/* ── Reset & Base ─────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg: #0f1117;
  --bg2: #161b25;
  --bg3: #1e2535;
  --border: #2a3148;
  --text: #e2e8f0;
  --text2: #94a3b8;
  --text3: #64748b;
  --blue: #3b82f6;
  --blue-light: #60a5fa;
  --green: #10b981;
  --orange: #f59e0b;
  --purple: #8b5cf6;
  --red: #ef4444;
  --radius: 12px;
  --shadow: 0 4px 20px rgba(0,0,0,.4);
}

body { background: var(--bg); color: var(--text); font-family: 'Segoe UI', system-ui, sans-serif;
  font-size: 15px; line-height: 1.6; min-height: 100vh; }

a { color: var(--blue-light); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ── Navbar ──────────────────────────────────────────────── */
.navbar {
  display: flex; align-items: center; justify-content: space-between;
  padding: 0 24px; height: 60px; background: var(--bg2);
  border-bottom: 1px solid var(--border); position: sticky; top: 0; z-index: 100;
}
.nav-brand { display: flex; align-items: center; gap: 8px; font-weight: 700; font-size: 16px; }
.nav-icon { font-size: 20px; }
.nav-links { display: flex; gap: 4px; }
.nav-link { padding: 6px 14px; border-radius: 8px; color: var(--text2); transition: .2s; font-size: 14px; }
.nav-link:hover { background: var(--bg3); color: var(--text); text-decoration: none; }
.nav-link.active { background: var(--bg3); color: var(--blue-light); }

/* ── Main ────────────────────────────────────────────────── */
.main-content { max-width: 1200px; margin: 0 auto; padding: 32px 24px; }

/* ── Hero ─────────────────────────────────────────────────── */
.hero { display: flex; align-items: center; justify-content: space-between;
  padding: 60px 0 40px; gap: 40px; }
.hero-content { flex: 1; }
.hero-title { font-size: 42px; font-weight: 800; line-height: 1.2; margin-bottom: 16px; }
.gradient-text {
  background: linear-gradient(135deg, var(--blue), var(--purple));
  -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text;
}
.hero-subtitle { font-size: 17px; color: var(--text2); margin-bottom: 28px; max-width: 520px; }
.btn-primary {
  display: inline-block; padding: 12px 28px; background: var(--blue);
  color: #fff; border-radius: 10px; font-weight: 600; font-size: 15px;
  transition: .2s; text-decoration: none;
}
.btn-primary:hover { background: #2563eb; transform: translateY(-1px); text-decoration: none; }
.hero-visual { font-size: 120px; line-height: 1; opacity: .15; user-select: none; }

/* ── Section ─────────────────────────────────────────────── */
.section-title { font-size: 24px; font-weight: 700; margin-bottom: 24px; color: var(--text); }

/* ── Domain Grid ─────────────────────────────────────────── */
.domains-section { margin-bottom: 48px; }
.domain-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 20px; }
.domain-card {
  background: var(--bg2); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 24px; transition: .2s; cursor: default;
}
.domain-card:hover { transform: translateY(-2px); box-shadow: var(--shadow); }
.domain-blue  { border-top: 3px solid var(--blue); }
.domain-green { border-top: 3px solid var(--green); }
.domain-orange{ border-top: 3px solid var(--orange); }
.domain-purple{ border-top: 3px solid var(--purple); }
.domain-header { display: flex; align-items: center; justify-content: space-between; margin-bottom: 10px; }
.domain-icon { font-size: 24px; }
.domain-num { font-size: 12px; color: var(--text3); background: var(--bg3); padding: 3px 8px; border-radius: 20px; }
.domain-name { font-size: 17px; font-weight: 700; margin-bottom: 8px; }
.domain-desc { font-size: 13px; color: var(--text2); margin-bottom: 14px; line-height: 1.5; }
.paper-list { margin-bottom: 16px; }
.paper-item { font-size: 12px; color: var(--text2); margin-bottom: 4px; display: flex; gap: 6px; }
.paper-dot { color: var(--text3); flex-shrink: 0; font-size: 10px; margin-top: 4px; }
.domain-link { font-size: 13px; color: var(--blue-light); }

/* ── Quick Questions ──────────────────────────────────────── */
.quick-questions { margin-bottom: 48px; }
.question-chips { display: flex; flex-wrap: wrap; gap: 10px; }
.chip {
  padding: 8px 16px; background: var(--bg2); border: 1px solid var(--border);
  border-radius: 20px; font-size: 13px; color: var(--text2); transition: .2s;
}
.chip:hover { border-color: var(--blue); color: var(--blue-light); text-decoration: none; background: var(--bg3); }

