:root {
  --bg: #0b0d12;
  --bg-elev: #11141b;
  --bg-elev-2: #161a23;
  --border: #232836;
  --border-strong: #2e3447;
  --text: #e6e9ef;
  --text-dim: #9aa3b2;
  --muted: #6b7280;
  --primary: #6366f1;
  --primary-hover: #7c7ff5;
  --primary-soft: rgba(99,102,241,.15);
  --accent: #22d3ee;
  --success: #10b981;
  --danger: #ef4444;
  --warning: #f59e0b;
  --radius: 12px;
  --radius-sm: 8px;
  --shadow: 0 10px 40px rgba(0,0,0,.45);
  --shadow-sm: 0 4px 14px rgba(0,0,0,.3);
  --transition: .18s ease;
  --font: 'Inter', system-ui, -apple-system, Segoe UI, Roboto, sans-serif;
  --mono: 'JetBrains Mono', ui-monospace, SFMono-Regular, Menlo, monospace;
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; height: 100%; }
/* The HTML `hidden` attribute must override our display:grid/flex rules */
[hidden] { display: none !important; }
body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  font-size: 15px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}
button { font-family: inherit; cursor: pointer; }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

.muted { color: var(--text-dim); }
.small { font-size: 12px; }

/* ============ LOGIN ============ */
.login-screen {
  position: fixed; inset: 0;
  display: grid; place-items: center;
  background:
    radial-gradient(800px 500px at 20% 10%, rgba(99,102,241,.15), transparent 60%),
    radial-gradient(600px 400px at 80% 90%, rgba(34,211,238,.12), transparent 60%),
    var(--bg);
  z-index: 50;
}
.login-card {
  width: min(420px, 92vw);
  background: var(--bg-elev);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 36px 32px;
  box-shadow: var(--shadow);
}
.login-logo { text-align: center; margin-bottom: 26px; }
.login-logo h1 { font-size: 22px; margin: 14px 0 6px; font-weight: 700; }
.logo-mark {
  width: 56px; height: 56px;
  margin: 0 auto;
  border-radius: 14px;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  display: grid; place-items: center;
  font-weight: 800; font-size: 26px; color: white;
  box-shadow: 0 8px 24px rgba(99,102,241,.4);
}
.logo-mark.small { width: 36px; height: 36px; font-size: 16px; border-radius: 10px; box-shadow: none; }
.login-form { display: flex; flex-direction: column; gap: 14px; }
.login-form label { display: flex; flex-direction: column; gap: 6px; font-size: 13px; color: var(--text-dim); }
.login-form input {
  background: var(--bg);
  border: 1px solid var(--border-strong);
  color: var(--text);
  padding: 11px 14px;
  border-radius: var(--radius-sm);
  font-size: 14px;
  outline: none;
  transition: var(--transition);
}
.login-form input:focus { border-color: var(--primary); box-shadow: 0 0 0 3px var(--primary-soft); }
.login-error {
  background: rgba(239,68,68,.1);
  border: 1px solid rgba(239,68,68,.3);
  color: #fca5a5;
  padding: 10px 12px;
  border-radius: var(--radius-sm);
  font-size: 13px;
}

/* ============ BUTTONS ============ */
.btn-primary {
  background: var(--primary);
  color: white;
  border: none;
  padding: 11px 16px;
  border-radius: var(--radius-sm);
  font-weight: 600;
  font-size: 14px;
  transition: var(--transition);
}
.btn-primary:hover { background: var(--primary-hover); }
.btn-primary.small { padding: 7px 12px; font-size: 12px; }
.btn-ghost {
  background: transparent;
  color: var(--text-dim);
  border: 1px solid var(--border-strong);
  padding: 9px 14px;
  border-radius: var(--radius-sm);
  font-weight: 500;
  font-size: 13px;
  transition: var(--transition);
}
.btn-ghost:hover { color: var(--text); border-color: var(--primary); }
.btn-ghost.small { padding: 6px 10px; font-size: 12px; }
.icon-btn {
  background: transparent;
  border: none;
  color: var(--text-dim);
  width: 30px; height: 30px;
  border-radius: 7px;
  display: grid; place-items: center;
  font-size: 16px;
  transition: var(--transition);
}
.icon-btn:hover { background: var(--bg-elev-2); color: var(--text); }

