/* ============================================================
   Nepali Date Converter — Shirjan Khadka
   Apple-inspired: system type, hairlines, calm motion.
   ============================================================ */
:root {
  --text: #1d1d1f;
  --secondary: #6e6e73;
  --alt: #f5f5f7;
  --white: #ffffff;
  --accent: #0b5c3f;
  --accent-bright: #46a37c;
  --accent-soft: #e9f3ed;
  --line: #e3e3e8;
  --font: -apple-system, BlinkMacSystemFont, "SF Pro Display", "SF Pro Text", Inter, "Segoe UI", Helvetica, Arial, sans-serif;
  --ease: cubic-bezier(.16, 1, .3, 1);
  --radius: 20px;
  --shadow: 0 12px 40px rgba(0, 0, 0, .08);
}
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
  font-family: var(--font);
  background:
    radial-gradient(900px 480px at 12% -60px, rgba(70, 163, 124, .10), transparent 60%),
    radial-gradient(800px 420px at 88% 0, rgba(11, 92, 63, .07), transparent 60%),
    var(--white);
  color: var(--text);
  font-size: 17px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}
::selection { background: var(--accent); color: #fff; }
a { color: inherit; }
.wrap { width: min(1060px, 100% - 44px); margin: 0 auto; }
.wrap.narrow { width: min(780px, 100% - 44px); }

.skip-link {
  position: absolute; left: 16px; top: -56px; z-index: 300;
  background: var(--text); color: #fff; padding: 10px 18px;
  border-radius: 980px; text-decoration: none; font-size: 15px; font-weight: 600;
}
.skip-link:focus { top: 12px; }

/* ---------- Top bar ---------- */
.topbar { position: sticky; top: 0; z-index: 50; background: rgba(255,255,255,.82); backdrop-filter: saturate(1.6) blur(14px); border-bottom: 1px solid var(--line); }
.topbar-inner { width: min(1060px, 100% - 44px); margin: 0 auto; height: 60px; display: flex; align-items: center; justify-content: space-between; }
.brand { display: flex; align-items: center; gap: 10px; text-decoration: none; font-weight: 700; letter-spacing: -0.01em; }
.brand-mark { width: 32px; height: 32px; border-radius: 9px; background: var(--text); color: #fff; display: grid; place-items: center; font-size: 13px; font-weight: 800; }
.topbar-link { text-decoration: none; font-size: 15px; font-weight: 600; color: var(--secondary); transition: color .2s; }
.topbar-link:hover { color: var(--accent); }

/* ---------- Hero ---------- */
.hero { padding: 72px 0 8px; text-align: center; }
.hero h1 { font-size: clamp(2.2rem, 5.4vw, 3.6rem); font-weight: 800; letter-spacing: -0.03em; line-height: 1.06; }
.lede { margin: 18px auto 0; max-width: 640px; color: var(--secondary); font-size: clamp(1.02rem, 2vw, 1.2rem); }

/* ---------- Tabs ---------- */
.tool { padding: 40px 0 24px; }
.tabs {
  position: relative; display: flex; gap: 4px; max-width: 620px; margin: 0 auto 28px;
  background: var(--alt); border: 1px solid var(--line); border-radius: 980px; padding: 6px;
}
.tabs-thumb {
  position: absolute; top: 6px; bottom: 6px; left: 0; width: 0; border-radius: 980px;
  background: var(--accent); box-shadow: 0 4px 14px rgba(11,92,63,.35);
  transition: transform .45s var(--ease), width .45s var(--ease);
}
.tab {
  position: relative; z-index: 1; flex: 1; border: 0; background: transparent; cursor: pointer;
  display: flex; align-items: center; justify-content: center; gap: 8px;
  padding: 13px 10px; border-radius: 980px; font: inherit; font-size: 16px; font-weight: 600;
  color: var(--secondary); transition: color .25s;
  font-family: var(--font);
}
.tab svg { flex: none; }
.tab.is-active { color: #fff; }
.tab:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

/* ---------- Panels & cards ---------- */
.panel { animation: panelIn .5s var(--ease); }
@keyframes panelIn { from { opacity: 0; transform: translateY(14px); } to { opacity: 1; transform: none; } }
.card {
  background: var(--white); border: 1px solid var(--line); border-radius: var(--radius);
  box-shadow: var(--shadow); padding: clamp(22px, 4vw, 40px); max-width: 1060px; margin: 0 auto;
}
.card-head { display: flex; align-items: center; justify-content: space-between; gap: 16px; margin-bottom: 18px; flex-wrap: wrap; }
.card-title { font-size: 1.15rem; font-weight: 800; margin: 0 0 14px; }
.field-label { font-size: 15px; font-weight: 600; color: var(--secondary); }

