:root {
  --paper: #f8f5f0;
  --paper-2: #f2ede5;
  --card: #fffdfa;
  --ink: #1d1b18;
  --ink-2: #3d3934;
  --muted: #726a62;
  --muted-2: #9a9188;
  --line: #e4ddd2;
  --line-2: #d6ccbe;
  --accent: #9c3b2e;
  --accent-2: #b4553f;
  --accent-soft: #f4e7e2;
  --green: #3f6b4f;
  --serif: "Noto Serif SC", "Source Han Serif SC", "Songti SC", "STSong", "SimSun", serif;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB",
    "Microsoft YaHei", "Source Han Sans SC", sans-serif;
  --mono: "SFMono-Regular", ui-monospace, "Cascadia Mono", Consolas, monospace;
  --shadow: 0 1px 2px rgba(29, 27, 24, .04), 0 8px 24px rgba(29, 27, 24, .06);
  --radius: 12px;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  height: 100%;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 15px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

button, input, select, textarea { font: inherit; color: inherit; }
button { cursor: pointer; }
.hidden { display: none !important; }

/* ---------- login ---------- */
.login {
  position: fixed;
  inset: 0;
  display: grid;
  place-items: center;
  background:
    radial-gradient(1200px 500px at 50% -10%, #fffdf8 0%, transparent 60%),
    var(--paper);
  padding: 24px;
  z-index: 50;
}
.login-card {
  width: 100%;
  max-width: 380px;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 40px 36px 28px;
  box-shadow: var(--shadow);
  text-align: center;
}
.brand-mark {
  width: 56px; height: 56px;
  margin: 0 auto 18px;
  display: grid; place-items: center;
  font-family: var(--serif);
  font-size: 30px;
  color: var(--accent);
  border: 1.5px solid var(--accent);
  border-radius: 10px;
  background: var(--accent-soft);
}
.brand-mark.small {
  width: 38px; height: 38px; font-size: 20px; margin: 0; border-radius: 8px;
}
.login h1 {
  font-family: var(--serif);
  font-size: 26px;
  letter-spacing: .04em;
  margin: 0 0 6px;
  font-weight: 600;
}
.login .sub { color: var(--muted); font-size: 13px; margin: 0 0 28px; letter-spacing: .08em; }
.login form { text-align: left; }
.login label { display: block; font-size: 12px; color: var(--muted); letter-spacing: .08em; margin-bottom: 6px; }
.login input {
  width: 100%;
  padding: 11px 13px;
  border: 1px solid var(--line-2);
  border-radius: 8px;
  background: #fff;
  outline: none;
  transition: border-color .15s, box-shadow .15s;
}
.login input:focus { border-color: var(--accent); box-shadow: 0 0 0 3px rgba(156, 59, 46, .1); }
.login .btn { width: 100%; margin-top: 14px; }
.fineprint { color: var(--muted-2); font-size: 11.5px; line-height: 1.6; margin: 22px 0 0; }
.error { color: var(--accent); font-size: 12.5px; min-height: 18px; margin: 8px 0 0; }

/* ---------- shell ---------- */
.app { display: flex; height: 100%; }

.sidebar {
  width: 252px;
  flex: 0 0 252px;
  background: var(--paper-2);
  border-right: 1px solid var(--line);
  display: flex;
  flex-direction: column;
  padding: 20px 14px 16px;
  gap: 18px;
  overflow-y: auto;
}
.brand { display: flex; align-items: center; gap: 11px; padding: 0 6px; }
.brand-name { font-family: var(--serif); font-size: 16px; font-weight: 600; letter-spacing: .04em; }
.brand-sub { font-size: 11px; color: var(--muted-2); letter-spacing: .14em; }

.nav { display: flex; flex-direction: column; gap: 2px; }
.nav-item {
  display: flex; align-items: center; gap: 10px;
  width: 100%;
  padding: 9px 10px;
  border: 0;
  border-radius: 8px;
  background: transparent;
  color: var(--ink-2);
  font-size: 14px;
  text-align: left;
  transition: background .15s, color .15s;
}
.nav-item:hover { background: rgba(156, 59, 46, .06); }
.nav-item.active { background: var(--card); color: var(--ink); box-shadow: 0 1px 2px rgba(0,0,0,.04); }
.nav-item.active .nav-ic { background: var(--accent); color: #fff; border-color: var(--accent); }
.nav-ic {
  width: 22px; height: 22px;
  display: grid; place-items: center;
  border: 1px solid var(--line-2);
  border-radius: 6px;
  font-family: var(--serif);
  font-size: 12px;
  color: var(--muted);
  background: #fff;
}