/* ============ APP LAYOUT ============ */
.app {
  display: grid;
  grid-template-columns: 280px 1fr;
  height: 100vh;
}
.sidebar {
  background: var(--bg-elev);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  overflow: hidden;
}
.sidebar-header {
  padding: 18px 18px;
  display: flex; align-items: center; gap: 12px;
  border-bottom: 1px solid var(--border);
}
.brand { font-weight: 700; font-size: 14px; }

.nav { flex: 1; overflow-y: auto; padding: 14px 10px; }
.nav-group + .nav-group { margin-top: 18px; }
.nav-title {
  padding: 6px 10px;
  font-size: 11px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: .08em;
  color: var(--muted);
}
.nav ul { list-style: none; padding: 0; margin: 4px 0 0; }
.nav li button {
  width: 100%;
  text-align: left;
  background: transparent;
  border: none;
  color: var(--text-dim);
  padding: 9px 12px;
  border-radius: var(--radius-sm);
  font-size: 13.5px;
  display: flex; align-items: center; gap: 10px;
  transition: var(--transition);
}
.nav li button:hover { background: var(--bg-elev-2); color: var(--text); }
.nav li button.active {
  background: var(--primary-soft);
  color: var(--text);
  font-weight: 500;
}
.nav-dot { width: 6px; height: 6px; border-radius: 50%; background: var(--primary); opacity: .7; }
.sidebar-footer {
  padding: 12px 14px;
  border-top: 1px solid var(--border);
}

/* ============ MAIN ============ */
.main { display: flex; flex-direction: column; overflow: hidden; }
.topbar {
  display: flex; align-items: center; gap: 16px;
  padding: 14px 28px;
  border-bottom: 1px solid var(--border);
  background: var(--bg);
  position: relative;
  z-index: 5;
}
.search-wrapper {
  flex: 1;
  position: relative;
  max-width: 720px;
}
.search-wrapper input {
  width: 100%;
  background: var(--bg-elev);
  border: 1px solid var(--border-strong);
  color: var(--text);
  padding: 11px 44px 11px 42px;
  border-radius: 10px;
  font-size: 14px;
  outline: none;
  transition: var(--transition);
}
.search-wrapper input:focus {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px var(--primary-soft);
}
.search-icon {
  position: absolute; left: 14px; top: 50%; transform: translateY(-50%);
  color: var(--muted);
}
.kbd {
  position: absolute; right: 12px; top: 50%; transform: translateY(-50%);
  background: var(--bg);
  border: 1px solid var(--border-strong);
  color: var(--muted);
  font-family: var(--mono);
  font-size: 11px;
  padding: 2px 7px;
  border-radius: 5px;
}
.search-results {
  position: absolute;
  top: calc(100% + 8px);
  left: 0; right: 0;
  background: var(--bg-elev);
  border: 1px solid var(--border-strong);
  border-radius: 12px;
  max-height: 460px;
  overflow-y: auto;
  box-shadow: var(--shadow);
  padding: 6px;
}
.search-result {
  padding: 10px 12px;
  border-radius: 8px;
  cursor: pointer;
  display: flex;
  flex-direction: column;
  gap: 2px;
}
.search-result:hover, .search-result.active {
  background: var(--primary-soft);
}
.search-result .sr-title { font-weight: 500; font-size: 13.5px; }
.search-result .sr-meta { font-size: 11.5px; color: var(--muted); }
.search-result .sr-snippet { font-size: 12.5px; color: var(--text-dim); margin-top: 2px; }
.search-result mark { background: rgba(99,102,241,.35); color: inherit; padding: 0 2px; border-radius: 3px; }
.search-empty { padding: 18px; text-align: center; color: var(--muted); font-size: 13px; }
.sr-section-head {
  padding: 8px 12px 4px;
  font-size: 10.5px;
  font-weight: 700;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--muted);
}

/* ============ CONTENT ============ */
.content {
  flex: 1;
  overflow-y: auto;
  padding: 36px 48px 80px;
  max-width: 100%;
}
.content .markdown { max-width: 920px; margin: 0 auto; }
.welcome { max-width: 920px; margin: 0 auto; }
.welcome h1 { font-size: 32px; margin: 12px 0 6px; }
.quick-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 16px;
  margin-top: 28px;
}
.quick-card {
  background: var(--bg-elev);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 18px;
  cursor: pointer;
  transition: var(--transition);
}
.quick-card:hover {
  border-color: var(--primary);
  transform: translateY(-2px);
  box-shadow: var(--shadow-sm);
}
.quick-card .qc-tag {
  font-size: 10px;
  text-transform: uppercase;
  letter-spacing: .1em;
  color: var(--accent);
  font-weight: 600;
}
.quick-card h3 { margin: 8px 0 4px; font-size: 16px; }
.quick-card p { margin: 0; color: var(--text-dim); font-size: 13px; }