/* Segmented BS/AD control */
.seg { display: inline-flex; background: var(--alt); border: 1px solid var(--line); border-radius: 980px; padding: 4px; gap: 2px; }
.seg-btn {
  border: 0; background: transparent; cursor: pointer; font: inherit; font-family: var(--font);
  font-size: 14px; font-weight: 700; padding: 8px 22px; border-radius: 980px; color: var(--secondary);
  transition: background .25s, color .25s, box-shadow .25s;
}
.seg-btn.is-active { background: var(--accent); color: #fff; box-shadow: 0 3px 10px rgba(11,92,63,.35); }
.seg-btn:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.seg-sm .seg-btn { padding: 6px 16px; font-size: 13px; }

/* Selects */
.selects { display: grid; grid-template-columns: 1fr 1.4fr 1fr; gap: 14px; }
.select-wrap label { display: block; font-size: 13px; font-weight: 600; color: var(--secondary); margin-bottom: 8px; }
.select-wrap select {
  width: 100%; appearance: none; -webkit-appearance: none; cursor: pointer;
  font: inherit; font-family: var(--font); font-size: 19px; font-weight: 600; color: var(--text);
  padding: 15px 44px 15px 18px; border: 1.5px solid var(--line); border-radius: 14px; background-color: #fff;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' viewBox='0 0 24 24' fill='none' stroke='%236e6e73' stroke-width='2.4' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='M6 9l6 6 6-6'/%3E%3C/svg%3E");
  background-repeat: no-repeat; background-position: right 16px center;
  transition: border-color .2s, box-shadow .2s;
  font-variant-numeric: tabular-nums;
}
.select-wrap select:hover { border-color: #b9b9c0; }
.select-wrap select:focus { outline: none; border-color: var(--accent); box-shadow: 0 0 0 4px rgba(11,92,63,.14); }

/* Quick actions */
.quick-row { display: flex; gap: 10px; margin: 20px 0 26px; flex-wrap: wrap; }
.btn-ghost {
  display: inline-flex; align-items: center; gap: 8px; cursor: pointer;
  font: inherit; font-family: var(--font); font-size: 15px; font-weight: 600; color: var(--accent);
  background: var(--accent-soft); border: 1px solid transparent; border-radius: 980px; padding: 10px 20px;
  transition: transform .2s var(--ease), box-shadow .2s, background .2s;
}
.btn-ghost:hover { transform: translateY(-1px); box-shadow: 0 6px 18px rgba(11,92,63,.18); background: #dcebe2; }
.btn-ghost:active { transform: translateY(0); }
.btn-ghost:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

/* Results */
.results { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.result {
  background: #fafafb; border: 1.5px solid var(--line); border-radius: 16px; padding: 22px 24px;
  transition: background .3s, border-color .3s, box-shadow .3s;
}
.result.is-result { background: var(--accent-soft); border-color: rgba(11,92,63,.35); box-shadow: 0 8px 24px rgba(11,92,63,.10); }
.result-top { display: flex; align-items: center; justify-content: space-between; margin-bottom: 10px; }
.result-kicker { font-size: 13px; font-weight: 700; text-transform: uppercase; letter-spacing: .08em; color: var(--secondary); }
.copy-btn {
  border: 1px solid var(--line); background: #fff; cursor: pointer; border-radius: 980px;
  font: inherit; font-family: var(--font); font-size: 13px; font-weight: 600; color: var(--secondary);
  padding: 6px 14px; transition: all .2s;
}
.copy-btn:hover { color: var(--accent); border-color: var(--accent); }
.copy-btn.copied { color: #fff; background: var(--accent); border-color: var(--accent); }
.result-date { font-size: clamp(1.5rem, 3.4vw, 2.1rem); font-weight: 800; letter-spacing: -0.02em; color: var(--accent); font-variant-numeric: tabular-nums; }
.result.is-result .result-date { color: var(--accent); }
.result-sub { color: var(--secondary); font-size: 16px; margin-top: 4px; }
.result-date.flash, .result-sub.flash { animation: flash .35s var(--ease); }
@keyframes flash { 0% { opacity: 0; transform: translateY(8px); } 100% { opacity: 1; transform: none; } }

