/* ============================================================
   TIANCAICHEN COLLECTION — Design System
   A restrained, auction-house aesthetic (Christie's / Sotheby's)
   Bilingual 中 / EN
   ============================================================ */

:root {
  --ink:        #1a1a1a;
  --ink-soft:   #4a4744;
  --ink-mute:   #8a847d;
  --line:       #e2ddd5;
  --line-soft:  #efebe4;
  --paper:      #fbf9f5;
  --paper-2:    #f4f0e8;
  --white:      #ffffff;
  --gold:       #9c7c38;
  --gold-soft:  #c2a878;
  --burgundy:   #6d2932;

  --serif: "Songti SC", "Noto Serif TC", "Times New Roman", Georgia, "STSong", serif;
  --sans:  "Helvetica Neue", "PingFang TC", "Microsoft JhengHei", Arial, sans-serif;

  --wrap: 1200px;
  --gutter: clamp(20px, 5vw, 64px);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: var(--sans);
  color: var(--ink);
  background: var(--paper);
  line-height: 1.7;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

img { max-width: 100%; display: block; }

a { color: inherit; text-decoration: none; }

h1, h2, h3, h4 { font-family: var(--serif); font-weight: 500; letter-spacing: .01em; }

.wrap { max-width: var(--wrap); margin: 0 auto; padding: 0 var(--gutter); }

.eyebrow {
  font-family: var(--sans);
  font-size: 12px;
  letter-spacing: .28em;
  text-transform: uppercase;
  color: var(--gold);
  margin: 0 0 18px;
}

.lead { font-size: clamp(18px, 2.4vw, 22px); color: var(--ink-soft); line-height: 1.75; }

.muted { color: var(--ink-mute); }

/* ---------- Buttons ---------- */
.btn {
  display: inline-block;
  font-family: var(--sans);
  font-size: 13px;
  letter-spacing: .16em;
  text-transform: uppercase;
  padding: 15px 34px;
  border: 1px solid var(--ink);
  background: var(--ink);
  color: var(--white);
  transition: all .25s ease;
  cursor: pointer;
}
.btn:hover { background: transparent; color: var(--ink); }
.btn--ghost { background: transparent; color: var(--ink); }
.btn--ghost:hover { background: var(--ink); color: var(--white); }
.btn--gold { background: var(--gold); border-color: var(--gold); }
.btn--gold:hover { background: transparent; color: var(--gold); }

/* ---------- Header / Nav ---------- */
.site-header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(251,249,245,.92);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
}
.nav {
  display: flex; align-items: center; justify-content: space-between;
  height: 78px;
}
.brand { display: flex; flex-direction: column; line-height: 1; }
.brand__mark {
  font-family: var(--serif);
  font-size: 22px; letter-spacing: .12em; color: var(--ink);
}
.brand__sub {
  font-size: 9.5px; letter-spacing: .34em; text-transform: uppercase;
  color: var(--gold); margin-top: 6px;
}
.nav__links { display: flex; gap: 30px; align-items: center; list-style: none; margin: 0; padding: 0; }
.nav__links a {
  font-size: 13px; letter-spacing: .1em; color: var(--ink-soft);
  padding: 6px 0; position: relative; transition: color .2s;
}
.nav__links a::after {
  content: ""; position: absolute; left: 0; bottom: 0; width: 0; height: 1px;
  background: var(--gold); transition: width .25s ease;
}
.nav__links a:hover, .nav__links a.is-active { color: var(--ink); }
.nav__links a:hover::after, .nav__links a.is-active::after { width: 100%; }
.nav__cta { margin-left: 8px; }
.nav__toggle { display: none; background: none; border: 0; cursor: pointer; padding: 8px; }
.nav__toggle span { display: block; width: 24px; height: 1.5px; background: var(--ink); margin: 5px 0; transition: .3s; }

