:root {
  --bg:           #0d1117;
  --sidebar:      #161b22;
  --card:         #1c2128;
  --primary:      #7c3aed;
  --primary-dark: #6d28d9;
  --primary-glow: rgba(124, 58, 237, 0.15);
  --text:         #e6edf3;
  --muted:        #7d8590;
  --border:       #30363d;
  --success:      #3fb950;
  --danger:       #f85149;
  --code-bg:      #161b22;
  --user-bubble:  #7c3aed;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
html, body { height: 100%; }

body {
  font-family: "Segoe UI", system-ui, -apple-system, sans-serif;
  background: var(--bg);
  color: var(--text);
  height: 100vh;
  overflow: hidden;
}

.app {
  display: grid;
  grid-template-columns: 260px 1fr;
  height: 100vh;
}

.sidebar {
  background: var(--sidebar);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  padding: 20px 14px;
  gap: 14px;
  overflow: hidden;
}

.logo { font-size: 22px; font-weight: 800; color: var(--primary); }
.logo-sub { font-size: 11px; color: var(--muted); margin-top: 2px; }

.btn-new {
  background: var(--primary);
  color: #fff;
  border: none;
  padding: 10px 14px;
  border-radius: 8px;
  cursor: pointer;
  font-weight: 600;
  font-size: 13px;
  text-align: left;
  transition: background 0.2s, transform 0.1s;
}
.btn-new:hover { background: var(--primary-dark); transform: translateY(-1px); }

.sessions-label {
  font-size: 11px;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 1px;
  padding: 0 4px;
}

.sessions-list {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 2px;
  overflow-y: auto;
}
.sessions-list::-webkit-scrollbar { width: 4px; }
.sessions-list::-webkit-scrollbar-thumb { background: var(--border); border-radius: 2px; }

.session-item {
  padding: 9px 10px;
  border-radius: 6px;
  font-size: 13px;
  color: var(--muted);
  cursor: pointer;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  border: 1px solid transparent;
  transition: background 0.15s, color 0.15s;
}
.session-item:hover { background: var(--card); color: var(--text); }
.session-item.active {
  background: var(--primary-glow);
  color: var(--text);
  border-color: var(--primary);
}

.sidebar-nav {
  margin-top: auto;
  padding-top: 8px;
}

.nav-link {
  display: flex;
  align-items: center;
  gap: 7px;
  padding: 8px 10px;
  border-radius: 6px;
  font-size: 12px;
  color: var(--muted);
  text-decoration: none;
  transition: background 0.15s, color 0.15s;
}

.nav-link:hover { background: var(--card); color: var(--text); }

.sidebar-footer {
  font-size: 11px;
  color: var(--muted);
  text-align: center;
  padding-top: 8px;
  border-top: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.sidebar-powered { font-size: 10px; color: var(--muted); }

.btn-logout {
  background: transparent;
  color: var(--muted);
  border: 1px solid var(--border);
  padding: 6px 12px;
  border-radius: 6px;
  cursor: pointer;
  font-size: 12px;
  font-family: inherit;
  transition: color 0.2s, border-color 0.2s;
  width: 100%;
}

.btn-logout:hover { color: #f85149; border-color: #f85149; }

.chat-area {
  display: flex;
  flex-direction: column;
  height: 100vh;
  overflow: hidden;
}

.chat-header {
  padding: 14px 24px;
  border-bottom: 1px solid var(--border);
  background: var(--sidebar);
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-shrink: 0;
}

.chat-header-left {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 600;
  font-size: 15px;
}

.chat-status { color: var(--success); font-size: 10px; }

.chat-header-right {
  display: flex;
  align-items: center;
  gap: 10px;
}

.phase-badge {
  background: var(--primary-glow);
  color: var(--primary);
  border: 1px solid var(--primary);
  padding: 3px 10px;
  border-radius: 20px;
  font-size: 11px;
  font-weight: 600;
}

.btn-export {
  background: transparent;
  color: var(--muted);
  border: 1px solid var(--border);
  padding: 6px 12px;
  border-radius: 6px;
  cursor: pointer;
  font-size: 12px;
  transition: all 0.2s;
}
.btn-export:hover { color: var(--text); border-color: var(--primary); }

.messages {
  flex: 1;
  overflow-y: auto;
  padding: 28px 24px;
  display: flex;
  flex-direction: column;
  gap: 20px;
}
.messages::-webkit-scrollbar { width: 6px; }
.messages::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }

.welcome {
  margin: auto;
  text-align: center;
  max-width: 480px;
  padding: 20px;
}
.welcome-icon { font-size: 52px; margin-bottom: 16px; }
.welcome h2 { font-size: 30px; font-weight: 800; color: var(--primary); margin-bottom: 10px; }
.welcome p { color: var(--muted); line-height: 1.7; margin-bottom: 24px; font-size: 15px; }
.welcome-tags { display: flex; flex-wrap: wrap; gap: 8px; justify-content: center; }
.welcome-tags span {
  background: var(--card);
  border: 1px solid var(--border);
  padding: 7px 14px;
  border-radius: 20px;
  font-size: 12px;
  color: var(--muted);
}

