@import url('https://fonts.googleapis.com/css2?family=Archivo:wght@700;800;900&family=Inter:wght@400;500;600;700&family=Noto+Sans+JP:wght@400;500;700;900&family=Noto+Serif+JP:wght@400;600&display=swap');

/* ==========================================================================
   Editorial Monotone Stylesheet (Black & White Minimal) - LIBERTA DESIGN
   Inspired by contemporary Japanese digital creative editorial design
   ========================================================================== */

:root {
  --bg-primary: #ffffff;
  --bg-subtle: #f7f7f8;
  --bg-card: #ffffff;
  --bg-dark-box: #111111;
  
  --border-light: #e5e7eb;
  --border-medium: #d1d5db;
  --border-dark: #111111;

  --text-primary: #111111;
  --text-secondary: #4b5563;
  --text-muted: #888888;
  --text-inverse: #ffffff;

  --font-en: 'Archivo', 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-jp: 'Noto Sans JP', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-serif: 'Noto Serif JP', 'YuMincho', serif;

  --max-width-article: 800px;
  --max-width-page: 1140px;
  --transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
}

/* Base Reset */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  background-color: var(--bg-primary);
  color: var(--text-primary);
  font-family: var(--font-jp);
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  min-height: 100vh;
  line-height: 1.9;
  font-size: 16px;
  letter-spacing: 0.02em;
  font-feature-settings: "palt";
  background-color: var(--bg-primary);
}

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

img {
  max-width: 100%;
  height: auto;
  display: block;
}

/* Layout Containers */
.container {
  max-width: var(--max-width-page);
  margin: 0 auto;
  padding: 0 28px;
}

.article-container {
  max-width: var(--max-width-article);
  margin: 0 auto;
  padding: 0 24px;
}

/* --- Reading Progress Bar --- */
#reading-progress {
  position: fixed;
  top: 0;
  left: 0;
  width: 0%;
  height: 2px;
  background: var(--text-primary);
  z-index: 9999;
  transition: width 0.1s ease-out;
}

/* --- Header / Navigation --- */
.site-header {
  position: sticky;
  top: 0;
  left: 0;
  width: 100%;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  z-index: 100;
  border-bottom: 1px solid var(--border-light);
}

.nav-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 72px;
}

.brand-logo {
  font-family: var(--font-en);
  font-size: 1.15rem;
  font-weight: 900;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-primary);
  display: flex;
  align-items: baseline;
  gap: 8px;
}

.brand-logo span {
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  color: var(--text-muted);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 24px;
}

.nav-link {
  font-family: var(--font-en);
  font-size: 0.85rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--text-secondary);
}

.nav-link:hover {
  color: var(--text-primary);
}

.nav-cta-btn {
  font-family: var(--font-en);
  font-size: 0.82rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  padding: 8px 18px;
  background: var(--text-primary);
  color: var(--text-inverse);
  border: 1px solid var(--text-primary);
  border-radius: 2px;
  transition: var(--transition);
}

.nav-cta-btn:hover {
  background: #333333;
  color: var(--text-inverse);
}

/* --- Breadcrumb --- */
.breadcrumb-nav {
  padding: 32px 0 16px;
  font-size: 0.8rem;
  color: var(--text-muted);
  letter-spacing: 0.04em;
}

.breadcrumb-nav a {
  color: var(--text-secondary);
}

.breadcrumb-nav a:hover {
  color: var(--text-primary);
  text-decoration: underline;
}

.breadcrumb-sep {
  margin: 0 8px;
  color: var(--border-medium);
}

/* ==========================================================================
   Article Header Section
   ========================================================================== */

.art-header {
  padding: 16px 0 36px;
}

.art-category {
  font-family: var(--font-en);
  font-size: 0.82rem;
  font-weight: 800;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 20px;
}

.art-title {
  font-size: clamp(1.8rem, 3.8vw, 2.5rem);
  font-weight: 900;
  line-height: 1.38;
  letter-spacing: -0.02em;
  color: var(--text-primary);
  margin-bottom: 24px;
}