/* ── Chat Layout ──────────────────────────────────────────── */
.main-content:has(.chat-layout) { max-width: 100%; padding: 0; }
.chat-layout { display: flex; height: calc(100vh - 60px); overflow: hidden; }

/* Sidebar */
.sidebar {
  width: 260px; min-width: 260px; background: var(--bg2);
  border-right: 1px solid var(--border); display: flex; flex-direction: column;
  overflow: hidden;
}
.sidebar-header { padding: 16px; border-bottom: 1px solid var(--border); }
.btn-new-chat {
  width: 100%; padding: 10px; background: var(--blue); color: #fff;
  border: none; border-radius: 8px; font-size: 14px; font-weight: 600;
  cursor: pointer; transition: .2s;
}
.btn-new-chat:hover { background: #2563eb; }
.conv-list { flex: 1; overflow-y: auto; padding: 8px; }
.conv-item {
  display: flex; align-items: center; justify-content: space-between;
  padding: 10px 12px; border-radius: 8px; cursor: pointer; transition: .15s;
  gap: 8px;
}
.conv-item:hover { background: var(--bg3); }
.conv-item.active { background: var(--bg3); border: 1px solid var(--border); }
.conv-title { font-size: 13px; color: var(--text2); overflow: hidden; text-overflow: ellipsis; white-space: nowrap; flex: 1; }
.conv-del {
  background: none; border: none; color: var(--text3); cursor: pointer;
  font-size: 12px; padding: 2px 4px; border-radius: 4px; flex-shrink: 0;
  opacity: 0; transition: .15s;
}
.conv-item:hover .conv-del { opacity: 1; }
.conv-del:hover { color: var(--red); background: rgba(239,68,68,.1); }

.sidebar-domains { padding: 12px 8px; border-top: 1px solid var(--border); }
.sidebar-label { font-size: 11px; color: var(--text3); padding: 0 8px 6px; text-transform: uppercase; letter-spacing: .5px; }
.domain-tag {
  display: block; width: 100%; text-align: left; padding: 8px 12px;
  background: none; border: none; color: var(--text2); font-size: 12px;
  border-radius: 6px; cursor: pointer; transition: .15s; margin-bottom: 2px;
}
.domain-tag:hover { background: var(--bg3); color: var(--text); }

/* Chat Main */
.chat-main { flex: 1; display: flex; flex-direction: column; overflow: hidden; }
.chat-header {
  padding: 0 24px; height: 52px; display: flex; align-items: center;
  border-bottom: 1px solid var(--border); font-weight: 600; font-size: 15px;
  background: var(--bg2);
}

.messages-wrap { flex: 1; overflow-y: auto; padding: 24px; }
.messages { max-width: 820px; margin: 0 auto; display: flex; flex-direction: column; gap: 20px; }

/* Welcome */
.welcome-msg { text-align: center; padding: 60px 20px; color: var(--text2); }
.welcome-icon { font-size: 48px; margin-bottom: 16px; }
.welcome-msg h3 { font-size: 20px; color: var(--text); margin-bottom: 10px; }
.welcome-msg p { font-size: 14px; line-height: 1.7; }

/* Message bubbles */
.msg { display: flex; gap: 12px; }
.msg.user { flex-direction: row-reverse; }
.msg-avatar {
  width: 36px; height: 36px; border-radius: 50%; display: flex; align-items: center;
  justify-content: center; font-size: 16px; flex-shrink: 0;
}
.msg.user .msg-avatar { background: var(--blue); }
.msg.assistant .msg-avatar { background: var(--bg3); border: 1px solid var(--border); }
.msg-body { max-width: 75%; }
.msg-content {
  padding: 12px 16px; border-radius: 12px; font-size: 14px; line-height: 1.7;
  word-break: break-word;
}
/* During streaming show raw text as-is */
.msg-content.msg-streaming { white-space: pre-wrap; }
.msg.user .msg-content { background: var(--blue); color: #fff; border-radius: 12px 12px 2px 12px; }
.msg.assistant .msg-content { background: var(--bg2); border: 1px solid var(--border); border-radius: 12px 12px 12px 2px; }
.msg-time { font-size: 11px; color: var(--text3); margin-top: 4px; padding: 0 4px; }
.msg.user .msg-time { text-align: right; }

