/* ===== AI実践ガイド — Redesign (Anti-AI Design) ===== */
:root {
  --c-text: #333;
  --c-text-64: rgba(51, 51, 51, 0.64);
  --c-text-40: rgba(51, 51, 51, 0.40);
  --c-text-20: rgba(51, 51, 51, 0.20);
  --c-bg: #fff;
  --c-bg-alt: #fafaf9;
  --c-border: rgba(51, 51, 51, 0.12);
  --c-dark: #111;
  --c-link: #111;
  --font: "Noto Sans JP", "Hiragino Kaku Gothic ProN", sans-serif;
  --max-w: 700px;
  --max-w-wide: 1080px;
}

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

html { font-size: 16px; scroll-behavior: smooth; }
body {
  font-family: var(--font);
  color: var(--c-text);
  background: var(--c-bg);
  line-height: 1.8;
  font-weight: 500;
  letter-spacing: 0.04em;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--c-link); }

/* ---- PR Notice (景品表示法) ---- */
.pr-notice {
  text-align: center;
  font-size: 0.6875rem;
  color: var(--c-text-40);
  padding: 6px 0;
  letter-spacing: 0.1em;
  font-weight: 500;
  border-bottom: 1px solid var(--c-border);
}

/* ---- Header ---- */
.site-header {
  padding: 24px 0;
  border-bottom: 1px solid var(--c-border);
}
.site-header__inner {
  display: flex; align-items: center; justify-content: space-between;
  max-width: var(--max-w-wide); margin: 0 auto; padding: 0 2.5rem;
}
.site-header__logo {
  font-size: 0.875rem; font-weight: 700; color: var(--c-dark);
  text-decoration: none; letter-spacing: 0.1em;
}
.site-header__nav { display: flex; gap: 28px; }
.site-header__nav a {
  color: var(--c-text-64); text-decoration: none;
  font-size: 0.8125rem; font-weight: 500; letter-spacing: 0.08em;
  transition: color 0.3s;
}
.site-header__nav a:hover { color: var(--c-text); }

/* ---- Hero ---- */
.hero {
  padding: 5rem 0 3rem;
  max-width: var(--max-w-wide); margin: 0 auto; padding-left: 2.5rem; padding-right: 2.5rem;
}
.hero__title {
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  font-weight: 900;
  line-height: 1.1;
  letter-spacing: -0.03em;
  color: var(--c-dark);
}
.hero__sub {
  margin-top: 1.25rem;
  font-size: 0.875rem;
  color: var(--c-text-64);
  font-weight: 500;
  letter-spacing: 0.04em;
  line-height: 1.7;
}

/* ---- Article List ---- */
.article-list {
  max-width: var(--max-w-wide); margin: 0 auto;
  padding: 0 2.5rem 5rem;
}
.article-list__item {
  display: block;
  text-decoration: none;
  color: inherit;
  padding: 2rem 0;
  border-bottom: 1px solid var(--c-border);
  transition: transform 0.5s cubic-bezier(0.16, 1, 0.3, 1);
}
.article-list__item:first-child {
  border-top: 1px solid var(--c-border);
}
.article-list__item:hover {
  transform: translateX(8px);
}
.article-list__meta {
  display: flex; align-items: center; gap: 16px;
  margin-bottom: 0.5rem;
}
.article-list__tag {
  font-size: 0.6875rem;
  color: var(--c-text-40);
  letter-spacing: 0.1em;
  font-weight: 600;
}
.article-list__date {
  font-size: 0.6875rem;
  color: var(--c-text-20);
  letter-spacing: 0.08em;
  font-weight: 500;
}
.article-list__title {
  font-size: 1.125rem;
  font-weight: 800;
  line-height: 1.4;
  letter-spacing: -0.02em;
  color: var(--c-dark);
}
.article-list__excerpt {
  margin-top: 0.375rem;
  font-size: 0.8125rem;
  color: var(--c-text-64);
  line-height: 1.7;
}

