:root {
  --bg: #ffffff;
  --fg: #24292f;
  --muted: #57606a;
  --accent: #1f6feb;
  --accent-fg: #ffffff;
  --border: #d0d7de;
  --card-bg: #ffffff;
  --code-bg: #f6f8fa;
  --nav-bg: #1b1f24;
  --max: 760px;
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Hiragino Sans", "Hiragino Kaku Gothic ProN", "Noto Sans JP", "Yu Gothic", Meiryo, sans-serif;
  line-height: 1.8;
  color: var(--fg);
  background: var(--bg);
}

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

/* ---- nav ---- */
.navbar {
  position: sticky;
  top: 0;
  z-index: 10;
  background: var(--nav-bg);
  padding: 0.75rem 1.25rem;
}
.navbar-brand {
  color: #fff;
  font-weight: 700;
  font-size: 1.05rem;
}
.navbar-brand:hover { text-decoration: none; opacity: 0.85; }

/* ---- layout ---- */
.container {
  max-width: var(--max);
  margin: 0 auto;
  padding: 1.5rem 1.25rem 3rem;
}
.container.wide { max-width: 1080px; }

h1 { font-size: 1.7rem; line-height: 1.35; margin: 0.2em 0 0.8em; }
h2 { font-size: 1.4rem; margin-top: 2rem; border-bottom: 1px solid var(--border); padding-bottom: 0.3rem; }
h3 { font-size: 1.2rem; margin-top: 1.6rem; }
h5 { font-size: 1.05rem; margin: 1.6rem 0 0.6rem; }

img.img-fluid, .book-cover { max-width: 100%; height: auto; }
.book-cover { border: 1px solid var(--border); border-radius: 6px; margin-bottom: 1rem; max-width: 240px; }

.link-back { font-size: 0.95rem; }

/* ---- top page announcement ---- */
.site-notice {
  background: var(--code-bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 0.9rem 1.1rem;
  margin: 0 0 1.5rem;
  font-size: 0.95rem;
  line-height: 1.7;
}

/* ---- index cards ---- */
.card-columns {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.5rem;
}
.card {
  border: 1px solid var(--border);
  border-radius: 8px;
  overflow: hidden;
  background: var(--card-bg);
  display: flex;
  flex-direction: column;
}
.card-img-top { width: 100%; height: auto; display: block; border-bottom: 1px solid var(--border); }
.card-body { padding: 1rem; display: flex; flex-direction: column; gap: 0.5rem; }
.card-title { margin: 0; font-size: 1.15rem; }
.card-price { margin: 0; color: var(--muted); font-size: 0.9rem; }
.card-text { margin: 0; color: var(--muted); font-size: 0.9rem; flex: 1; }
.badge-free {
  display: inline-block;
  background: #1a7f37;
  color: #fff;
  font-size: 0.72rem;
  padding: 0.1rem 0.45rem;
  border-radius: 999px;
  vertical-align: middle;
  margin-left: 0.3rem;
}
.btn {
  display: inline-block;
  align-self: flex-start;
  background: var(--accent);
  color: var(--accent-fg);
  padding: 0.4rem 0.9rem;
  border-radius: 6px;
  font-size: 0.9rem;
}
.btn:hover { text-decoration: none; opacity: 0.9; }

/* ---- toc ---- */
ul.toc { padding-left: 1.2rem; }
ul.toc li { margin: 0.35rem 0; }

.summary { color: var(--muted); margin: 1rem 0 1.5rem; }
.summary a { word-break: break-all; }

/* ---- post body ---- */
.post-body { font-size: 1.02rem; }
.post-body p { margin: 1rem 0; }
.post-body img { border: 1px solid var(--border); border-radius: 6px; margin: 0.5rem 0; }
.post-body ul, .post-body ol { padding-left: 1.5rem; }
.post-body blockquote {
  margin: 1rem 0;
  padding: 0.2rem 1rem;
  color: var(--muted);
  border-left: 4px solid var(--border);
}
.post-body table { border-collapse: collapse; width: 100%; margin: 1rem 0; display: block; overflow-x: auto; }
.post-body th, .post-body td { border: 1px solid var(--border); padding: 0.4rem 0.7rem; }
.post-body th { background: var(--code-bg); }

/* inline code */
.post-body code {
  background: var(--code-bg);
  padding: 0.15em 0.35em;
  border-radius: 4px;
  font-size: 0.88em;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
}
/* code blocks */
pre.hl {
  background: var(--code-bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 1rem;
  overflow-x: auto;
  line-height: 1.5;
}
pre.hl code { background: none; padding: 0; font-size: 0.85rem; }

/* ---- embeds ---- */
.video-container {
  position: relative;
  padding-bottom: 56.25%;
  height: 0;
  margin: 1.25rem 0;
}
.video-container iframe { position: absolute; top: 0; left: 0; width: 100%; height: 100%; border: 0; }
.scratch-embed { max-width: 100%; margin: 1rem 0 0.25rem; border: 1px solid var(--border); border-radius: 6px; }

.amazlet-box {
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 1rem;
  margin: 1.5rem 0;
  display: flex;
  gap: 1rem;
  align-items: center;
}
.amazlet-box img { border: 0; }
.amazlet-detail { color: var(--muted); font-size: 0.85rem; margin-top: 0.3rem; }

/* ---- post nav ---- */
.post-nav {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin: 1.5rem 0;
  font-size: 0.9rem;
}
.post-nav .nav-next { text-align: right; margin-left: auto; }

/* ---- footer ---- */
.footer {
  border-top: 1px solid var(--border);
  padding: 1.5rem 0;
  color: var(--muted);
  font-size: 0.85rem;
}
.footer .container { padding-top: 1.5rem; padding-bottom: 1.5rem; }

/* ---- highlight.js (github light theme, minimal) ---- */
.hljs { color: #24292f; }
.hljs-comment, .hljs-quote { color: #6a737d; font-style: italic; }
.hljs-keyword, .hljs-selector-tag, .hljs-built_in, .hljs-name { color: #d73a49; }
.hljs-string, .hljs-attr, .hljs-template-tag, .hljs-addition { color: #032f62; }
.hljs-number, .hljs-literal, .hljs-variable, .hljs-type, .hljs-selector-attr { color: #005cc5; }
.hljs-title, .hljs-section, .hljs-function .hljs-title { color: #6f42c1; }
.hljs-tag { color: #22863a; }
.hljs-attribute { color: #005cc5; }
.hljs-deletion { color: #b31d28; }
.hljs-emphasis { font-style: italic; }
.hljs-strong { font-weight: 700; }

@media (max-width: 480px) {
  h1 { font-size: 1.4rem; }
  .amazlet-box { flex-direction: column; align-items: flex-start; }
}