/* ---------- Hero ---------- */
.hero {
  position: relative;
  min-height: 82vh;
  display: flex; align-items: center;
  background: linear-gradient(160deg, #232020 0%, #3a322c 55%, #4a3f36 100%);
  color: #f3ece2;
  overflow: hidden;
}
.hero::before {
  content: ""; position: absolute; inset: 0;
  background-image:
    radial-gradient(circle at 78% 30%, rgba(194,168,120,.18), transparent 45%),
    url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='60' height='60'%3E%3Cpath d='M0 59h60M59 0v60' stroke='%23ffffff' stroke-opacity='.03' fill='none'/%3E%3C/svg%3E");
}
.hero__inner { position: relative; padding: 90px 0; max-width: 760px; }
.hero h1 { font-size: clamp(38px, 6vw, 68px); line-height: 1.12; margin: 0 0 26px; color: #fbf6ee; }
.hero .lead { color: #d8cdbd; }
.hero__actions { margin-top: 40px; display: flex; gap: 16px; flex-wrap: wrap; }
.hero .btn { border-color: var(--gold-soft); }
.hero .btn--ghost { color: #f3ece2; }
.hero .btn--ghost:hover { background: #f3ece2; color: var(--ink); }

/* ---------- Sections ---------- */
.section { padding: clamp(64px, 9vw, 120px) 0; }
.section--paper2 { background: var(--paper-2); }
.section--ink { background: #232020; color: #e7ded1; }
.section--ink .eyebrow { color: var(--gold-soft); }
.section--ink h2 { color: #fbf6ee; }

.section-head { max-width: 720px; margin-bottom: 56px; }
.section-head h2 { font-size: clamp(28px, 4vw, 44px); margin: 0 0 20px; line-height: 1.2; }

.divider { width: 46px; height: 2px; background: var(--gold); margin: 0 0 26px; border: 0; }

/* ---------- Feature grid ---------- */
.grid { display: grid; gap: 32px; }
.grid--2 { grid-template-columns: repeat(2, 1fr); }
.grid--3 { grid-template-columns: repeat(3, 1fr); }
.grid--4 { grid-template-columns: repeat(4, 1fr); }

.card {
  background: var(--white);
  border: 1px solid var(--line);
  padding: 38px 34px;
  transition: transform .3s ease, box-shadow .3s ease;
}
.card:hover { transform: translateY(-4px); box-shadow: 0 18px 40px rgba(40,32,24,.08); }
.card__num { font-family: var(--serif); font-size: 15px; color: var(--gold); letter-spacing: .1em; }
.card h3 { font-size: 21px; margin: 14px 0 12px; }
.card p { margin: 0; color: var(--ink-soft); font-size: 15px; }

/* ---------- Collections grid ---------- */
.collection-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 4px; }
.lot {
  position: relative; display: block; background: var(--white);
  border: 1px solid var(--line-soft); overflow: hidden;
}
.lot__img {
  aspect-ratio: 4/5; display: flex; align-items: center; justify-content: center;
  background: linear-gradient(135deg, var(--paper-2), #e8e1d5);
  color: var(--ink-mute); position: relative; overflow: hidden;
}
.lot__img svg { width: 46%; opacity: .55; transition: transform .5s ease; }
.lot:hover .lot__img svg { transform: scale(1.06); }
.lot__img img { width: 100%; height: 100%; object-fit: cover; object-position: center top; transition: transform .6s ease; }
.lot:hover .lot__img img { transform: scale(1.04); }
.lot__badge {
  position: absolute; top: 14px; left: 14px; background: rgba(26,26,26,.86); color: #fff;
  font-size: 10.5px; letter-spacing: .12em; padding: 5px 11px; text-transform: uppercase;
}
.lot__body { padding: 22px 24px 26px; }
.lot__cat { font-size: 11px; letter-spacing: .2em; text-transform: uppercase; color: var(--gold); }
.lot__title { font-family: var(--serif); font-size: 19px; margin: 8px 0 6px; }
.lot__meta { font-size: 13.5px; color: var(--ink-mute); }
.lot__est { font-size: 13.5px; color: var(--ink-soft); margin-top: 12px; padding-top: 12px; border-top: 1px solid var(--line-soft); }

/* ---------- Filters ---------- */
.filters { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 40px; }
.filter {
  font-family: var(--sans); font-size: 12.5px; letter-spacing: .1em;
  padding: 9px 20px; border: 1px solid var(--line); background: transparent;
  color: var(--ink-soft); cursor: pointer; transition: all .2s; text-transform: uppercase;
}
.filter:hover { border-color: var(--ink); color: var(--ink); }
.filter.is-active { background: var(--ink); border-color: var(--ink); color: #fff; }