.message { display: flex; flex-direction: column; max-width: 82%; }
.message.user { align-self: flex-end; }
.message.agent { align-self: flex-start; }

.msg-role {
  font-size: 11px;
  font-weight: 600;
  color: var(--muted);
  margin-bottom: 5px;
  padding: 0 4px;
}
.message.user .msg-role { text-align: right; }

.bubble {
  padding: 14px 18px;
  border-radius: 14px;
  font-size: 14px;
  line-height: 1.65;
}

.message.user .bubble {
  background: var(--user-bubble);
  color: #fff;
  border-bottom-right-radius: 4px;
}

.message.agent .bubble {
  background: var(--card);
  border: 1px solid var(--border);
  border-bottom-left-radius: 4px;
}

.message.agent .bubble h1,
.message.agent .bubble h2,
.message.agent .bubble h3 { color: var(--primary); margin: 14px 0 7px; font-weight: 700; }
.message.agent .bubble h1 { font-size: 18px; }
.message.agent .bubble h2 { font-size: 16px; }
.message.agent .bubble h3 { font-size: 14px; }
.message.agent .bubble p { margin-bottom: 10px; }
.message.agent .bubble p:last-child { margin-bottom: 0; }
.message.agent .bubble ul,
.message.agent .bubble ol { padding-left: 20px; margin-bottom: 10px; }
.message.agent .bubble li { margin-bottom: 4px; }
.message.agent .bubble strong { color: #fff; font-weight: 700; }
.message.agent .bubble em { color: #a5b4fc; }
.message.agent .bubble hr { border: none; border-top: 1px solid var(--border); margin: 14px 0; }
.message.agent .bubble blockquote {
  border-left: 3px solid var(--primary);
  padding-left: 12px;
  color: var(--muted);
  margin: 10px 0;
}
.message.agent .bubble code {
  background: var(--code-bg);
  color: #a5b4fc;
  padding: 2px 7px;
  border-radius: 4px;
  font-size: 12px;
  font-family: "Consolas", "Courier New", monospace;
  border: 1px solid var(--border);
}
.message.agent .bubble pre {
  background: var(--code-bg);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 16px;
  overflow-x: auto;
  margin: 12px 0;
}
.message.agent .bubble pre code {
  background: none;
  border: none;
  padding: 0;
  font-size: 13px;
  color: #e6edf3;
}
.message.agent .bubble table { border-collapse: collapse; width: 100%; margin: 10px 0; font-size: 13px; }
.message.agent .bubble th,
.message.agent .bubble td { border: 1px solid var(--border); padding: 8px 12px; text-align: left; }
.message.agent .bubble th { background: var(--primary-glow); color: var(--primary); font-weight: 600; }

.msg-time { font-size: 11px; color: var(--muted); margin-top: 5px; padding: 0 4px; }
.message.user .msg-time { text-align: right; }

.typing-wrapper { display: flex; flex-direction: column; max-width: 82%; align-self: flex-start; }
.typing {
  display: flex;
  gap: 5px;
  align-items: center;
  padding: 14px 18px;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 14px;
  border-bottom-left-radius: 4px;
  width: fit-content;
}
.typing span {
  width: 7px; height: 7px;
  background: var(--muted);
  border-radius: 50%;
  animation: bounce 1.3s infinite ease-in-out;
}
.typing span:nth-child(2) { animation-delay: 0.2s; }
.typing span:nth-child(3) { animation-delay: 0.4s; }

@keyframes bounce {
  0%, 60%, 100% { transform: translateY(0); opacity: 0.4; }
  30% { transform: translateY(-7px); opacity: 1; }
}

.input-area {
  padding: 16px 24px 20px;
  border-top: 1px solid var(--border);
  background: var(--sidebar);
  flex-shrink: 0;
}

.input-wrapper { display: flex; gap: 10px; align-items: flex-end; }

textarea {
  flex: 1;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 12px 16px;
  color: var(--text);
  font-family: inherit;
  font-size: 14px;
  resize: none;
  line-height: 1.5;
  max-height: 130px;
  transition: border-color 0.2s;
}
textarea::placeholder { color: var(--muted); }
textarea:focus { outline: none; border-color: var(--primary); }

#btnSend {
  background: var(--primary);
  color: #fff;
  border: none;
  width: 46px;
  height: 46px;
  border-radius: 10px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  transition: background 0.2s, transform 0.1s;
}
#btnSend:hover { background: var(--primary-dark); transform: translateY(-1px); }
#btnSend:disabled { opacity: 0.4; cursor: not-allowed; transform: none; }

.input-hint { font-size: 11px; color: var(--muted); text-align: center; margin-top: 8px; }

@media (max-width: 700px) {
  .app { grid-template-columns: 1fr; }
  .sidebar { display: none; }
  .messages { padding: 16px; }
  .message { max-width: 95%; }
}