:root {
  --bg: #f4f6f8;
  --panel: #ffffff;
  --line: #d8dde3;
  --text: #1c232c;
  --muted: #5b6572;
  --accent: #1f6feb;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
  background: linear-gradient(180deg, #f8fafc 0%, #eef2f7 100%);
  color: var(--text);
}

.layout {
  display: grid;
  grid-template-columns: 260px 1fr;
  min-height: 100vh;
}

.topics-pane {
  border-right: 1px solid var(--line);
  background: var(--panel);
  padding: 20px;
}

.site-title {
  margin: 0 0 16px;
  font-size: 20px;
}

.topics {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.topic-check {
  display: flex;
  align-items: center;
  gap: 8px;
  border: 1px solid var(--line);
  background: #fff;
  padding: 8px 10px;
  border-radius: 8px;
  cursor: pointer;
  user-select: none;
}

.topic-check input {
  margin: 0;
}

.topic-check:has(input:checked) {
  border-color: var(--accent);
  color: var(--accent);
  font-weight: 700;
}

.articles-pane {
  padding: 20px;
}

.articles-header {
  margin-bottom: 14px;
}

.article-card {
  border: 1px solid var(--line);
  background: var(--panel);
  border-radius: 10px;
  padding: 14px;
  margin-bottom: 12px;
}

.article-meta {
  font-size: 12px;
  color: var(--muted);
  margin-bottom: 8px;
}

.article-title {
  margin: 0 0 8px;
  font-size: 18px;
}

.article-link {
  color: var(--accent);
  text-decoration: none;
}

.article-link:hover {
  text-decoration: underline;
}

.article-bullets {
  margin: 0;
  padding-left: 18px;
}

.empty {
  color: var(--muted);
}

@media (max-width: 860px) {
  .layout {
    grid-template-columns: 1fr;
  }

  .topics-pane {
    border-right: 0;
    border-bottom: 1px solid var(--line);
  }

  .topics {
    flex-direction: row;
    flex-wrap: wrap;
  }
}