/* ---------- Split media ---------- */
.split { display: grid; grid-template-columns: 1fr 1fr; gap: clamp(30px, 5vw, 72px); align-items: center; }
.split__media {
  aspect-ratio: 5/4; background: linear-gradient(135deg, #efe8db, #ddd2c1);
  display: flex; align-items: center; justify-content: center; color: var(--ink-mute);
  border: 1px solid var(--line);
}
.split__media svg { width: 40%; opacity: .5; }

/* ---------- Stats ---------- */
.stats { display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px; }
.stat { text-align: center; }
.stat__num { font-family: var(--serif); font-size: clamp(34px, 5vw, 52px); color: var(--gold-soft); line-height: 1; }
.stat__label { font-size: 12px; letter-spacing: .18em; text-transform: uppercase; margin-top: 14px; color: #c9beac; }

/* ---------- Process / timeline ---------- */
.steps { counter-reset: step; display: grid; gap: 2px; }
.step {
  display: grid; grid-template-columns: 90px 1fr; gap: 30px;
  padding: 36px 0; border-top: 1px solid var(--line);
}
.step:last-child { border-bottom: 1px solid var(--line); }
.step__no { font-family: var(--serif); font-size: 40px; color: var(--gold-soft); line-height: 1; }
.step h3 { font-size: 22px; margin: 0 0 10px; }
.step p { margin: 0; color: var(--ink-soft); }
.step__tag { font-size: 12px; letter-spacing: .16em; text-transform: uppercase; color: var(--ink-mute); margin-top: 12px; }

/* ---------- Fee table ---------- */
.table-wrap { overflow-x: auto; border: 1px solid var(--line); background: var(--white); }
table.fees { width: 100%; border-collapse: collapse; min-width: 560px; }
table.fees th, table.fees td { text-align: left; padding: 20px 26px; border-bottom: 1px solid var(--line-soft); font-size: 15px; }
table.fees th { font-family: var(--sans); font-size: 11px; letter-spacing: .18em; text-transform: uppercase; color: var(--ink-mute); background: var(--paper-2); }
table.fees td:first-child { font-family: var(--serif); font-size: 17px; }
table.fees .price { color: var(--burgundy); font-weight: 500; white-space: nowrap; }
table.fees tr:last-child td { border-bottom: 0; }

/* ---------- Detail page ---------- */
.detail { display: grid; grid-template-columns: 1.1fr .9fr; gap: clamp(30px, 5vw, 64px); }
.detail__gallery { display: grid; gap: 4px; }
.detail__main {
  aspect-ratio: 4/5; background: linear-gradient(135deg, var(--paper-2), #e4dccd);
  display: flex; align-items: center; justify-content: center; border: 1px solid var(--line);
}
.detail__main svg { width: 44%; opacity: .55; }
.detail__thumbs { display: grid; grid-template-columns: repeat(4, 1fr); gap: 4px; }
.detail__thumb { aspect-ratio: 1; background: var(--paper-2); border: 1px solid var(--line); display:flex; align-items:center; justify-content:center; }
.detail__thumb svg { width: 44%; opacity: .4; }
.spec-list { list-style: none; margin: 0; padding: 0; border-top: 1px solid var(--line); }
.spec-list li { display: flex; justify-content: space-between; gap: 20px; padding: 15px 0; border-bottom: 1px solid var(--line-soft); font-size: 14.5px; }
.spec-list .k { color: var(--ink-mute); letter-spacing: .04em; }
.spec-list .v { color: var(--ink); text-align: right; }
.est-box { background: var(--paper-2); border: 1px solid var(--line); padding: 28px 30px; margin: 30px 0; }
.est-box .label { font-size: 11px; letter-spacing: .2em; text-transform: uppercase; color: var(--ink-mute); }
.est-box .amount { font-family: var(--serif); font-size: 30px; color: var(--burgundy); margin-top: 8px; }