.art-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 20px;
  font-size: 0.84rem;
  color: var(--text-muted);
  padding-bottom: 24px;
  border-bottom: 1px solid var(--border-light);
  margin-bottom: 36px;
}

.art-meta-item {
  display: flex;
  align-items: center;
  gap: 6px;
}

.art-hero-image {
  margin: 0 0 44px;
  background: var(--bg-subtle);
  border: 1px solid var(--border-light);
}

.art-hero-image img {
  width: 100%;
  aspect-ratio: 16 / 9;
  object-fit: cover;
}

.art-hero-image figcaption {
  font-size: 0.76rem;
  color: var(--text-muted);
  padding: 10px 14px;
  border-top: 1px solid var(--border-light);
  text-align: right;
  letter-spacing: 0.02em;
}

/* ==========================================================================
   TL;DR / Key Takeaways Box (irka-style minimal)
   ========================================================================== */

.art-tldr {
  background: var(--bg-subtle);
  border: 1px solid var(--border-medium);
  padding: 28px 32px;
  margin-bottom: 48px;
}

.art-tldr-label {
  font-size: 0.95rem;
  font-weight: 800;
  letter-spacing: 0.06em;
  color: var(--text-primary);
  margin-bottom: 16px;
  text-transform: uppercase;
}

.art-tldr-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.art-tldr-list li {
  position: relative;
  padding-left: 18px;
  font-size: 0.94rem;
  line-height: 1.75;
  color: var(--text-secondary);
}

.art-tldr-list li::before {
  content: "—";
  position: absolute;
  left: 0;
  top: 0;
  color: var(--text-primary);
  font-weight: 700;
}

.art-tldr-list li strong {
  color: var(--text-primary);
  font-weight: 700;
}

/* ==========================================================================
   Table of Contents
   ========================================================================== */

.art-toc {
  background: var(--bg-primary);
  border: 1px solid var(--border-light);
  padding: 24px 28px;
  margin-bottom: 56px;
}

.art-toc-head {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 14px;
}

.art-toc-title {
  font-family: var(--font-en);
  font-size: 0.9rem;
  font-weight: 800;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-primary);
}

.art-toc-toggle {
  background: none;
  border: none;
  font-size: 0.8rem;
  color: var(--text-muted);
  cursor: pointer;
  padding: 2px 6px;
}

.art-toc-toggle:hover {
  color: var(--text-primary);
}

.art-toc-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 10px;
  padding-top: 14px;
  border-top: 1px solid var(--border-light);
}

.art-toc-list li {
  font-size: 0.9rem;
  line-height: 1.6;
}

.art-toc-list li a {
  color: var(--text-secondary);
  border-bottom: 1px solid transparent;
}

.art-toc-list li a:hover {
  color: var(--text-primary);
  border-bottom-color: var(--text-primary);
}

.art-toc-list li.toc-sub {
  padding-left: 18px;
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* ==========================================================================
   Article Body Typography
   ========================================================================== */

.art-body {
  font-size: 1.05rem;
  color: var(--text-primary);
}

.art-body p {
  margin-bottom: 2em;
  line-height: 1.95;
  color: #222222;
  text-align: justify;
}

.art-body h2 {
  font-size: clamp(1.45rem, 2.8vw, 1.85rem);
  font-weight: 800;
  line-height: 1.4;
  letter-spacing: -0.01em;
  margin: 64px 0 24px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--text-primary);
  color: var(--text-primary);
}

.art-body h3 {
  font-size: clamp(1.15rem, 2vw, 1.35rem);
  font-weight: 700;
  line-height: 1.5;
  margin: 40px 0 16px;
  color: var(--text-primary);
}

.art-body ul,
.art-body ol {
  margin: 0 0 2.2em 1.4em;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.art-body li {
  line-height: 1.8;
  color: var(--text-secondary);
}

