/* ===== Reset & Base ===== */
*, *::before, *::after{
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --color-bg: #ffffff;
  --color-text: #1a1a1a;
  --color-text-secondary: #555555;
  --color-accent: #8b0000;
  --color-border: #d0d0d0;
  --color-border-light: #e8e8e8;
  --color-bg-subtle: #f7f7f5;
  --color-link: #2a5a8a;
  --font-body: "Noto Serif JP", "游明朝", "YuMincho", "Hiragino Mincho ProN", "HG明朝E", serif;
  --font-heading: "Noto Serif JP", "游明朝", "YuMincho", "Hiragino Mincho ProN", serif;
  --font-ui: "Noto Sans JP", "游ゴシック", "YuGothic", "Hiragino Kaku Gothic ProN", sans-serif;
  --max-width: 820px;
  --side-padding: 2rem;
}

html{
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body{
  background-color: var(--color-bg);
  color: var(--color-text);
  font-family: var(--font-body);
  font-weight: 400;
  line-height: 2;
  letter-spacing: 0.04em;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}

/* ===== Breadcrumb ===== */
.breadcrumb{
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 1.2rem var(--side-padding) 0;
  font-family: var(--font-ui);
  font-size: 0.78rem;
  color: var(--color-text-secondary);
  letter-spacing: 0.02em;
  line-height: 1.6;
}

.breadcrumb a{
  color: var(--color-text-secondary);
  text-decoration: none;
  transition: color 0.2s ease;
}

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

.breadcrumb .separator{
  margin: 0 0.5em;
  color: #aaa;
  font-size: 0.7rem;
}

.breadcrumb .current {
  color: var(--color-text);
}

/* ===== Article Header ===== */
.article-header{
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 3rem var(--side-padding) 2rem;
}

.article-header .overline{
  display: block;
  font-family: var(--font-ui);
  font-size: 0.75rem;
  font-weight: 500;
  letter-spacing: 0.18em;
  color: var(--color-accent);
  text-transform: uppercase;
  margin-bottom: 1.5rem;
}

.article-title{
  font-family: var(--font-heading);
  font-size: 2rem;
  font-weight: 700;
  line-height: 1.55;
  letter-spacing: 0.06em;
  color: var(--color-text);
  margin-bottom: 1rem;
}

.article-subtitle{
  font-family: var(--font-heading);
  font-size: 1.05rem;
  font-weight: 400;
  line-height: 1.8;
  color: var(--color-text-secondary);
  letter-spacing: 0.05em;
}

.header-rule{
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--side-padding);
}

.header-rule hr{
  border: none;
  border-top: 2px solid var(--color-text);
  width: 100%;
}

/* ===== Table of Contents ===== */
.toc-container{
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 2.5rem var(--side-padding) 1.5rem;
}

.toc-container summary{
  font-family: var(--font-ui);
  font-size: 0.85rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  color: var(--color-text-secondary);
  cursor: pointer;
  list-style: none;
  display: flex;
  align-items: center;
  gap: 0.5em;
}

.toc-container summary::-webkit-details-marker {
  display: none;
}

.toc-container summary::before{
  content: "＋";
  font-size: 0.9rem;
  transition: transform 0.2s ease;
}

.toc-container[open] summary::before{
  content: "－";
}

.toc-list{
  list-style: none;
  margin-top: 1.2rem;
  padding-left: 0;
  border-left: 1px solid var(--color-border);
  padding-left: 1.5rem;
}

.toc-list li{
  margin-bottom: 0.6rem;
  line-height: 1.7;
}

.toc-list a{
  font-family: var(--font-ui);
  font-size: 0.88rem;
  color: var(--color-text-secondary);
  text-decoration: none;
  letter-spacing: 0.03em;
  transition: color 0.2s ease;
}

