:root {
  --bg: #f7f4ee;
  --text: #1c1c1c;
  --muted: #6b6b6b;
  --accent: #1a2740;
  --accent-hover: #2a3a5e;
  --user-bg: #1a2740;
  --user-text: #f7f4ee;
  --card-bg: #fffdf7;
  --card-border: #e8e1d0;
  --input-bg: #fffdf7;
  --input-border: #c9bfac;
  --input-focus: #1a2740;
  --placeholder: rgba(28, 28, 28, 0.4);
  --btn-disabled: #999;
  --thinking-color: #888;
  --error-color: #8a1a1a;
  --rule: #d8d2c4;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #1a1815;
    --text: #e8e1d0;
    --muted: #9a9485;
    --accent: #c9bfac;
    --accent-hover: #d8cfb9;
    --user-bg: #2a3a5e;
    --user-text: #f7f4ee;
    --card-bg: #232128;
    --card-border: #3a3530;
    --input-bg: #232128;
    --input-border: #3a3530;
    --input-focus: #c9bfac;
    --placeholder: rgba(232, 225, 208, 0.4);
    --btn-disabled: #555;
    --thinking-color: #888;
    --error-color: #c45a5a;
    --rule: #2a2620;
  }
}

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

html, body {
  font-family: Georgia, "Times New Roman", serif;
  font-size: 13pt;
  line-height: 1.5;
  color: var(--text);
  background: var(--bg);
}

body {
  max-width: 720px;
  margin: 0 auto;
  padding: 64px 48px 96px;
}

.wordmark { margin-bottom: 56px; }

.wordmark h1 {
  font-size: 28pt;
  font-weight: normal;
  color: var(--accent);
  letter-spacing: 0.5px;
  margin-bottom: 12px;
}

.tagline {
  font-size: 14pt;
  color: var(--muted);
  font-style: italic;
}

main > section { margin-bottom: 56px; }

.demo-intro { margin-bottom: 18px; color: var(--muted); }

.samples {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-bottom: 24px;
}

.sample {
  font-family: Georgia, "Times New Roman", serif;
  font-size: 12pt;
  text-align: left;
  padding: 10px 14px;
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  color: var(--text);
  cursor: pointer;
  transition: border-color 0.15s;
}

.sample:hover { border-color: var(--input-focus); }

#ask {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-bottom: 28px;
}

textarea#q {
  width: 100%;
  font-family: Georgia, "Times New Roman", serif;
  font-size: 12pt;
  line-height: 1.4;
  padding: 12px 14px;
  border: 1px solid var(--input-border);
  background: var(--input-bg);
  resize: none;
  color: var(--text);
  overflow-y: hidden;
}

textarea#q::placeholder { color: var(--placeholder); }
textarea#q:focus { outline: none; border-color: var(--input-focus); }

.form-bottom {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
}

.form-thinking {
  display: none;
  color: var(--thinking-color);
  font-style: italic;
  font-size: 12pt;
}

.form-thinking.active { display: inline-block; }

button#send {
  margin-left: auto;
  font-family: Georgia, "Times New Roman", serif;
  font-size: 12pt;
  padding: 10px 24px;
  background: var(--accent);
  color: var(--user-text);
  border: none;
  cursor: pointer;
  letter-spacing: 0.5px;
}

button#send:hover { background: var(--accent-hover); }
button#send:disabled { background: var(--btn-disabled); cursor: not-allowed; }

#chain {
  display: flex;
  flex-direction: column;
  gap: 28px;
}

.card {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.estimate {
  font-size: 10pt;
  color: var(--muted);
  font-style: normal;
}

.msg.user {
  background: var(--user-bg);
  color: var(--user-text);
  padding: 14px 18px;
  white-space: pre-wrap;
}

.msg.arke {
  background: var(--card-bg);
  border: 1px solid var(--card-border);
  padding: 18px 22px;
}

.msg.thinking { color: var(--thinking-color); font-style: italic; }

.dots::after {
  content: '';
  animation: thinking-dots 1.6s steps(4) infinite;
}
@keyframes thinking-dots {
  0%   { content: ''; }
  25%  { content: '.'; }
  50%  { content: '..'; }
  75%  { content: '...'; }
  100% { content: ''; }
}

.msg.error { color: var(--error-color); }

#built-by {
  border-top: 1px solid var(--rule);
  padding-top: 28px;
  color: var(--muted);
  font-size: 11pt;
}

#built-by p { margin-bottom: 6px; }

a {
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px solid var(--rule);
}

a:hover { border-bottom-color: var(--accent); }

@media (max-width: 600px) {
  body { padding: 36px 20px 64px; }
  .wordmark { margin-bottom: 36px; }
  .wordmark h1 { font-size: 22pt; }
  .tagline { font-size: 12pt; }
  main > section { margin-bottom: 40px; }
  html, body { font-size: 12pt; }
}