/* ============ MARKDOWN ============ */
.markdown { color: var(--text); }
.markdown h1, .markdown h2, .markdown h3, .markdown h4 {
  color: var(--text);
  margin-top: 1.6em;
  margin-bottom: .6em;
  line-height: 1.3;
  scroll-margin-top: 80px;
}
.markdown h1 { font-size: 28px; border-bottom: 1px solid var(--border); padding-bottom: .35em; }
.markdown h2 { font-size: 22px; }
.markdown h3 { font-size: 18px; }
.markdown h4 { font-size: 15px; color: var(--text-dim); }
.markdown p { margin: .8em 0; }
.markdown ul, .markdown ol { padding-left: 1.4em; }
.markdown li { margin: .25em 0; }
.markdown blockquote {
  border-left: 3px solid var(--primary);
  background: var(--bg-elev);
  padding: 8px 16px;
  margin: 1em 0;
  color: var(--text-dim);
  border-radius: 0 8px 8px 0;
}
.markdown code {
  font-family: var(--mono);
  font-size: 13px;
  background: var(--bg-elev-2);
  padding: 2px 6px;
  border-radius: 4px;
  color: #f0abfc;
}
.markdown pre {
  background: #0d1117 !important;
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 14px 16px;
  overflow-x: auto;
  margin: 1em 0;
}
.markdown pre code { background: transparent; padding: 0; color: inherit; font-size: 13px; }
.markdown img {
  max-width: 100%;
  border-radius: 8px;
  margin: 14px 0;
  border: 1px solid var(--border);
  display: block;
}
.markdown table {
  width: 100%;
  border-collapse: collapse;
  margin: 1em 0;
  font-size: 13.5px;
}
.markdown th, .markdown td {
  border: 1px solid var(--border-strong);
  padding: 8px 12px;
  text-align: left;
}
.markdown th { background: var(--bg-elev); font-weight: 600; }
.markdown hr { border: none; border-top: 1px solid var(--border); margin: 2em 0; }
.markdown a { color: var(--accent); }

.pdf-viewer {
  width: 100%;
  height: calc(100vh - 160px);
  border: 1px solid var(--border);
  border-radius: 10px;
}

/* ============ CHAT ============ */
.chat-toggle {
  position: fixed; bottom: 24px; right: 24px;
  width: 56px; height: 56px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  color: white;
  border: none;
  display: grid; place-items: center;
  box-shadow: 0 12px 30px rgba(99,102,241,.45);
  z-index: 30;
  transition: transform var(--transition);
}
.chat-toggle:hover { transform: scale(1.06); }

.chat-window {
  position: fixed; bottom: 96px; right: 24px;
  width: min(1020px, 96vw);
  height: min(820px, 88vh);
  background: #2e3650;
  border: 1px solid #4a5577;
  border-radius: 16px;
  box-shadow: 0 24px 60px rgba(0,0,0,.75), 0 0 0 1px rgba(99,102,241,.35);
  display: flex;
  flex-direction: column;
  overflow: hidden;
  z-index: 40;
}
.chat-header {
  background: linear-gradient(180deg, #3a4368 0%, #2e3650 100%);
  border-bottom-color: #4a5577;
}
.chat-messages {
  background:
    radial-gradient(600px 400px at 30% 0%, rgba(99,102,241,.10), transparent 60%),
    #2e3650;
}
.chat-form {
  background: #3a4368;
  border-top-color: #4a5577;
}
.msg.assistant {
  background: #444f73;
  border: 1px solid #5a6691;
  color: #f1f3f9;
}
.chat-form textarea {
  background: #232a42;
  border-color: #5a6691;
  color: #f1f3f9;
}
.markdown a.dead-link { color: var(--text-dim); text-decoration: line-through; cursor: not-allowed; }
.markdown li.toc-item > a { color: var(--text); text-decoration: none; }
.markdown li.toc-item > a:hover { color: var(--accent); text-decoration: underline; }
.chat-header {
  display: flex; align-items: center; justify-content: space-between;
  padding: 14px 16px;
  border-bottom: 1px solid var(--border);
}
.chat-title { font-weight: 600; font-size: 14px; }
.chat-actions { display: flex; gap: 4px; }