.side-block { border-top: 1px solid var(--line); padding-top: 16px; }
.side-title { font-size: 11px; letter-spacing: .14em; color: var(--muted-2); padding: 0 8px 8px; }
.session-list { display: flex; flex-direction: column; gap: 1px; margin-bottom: 8px; max-height: 240px; overflow-y: auto; }
.session-item {
  border: 0; background: transparent; text-align: left;
  padding: 7px 9px; border-radius: 6px; font-size: 13px; color: var(--ink-2);
  overflow: hidden; text-overflow: ellipsis; white-space: nowrap;
}
.session-item:hover { background: rgba(0,0,0,.035); }
.session-item.active { background: var(--card); color: var(--accent); }

.side-foot { margin-top: auto; border-top: 1px solid var(--line); padding: 14px 8px 0; color: var(--muted-2); font-size: 11px; line-height: 1.6; }
.corpus-stat { color: var(--ink-2); font-size: 12px; margin-bottom: 6px; font-variant-numeric: tabular-nums; }

.main { flex: 1; display: flex; flex-direction: column; min-width: 0; }
.topbar {
  height: 58px; flex: 0 0 58px;
  display: flex; align-items: center; gap: 12px;
  padding: 0 22px;
  border-bottom: 1px solid var(--line);
  background: rgba(248, 245, 240, .9);
  backdrop-filter: blur(6px);
}
.topbar h2 { font-family: var(--serif); font-size: 16px; font-weight: 600; margin: 0; letter-spacing: .06em; }
.topbar-right { margin-left: auto; display: flex; align-items: center; gap: 10px; }
.badge {
  font-size: 11px; color: var(--green);
  border: 1px solid #cfded3; background: #eef4ef;
  padding: 2px 8px; border-radius: 999px; letter-spacing: .06em;
}

.view { flex: 1; overflow-y: auto; display: none; }
.view.active { display: flex; flex-direction: column; }

/* ---------- buttons ---------- */
.btn {
  border: 1px solid var(--line-2);
  background: #fff;
  border-radius: 8px;
  padding: 9px 16px;
  font-size: 14px;
  transition: background .15s, border-color .15s, transform .05s;
}
.btn:hover { border-color: var(--muted-2); }
.btn:active { transform: translateY(1px); }
.btn.primary { background: var(--accent); border-color: var(--accent); color: #fff; }
.btn.primary:hover { background: var(--accent-2); border-color: var(--accent-2); }
.btn.ghost { background: transparent; }
.btn.tiny { padding: 5px 10px; font-size: 12px; }
.btn.more { margin: 18px auto 40px; display: block; }
.icon-btn { border: 0; background: transparent; font-size: 16px; color: var(--muted); padding: 6px 8px; border-radius: 6px; }
.icon-btn:hover { background: rgba(0,0,0,.05); }

/* ---------- chat ---------- */
.chat-scroll { flex: 1; overflow-y: auto; scroll-behavior: smooth; }
.chat-inner { max-width: 780px; margin: 0 auto; padding: 36px 24px 24px; }

.welcome { padding: 8vh 0 0; }
.welcome h1 {
  font-family: var(--serif); font-size: 30px; font-weight: 600;
  letter-spacing: .03em; margin: 0 0 12px;
}
.welcome p { color: var(--muted); margin: 0 0 28px; max-width: 520px; }
.suggest { display: flex; flex-wrap: wrap; gap: 9px; }
.chip {
  border: 1px solid var(--line-2); background: #fff; color: var(--ink-2);
  border-radius: 999px; padding: 7px 14px; font-size: 13px;
  transition: border-color .15s, color .15s, background .15s;
}
.chip:hover { border-color: var(--accent); color: var(--accent); background: var(--accent-soft); }

.msg { margin-bottom: 26px; animation: fade .25s ease; }
@keyframes fade { from { opacity: 0; transform: translateY(4px); } to { opacity: 1; transform: none; } }
.msg.user { display: flex; justify-content: flex-end; }
.msg.user .bubble {
  background: var(--accent-soft);
  border: 1px solid #ecd9d3;
  color: var(--ink);
  padding: 10px 15px;
  border-radius: 14px 14px 4px 14px;
  max-width: 78%;
  white-space: pre-wrap;
}
.msg.assistant .doc {
  border-left: 2px solid var(--line-2);
  padding-left: 18px;
}
.msg.assistant .role {
  font-size: 11px; letter-spacing: .12em; color: var(--muted-2);
  margin-bottom: 6px;
}
.stage {
  display: flex; align-items: center; gap: 8px;
  color: var(--muted); font-size: 12.5px; padding: 4px 0;
}
.dots { display: inline-flex; gap: 3px; }
.dots i { width: 4px; height: 4px; border-radius: 50%; background: var(--accent); opacity: .35; animation: blink 1.1s infinite; }
.dots i:nth-child(2) { animation-delay: .18s; }
.dots i:nth-child(3) { animation-delay: .36s; }
@keyframes blink { 0%, 60%, 100% { opacity: .25; } 30% { opacity: 1; } }

