:root {
  --bg: #f7f8fb;
  --panel: #ffffff;
  --border: #e5e7ed;
  --accent: #1f6feb;
  --text: #1f2430;
  --muted: #6b7280;
  --radius: 14px;
  --shadow: 0 8px 24px rgba(31, 47, 79, 0.08);
}

* { box-sizing: border-box; }

html, body { height: 100%; }

body {
  margin: 0;
  font-family: "SF Pro Display", "Segoe UI", system-ui, -apple-system, sans-serif;
  background: radial-gradient(circle at 20% 20%, rgba(31,111,235,0.05), transparent 35%),
              radial-gradient(circle at 80% 10%, rgba(31,111,235,0.08), transparent 30%),
              var(--bg);
  color: var(--text);
  min-height: 100vh;
}

.app-shell {
  display: grid;
  grid-template-columns: 280px 1fr;
  min-height: 100vh;
  height: 100vh;
}

.sidebar {
  background: #fff;
  border-right: 1px solid var(--border);
  padding: 18px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.sidebar-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
}

.logo {
  font-weight: 700;
  letter-spacing: 0.4px;
}

button {
  border: 1px solid var(--border);
  background: #fff;
  color: var(--text);
  padding: 8px 12px;
  border-radius: 10px;
  cursor: pointer;
  transition: all 0.15s ease;
  font-size: 14px;
}

button:hover { border-color: #c8d0e0; box-shadow: 0 2px 10px rgba(0,0,0,0.04); }
button:active { transform: translateY(1px); }

button.primary {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
  box-shadow: 0 6px 20px rgba(31,111,235,0.25);
}
button.primary:hover { background: #195cc4; }
button.ghost { background: transparent; border: none; font-size: 18px; padding: 6px 10px; }

.sidebar-actions { display: flex; gap: 10px; }

.history-header { font-size: 13px; color: var(--muted); padding: 4px 2px; }

.conversation-list {
  list-style: none;
  margin: 0;
  padding: 0;
  overflow-y: auto;
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.conversation-list li {
  padding: 10px 12px;
  border: 1px solid transparent;
  border-radius: 12px;
  background: #f9fafc;
  cursor: pointer;
  transition: all 0.15s ease;
  color: var(--text);
}

.conversation-list li:hover { border-color: var(--border); }
.conversation-list li.active {
  background: #e9f1ff;
  border-color: var(--accent);
  color: #0f2a5f;
}

.chat-pane {
  display: grid;
  grid-template-rows: auto 1fr auto;
  background: transparent;
  height: 100vh;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 18px 24px 12px;
}

.topbar .title { font-weight: 600; font-size: 16px; }

.status { color: var(--muted); font-size: 13px; }

.chat-log {
  padding: 12px 24px 24px;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.message {
  display: inline-block;
  width: auto;
  max-width: 70%;
  padding: 12px 14px;
  border-radius: var(--radius);
  background: #fff;
  border: 1px solid var(--border);
  box-shadow: var(--shadow);
  line-height: 1.5;
  white-space: normal;
  word-break: break-word;
}

.message.assistant { background: #f1f4fb; border-color: #dfe6f5; }
.message.user {
  background: #fff;
  margin-left: auto;
  border-color: #d7dbe5;
  white-space: pre-wrap;
}
.assistant-before,
.assistant-after {
  white-space: pre-wrap;
  line-height: 1.5;
}
.assistant-tool { margin: 2px 0 2px 0; }
.search-state {
  display: block;
  margin: 0;
  color: #1f6feb;
  font-weight: 600;
  line-height: 1.5;
  white-space: normal;
}
.search-state .loader-wrapper { margin: 0; justify-content: flex-start; }
.search-state.done { color: #1f6feb; }

.composer {
  border-top: 1px solid var(--border);
  padding: 14px 20px 16px;
  background: linear-gradient(180deg, rgba(255,255,255,0.92), #fff);
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.composer textarea {
  width: 100%;
  resize: none;
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 12px;
  font-size: 14px;
  line-height: 1.5;
  outline: none;
  background: #fff;
  transition: border 0.15s ease;
}

.composer textarea:focus { border-color: var(--accent); box-shadow: 0 0 0 3px rgba(31,111,235,0.12); }

.composer-actions {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.hint { color: var(--muted); font-size: 13px; }

.loader-wrapper {
  position: relative;
  display: inline-flex;
  min-height: 24px;
  align-items: center;
  justify-content: flex-start;
  color: #1f6feb;
  user-select: none;
  gap: 10px;
}

.letter-wrapper {
  display: flex;
  gap: 1px;
}
.loader-letter {
  display: inline-block;
  opacity: 0.4;
  transform: translateY(0);
  animation: loader-letter-anim 2s infinite;
  z-index: 1;
  border-radius: 50ch;
  border: none;
  color: #1f6feb;
  font-weight: 600;
}
.search-done {
  display: inline-block;
  color: #1f6feb;
  font-weight: 600;
}
.loader-letter:nth-child(1) { animation-delay: 0s; }
.loader-letter:nth-child(2) { animation-delay: 0.1s; }
.loader-letter:nth-child(3) { animation-delay: 0.2s; }
.loader-letter:nth-child(4) { animation-delay: 0.3s; }
.loader-letter:nth-child(5) { animation-delay: 0.4s; }
.loader-letter:nth-child(6) { animation-delay: 0.5s; }
.loader-letter:nth-child(7) { animation-delay: 0.6s; }
.loader-letter:nth-child(8) { animation-delay: 0.7s; }
.loader-letter:nth-child(9) { animation-delay: 0.8s; }
.loader-letter:nth-child(10) { animation-delay: 0.9s; }

@keyframes loader-letter-anim {
  0%, 100% {
    opacity: 0.4;
    transform: translateY(0);
  }
  20% {
    opacity: 1;
    transform: scale(1.15);
  }
  40% {
    opacity: 0.7;
    transform: translateY(0);
  }
}

@media (max-width: 900px) {
  .app-shell { grid-template-columns: 1fr; }
  .sidebar { position: fixed; inset: 0 auto 0 -100%; max-width: 260px; z-index: 10; transition: transform 0.2s ease; box-shadow: var(--shadow); }
  .sidebar.open { transform: translateX(100%); }
  .chat-pane { margin-left: 0; }
  .chat-log .message { max-width: 100%; }
  .topbar { padding-right: 12px; }
}