/* ---- Article Page ---- */
.article-header {
  max-width: var(--max-w); margin: 0 auto;
  padding: 4rem 1.5rem 2rem;
}
.article-header__tag {
  font-size: 0.6875rem;
  color: var(--c-text-40);
  letter-spacing: 0.1em;
  font-weight: 600;
  margin-bottom: 1rem;
  display: block;
}
.article-header__title {
  font-size: clamp(1.375rem, 3.5vw, 1.75rem);
  font-weight: 900;
  line-height: 1.3;
  letter-spacing: -0.03em;
  color: var(--c-dark);
}
.article-header__meta {
  margin-top: 1rem;
  font-size: 0.75rem;
  color: var(--c-text-40);
  letter-spacing: 0.08em;
  font-weight: 500;
}

.article-body {
  max-width: var(--max-w); margin: 0 auto;
  padding: 0 1.5rem 3rem;
}
.article-body h2 {
  font-size: 1.125rem;
  font-weight: 800;
  margin: 3rem 0 1rem;
  padding-bottom: 0.625rem;
  border-bottom: 1px solid var(--c-border);
  color: var(--c-dark);
  letter-spacing: -0.02em;
  line-height: 1.4;
}
.article-body h2:first-child { margin-top: 0; }
.article-body h3 {
  font-size: 0.9375rem;
  font-weight: 700;
  margin: 2rem 0 0.75rem;
  color: var(--c-text);
  letter-spacing: -0.01em;
}
.article-body p {
  margin-bottom: 1.25rem;
  line-height: 1.9;
  font-size: 0.9375rem;
}
.article-body ul, .article-body ol {
  margin: 0 0 1.25rem 1.25rem;
}
.article-body li {
  margin-bottom: 0.5rem;
  line-height: 1.8;
  font-size: 0.9375rem;
}
.article-body code {
  background: rgba(51, 51, 51, 0.06);
  padding: 2px 6px;
  font-size: 0.875em;
  border-radius: 2px;
}
.article-body pre {
  background: var(--c-dark);
  color: #e8e8e8;
  padding: 1.25rem 1.5rem;
  overflow-x: auto;
  margin-bottom: 1.5rem;
  font-size: 0.8125rem;
  line-height: 1.7;
  border-radius: 0;
}
.article-body blockquote {
  border-left: 2px solid var(--c-dark);
  padding-left: 1.25rem;
  margin: 0 0 1.25rem;
  color: var(--c-text-64);
  font-style: normal;
}
.article-body img {
  max-width: 100%; height: auto; margin: 1.5rem 0;
}
.article-body strong {
  font-weight: 700;
  color: var(--c-dark);
}

/* ---- CTA Section ---- */
.cta-section {
  max-width: var(--max-w); margin: 0 auto;
  padding: 0 1.5rem 4rem;
  border-top: 1px solid var(--c-border);
  padding-top: 2.5rem;
}
.cta-box {
  padding: 1.75rem 0;
  border-bottom: 1px solid var(--c-border);
}
.cta-box:first-child { padding-top: 0; }
.cta-box:last-child { border-bottom: none; }
.cta-box--accent {
  padding-left: 1.25rem;
  border-left: 2px solid var(--c-dark);
  border-bottom: 1px solid var(--c-border);
}
.cta-box__eyebrow {
  font-size: 0.625rem;
  color: var(--c-text-40);
  letter-spacing: 0.12em;
  font-weight: 600;
  margin-bottom: 0.375rem;
}
.cta-box__title {
  font-size: 0.9375rem;
  font-weight: 800;
  color: var(--c-dark);
  margin-bottom: 0.375rem;
  letter-spacing: -0.01em;
}
.cta-box__desc {
  font-size: 0.8125rem;
  color: var(--c-text-64);
  line-height: 1.7;
  margin-bottom: 0.75rem;
}
.cta-box__link {
  display: inline-block;
  color: var(--c-dark);
  text-decoration: none;
  font-size: 0.8125rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  border-bottom: 1px solid var(--c-dark);
  padding-bottom: 2px;
  transition: opacity 0.3s;
}
.cta-box__link:hover { opacity: 0.6; }

/* ---- Feed Filters ---- */
.feed-filters {
  max-width: var(--max-w-wide); margin: 0 auto;
  padding: 0 2.5rem 1.5rem;
  display: flex; gap: 8px;
}
.feed-filter {
  background: none; border: 1px solid var(--c-border);
  padding: 6px 16px;
  font-size: 0.75rem; font-weight: 600; font-family: var(--font);
  color: var(--c-text-64);
  letter-spacing: 0.06em;
  cursor: pointer;
  transition: all 0.2s;
}
.feed-filter:hover { color: var(--c-text); border-color: var(--c-text-40); }
.feed-filter--active {
  background: var(--c-dark); color: #fff;
  border-color: var(--c-dark);
}

