:root {
  --bg: #ffffff;
  --text: #222222;
  --muted: #6b7280;
  --line: #d9dde3;
  --accent: #4f81bd;
  --code-bg: #f3f5f7;
  --code-dark: #1e2329;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Hiragino Kaku Gothic ProN", "Yu Gothic", Meiryo, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.9;
}

.container {
  margin: 56px auto;
  padding: 0 24px;
}

.blog-list {
  max-width: 1000px;
}

.blog-post {
  max-width: 820px;
}

article {
  width: 100%;
}

header {
  margin-bottom: 48px;
  padding-bottom: 24px;
  border-bottom: 1px solid var(--line);
}

h1 {
  margin: 0;
  font-size: 2.4rem;
  line-height: 1.4;
  letter-spacing: 0.02em;
}

.date {
  margin-top: 12px;
  color: var(--muted);
  font-size: 1rem;
  font-weight: 500;
}

h2 {
  margin-top: 56px;
  margin-bottom: 18px;
  padding-bottom: 8px;
  border-bottom: 2px solid var(--accent);
  font-size: 1.45rem;
}

h3 {
  margin-top: 40px;
  margin-bottom: 12px;
  font-size: 1.2rem;
}

p {
  margin: 18px 0;
}

ul,
ol {
  margin: 18px 0;
  padding-left: 1.5em;
}

li {
  margin: 8px 0;
}

.post-list {
  list-style: none;
  padding: 0;
  margin: 0;
}

.post-list li {
  padding: 28px 0;
  border-bottom: 1px solid var(--line);
  margin: 0;
}

.post-list h3 {
  margin: 8px 0 10px;
  font-size: 1.3rem;
}

.post-list .date {
  font-size: 1.05rem;
  font-weight: 600;
}

.post-list p {
  margin: 0;
  color: var(--muted);
}

img {
  display: block;
  max-width: 100%;
  height: auto;
  margin: 32px auto;
  border-radius: 6px;
}

figure {
  margin: 40px 0;
}

figure img {
  margin-bottom: 10px;
}

figcaption {
  text-align: center;
  color: var(--muted);
  font-size: 0.9rem;
}

code {
  padding: 2px 6px;
  background: var(--code-bg);
  border-radius: 4px;
  font-family: "SFMono-Regular", Consolas, monospace;
  font-size: 0.95em;
}

pre {
  overflow-x: auto;
  margin: 28px 0;
  padding: 18px;
  border-radius: 8px;
  background: var(--code-dark);
  color: #f5f5f5;
}

pre code {
  padding: 0;
  background: transparent;
  color: inherit;
}

blockquote {
  margin: 28px 0;
  padding: 4px 0 4px 18px;
  border-left: 4px solid var(--line);
  color: var(--muted);
}

a {
  color: var(--accent);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

.back-link {
  margin-top: 56px;
  padding-top: 24px;
  border-top: 1px solid var(--line);
}

@media (max-width: 640px) {
  .container {
    margin: 32px auto;
    padding: 0 18px;
  }

  header {
    margin-bottom: 36px;
  }

  h1 {
    font-size: 1.85rem;
  }

  h2 {
    margin-top: 44px;
    font-size: 1.3rem;
  }
}