: rgba(15, 108, 172, 0.35);
  box-shadow: var(--shadow-lg);
}
.tool-card:active { transform: translateY(-1px) scale(0.99); transition-duration: 0.15s; }
.tool-card b { display: block; margin-bottom: 6px; color: var(--ink); font-size: 1.05rem; letter-spacing: -0.015em; }
.tool-card span { font-size: 0.86rem; color: var(--muted); display: block; line-height: 1.5; }

/* ---------- FAQ ---------- */
.faq details {
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  padding: 16px 20px;
  margin-bottom: 12px;
  background: var(--card);
  box-shadow: var(--shadow-sm);
  transition: border-color 0.2s var(--ease), box-shadow 0.2s var(--ease);
}
.faq details:hover { border-color: var(--line-strong); box-shadow: var(--shadow-md); }
.faq details.open { border-color: rgba(15, 108, 172, 0.3); }
.faq summary { font-weight: 600; cursor: pointer; font-size: 0.98rem; list-style: none; }
.faq summary::-webkit-details-marker { display: none; }
.faq summary::before {
  position: absolute; left: 14px; top: 50%; margin-top: -10px;
  width: 20px; height: 20px; border-radius: 50%; background: var(--bg);
  color: var(--muted); font-weight: 700; font-size: 0.9rem; line-height: 20px; text-align: center;
  content: "+"; transition: transform 0.3s var(--ease), background 0.3s var(--ease), color 0.3s var(--ease);
}
.faq details:hover summary::before { color: var(--accent); }
.faq details.open summary::before { transform: rotate(45deg); background: var(--accent); color: #fff; }
.faq .faq-body {
  display: grid;
  grid-template-rows: 0fr;
  padding-top: 0;
  transition: grid-template-rows 0.4s var(--ease), padding-top 0.4s var(--ease);
}
.faq details.open .faq-body { grid-template-rows: 1fr; padding-top: 10px; }
.faq .faq-body > p { overflow: hidden; min-height: 0; margin: 0 0 0 34px; font-size: 0.94rem; color: var(--muted); }

/* ---------- Footer ---------- */
footer.site {
  position: relative;
  margin-top: 72px;
  background: #23201a;
  color: #9a9386;
  font-size: 0.84rem;
  padding: 44px 0 64px;
}
footer.site::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 2px;
  background: linear-gradient(90deg, transparent, var(--accent), transparent);
  opacity: 0.6;
}
footer.site .foot-grid { display: grid; grid-template-columns: 1.3fr 2fr 1fr; gap: 48px; padding-bottom: 26px; }
footer.site .foot-brand b { display: block; color: #f2ecdf; font-size: 1.06rem; letter-spacing: -0.01em; margin-bottom: 8px; }
footer.site .foot-brand span { display: block; line-height: 1.6; max-width: 260px; }
footer.site .foot-head { display: block; color: #f2ecdf; font-size: 0.76rem; text-transform: uppercase; letter-spacing: 0.09em; margin-bottom: 14px; }
footer.site .foot-tools { display: grid; grid-template-columns: 1fr 1fr; gap: 7px 22px; }
footer.site .foot-links { display: flex; flex-direction: column; gap: 7px; }
footer.site a { color: #d6d0c4; text-decoration: none; transition: color 0.25s var(--ease); }
footer.site a:hover { color: #fff; }
footer.site .foot-bottom {
  border-top: 1px solid #3a362d;
  padding-top: 20px;
  display: flex;
  justify-content: space-between;
  gap: 20px;
  flex-wrap: wrap;
}
@media (max-width: 640px) {
  footer.site .foot-grid { grid-template-columns: 1fr; gap: 30px; }
  footer.site .foot-bottom { flex-direction: column; }
}

/* ---------- Motion preference ---------- */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: 0.01ms !important; transition-duration: 0.01ms !important; }
  html { scroll-behavior: auto !important; }
}

@media (max-width: 640px) {
  .wrap { padding: 0 16px; }
  header.site .wrap { padding: 12px 16px; }
  .hero { padding: 48px 0 20px; }
  nav.site a { padding: 7px 10px; font-size: 0.85rem; }
  .card { padding: 20px; }
  .result { flex-direction: column; align-items: flex-start; gap: 4px; }
  .result .note { text-align: left; }
  .hero h1 { font-size: 2rem; }
}

/* ---------- Print ---------- */
@media print {
  header.site, footer.site, nav.site, .ad-slot, .share-row, #theme-toggle,
  #lang-select, #unit-select, #print-btn, .hero, .howto, .faq, .related,
  #saved-msg { display: none !important; }
  body { background: #fff !important; color: #000 !important; }
  .card, .result, .result-box { box-shadow: none !important; border: none !important; background: #fff !important; }
  .card { padding: 0 !important; }
  .wrap { padding: 0 !important; max-width: 100% !important; }
  .result { border-top: 1px solid #ccc; border-bottom: 1px solid #ccc; }
  input[type="number"], select { border-color: #999 !important; background: #fff !important; color: #000 !important; }
  a { color: #000 !important; }
}