.chat-messages {
  flex: 1;
  overflow-y: auto;
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.msg {
  max-width: 85%;
  padding: 10px 14px;
  border-radius: 14px;
  font-size: 13.5px;
  line-height: 1.55;
  white-space: pre-wrap;
  word-wrap: break-word;
}
.msg.user {
  align-self: flex-end;
  background: var(--primary);
  color: white;
  border-bottom-right-radius: 4px;
}
.msg.assistant {
  align-self: flex-start;
  background: var(--bg-elev-2);
  color: var(--text);
  border-bottom-left-radius: 4px;
  white-space: normal;
}
.msg.assistant .markdown { font-size: 13.5px; }
.msg.assistant .markdown p { margin: .35em 0; }
.msg.assistant .markdown pre { margin: .5em 0; padding: 10px; }
.msg.assistant .markdown ul,
.msg.assistant .markdown ol { margin: .35em 0; padding-left: 1.4em; }
.msg.assistant .markdown li { margin: .2em 0; }
.msg.assistant .markdown h1,
.msg.assistant .markdown h2,
.msg.assistant .markdown h3 { margin: .5em 0 .25em; }
.msg.error { align-self: stretch; background: rgba(239,68,68,.12); border: 1px solid rgba(239,68,68,.3); color: #fca5a5; }
.typing { display: inline-flex; gap: 4px; }
.typing span {
  width: 6px; height: 6px; border-radius: 50%;
  background: var(--text-dim);
  animation: bounce 1.2s infinite;
}
.typing span:nth-child(2) { animation-delay: .15s; }
.typing span:nth-child(3) { animation-delay: .3s; }
@keyframes bounce { 0%,80%,100%{transform:translateY(0);opacity:.4} 40%{transform:translateY(-4px);opacity:1} }

.chat-form {
  display: flex;
  gap: 8px;
  padding: 12px;
  border-top: 1px solid var(--border);
  background: var(--bg-elev);
}
.chat-form textarea {
  flex: 1;
  background: var(--bg);
  border: 1px solid var(--border-strong);
  color: var(--text);
  padding: 10px 12px;
  border-radius: 10px;
  font-family: inherit;
  font-size: 13.5px;
  resize: none;
  outline: none;
  transition: var(--transition);
}
.chat-form textarea:focus { border-color: var(--primary); box-shadow: 0 0 0 3px var(--primary-soft); }
.chat-form .btn-primary { align-self: flex-end; }

.chat-history-panel, .chat-prompt-panel {
  position: absolute;
  inset: 56px 0 0 0;
  background: var(--bg-elev);
  z-index: 5;
  padding: 14px;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.chat-history-head { display: flex; justify-content: space-between; align-items: center; }
.chat-history-panel ul { list-style: none; padding: 0; margin: 0; display: flex; flex-direction: column; gap: 4px; }
.chat-history-panel li {
  padding: 10px 12px;
  background: var(--bg-elev-2);
  border-radius: 8px;
  cursor: pointer;
  font-size: 13px;
  display: flex; justify-content: space-between; align-items: center; gap: 8px;
}
.chat-history-panel li:hover { background: var(--primary-soft); }
.chat-history-panel li.active { background: var(--primary-soft); border: 1px solid var(--primary); }
.chat-history-panel .conv-title { flex: 1; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.chat-history-panel .conv-del { color: var(--danger); font-size: 14px; padding: 0 4px; }

.chat-prompt-panel textarea {
  background: var(--bg);
  border: 1px solid var(--border-strong);
  color: var(--text);
  padding: 10px 12px;
  border-radius: 8px;
  font-family: var(--mono);
  font-size: 12.5px;
  resize: vertical;
  outline: none;
  min-height: 120px;
}
.chat-prompt-panel .row { display: flex; gap: 8px; }

/* Scrollbars */
::-webkit-scrollbar { width: 10px; height: 10px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border-strong); border-radius: 5px; }
::-webkit-scrollbar-thumb:hover { background: #3a4259; }

/* Responsive */
@media (max-width: 860px) {
  .app { grid-template-columns: 1fr; }
  .sidebar {
    position: fixed; inset: 0 auto 0 0; width: 280px;
    transform: translateX(-100%); transition: transform .25s ease;
    z-index: 20;
  }
  .sidebar.open { transform: translateX(0); }
  .content { padding: 20px; }
}