/* ---- Unified Feed ---- */
.feed {
  max-width: var(--max-w-wide); margin: 0 auto;
  padding: 0 2.5rem 5rem;
}
.feed__item {
  display: block;
  text-decoration: none;
  color: inherit;
  padding: 2rem 0;
  border-bottom: 1px solid var(--c-border);
  transition: transform 0.5s cubic-bezier(0.16, 1, 0.3, 1);
}
.feed__item:first-child { border-top: 1px solid var(--c-border); }
.feed__item:hover { transform: translateX(8px); }
.feed__item-meta {
  display: flex; align-items: center; gap: 12px;
  margin-bottom: 0.5rem;
}
.feed__item-type {
  font-size: 0.5625rem;
  color: var(--c-text-40);
  letter-spacing: 0.14em;
  font-weight: 600;
  text-transform: uppercase;
}
.feed__item-tag {
  font-size: 0.6875rem;
  color: var(--c-text-40);
  letter-spacing: 0.1em;
  font-weight: 600;
}
.feed__item-date {
  font-size: 0.6875rem;
  color: var(--c-text-20);
  letter-spacing: 0.08em;
  font-weight: 500;
}
.feed__item-title {
  font-size: 1.125rem;
  font-weight: 800;
  line-height: 1.4;
  letter-spacing: -0.02em;
  color: var(--c-dark);
}
.feed__item-excerpt {
  margin-top: 0.375rem;
  font-size: 0.8125rem;
  color: var(--c-text-64);
  line-height: 1.7;
}
/* Post-type in feed: inline body preview */
.feed__item-body {
  margin-top: 0.375rem;
  font-size: 0.9375rem;
  color: var(--c-text);
  line-height: 1.8;
}

/* ---- Short Post Page ---- */
.post {
  max-width: var(--max-w); margin: 0 auto;
  padding: 4rem 1.5rem;
}
.post__meta {
  margin-bottom: 1.5rem;
}
.post__date {
  font-size: 0.75rem;
  color: var(--c-text-40);
  letter-spacing: 0.08em;
  font-weight: 500;
}
.post__body {
  font-size: 1.0625rem;
  line-height: 2;
  color: var(--c-text);
}
.post__body p { margin-bottom: 1.25rem; }
.post__body a { color: var(--c-dark); text-decoration: underline; }

/* ---- Video Page ---- */
.video-page {
  max-width: var(--max-w); margin: 0 auto;
  padding: 0 1.5rem;
}
.video-page__player {
  margin: 2rem 0;
  position: relative;
  padding-bottom: 56.25%; /* 16:9 */
  height: 0; overflow: hidden;
}
.video-page__player iframe {
  position: absolute; top: 0; left: 0;
  width: 100%; height: 100%; border: 0;
}
.video-page__header {
  padding: 1.5rem 0 2rem;
}
.video-page__tag {
  font-size: 0.6875rem;
  color: var(--c-text-40);
  letter-spacing: 0.1em;
  font-weight: 600;
  display: block;
  margin-bottom: 0.75rem;
}
.video-page__title {
  font-size: clamp(1.25rem, 3vw, 1.625rem);
  font-weight: 900;
  line-height: 1.3;
  letter-spacing: -0.03em;
  color: var(--c-dark);
}
.video-page__meta {
  margin-top: 0.75rem;
  font-size: 0.75rem;
  color: var(--c-text-40);
  letter-spacing: 0.08em;
}
.video-page__body {
  padding-bottom: 3rem;
}

/* ---- Footer ---- */
.site-footer {
  border-top: 1px solid var(--c-border);
  padding: 2.5rem 0;
  text-align: center;
  font-size: 0.75rem;
  color: var(--c-text-40);
  letter-spacing: 0.08em;
  font-weight: 500;
}
.site-footer a {
  color: var(--c-text-40);
  text-decoration: none;
  transition: color 0.3s;
}
.site-footer a:hover { color: var(--c-text); }

/* ---- Responsive ---- */
@media (max-width: 640px) {
  .site-header__inner { padding: 0 1.5rem; }
  .hero { padding: 3rem 1.5rem 2rem; }
  .article-list { padding: 0 1.5rem 3rem; }
}