*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: "Helvetica Neue", Arial, "Hiragino Kaku Gothic ProN", "Meiryo", sans-serif;
  background: #f9f9f9;
  color: #222;
  line-height: 1.7;
  padding: 2rem 1rem;
}

.container {
  max-width: 720px;
  margin: 0 auto;
}

header { margin-bottom: 2rem; }
header h1 { font-size: 1.8rem; }
header p { color: #666; margin-top: 0.3rem; }

/* tag filter buttons */
.tag-filter { margin-bottom: 1.5rem; display: flex; gap: 0.5rem; flex-wrap: wrap; }
.tag-btn {
  padding: 0.3rem 0.9rem;
  border: 1px solid #0066cc;
  border-radius: 20px;
  background: #fff;
  color: #0066cc;
  cursor: pointer;
  font-size: 0.85rem;
  transition: background 0.2s, color 0.2s;
}
.tag-btn:hover, .tag-btn.active { background: #0066cc; color: #fff; }

/* post list */
.post-list { list-style: none; }
.post-list li {
  border-bottom: 1px solid #e0e0e0;
  padding: 1rem 0;
  opacity: 0;
  transform: translateY(8px);
  transition: opacity 0.3s, transform 0.3s;
}
.post-list li:first-child { border-top: 1px solid #e0e0e0; }
.post-list li.visible { opacity: 1; transform: translateY(0); }
.post-list a { font-size: 1.1rem; font-weight: bold; text-decoration: none; color: #0066cc; }
.post-list a:hover { text-decoration: underline; }
.post-list .meta { font-size: 0.85rem; color: #888; margin-top: 0.3rem; display: flex; gap: 0.5rem; align-items: center; flex-wrap: wrap; }
.post-list .tag {
  background: #e8f0fe;
  color: #0066cc;
  padding: 0.1rem 0.5rem;
  border-radius: 10px;
  font-size: 0.78rem;
}

/* article page */
article h1 { font-size: 1.6rem; margin-bottom: 0.3rem; }
article .meta { color: #888; font-size: 0.85rem; margin-bottom: 2rem; }
article h2 { font-size: 1.2rem; margin: 2rem 0 0.5rem; border-left: 4px solid #0066cc; padding-left: 0.6rem; }
article h3 { font-size: 1rem; margin: 1.5rem 0 0.4rem 1rem; border-left: 3px solid #aac4e8; padding-left: 0.5rem; }
article p { margin-bottom: 1rem; }
article pre { background: #272822; color: #f8f8f2; padding: 1rem; border-radius: 6px; overflow-x: auto; margin-bottom: 1rem; font-size: 0.9rem; }
article code { font-family: "SFMono-Regular", Consolas, monospace; }
article p code { background: #eee; padding: 0.1em 0.3em; border-radius: 3px; font-size: 0.9em; }
article ul, article ol { margin: 0.5rem 0 1rem 1.5rem; }

.back { display: inline-block; margin-top: 2.5rem; color: #0066cc; text-decoration: none; font-size: 0.9rem; }
.back:hover { text-decoration: underline; }