.answer { font-size: 15px; }
.answer p { margin: 0 0 12px; }
.answer h1, .answer h2, .answer h3 { font-family: var(--serif); font-size: 17px; margin: 22px 0 10px; }
.answer ul, .answer ol { margin: 0 0 12px; padding-left: 22px; }
.answer li { margin-bottom: 5px; }
.answer strong { font-weight: 600; }
.answer blockquote {
  margin: 12px 0; padding: 8px 14px;
  border-left: 2px solid var(--accent);
  background: #fbf7f2; color: var(--ink-2);
}
.answer hr { border: 0; border-top: 1px solid var(--line); margin: 20px 0; }
.answer code { font-family: var(--mono); font-size: 13px; background: #f1ece4; padding: 1px 5px; border-radius: 4px; }

.cite {
  border: 0; background: var(--accent-soft); color: var(--accent);
  font-family: var(--mono); font-size: 11px; line-height: 1;
  padding: 3px 5px; border-radius: 4px; margin: 0 1px;
  vertical-align: 1px; white-space: nowrap; letter-spacing: 0;
}
.cite:hover { background: var(--accent); color: #fff; }

.cite-bar { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 14px; padding-top: 12px; border-top: 1px dashed var(--line); }
.cite-pill {
  border: 1px solid var(--line-2); background: #fff; border-radius: 6px;
  font-size: 11.5px; color: var(--muted); padding: 3px 8px;
}
.cite-pill:hover { border-color: var(--accent); color: var(--accent); }
.safety-note {
  margin-top: 12px; font-size: 12px; color: var(--accent);
  background: var(--accent-soft); border: 1px solid #ecd9d3;
  padding: 8px 12px; border-radius: 8px;
}

.composer { flex: 0 0 auto; border-top: 1px solid var(--line); background: var(--paper); padding: 14px 24px 10px; }
.composer-inner {
  max-width: 780px; margin: 0 auto;
  display: flex; gap: 10px; align-items: flex-end;
  background: #fff; border: 1px solid var(--line-2); border-radius: 14px;
  padding: 8px 8px 8px 14px;
  box-shadow: 0 1px 2px rgba(0,0,0,.03);
}
.composer-inner:focus-within { border-color: var(--accent); box-shadow: 0 0 0 3px rgba(156,59,46,.08); }
#chat-input {
  flex: 1; border: 0; outline: none; resize: none;
  background: transparent; padding: 7px 0; max-height: 160px; line-height: 1.6;
}
.composer-note { max-width: 780px; margin: 8px auto 0; text-align: center; color: var(--muted-2); font-size: 11px; }

/* ---------- toolbars & lists ---------- */
.toolbar {
  display: flex; gap: 10px; padding: 20px 24px 0;
  max-width: 1080px; width: 100%; margin: 0 auto;
}
.input {
  flex: 1; min-width: 0;
  border: 1px solid var(--line-2); background: #fff;
  border-radius: 9px; padding: 9px 13px; outline: none;
}
.input:focus { border-color: var(--accent); box-shadow: 0 0 0 3px rgba(156,59,46,.08); }
.input.select { flex: 0 0 110px; }
.result-meta { max-width: 1080px; width: 100%; margin: 14px auto 0; padding: 0 24px; color: var(--muted); font-size: 12.5px; }

.case-list { max-width: 1080px; width: 100%; margin: 8px auto 0; padding: 0 24px; }
.case-item {
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 16px 18px; margin-bottom: 10px; cursor: pointer;
  transition: border-color .15s, box-shadow .15s, transform .1s;
}
.case-item:hover { border-color: var(--line-2); box-shadow: var(--shadow); transform: translateY(-1px); }
.case-head { display: flex; align-items: baseline; gap: 10px; margin-bottom: 6px; }
.case-id { font-family: var(--mono); font-size: 11px; color: var(--muted-2); }
.case-title { font-family: var(--serif); font-size: 16px; font-weight: 600; }
.case-tag { font-size: 11px; color: var(--green); background: #eef4ef; border: 1px solid #d5e2d8; padding: 1px 7px; border-radius: 999px; }
.case-sub { color: var(--muted); font-size: 13px; }
.case-sub b { color: var(--ink-2); font-weight: 500; }

