:root {
  --bg: #0f1115;
  --surface: #1a1d24;
  --surface-2: #23272f;
  --text: #eef0f3;
  --text-dim: #9aa0ac;
  --accent: #4f8cff;
  --accent-text: #ffffff;
  --danger: #ff5c5c;
  --bubble-me: #4f8cff;
  --bubble-them: #2a2f3a;
  --radius: 14px;
}

* {
  box-sizing: border-box;
}

html, body {
  height: 100%;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
}

.screen {
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 24px;
  gap: 16px;
}

.screen[hidden] {
  display: none;
}

.card {
  width: 100%;
  max-width: 380px;
  background: var(--surface);
  border-radius: var(--radius);
  padding: 28px 22px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

h1 {
  font-size: 1.4rem;
  margin: 0 0 4px;
  text-align: center;
}

p.subtitle {
  color: var(--text-dim);
  text-align: center;
  margin: 0 0 8px;
  font-size: 0.9rem;
}

button {
  font: inherit;
  border: none;
  border-radius: var(--radius);
  padding: 14px 18px;
  cursor: pointer;
}

button.primary {
  background: var(--accent);
  color: var(--accent-text);
  font-weight: 600;
  font-size: 1rem;
}

button.primary:active {
  opacity: 0.85;
}

button.secondary {
  background: var(--surface-2);
  color: var(--text);
  font-weight: 600;
}

button:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

input[type="text"] {
  font: inherit;
  padding: 14px 16px;
  border-radius: var(--radius);
  border: 1px solid var(--surface-2);
  background: var(--surface-2);
  color: var(--text);
  text-align: center;
  letter-spacing: 2px;
  text-transform: uppercase;
}

input[type="text"]::placeholder {
  letter-spacing: normal;
  text-transform: none;
  color: var(--text-dim);
}

.error {
  color: var(--danger);
  font-size: 0.85rem;
  text-align: center;
  min-height: 1.2em;
}

.code-display {
  font-size: 1.8rem;
  font-weight: 700;
  letter-spacing: 3px;
  text-align: center;
  background: var(--surface-2);
  border-radius: var(--radius);
  padding: 16px;
  word-break: break-all;
}

.hint {
  color: var(--text-dim);
  font-size: 0.8rem;
  text-align: center;
}

a.back {
  color: var(--text-dim);
  text-decoration: none;
  text-align: center;
  font-size: 0.85rem;
}

/* --- Chat page --- */

.chat-page {
  display: flex;
  flex-direction: column;
  height: 100dvh;
}

.chat-header {
  padding: 14px 16px;
  background: var(--surface);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
}

.chat-header .code {
  font-weight: 700;
  letter-spacing: 2px;
}

.chat-messages {
  flex: 1;
  overflow-y: auto;
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.bubble {
  max-width: 75%;
  padding: 10px 14px;
  border-radius: 16px;
  line-height: 1.35;
  word-wrap: break-word;
  white-space: pre-wrap;
}

.bubble.me {
  align-self: flex-end;
  background: var(--bubble-me);
  color: #fff;
  border-bottom-right-radius: 4px;
}

.bubble.them {
  align-self: flex-start;
  background: var(--bubble-them);
  color: var(--text);
  border-bottom-left-radius: 4px;
}

.bubble .meta {
  display: block;
  font-size: 0.65rem;
  opacity: 0.7;
  margin-top: 4px;
}

.chat-input {
  display: flex;
  gap: 8px;
  padding: 12px;
  background: var(--surface);
}

.chat-input textarea {
  flex: 1;
  resize: none;
  font: inherit;
  border-radius: var(--radius);
  border: none;
  background: var(--surface-2);
  color: var(--text);
  padding: 12px 14px;
  max-height: 120px;
}

.chat-input button {
  background: var(--accent);
  color: var(--accent-text);
  font-weight: 600;
  padding: 0 18px;
}

.chat-empty {
  color: var(--text-dim);
  text-align: center;
  margin-top: 40px;
  font-size: 0.9rem;
}