:root {
  --fg: #1a2332;
  --bg: #f7f8f6;
  --surface: #ffffff;
  --border: #dde3e0;
  --accent: #1e5f4e;
  --accent-strong: #16493c;
  --muted: #5b6b66;
  --error: #b3402f;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial,
    "PingFang SC", "Microsoft YaHei", sans-serif;
  color: var(--fg);
  background: var(--bg);
  line-height: 1.6;
}
a { color: var(--accent); }
main { max-width: 860px; margin: 0 auto; padding: 0 16px 48px; }

.site-header {
  display: flex; align-items: center; justify-content: space-between;
  flex-wrap: wrap; gap: 8px;
  padding: 12px 16px; background: var(--surface);
  border-bottom: 1px solid var(--border);
}
.brand { font-weight: 700; font-size: 18px; color: var(--accent-strong); text-decoration: none; }
.top-nav { display: flex; gap: 14px; }
.top-nav a { color: var(--muted); text-decoration: none; font-size: 15px; }
.top-nav a.active, .top-nav a:hover { color: var(--accent-strong); }

.hero { padding: 32px 0 16px; text-align: center; }
.hero h1 { font-size: 30px; margin: 0 0 8px; letter-spacing: -0.5px; }
.hero-sub { color: var(--muted); margin: 0 auto; max-width: 560px; }

.tool-card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: 12px; padding: 16px; margin: 16px 0 32px;
  box-shadow: 0 2px 8px rgba(26, 35, 50, 0.05);
}
.tool-input {
  width: 100%; border: 1px solid var(--border); border-radius: 8px;
  padding: 12px; font-size: 15px; font-family: inherit; resize: vertical;
  min-height: 160px;
}
.tool-input:focus { outline: 2px solid var(--accent); outline-offset: -1px; }
.tool-bar {
  display: flex; align-items: center; gap: 10px; flex-wrap: wrap;
  margin-top: 12px;
}
.counter { color: var(--muted); font-size: 13px; margin-right: auto; }
.tool-field { display: flex; align-items: center; gap: 6px; font-size: 14px; color: var(--muted); }
.tool-field select {
  min-height: 44px; border: 1px solid var(--border); border-radius: 8px;
  padding: 0 10px; font-size: 14px; background: var(--surface); color: var(--fg);
}
.btn {
  min-height: 44px; min-width: 44px; padding: 0 18px;
  border: 1px solid var(--border); border-radius: 8px;
  background: var(--surface); color: var(--fg); font-size: 15px;
  cursor: pointer; text-decoration: none; display: inline-flex;
  align-items: center; justify-content: center;
}
.btn:hover { border-color: var(--accent); }
.btn:disabled { opacity: 0.5; cursor: default; }
.btn-primary { background: var(--accent); color: #fff; border-color: var(--accent); font-weight: 600; }
.btn-primary:hover { background: var(--accent-strong); }

.tool-msg { color: var(--error); font-size: 14px; margin: 10px 0 0; }
.tool-msg a { color: var(--accent); }

.tool-result { margin-top: 16px; border-top: 1px solid var(--border); padding-top: 16px; }
.result-title { margin: 0 0 8px; font-size: 16px; }
.result-text, .diff-text {
  white-space: pre-wrap; background: var(--bg); border-radius: 8px;
  padding: 12px; font-size: 15px;
}
.result-actions { display: flex; gap: 10px; margin-top: 10px; }
.diff { display: grid; grid-template-columns: 1fr; gap: 12px; margin-top: 12px; }
.diff h4 { margin: 0 0 6px; font-size: 14px; color: var(--muted); }
@media (min-width: 640px) {
  .diff { grid-template-columns: 1fr 1fr; }
}

.section { margin: 36px 0; }
.section h2 { font-size: 22px; margin: 0 0 14px; }
.steps { padding-left: 22px; }
.steps li { margin-bottom: 8px; }
.cards { display: grid; grid-template-columns: 1fr; gap: 12px; }
@media (min-width: 640px) { .cards { grid-template-columns: repeat(2, 1fr); } }
@media (min-width: 860px) { .cards { grid-template-columns: repeat(3, 1fr); } }
.card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: 10px; padding: 14px 16px;
}
.card h3 { margin: 0 0 6px; font-size: 16px; }
.card p { margin: 0; font-size: 14px; color: var(--muted); }
.pack-words { font-size: 20px !important; color: var(--fg) !important; font-weight: 600; }
.pack-price { font-size: 18px !important; color: var(--accent) !important; font-weight: 700; margin-bottom: 10px !important; }
.pack-buy { width: 100%; }

details { border-bottom: 1px solid var(--border); padding: 10px 0; }
summary { cursor: pointer; font-weight: 600; min-height: 44px; display: flex; align-items: center; }
details p { color: var(--muted); margin: 8px 0; }

.code {
  background: #14201c; color: #d9efe7; border-radius: 8px;
  padding: 14px; overflow-x: auto; font-size: 13px;
}
.key-input {
  flex: 1; min-width: 200px; min-height: 44px; border: 1px solid var(--border);
  border-radius: 8px; padding: 0 12px; font-size: 15px;
}
.muted { color: var(--muted); font-size: 13px; }
.prose h2 { font-size: 18px; margin: 20px 0 8px; }
.prose p, .prose li { color: var(--fg); }

.history-item {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: 10px; padding: 14px 16px; margin-bottom: 12px;
}
.history-item .h-meta { color: var(--muted); font-size: 13px; margin-bottom: 8px; }
.history-item .h-io { display: grid; gap: 8px; }
@media (min-width: 640px) { .history-item .h-io { grid-template-columns: 1fr 1fr; } }

.site-footer {
  border-top: 1px solid var(--border); margin-top: 40px;
  padding: 20px 0 24px; text-align: center;
}
.disclaimer { color: var(--muted); font-size: 13px; margin: 4px 0; }
.footer-link { color: var(--accent); text-decoration: none; }