.art-body li strong {
  color: var(--text-primary);
  font-weight: 700;
}

.art-body blockquote {
  margin: 2.5em 0;
  padding: 24px 28px;
  background: var(--bg-subtle);
  border-left: 3px solid var(--text-primary);
  font-size: 1.02rem;
  line-height: 1.85;
  color: var(--text-primary);
  font-family: var(--font-serif);
}

/* Note / Lead Box */
.art-box {
  background: var(--bg-subtle);
  border: 1px solid var(--border-light);
  padding: 24px 28px;
  margin: 36px 0;
}

.art-box-label {
  font-size: 0.85rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 10px;
}

.art-box p {
  margin-bottom: 0;
  font-size: 0.95rem;
  color: var(--text-secondary);
}

/* Feature 4-Points Grid */
.points-list {
  display: flex;
  flex-direction: column;
  gap: 20px;
  margin: 36px 0;
}

.point-item {
  border: 1px solid var(--border-light);
  padding: 24px 28px;
  background: var(--bg-primary);
  transition: var(--transition);
}

.point-item:hover {
  border-color: var(--border-dark);
}

.point-num-label {
  font-family: var(--font-en);
  font-size: 0.82rem;
  font-weight: 800;
  letter-spacing: 0.1em;
  color: var(--text-muted);
  margin-bottom: 6px;
}

.point-heading {
  font-size: 1.12rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 10px;
}

.point-text {
  font-size: 0.94rem;
  color: var(--text-secondary);
  line-height: 1.75;
  margin-bottom: 0 !important;
}

/* Comparison Table (Monotone Minimal) */
.table-wrap {
  overflow-x: auto;
  margin: 40px 0;
  border: 1px solid var(--border-dark);
}

.table-monotone {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.92rem;
  text-align: left;
}

.table-monotone th,
.table-monotone td {
  padding: 16px 20px;
  border-bottom: 1px solid var(--border-light);
  vertical-align: middle;
}

.table-monotone thead th {
  background: var(--bg-dark-box);
  color: var(--text-inverse);
  font-weight: 700;
  letter-spacing: 0.04em;
  border-bottom: none;
}

.table-monotone thead th.th-highlight {
  background: #222222;
}

.table-monotone td.td-highlight {
  background: var(--bg-subtle);
  font-weight: 600;
  color: var(--text-primary);
}

.table-monotone tbody tr:last-child td {
  border-bottom: none;
}

/* ==========================================================================
   FAQ Section (Text-only minimalist Q&A)
   ========================================================================== */

.art-faq-section {
  margin: 56px 0;
}

.art-faq-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
  margin-top: 24px;
}

.art-faq-item {
  border: 1px solid var(--border-light);
  background: var(--bg-primary);
  transition: var(--transition);
}

.art-faq-item[open] {
  border-color: var(--border-dark);
}

.art-faq-q {
  padding: 20px 24px;
  font-weight: 700;
  font-size: 1rem;
  cursor: pointer;
  user-select: none;
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 16px;
  color: var(--text-primary);
}

.art-faq-q::-webkit-details-marker {
  display: none;
}

.art-faq-q-text {
  flex: 1;
}

.art-faq-toggle-sym {
  font-family: var(--font-en);
  font-size: 1.1rem;
  font-weight: 400;
  color: var(--text-muted);
}

.art-faq-item[open] .art-faq-toggle-sym {
  transform: rotate(45deg);
  display: inline-block;
}

.art-faq-a {
  padding: 0 24px 24px;
  font-size: 0.94rem;
  color: var(--text-secondary);
  line-height: 1.8;
  border-top: 1px solid var(--border-light);
  padding-top: 16px;
}

/* ==========================================================================
   Author Card (Monotone E-E-A-T)
   ========================================================================== */

.author-card {
  border: 1px solid var(--border-dark);
  padding: 36px 32px;
  margin: 64px 0 44px;
  background: var(--bg-primary);
  display: flex;
  gap: 28px;
  align-items: flex-start;
}

