:root {
  color-scheme: light;
  font-family: 'Segoe UI', -apple-system, BlinkMacSystemFont, 'Helvetica Neue', sans-serif;
  background-color: #f4f5f7;
  color: #1f2933;
}

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
}

.chat-shell {
  width: min(680px, 92vw);
  margin: 2rem auto;
  background: #ffffff;
  border-radius: 16px;
  box-shadow: 0 24px 48px rgba(15, 23, 42, 0.12);
  padding: 24px;
  display: flex;
}

.chat-panel {
  flex: 1;
  display: flex;
  flex-direction: column;
}

.chat-header h1 {
  margin: 0 0 0.25rem;
  font-size: 1.4rem;
}

.chat-header p {
  margin: 0;
  color: #52606d;
  font-size: 0.95rem;
}

.chat-thread {
  list-style: none;
  flex: 1;
  padding: 0;
  margin: 1.5rem 0;
  overflow-y: auto;
  gap: 0.75rem;
  display: flex;
  flex-direction: column;
}

.chat-bubble {
  max-width: 82%;
  align-self: flex-start;
  background: #f1f5f9;
  border-radius: 14px;
  padding: 12px 16px;
  line-height: 1.45;
  font-size: 0.98rem;
  box-shadow: 0 5px 16px rgba(15, 23, 42, 0.08);
}

.chat-bubble.assistant {
  border-bottom-left-radius: 6px;
}

.chat-bubble.user {
  align-self: flex-end;
  background: linear-gradient(135deg, #2563eb, #38bdf8);
  color: #fff;
  border-bottom-right-radius: 6px;
}

.chat-input {
  display: flex;
  gap: 12px;
}

.chat-input.loading {
  opacity: 0.6;
}

.chat-input input {
  flex: 1;
  border-radius: 10px;
  border: 1px solid #cbd5e1;
  padding: 12px 14px;
  font-size: 1rem;
  transition: border-color 0.2s ease;
}

.chat-input input:focus {
  border-color: #2563eb;
  outline: none;
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.15);
}

.chat-input button {
  border: none;
  background: #2563eb;
  color: #fff;
  padding: 12px 18px;
  border-radius: 10px;
  font-weight: 600;
  font-size: 1rem;
  cursor: pointer;
  transition: background 0.2s ease;
}

.chat-input button:disabled {
  cursor: not-allowed;
  background: #94a3b8;
}

.chat-input button:hover:not(:disabled) {
  background: #1d4ed8;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}