.formula-grid {
  max-width: 1080px; width: 100%; margin: 8px auto 0; padding: 0 24px 40px;
  display: grid; grid-template-columns: repeat(auto-fill, minmax(300px, 1fr)); gap: 12px;
}
.formula-card {
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 15px 17px; cursor: pointer; transition: border-color .15s, box-shadow .15s;
  min-height: 112px; display: flex; flex-direction: column; gap: 4px;
}
.formula-card:hover { border-color: var(--line-2); box-shadow: var(--shadow); }
.formula-name { font-family: var(--serif); font-size: 16px; font-weight: 600; margin-bottom: 6px; }
.formula-line { font-size: 12.5px; color: var(--muted); line-height: 1.65;
  display: -webkit-box; -webkit-line-clamp: 3; -webkit-box-orient: vertical; overflow: hidden; }

.search-list { max-width: 1080px; width: 100%; margin: 8px auto 40px; padding: 0 24px; }
.search-item {
  border-bottom: 1px solid var(--line); padding: 14px 2px; cursor: pointer;
}
.search-item:hover { background: rgba(255,255,255,.6); }
.search-head { display: flex; gap: 10px; align-items: baseline; margin-bottom: 4px; }
.search-title { font-weight: 600; font-size: 14px; }
.search-path { font-family: var(--mono); font-size: 11px; color: var(--muted-2); }
.search-snippet { color: var(--ink-2); font-size: 13.5px; line-height: 1.7; }

/* ---------- drawer ---------- */
.scrim { position: fixed; inset: 0; background: rgba(29,27,24,.28); z-index: 30; }
.drawer {
  position: fixed; top: 0; right: 0; bottom: 0; width: min(560px, 92vw);
  background: var(--card); border-left: 1px solid var(--line);
  box-shadow: -12px 0 40px rgba(29,27,24,.12);
  transform: translateX(102%); transition: transform .22s ease;
  z-index: 40; display: flex; flex-direction: column;
}
.drawer.open { transform: none; }
.drawer-head {
  display: flex; align-items: flex-start; gap: 12px;
  padding: 18px 20px 14px; border-bottom: 1px solid var(--line);
}
.drawer-title { font-family: var(--serif); font-size: 15px; font-weight: 600; }
.drawer-path { font-family: var(--mono); font-size: 11px; color: var(--muted-2); margin-top: 2px; }
.drawer-body { flex: 1; overflow: auto; padding: 6px 0 30px; }
.src { display: flex; font-family: var(--mono); font-size: 12.5px; line-height: 1.85; }
.src .ln { flex: 0 0 52px; text-align: right; padding-right: 12px; color: var(--muted-2); user-select: none; }
.src .tx { white-space: pre-wrap; word-break: break-word; padding-right: 20px; color: var(--ink-2); }
.src.hit { background: #fdf3ee; }
.src.hit .tx { color: var(--ink); }

/* ---------- modal ---------- */
.modal { position: fixed; inset: 0; display: grid; place-items: center; background: rgba(29,27,24,.3); z-index: 45; padding: 24px; }
.modal-card {
  background: var(--card); border: 1px solid var(--line); border-radius: 14px;
  width: min(720px, 100%); max-height: 86vh; display: flex; flex-direction: column;
  box-shadow: 0 20px 60px rgba(29,27,24,.2);
}
.modal-head { display: flex; align-items: center; gap: 12px; padding: 18px 20px 14px; border-bottom: 1px solid var(--line); }
.modal-head h3 { font-family: var(--serif); font-size: 17px; margin: 0; font-weight: 600; }
.modal-head .icon-btn { margin-left: auto; }
.modal-body { overflow: auto; padding: 18px 22px 26px; }
.field { margin-bottom: 14px; }
.field dt { font-size: 11px; letter-spacing: .12em; color: var(--muted-2); margin-bottom: 3px; }
.field dd { margin: 0; font-size: 14px; line-height: 1.75; color: var(--ink-2); }

/* ---------- responsive ---------- */
.only-mobile { display: none; }
@media (max-width: 900px) {
  .only-mobile { display: inline-flex; }
  .sidebar {
    position: fixed; inset: 0 auto 0 0; z-index: 35;
    transform: translateX(-102%); transition: transform .2s ease;
    width: 270px; box-shadow: 12px 0 40px rgba(29,27,24,.14);
  }
  .sidebar.open { transform: none; }
  .topbar { padding: 0 14px; }
  .chat-inner { padding: 20px 16px; }
  .welcome { padding-top: 4vh; }
  .welcome h1 { font-size: 24px; }
  .toolbar { padding: 14px 16px 0; flex-wrap: wrap; }
  .input.select { flex: 0 0 96px; }
  .result-meta, .case-list, .formula-grid, .search-list { padding-left: 16px; padding-right: 16px; }
  .composer { padding: 10px 12px 8px; }
  .msg.user .bubble { max-width: 88%; }
}