:root {
  --bg: #0f1115;
  --panel: #181b22;
  --panel-2: #222732;
  --text: #e6e8ee;
  --muted: #9098a5;
  --brand: #4da3ff;
  --brand-h: #6fb6ff;
  --accent: #ffd166;
  --ok: #3ecf8e;
  --err: #ff6b6b;
  --radius: 10px;
}
* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Microsoft JhengHei", "Noto Sans TC", "Noto Sans SC", sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}
header {
  background: var(--panel);
  padding: 12px 20px;
  display: flex; align-items: center; justify-content: space-between;
  border-bottom: 1px solid #282c38;
}
header .brand { font-weight: 600; font-size: 1.05rem; }
header nav { display: flex; align-items: center; gap: 14px; }
header .user { color: var(--muted); font-size: 0.9rem; }
.inline { display: inline; margin: 0; }
.link {
  background: none; border: none; color: var(--brand); cursor: pointer;
  font-size: 0.9rem; padding: 0;
}
.link:hover { color: var(--brand-h); }

main { flex: 1; padding: 24px 20px; max-width: 900px; width: 100%; margin: 0 auto; }

footer {
  text-align: center; padding: 12px; color: var(--muted);
  border-top: 1px solid #282c38;
}

/* 登入 / 註冊框 */
.auth-box {
  max-width: 420px; margin: 40px auto;
  background: var(--panel); padding: 28px 28px;
  border-radius: var(--radius);
  box-shadow: 0 4px 24px rgba(0,0,0,0.3);
}
.auth-box h2 { margin: 0 0 12px; }
.auth-box .hint { color: var(--muted); font-size: 0.9rem; margin-top: 0; }
.auth-box label {
  display: block; margin: 12px 0; font-size: 0.9rem; color: var(--muted);
}
.auth-box input[type=email],
.auth-box input[type=password] {
  width: 100%; padding: 10px; margin-top: 6px;
  background: var(--panel-2); color: var(--text);
  border: 1px solid #2c3240; border-radius: 6px;
  font-size: 0.95rem;
}
.auth-box input:focus { outline: none; border-color: var(--brand); }
.auth-box button.primary {
  width: 100%; padding: 10px; margin-top: 12px;
  background: var(--brand); color: #fff; font-weight: 600;
  border: none; border-radius: 6px; cursor: pointer;
  font-size: 0.95rem;
}
.auth-box button.primary:hover { background: var(--brand-h); }
.auth-box .error { color: var(--err); font-size: 0.9rem; }
.auth-box .success { color: var(--ok); font-size: 0.9rem; }
.auth-box .link-row {
  margin-top: 16px; font-size: 0.85rem; color: var(--muted); text-align: center;
}
.auth-box .link-row a { color: var(--brand); }
.lang-pick {
  border: 1px solid #2c3240; border-radius: 6px; padding: 10px; margin: 12px 0;
}
.lang-pick legend { color: var(--muted); font-size: 0.85rem; padding: 0 6px; }
.lang-pick .radio { font-size: 0.9rem; color: var(--text); margin: 4px 0; }

/* 聊天介面 */
.chat-wrap .hint { color: var(--muted); font-size: 0.9rem; }
#messages {
  min-height: 50vh; max-height: 65vh; overflow-y: auto;
  padding: 8px 0;
}
.msg { display: flex; margin: 10px 0; }
.msg.me { justify-content: flex-end; }
.msg .bubble {
  max-width: 80%; padding: 10px 14px; border-radius: 14px;
  line-height: 1.55; white-space: pre-wrap; word-wrap: break-word;
}
.msg.me .bubble { background: var(--brand); color: #fff; border-bottom-right-radius: 4px; }
.msg.ai .bubble { background: var(--panel); color: var(--text); border-bottom-left-radius: 4px; }
.msg.ai code {
  background: var(--panel-2); padding: 2px 5px; border-radius: 4px;
  font-size: 0.88rem;
}
.msg.ai pre {
  background: var(--panel-2); padding: 10px; border-radius: 6px; overflow-x: auto;
}
.loader::after {
  content: '...'; animation: dots 1s steps(3, end) infinite;
}
@keyframes dots { 0%{content:'.'} 33%{content:'..'} 66%{content:'...'} }

#ask-form {
  display: flex; gap: 10px; margin-top: 14px;
  background: var(--panel); padding: 12px; border-radius: var(--radius);
}
#question {
  flex: 1; background: var(--panel-2); color: var(--text);
  border: 1px solid #2c3240; border-radius: 6px;
  padding: 10px; resize: vertical; min-height: 60px;
  font-family: inherit; font-size: 0.95rem;
}
#question:focus { outline: none; border-color: var(--brand); }
#ask-form button.primary {
  padding: 0 18px; min-width: 110px;
  background: var(--brand); color: #fff; font-weight: 600;
  border: none; border-radius: 6px; cursor: pointer;
}
#ask-form button.primary:hover:not(:disabled) { background: var(--brand-h); }
#ask-form button:disabled { opacity: 0.5; cursor: not-allowed; }

.fb-bar {
  margin-top: 6px; display: flex; gap: 8px; align-items: center;
}
.fb-bar small { color: var(--muted); flex: 1; }
.fb-bar .fb {
  background: var(--panel-2); border: 1px solid #2c3240; border-radius: 4px;
  padding: 4px 10px; cursor: pointer; font-size: 0.9rem;
}
.fb-bar .fb:hover { background: #2e3340; }