.author-avatar-wrap {
  flex-shrink: 0;
}

.author-photo {
  width: 96px;
  height: 96px;
  border-radius: 50%;
  object-fit: cover;
  border: 1px solid var(--border-medium);
  filter: grayscale(100%);
  transition: var(--transition);
}

.author-card:hover .author-photo {
  filter: grayscale(0%);
}

.author-details {
  flex: 1;
}

.author-role {
  font-family: var(--font-en);
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 4px;
}

.author-name-title {
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--text-primary);
  margin-bottom: 12px;
}

.author-desc {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.75;
  margin-bottom: 16px !important;
}

.author-creds {
  font-size: 0.82rem;
  color: var(--text-muted);
  background: var(--bg-subtle);
  padding: 14px 18px;
  line-height: 1.7;
  margin-bottom: 16px;
}

.author-links {
  display: flex;
  gap: 16px;
  font-family: var(--font-en);
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--text-primary);
}

.author-links a {
  border-bottom: 1px solid var(--text-primary);
}

.author-links a:hover {
  opacity: 0.6;
}

/* ==========================================================================
   Article CTA (Solid Black Block, Irka Style)
   ========================================================================== */

.art-cta-block,
.art-body .art-cta-block {
  background: #111111 !important;
  color: #ffffff !important;
  padding: 48px 36px;
  margin: 56px 0;
  text-align: left;
  border-radius: 0;
  border: 1px solid #111111;
}

.art-cta-label,
.art-body .art-cta-block .art-cta-label {
  font-family: var(--font-en);
  font-size: 0.8rem;
  font-weight: 800;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: #a1a1aa !important;
  margin-bottom: 14px;
  display: block;
}

.art-cta-h2,
.art-body .art-cta-block .art-cta-h2,
.art-body .art-cta-block h2 {
  font-size: clamp(1.4rem, 2.8vw, 1.9rem) !important;
  font-weight: 800 !important;
  line-height: 1.4 !important;
  margin: 0 0 16px !important;
  padding: 0 !important;
  border-bottom: none !important;
  color: #ffffff !important;
}

.art-cta-desc,
.art-body .art-cta-block .art-cta-desc,
.art-body .art-cta-block p {
  font-size: 0.95rem !important;
  color: #d4d4d8 !important;
  margin-bottom: 28px !important;
  line-height: 1.75 !important;
  text-align: left !important;
}

.art-cta-btn-group,
.art-body .art-cta-block .art-cta-btn-group {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

.btn-solid-white,
.art-body .art-cta-block a.btn-solid-white {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 14px 28px;
  background: #ffffff !important;
  color: #111111 !important;
  font-size: 0.92rem;
  font-weight: 800;
  border-radius: 2px;
  letter-spacing: 0.04em;
  transition: var(--transition);
  text-decoration: none;
}

.btn-solid-white:hover,
.art-body .art-cta-block a.btn-solid-white:hover {
  background: #e4e4e7 !important;
  color: #000000 !important;
  transform: translateX(4px);
}

.btn-outline-white,
.art-body .art-cta-block a.btn-outline-white {
  display: inline-flex;
  align-items: center;
  padding: 14px 24px;
  background: transparent !important;
  color: #ffffff !important;
  border: 1px solid rgba(255, 255, 255, 0.4) !important;
  font-size: 0.92rem;
  font-weight: 700;
  border-radius: 2px;
  transition: var(--transition);
  text-decoration: none;
}

.btn-outline-white:hover,
.art-body .art-cta-block a.btn-outline-white:hover {
  border-color: #ffffff !important;
  background: rgba(255, 255, 255, 0.1) !important;
  color: #ffffff !important;
}

/* Article Note */
.art-disclaimer {
  font-size: 0.8rem;
  color: var(--text-muted);
  line-height: 1.7;
  padding: 24px 0;
  border-top: 1px solid var(--border-light);
  margin-top: 40px;
}

/* ==========================================================================
   Column Index (List Page) Styles
   ========================================================================== */

.idx-hero {
  padding: 64px 0 40px;
  border-bottom: 1px solid var(--border-light);
  margin-bottom: 48px;
}

