:root {
  color-scheme: light;
  --bg: #f7f8fa;
  --surface: #ffffff;
  --surface-muted: #eef2f5;
  --text: #24313d;
  --muted: #697887;
  --line: #d9e1e8;
  --accent: #df6f61;
  --accent-dark: #ad493e;
  --focus: #2563eb;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  background: var(--bg);
  color: var(--text);
}

a {
  color: var(--accent-dark);
}

a:focus-visible,
button:focus-visible,
input:focus-visible {
  outline: 3px solid var(--focus);
  outline-offset: 2px;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  min-height: 68px;
  padding: 12px clamp(18px, 4vw, 48px);
  background: rgba(255, 255, 255, 0.94);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(12px);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--text);
  font-size: 17px;
  font-weight: 800;
  text-decoration: none;
}

.brand img {
  border-radius: 8px;
}

.topbar nav {
  display: flex;
  align-items: center;
  gap: 18px;
  font-size: 14px;
  font-weight: 700;
}

.topbar nav a {
  text-decoration: none;
}

.shell {
  display: grid;
  grid-template-columns: minmax(280px, 340px) minmax(0, 1fr);
  gap: 28px;
  width: min(1240px, 100%);
  margin: 0 auto;
  padding: 28px clamp(18px, 4vw, 48px) 56px;
}

.sidebar {
  align-self: start;
  position: sticky;
  top: 92px;
}

.search {
  padding: 16px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 8px;
}

.search label {
  display: block;
  margin-bottom: 8px;
  color: var(--muted);
  font-size: 13px;
  font-weight: 800;
}

.search input {
  width: 100%;
  min-height: 42px;
  padding: 10px 12px;
  border: 1px solid var(--line);
  border-radius: 6px;
  color: var(--text);
  font: inherit;
}

.article-list {
  margin-top: 14px;
  display: grid;
  gap: 12px;
}

.category {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 8px;
  overflow: hidden;
}

.category h2 {
  margin: 0;
  padding: 13px 14px;
  background: var(--surface-muted);
  font-size: 14px;
}

.article-link {
  display: block;
  width: 100%;
  padding: 12px 14px;
  border: 0;
  border-top: 1px solid var(--line);
  background: transparent;
  color: var(--text);
  font: inherit;
  text-align: left;
  cursor: pointer;
}

.article-link strong {
  display: block;
  font-size: 14px;
}

.article-link span {
  display: block;
  margin-top: 4px;
  color: var(--muted);
  font-size: 13px;
  line-height: 1.35;
}

.article-link:hover,
.article-link.active {
  background: #fff4f1;
}

.article {
  min-height: 520px;
  padding: clamp(24px, 5vw, 48px);
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 8px;
  line-height: 1.65;
}

.article h1 {
  margin: 0 0 18px;
  color: var(--text);
  font-size: clamp(30px, 4vw, 46px);
  line-height: 1.08;
}

.article h2 {
  margin-top: 34px;
  padding-top: 16px;
  border-top: 1px solid var(--line);
  font-size: 23px;
}

.article h3 {
  margin-top: 28px;
  font-size: 18px;
}

.article p,
.article li {
  color: #354554;
}

.article code {
  padding: 2px 5px;
  background: var(--surface-muted);
  border-radius: 4px;
}

.article blockquote {
  margin: 22px 0;
  padding: 14px 16px;
  border-left: 4px solid var(--accent);
  background: #fff7ed;
}

.article .meta {
  margin-bottom: 24px;
  color: var(--muted);
  font-size: 14px;
}

.empty-state {
  max-width: 680px;
}

.error {
  padding: 16px;
  background: #fff1f2;
  border: 1px solid #fecdd3;
  border-radius: 8px;
  color: #9f1239;
}

@media (max-width: 840px) {
  .topbar {
    align-items: flex-start;
    flex-direction: column;
    gap: 10px;
  }

  .shell {
    grid-template-columns: 1fr;
  }

  .sidebar {
    position: static;
  }

  .article {
    padding: 22px;
  }
}