:root {
  color-scheme: light;
  --bg: #f3f6fb;
  --panel: #ffffff;
  --ink: #20224a;
  --muted: #68708e;
  --line: #d8def0;
  --brand-indigo: #424195;
  --brand-indigo-dark: #2f2f72;
  --brand-blue: #0c7fbc;
  --brand-cyan: #13b1dd;
  --assistant: #f6f8ff;
  --user: #e9f8fc;
  --composer: #f8fbff;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  background:
    linear-gradient(135deg, rgba(66, 65, 149, 0.11), rgba(19, 177, 221, 0.12)),
    var(--bg);
  color: var(--ink);
  font-family: Arial, Helvetica, sans-serif;
}

.shell {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 24px;
}

.chat-panel {
  width: min(960px, 100%);
  height: min(760px, calc(100vh - 48px));
  display: grid;
  grid-template-rows: auto 1fr auto;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 8px;
  overflow: hidden;
  box-shadow: 0 22px 65px rgba(32, 34, 74, 0.18);
}

.chat-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 18px 20px;
  border-bottom: 4px solid var(--brand-cyan);
  background: #ffffff;
}

.brand {
  display: flex;
  align-items: center;
  gap: 14px;
  min-width: 0;
}

.brand-logo {
  width: 58px;
  height: 58px;
  flex: 0 0 auto;
  object-fit: contain;
}

.eyebrow {
  margin: 0 0 4px;
  color: var(--brand-blue);
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
}

h1 {
  margin: 0;
  color: var(--brand-indigo);
  font-size: 24px;
  line-height: 1.2;
}

.status {
  color: var(--brand-indigo-dark);
  font-size: 14px;
  font-weight: 700;
  white-space: nowrap;
}

.messages {
  display: flex;
  flex-direction: column;
  gap: 12px;
  overflow-y: auto;
  padding: 20px;
  background: linear-gradient(180deg, #ffffff 0%, #f9fbff 100%);
}

.message {
  width: min(720px, 92%);
  padding: 13px 15px;
  border: 1px solid var(--line);
  border-radius: 8px;
  line-height: 1.5;
  white-space: pre-wrap;
}

.message p {
  margin: 0;
}

.assistant {
  align-self: flex-start;
  background: var(--assistant);
  border-left: 4px solid var(--brand-indigo);
}

.user {
  align-self: flex-end;
  background: var(--user);
  border-right: 4px solid var(--brand-cyan);
}

.sources {
  margin-top: 12px;
  padding-top: 10px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: 13px;
}

.sources a {
  color: var(--brand-indigo);
  font-weight: 700;
}

.composer {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 12px;
  padding: 16px;
  border-top: 1px solid var(--line);
  background: var(--composer);
}

textarea {
  width: 100%;
  resize: none;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 12px;
  color: var(--ink);
  font: inherit;
  background: #ffffff;
}

textarea:focus {
  border-color: var(--brand-cyan);
  outline: 3px solid rgba(19, 177, 221, 0.2);
}

button {
  min-width: 92px;
  border: 0;
  border-radius: 8px;
  background: var(--brand-indigo);
  color: #fff;
  font: inherit;
  font-weight: 700;
  cursor: pointer;
  box-shadow: inset 0 -3px 0 rgba(0, 0, 0, 0.12);
}

button:hover {
  background: var(--brand-indigo-dark);
}

button:focus-visible {
  outline: 3px solid rgba(19, 177, 221, 0.35);
  outline-offset: 2px;
}

button:disabled {
  cursor: wait;
  opacity: 0.7;
}

.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;
}

@media (max-width: 640px) {
  .shell {
    padding: 0;
  }

  .chat-panel {
    height: 100vh;
    border: 0;
    border-radius: 0;
  }

  .chat-header {
    align-items: flex-start;
    flex-direction: column;
  }

  .brand-logo {
    width: 50px;
    height: 50px;
  }

  .composer {
    grid-template-columns: 1fr;
  }

  button {
    min-height: 44px;
  }
}