.idx-hero-cat {
  font-family: var(--font-en);
  font-size: 0.82rem;
  font-weight: 800;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 12px;
}

.idx-hero-title {
  font-family: var(--font-en);
  font-size: clamp(2.2rem, 4.5vw, 3.2rem);
  font-weight: 900;
  letter-spacing: -0.02em;
  text-transform: uppercase;
  color: var(--text-primary);
  margin-bottom: 16px;
}

.idx-hero-desc {
  font-size: 1rem;
  color: var(--text-secondary);
  max-width: 640px;
  line-height: 1.8;
}

.idx-filters {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 40px;
}

.idx-filter-btn {
  padding: 6px 16px;
  font-size: 0.84rem;
  font-weight: 700;
  border: 1px solid var(--border-medium);
  background: var(--bg-primary);
  color: var(--text-secondary);
  cursor: pointer;
  border-radius: 2px;
  transition: var(--transition);
}

.idx-filter-btn.active,
.idx-filter-btn:hover {
  background: var(--text-primary);
  color: var(--text-inverse);
  border-color: var(--text-primary);
}

.idx-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
  gap: 36px;
  margin-bottom: 64px;
}

.idx-card {
  border: 1px solid var(--border-light);
  background: var(--bg-primary);
  display: flex;
  flex-direction: column;
  transition: var(--transition);
}

.idx-card:hover {
  border-color: var(--border-dark);
  transform: translateY(-4px);
}

.idx-card-img-wrap {
  aspect-ratio: 16 / 9;
  overflow: hidden;
  background: var(--bg-subtle);
  border-bottom: 1px solid var(--border-light);
}

.idx-card-img-wrap img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.4s ease;
}

.idx-card:hover .idx-card-img-wrap img {
  transform: scale(1.03);
}

.idx-card-content {
  padding: 24px;
  display: flex;
  flex-direction: column;
  flex-grow: 1;
}

.idx-card-meta {
  font-family: var(--font-en);
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--text-muted);
  margin-bottom: 10px;
  display: flex;
  justify-content: space-between;
}

.idx-card-title {
  font-size: 1.15rem;
  font-weight: 800;
  line-height: 1.45;
  color: var(--text-primary);
  margin-bottom: 12px;
}

.idx-card-excerpt {
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: 20px;
  flex-grow: 1;
}

.idx-card-foot {
  padding-top: 14px;
  border-top: 1px solid var(--border-light);
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--text-primary);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

/* ==========================================================================
   Footer (Monotone Minimal)
   ========================================================================== */

.site-footer {
  border-top: 1px solid var(--border-dark);
  background: var(--bg-primary);
  padding: 56px 0 36px;
  margin-top: 80px;
}

.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  flex-wrap: wrap;
  gap: 32px;
  margin-bottom: 40px;
}

.footer-brand h4 {
  font-family: var(--font-en);
  font-size: 1.1rem;
  font-weight: 900;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  margin-bottom: 8px;
}

.footer-brand p {
  font-size: 0.84rem;
  color: var(--text-muted);
}

.footer-nav-list {
  display: flex;
  flex-wrap: wrap;
  gap: 20px;
  list-style: none;
}

.footer-nav-list a {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.footer-nav-list a:hover {
  color: var(--text-primary);
  text-decoration: underline;
}

.footer-bottom {
  padding-top: 24px;
  border-top: 1px solid var(--border-light);
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.78rem;
  color: var(--text-muted);
}

/* Responsive */
@media (max-width: 768px) {
  .author-card {
    flex-direction: column;
    align-items: center;
    text-align: center;
    padding: 28px 20px;
  }

  .author-links {
    justify-content: center;
  }

  .art-cta-block {
    padding: 36px 24px;
  }

  .btn-solid-white,
  .btn-outline-white {
    width: 100%;
    justify-content: center;
  }

  .idx-grid {
    grid-template-columns: 1fr;
  }

  .footer-inner {
    flex-direction: column;
  }
}