:root {
  --paper: #e5ddd5;
  --mine: #dcf8c6;
  --theirs: #ffffff;
  --sys: #fff4c2;
  --ink: #111827;
  --muted: #4b5563;
  --bar: #075e54;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  font-size: 16px;
  line-height: 1.7;
}

a {
  color: inherit;
}

svg {
  display: block;
}

.chatbar {
  background: var(--bar);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 14px 5vw;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 800;
  text-decoration: none;
}

.nav {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

.nav a {
  color: #d1fae5;
  text-decoration: none;
  font-size: 14px;
}

.hero {
  background: #128c7e;
  color: #fff;
  padding: 36px 5vw 32px;
}

.hero h1 {
  margin: 0 0 14px;
  font-size: clamp(26px, 4vw, 40px);
}

.hero p {
  margin: 0 0 12px;
  max-width: 68ch;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 46px;
  padding: 10px 20px;
  background: #dcf8c6;
  color: #14532d;
  font-weight: 800;
  text-decoration: none;
  border-radius: 18px 18px 4px 18px;
  margin-top: 8px;
}

.thread {
  width: min(980px, calc(100% - 8vw));
  margin: 0 auto;
  padding: 24px 0 12px;
}

.section {
  margin: 0 0 28px;
}

.section h2 {
  margin: 0 0 12px;
  font-size: 24px;
}

.lead {
  color: var(--muted);
  margin: 0 0 14px;
}

.bubbles {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.bubble {
  max-width: 78%;
  padding: 12px 14px;
  border-radius: 8px;
  box-shadow: 0 1px 1px rgba(0, 0, 0, 0.06);
}

.bubble h3 {
  margin: 0 0 6px;
  font-size: 16px;
}

.bubble p,
.bubble li {
  margin: 0 0 6px;
  color: #1f2937;
}

.bubble.left {
  align-self: flex-start;
  background: var(--theirs);
  border-radius: 0 10px 10px 10px;
}

.bubble.right {
  align-self: flex-end;
  background: var(--mine);
  border-radius: 10px 0 10px 10px;
}

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

.round .bubble {
  position: relative;
}

.tag {
  display: inline-block;
  font-size: 12px;
  font-weight: 800;
  color: #047857;
  margin-bottom: 4px;
}

.compare-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
}

.compare-row .bubble {
  max-width: none;
}

.sys {
  align-self: center;
  max-width: 88%;
  background: var(--sys);
  border-radius: 12px;
  padding: 12px 14px;
  text-align: left;
  box-shadow: none;
}

.sys h3 {
  margin: 0 0 6px;
  font-size: 15px;
}

.sys p {
  margin: 0;
  color: #374151;
}

.footer {
  background: #075e54;
  color: #d1fae5;
  padding: 22px 5vw 32px;
  font-size: 13px;
}

.footer p {
  margin: 0 0 8px;
}

@media (max-width: 760px) {
  .chatbar {
    flex-direction: column;
    align-items: flex-start;
  }

  .bubble,
  .compare-row .bubble {
    max-width: 100%;
  }

  .compare-row {
    grid-template-columns: 1fr;
  }
}

#news .news-list { display: flex; flex-direction: column; gap: 10px; }
#news article { max-width: 92%; padding: 12px 16px; border-radius: 16px; background: var(--theirs); }
#news article:nth-child(even) { align-self: flex-end; background: var(--mine); }
#news article:nth-child(odd) { align-self: flex-start; }
#news h3 { margin: 0 0 4px; font-size: 15px; }
#news time { color: var(--muted); font-size: 12px; }
#news p { margin: 6px 0 0; font-size: 14px; color: var(--ink); }