/* Difference / Age */
.diff-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 28px; margin-bottom: 8px; }
.result-single { margin-top: 26px; background: #fafafb; border: 1.5px solid var(--line); border-radius: 16px; padding: 26px clamp(20px, 4vw, 34px); }
.result-big { font-size: clamp(1.7rem, 4vw, 2.6rem); font-weight: 800; letter-spacing: -0.025em; color: var(--accent); margin: 8px 0 18px; font-variant-numeric: tabular-nums; }
.result-big.flash { animation: flash .35s var(--ease); }
.chips { display: flex; flex-wrap: wrap; gap: 10px; }
.chip {
  background: #fff; border: 1px solid var(--line); border-radius: 980px; padding: 8px 16px;
  font-size: 14px; font-weight: 600; color: var(--text); font-variant-numeric: tabular-nums;
}
.chip strong { color: var(--accent); }

/* ---------- About & FAQ ---------- */
.about { padding: 84px 0 20px; }
.about h2, .faq h2 { font-size: clamp(1.6rem, 3.6vw, 2.3rem); font-weight: 800; letter-spacing: -0.025em; margin-bottom: 22px; }
.about h3 { font-size: 1.25rem; font-weight: 700; letter-spacing: -0.01em; margin: 34px 0 10px; }
.about p { color: #3a3a3c; margin-bottom: 16px; }
.faq { padding: 40px 0 90px; }
.faq-item { border: 1px solid var(--line); border-radius: 14px; margin-bottom: 12px; background: #fff; overflow: hidden; transition: box-shadow .25s; }
.faq-item:hover { box-shadow: 0 6px 20px rgba(0,0,0,.06); }
.faq-item summary {
  cursor: pointer; list-style: none; display: flex; align-items: center; justify-content: space-between; gap: 16px;
  padding: 18px 22px; font-weight: 700; font-size: 16.5px;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after {
  content: "+"; flex: none; width: 30px; height: 30px; border-radius: 50%; display: grid; place-items: center;
  background: var(--alt); color: var(--accent); font-size: 20px; font-weight: 400; line-height: 1;
  transition: transform .3s var(--ease), background .3s, color .3s;
}
.faq-item[open] summary::after { transform: rotate(45deg); background: var(--accent); color: #fff; }
.faq-item p { padding: 0 22px 20px; color: #3a3a3c; }

/* ---------- Footer ---------- */
.footer { border-top: 1px solid var(--line); padding: 34px 0 44px; text-align: center; color: var(--secondary); font-size: 15px; }
.footer a { font-weight: 700; color: var(--text); text-decoration: none; }
.footer a:hover { color: var(--accent); }
.footer-sub { font-size: 13.5px; margin-top: 6px; }

/* ---------- Responsive ---------- */
@media (max-width: 720px) {
  .selects { grid-template-columns: 1fr; gap: 12px; }
  .results { grid-template-columns: 1fr; }
  .diff-grid { grid-template-columns: 1fr; gap: 22px; }
  .hero { padding: 52px 0 4px; }
  .tab { font-size: 14.5px; padding: 12px 6px; }
  .tab svg { display: none; }
}

/* ---------- Reduced motion ---------- */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: .01ms !important; transition-duration: .01ms !important; }
  html { scroll-behavior: auto; }
}

/* ---- premium 3D layer ---- */
.card{
  background: linear-gradient(180deg, rgba(255,255,255,.5), rgba(255,255,255,0) 35%), var(--white);
  box-shadow: inset 0 1px 0 rgba(255,255,255,.7), 0 1px 2px rgba(0,0,0,.08), 0 12px 32px rgba(0,0,0,.1);
}
.seg{
  box-shadow: inset 0 2px 6px rgba(0,0,0,.1), inset 0 1px 0 rgba(255,255,255,.04);
}
.seg-btn.is-active{
  background: linear-gradient(180deg, rgba(255,255,255,.2), rgba(255,255,255,0) 45%), var(--accent);
  box-shadow: inset 0 1px 0 rgba(255,255,255,.3), 0 3px 10px rgba(11,92,63,.35);
}
.seg-btn{ transition: transform .15s; }
.seg-btn:active{ transform: scale(.96); }
@media (prefers-reduced-motion: reduce){
  .seg-btn{ transition: none; }
}