:root {
  --bg: #f3f4f6;
  --card: #ffffff;
  --text: #111827;
  --accent: #1f2937;
  --accent-soft: #e5e7eb;
  --line: #d1d5db;
}

* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: system-ui, -apple-system, Segoe UI, Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.55;
}

header {
  background: #1f2937;
  color: #fff;
  padding: 1.6rem 1rem;
  border-bottom: 1px solid #111827;
}

.wrap { max-width: 980px; margin: 0 auto; }
h1 { margin: 0 0 .5rem; }
.subtitle { margin: 0; opacity: 0.9; max-width: 780px; }

nav {
  position: sticky;
  top: 0;
  z-index: 2;
  background: #e5e7ebf0;
  border-bottom: 1px solid var(--line);
}

nav ul {
  display: flex;
  gap: .5rem;
  overflow-x: auto;
  list-style: none;
  margin: 0;
  padding: .75rem 1rem;
}

nav button {
  border: 0;
  border-radius: .45rem;
  padding: .5rem .9rem;
  cursor: pointer;
  background: var(--card);
  color: var(--text);
  white-space: nowrap;
  border: 1px solid var(--line);
}

nav button.active { background: var(--accent); color: #fff; }

main { padding: 1rem; }

section {
  display: none;
  background: var(--card);
  border-radius: .5rem;
  padding: 1rem 1.2rem;
  margin-bottom: 1rem;
  border: 1px solid var(--line);
  box-shadow: 0 2px 6px #11182712;
}

section.active { display: block; }
.tag {
  display: inline-block;
  background: var(--accent-soft);
  color: var(--accent);
  padding: .2rem .5rem;
  border-radius: .3rem;
  font-size: .85rem;
  margin-right: .3rem;
  margin-bottom: .4rem;
  border: 1px solid var(--line);
}

img {
  max-width: 100%;
  border-radius: .35rem;
  margin-top: .8rem;
  border: 1px solid var(--line);
}

.links a { display: inline-block; margin: .3rem .5rem .3rem 0; }
.fact {
  margin-top: .8rem;
  padding: .6rem .8rem;
  background: #f9fafb;
  border-left: 3px solid #374151;
  border-radius: .35rem;
  font-size: .96rem;
}