/* ---------- Forms ---------- */
.form-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; }
.field { display: flex; flex-direction: column; gap: 8px; }
.field--full { grid-column: 1 / -1; }
.field label { font-size: 12px; letter-spacing: .12em; text-transform: uppercase; color: var(--ink-mute); }
.field input, .field select, .field textarea {
  font-family: var(--sans); font-size: 15px; padding: 14px 16px;
  border: 1px solid var(--line); background: var(--white); color: var(--ink);
}
.field input:focus, .field select:focus, .field textarea:focus { outline: none; border-color: var(--gold); }
.field textarea { min-height: 130px; resize: vertical; }

/* ---------- Login card ---------- */
.login-card {
  max-width: 440px; margin: 0 auto; background: var(--white);
  border: 1px solid var(--line); padding: 48px 44px;
}
.login-card .lock { width: 44px; margin: 0 auto 22px; opacity: .6; }

/* ---------- CTA band ---------- */
.cta-band { background: #232020; color: #f0e7da; text-align: center; padding: clamp(60px, 8vw, 100px) 0; }
.cta-band h2 { font-size: clamp(28px, 4vw, 42px); margin: 0 0 18px; color: #fbf6ee; }
.cta-band p { color: #cabfad; max-width: 560px; margin: 0 auto 34px; }

/* ---------- Footer ---------- */
.site-footer { background: #1a1815; color: #b3a996; padding: 72px 0 34px; }
.footer-grid { display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 40px; }
.site-footer .brand__mark { color: #f3ece2; }
.site-footer h4 { font-family: var(--sans); font-size: 11px; letter-spacing: .2em; text-transform: uppercase; color: #8a8071; margin: 0 0 18px; }
.site-footer ul { list-style: none; margin: 0; padding: 0; }
.site-footer li { margin-bottom: 11px; }
.site-footer a { font-size: 14px; color: #b3a996; transition: color .2s; }
.site-footer a:hover { color: #f3ece2; }
.footer-note {
  margin-top: 56px; padding-top: 26px; border-top: 1px solid #322e28;
  display: flex; justify-content: space-between; flex-wrap: wrap; gap: 14px;
  font-size: 12px; color: #6f665a; letter-spacing: .04em;
}

/* ---------- Page banner ---------- */
.page-banner { background: linear-gradient(160deg, #2a2521, #3c332b); color: #f0e7da; padding: clamp(56px, 8vw, 96px) 0; }
.page-banner .eyebrow { color: var(--gold-soft); }
.page-banner h1 { font-size: clamp(32px, 5vw, 54px); margin: 0 0 18px; color: #fbf6ee; }
.page-banner p { color: #cdc2b0; max-width: 620px; margin: 0; }
.breadcrumb { font-size: 12px; letter-spacing: .1em; color: #a89c88; margin-bottom: 24px; }
.breadcrumb a:hover { color: #f0e7da; }

/* ---------- Prose ---------- */
.prose { max-width: 760px; }
.prose h3 { font-size: 24px; margin: 44px 0 16px; }
.prose p { color: var(--ink-soft); margin: 0 0 18px; }
.prose ul { color: var(--ink-soft); padding-left: 20px; }
.prose li { margin-bottom: 10px; }

/* ---------- Reveal ---------- */
.reveal { opacity: 0; transform: translateY(24px); transition: opacity .7s ease, transform .7s ease; }
.reveal.in { opacity: 1; transform: none; }

/* ---------- Responsive ---------- */
@media (max-width: 900px) {
  .grid--3, .grid--4, .collection-grid, .stats { grid-template-columns: repeat(2, 1fr); }
  .split, .detail, .form-grid, .footer-grid { grid-template-columns: 1fr; }
  .detail__main { max-width: 480px; }
  .nav__links {
    position: fixed; inset: 78px 0 auto 0; flex-direction: column; gap: 0;
    background: var(--paper); border-bottom: 1px solid var(--line);
    padding: 10px 0; transform: translateY(-120%); transition: transform .3s ease;
  }
  .nav__links.is-open { transform: none; }
  .nav__links li { width: 100%; text-align: center; padding: 12px 0; border-bottom: 1px solid var(--line-soft); }
  .nav__cta { display: none; }
  .nav__toggle { display: block; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 560px) {
  .grid--2, .grid--3, .grid--4, .collection-grid, .stats, .footer-grid { grid-template-columns: 1fr; }
  .step { grid-template-columns: 1fr; gap: 10px; }
}