:root {
  --bg: #0a0a0a;
  --surface: #141414;
  --border: #222;
  --text: #d4d4d4;
  --dim: #555;
  --accent: #888;
  --error: #c0392b;
  --font: 'SF Mono', 'Fira Code', 'Cascadia Code', 'JetBrains Mono', 'Consolas', monospace;
}

*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }

html, body {
  height: 100%;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow: hidden;
}

/* ── Gate ── */
#gate {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100dvh;
  padding: 24px;
  transition: opacity 0.4s ease;
}

#question-wrap {
  text-align: center;
  width: 100%;
  max-width: 480px;
}

#question {
  font-size: clamp(1.1rem, 4vw, 1.5rem);
  font-weight: 600;
  letter-spacing: 0.14em;
  line-height: 1.5;
  margin-bottom: 2.5rem;
  transition: opacity 0.25s ease;
}

#answer {
  background: transparent;
  border: none;
  border-bottom: 1.5px solid var(--border);
  color: var(--text);
  font-family: var(--font);
  font-size: 1.1rem;
  text-align: center;
  width: 100%;
  max-width: 240px;
  padding: 8px 4px;
  outline: none;
  transition: border-color 0.3s ease;
  -webkit-appearance: none;
}

#answer:focus {
  border-color: var(--accent);
}

#answer:disabled {
  opacity: 0.4;
}

#feedback {
  margin-top: 1.8rem;
  font-size: 0.85rem;
  color: var(--error);
  opacity: 0;
  transition: opacity 0.4s ease;
  min-height: 1.4em;
}

#feedback.visible {
  opacity: 1;
}

/* ── Chat ── */
#chat {
  display: flex;
  flex-direction: column;
  height: 100dvh;
  max-width: 640px;
  margin: 0 auto;
  transition: opacity 0.4s ease;
}

#chat-header {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 14px 16px;
  border-bottom: 1px solid var(--border);
  font-size: 0.78rem;
  color: var(--dim);
  flex-shrink: 0;
}

#name-input {
  background: transparent;
  border: none;
  border-bottom: 1px solid var(--border);
  color: var(--text);
  font-family: var(--font);
  font-size: 0.78rem;
  padding: 2px 4px;
  outline: none;
  width: 120px;
  transition: border-color 0.3s ease;
}

#name-input:focus {
  border-color: var(--accent);
}

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

.message {
  background: var(--surface);
  border-radius: 6px;
  padding: 10px 14px;
  max-width: 85%;
  word-wrap: break-word;
  animation: fadeUp 0.3s ease;
}

.msg-from {
  font-size: 0.7rem;
  color: var(--accent);
  margin-bottom: 4px;
  font-weight: 600;
  letter-spacing: 0.06em;
}

.msg-body {
  font-size: 0.88rem;
  line-height: 1.45;
  white-space: pre-wrap;
}

.msg-time {
  font-size: 0.62rem;
  color: var(--dim);
  margin-top: 5px;
}

#compose {
  display: flex;
  gap: 8px;
  padding: 12px 16px;
  border-top: 1px solid var(--border);
  background: var(--bg);
  flex-shrink: 0;
}

#msg-input {
  flex: 1;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text);
  font-family: var(--font);
  font-size: 0.85rem;
  padding: 10px 12px;
  resize: none;
  outline: none;
  min-height: 40px;
  max-height: 120px;
  line-height: 1.4;
  transition: border-color 0.3s ease;
}

#msg-input:focus {
  border-color: var(--accent);
}

#send {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text);
  font-size: 1.1rem;
  padding: 0 16px;
  cursor: pointer;
  transition: background 0.2s, border-color 0.2s;
  flex-shrink: 0;
}

#send:hover {
  background: var(--border);
  border-color: var(--accent);
}

#send:active {
  background: #333;
}

#send:disabled {
  opacity: 0.3;
  cursor: default;
}

/* ── Animations ── */
@keyframes shake {
  0%, 100% { transform: translateX(0); }
  20% { transform: translateX(-8px); }
  40% { transform: translateX(8px); }
  60% { transform: translateX(-5px); }
  80% { transform: translateX(5px); }
}

.shake { animation: shake 0.4s ease; }

@keyframes fadeUp {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

/* ── Scrollbar ── */
::-webkit-scrollbar { width: 4px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 2px; }

/* ── Empty state ── */
#messages:empty::after {
  content: 'no messages yet.';
  color: var(--dim);
  font-size: 0.8rem;
  text-align: center;
  margin: auto;
}

/* ── Mobile ── */
@media (max-width: 480px) {
  #question-wrap { padding: 0 8px; }
  #compose { padding: 8px 12px; }
  .message { max-width: 92%; }
  #send { padding: 0 12px; }
}