:root {
  --bg-color: #0f172a;
  --card-bg: #1e293b;
  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  --accent-gradient: linear-gradient(135deg, #38bdf8 0%, #818cf8 100%);
  --accent-color: #38bdf8;
  --border-color: #334155;
  --tag-bg: #334155;
}

body {
  background-color: var(--bg-color);
  color: var(--text-main);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  line-height: 1.7;
  margin: 0;
  padding: 0;
  min-height: 100vh;
}

.container {
  max-width: 800px;
  margin: 0 auto;
  padding: 4rem 1.5rem;
}

/* ヘッダー */
header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 4rem;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid var(--border-color);
}

header h1 {
  margin: 0;
  font-size: 1.5rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

header a {
  text-decoration: none;
}

nav a {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.95rem;
  font-weight: 500;
  transition: color 0.2s;
}

nav a:hover {
  color: var(--accent-color);
}

/* 記事一覧カード */
.post-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  gap: 1.5rem;
}

.post-card {
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 16px;
  padding: 1.75rem;
  transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
  position: relative;
  overflow: hidden;
}

.post-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 4px;
  height: 100%;
  background: var(--accent-gradient);
  opacity: 0;
  transition: opacity 0.25s;
}

.post-card:hover {
  transform: translateY(-4px);
  border-color: #475569;
  box-shadow: 0 12px 24px -8px rgba(0, 0, 0, 0.5);
}

.post-card:hover::before {
  opacity: 1;
}

.post-meta-top {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 0.75rem;
}

.post-date {
  color: var(--text-muted);
  font-size: 0.85rem;
  font-weight: 500;
}

.post-tag {
  background: var(--tag-bg);
  color: var(--accent-color);
  font-size: 0.75rem;
  font-weight: 600;
  padding: 0.2rem 0.6rem;
  border-radius: 20px;
}

.post-title {
  font-size: 1.35rem;
  margin: 0;
  font-weight: 700;
  line-height: 1.4;
}

.post-title a {
  color: var(--text-main);
  text-decoration: none;
  transition: color 0.2s;
}

.post-card:hover .post-title a {
  color: var(--accent-color);
}

/* 記事詳細ページ */
article {
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 20px;
  padding: 2.5rem;
}

article h1 {
  font-size: 2.2rem;
  font-weight: 800;
  line-height: 1.3;
  margin-top: 0;
  margin-bottom: 1rem;
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

article .article-meta {
  color: var(--text-muted);
  font-size: 0.9rem;
  margin-bottom: 2.5rem;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid var(--border-color);
}

article p {
  color: #cbd5e1;
  font-size: 1.1rem;
  margin-bottom: 1.75rem;
}

article h2, article h3 {
  color: var(--text-main);
  margin-top: 2.5rem;
  margin-bottom: 1rem;
}

article code {
  background: #090d16;
  color: #38bdf8;
  padding: 0.25rem 0.5rem;
  border-radius: 6px;
  font-size: 0.9em;
  border: 1px solid #1e293b;
}

footer {
  margin-top: 5rem;
  padding-top: 2rem;
  border-top: 1px solid var(--border-color);
  text-align: center;
  color: var(--text-muted);
  font-size: 0.85rem;
}

/* ロゴ画像のスタイリング */
.site-logo-img {
  height: 40px;
  width: auto;
  object-fit: contain;
}

/* ロゴ画像のスタイリング */
.site-logo-img {
  height: 40px;
  width: auto;
  object-fit: contain;
}

/* ヘッダーとナビゲーションのスタイル調整 */
.site-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
  margin-bottom: 2rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid #eaeaea;
}

.site-nav {
  display: flex;
  gap: 1.5rem;
  flex-wrap: wrap;
}

.site-nav a {
  text-decoration: none;
  color: #555;
  font-size: 0.95rem;
  transition: color 0.2s ease;
}

.site-nav a:hover {
  color: #000;
  text-decoration: underline;
}

/* ナビゲーションリンクを明るく見やすいタグ風デザインに変更 */
.site-nav a {
  background-color: #eff6ff; /* 明るく爽やかなライトブルーの背景 */
  color: #1d4ed8;            /* 視認性の高い鮮やかな青色の文字 */
  padding: 0.35rem 0.9rem;
  border-radius: 9999px;
  font-size: 0.85rem;
  font-weight: 500;
  transition: all 0.2s ease;
}

.site-nav a:hover {
  background-color: #1d4ed8; /* ホバー時はしっかり反転 */
  color: #ffffff;
  text-decoration: none;
}