/* Typing indicator */
.typing-dots span {
  display: inline-block; width: 6px; height: 6px; background: var(--text3);
  border-radius: 50%; margin: 0 2px; animation: blink 1.2s infinite;
}
.typing-dots span:nth-child(2) { animation-delay: .2s; }
.typing-dots span:nth-child(3) { animation-delay: .4s; }
@keyframes blink { 0%,60%,100%{opacity:.2} 30%{opacity:1} }

/* Input area */
.input-area {
  padding: 16px 24px 20px; border-top: 1px solid var(--border);
  background: var(--bg2);
}
.input-wrap { display: flex; gap: 10px; max-width: 820px; margin: 0 auto; }
#userInput {
  flex: 1; background: var(--bg3); border: 1px solid var(--border);
  border-radius: 10px; padding: 12px 16px; color: var(--text); font-size: 14px;
  font-family: inherit; resize: none; max-height: 160px; overflow-y: auto;
  transition: border-color .2s; line-height: 1.5;
}
#userInput:focus { outline: none; border-color: var(--blue); }
#userInput::placeholder { color: var(--text3); }
.btn-send {
  width: 44px; height: 44px; background: var(--blue); border: none; border-radius: 10px;
  color: #fff; cursor: pointer; display: flex; align-items: center; justify-content: center;
  transition: .2s; flex-shrink: 0; align-self: flex-end;
}
.btn-send:hover { background: #2563eb; }
.btn-send:disabled { background: var(--bg3); color: var(--text3); cursor: not-allowed; }
.input-hint { font-size: 11px; color: var(--text3); text-align: center; margin-top: 6px; }

/* ── Knowledge Page ──────────────────────────────────────── */
.knowledge-page { padding: 0; }
.page-header { margin-bottom: 28px; }
.page-header h2 { font-size: 28px; font-weight: 700; margin-bottom: 6px; }
.page-header p { color: var(--text2); }

.domain-tabs { display: flex; gap: 8px; margin-bottom: 24px; flex-wrap: wrap; }
.tab-btn {
  padding: 9px 20px; background: var(--bg2); border: 1px solid var(--border);
  border-radius: 8px; color: var(--text2); font-size: 13px; cursor: pointer; transition: .2s;
}
.tab-btn:hover { border-color: var(--blue); color: var(--text); }
.tab-btn.active { background: var(--blue); border-color: var(--blue); color: #fff; }
.tab-panel { display: none; }
.tab-panel.active { display: block; }

.domain-intro {
  padding: 20px 24px; border-radius: var(--radius); margin-bottom: 20px;
  border-left: 4px solid var(--blue);
}
.domain-intro.kblue  { background: rgba(59,130,246,.1); border-color: var(--blue); }
.domain-intro.kgreen { background: rgba(16,185,129,.1); border-color: var(--green); }
.domain-intro.korange{ background: rgba(245,158,11,.1); border-color: var(--orange); }
.domain-intro.kpurple{ background: rgba(139,92,246,.1); border-color: var(--purple); }
.domain-intro h3 { font-size: 18px; font-weight: 700; margin-bottom: 8px; }
.domain-intro p { font-size: 14px; color: var(--text2); }

.paper-cards { display: grid; grid-template-columns: repeat(auto-fill, minmax(340px,1fr)); gap: 16px; }
.paper-card { background: var(--bg2); border: 1px solid var(--border); border-radius: var(--radius); padding: 20px; }
.paper-card-header { margin-bottom: 8px; }
.paper-num { font-size: 11px; color: var(--text3); background: var(--bg3); padding: 3px 8px; border-radius: 20px; }
.paper-card-title { font-size: 15px; font-weight: 600; margin-bottom: 10px; line-height: 1.4; }
.paper-abstract { font-size: 13px; color: var(--text2); line-height: 1.6; margin-bottom: 14px; }
.paper-meta { display: flex; align-items: center; justify-content: space-between; }
.meta-badge { font-size: 11px; color: var(--text3); background: var(--bg3); padding: 3px 8px; border-radius: 20px; }
.ask-btn { font-size: 13px; color: var(--blue-light); }

/* ── Plain-text messages ─────────────────────────────────── */
.msg-content p { margin: 0 0 8px; }
.msg-content p:last-child { margin-bottom: 0; }

/* ── Scrollbar ────────────────────────────────────────────── */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }

/* ── Responsive ──────────────────────────────────────────── */
@media (max-width: 768px) {
  .hero { flex-direction: column; padding: 30px 0; }
  .hero-visual { display: none; }
  .hero-title { font-size: 28px; }
  .sidebar { width: 220px; min-width: 220px; }
  .domain-grid { grid-template-columns: 1fr; }
}