.toc-list a:hover {
  color: var(--color-accent);
}

.toc-list .toc-sub{
  padding-left: 1.2rem;
  margin-top: 0.4rem;
}

.toc-list .toc-sub li{
  margin-bottom: 0.4rem;
}

.toc-list .toc-sub a{
  font-size: 0.82rem;
}

/* ===== Main Article ===== */
.article-body{
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 1rem var(--side-padding) 4rem;
}

/* Section Headings */
.article-body h2{
  font-family: var(--font-heading);
  font-size: 1.4rem;
  font-weight: 700;
  line-height: 1.6;
  letter-spacing: 0.06em;
  color: var(--color-text);
  margin-top: 4rem;
  margin-bottom: 1.5rem;
  padding-bottom: 0.6rem;
  border-bottom: 1px solid var(--color-border);
}

.article-body h2:first-child{
  margin-top: 2rem;
}

.article-body h3{
  font-family: var(--font-heading);
  font-size: 1.15rem;
  font-weight: 700;
  line-height: 1.6;
  letter-spacing: 0.05em;
  color: var(--color-text);
  margin-top: 3rem;
  margin-bottom: 1.2rem;
  padding-left: 0.8rem;
  border-left: 3px solid var(--color-accent);
}

/* Paragraphs */
.article-body p{
  margin-bottom: 1.6rem;
  font-size: 1rem;
  line-height: 2;
  text-align: justify;
  text-justify: inter-ideograph;
  hanging-punctuation: allow-end;
  overflow-wrap: break-word;
}

/* Source Citations */
.article-body .source{
  display: block;
  font-family: var(--font-ui);
  font-size: 0.8rem;
  line-height: 1.7;
  color: var(--color-text-secondary);
  margin-top: -0.8rem;
  margin-bottom: 2rem;
  padding: 0.8rem 1rem;
  background-color: var(--color-bg-subtle);
  border-radius: 3px;
}

.article-body .source a{
  color: var(--color-link);
  text-decoration: none;
  word-break: break-all;
}

.article-body .source a:hover{
  text-decoration: underline;
}

/* Emphasis */
.article-body strong{
  font-weight: 700;
}

.article-body em{
  font-style: normal;
  border-bottom: 1px solid var(--color-accent);
  padding-bottom: 1px;
}

/* ===== Footer ===== */
.site-footer{
  border-top: 1px solid var(--color-border-light);
  padding: 2rem var(--side-padding);
  text-align: center;
}

.site-footer p{
  font-family: var(--font-ui);
  font-size: 0.75rem;
  color: var(--color-text-secondary);
  letter-spacing: 0.08em;
}

/* ===== Responsive ===== */
@media screen and (max-width: 768px) {
  :root {
    --side-padding: 1.2rem;
  }

  html{
    font-size: 15px;
  }

  .article-title{
    font-size: 1.55rem;
    line-height: 1.6;
  }

  .article-subtitle{
    font-size: 0.95rem;
  }

  .article-body h2{
    font-size: 1.25rem;
    margin-top: 3rem;
  }

  .article-body h3{
    font-size: 1.05rem;
    margin-top: 2.2rem;
  }

  .article-body p{
    font-size: 0.95rem;
    line-height: 1.95;
    text-align: left;
  }
}

@media screen and (max-width: 480px) {
  :root {
    --side-padding: 1rem;
  }

  html{
    font-size: 14px;
  }

  .article-title{
    font-size: 1.4rem;
  }

  .article-header{
    padding-top: 2rem;
  }

  .toc-list{
    padding-left: 1rem;
  }

  .article-body .source{
    font-size: 0.75rem;
    padding: 0.6rem 0.8rem;
  }
}

/* ===== Print ===== */
@media print {
  body{
    font-size: 10.5pt;
    line-height: 1.8;
  }

  .breadcrumb,
  .toc-container{
    display: none;
  }

  .article-body h2{
    page-break-after: avoid;
  }

  .article-body h3{
    page-break-after: avoid;
  }

  .site-footer{
    border-top: 0.5pt solid #999;
  }
}

/* ===== Web Fonts Fallback ===== */
@import url('https://fonts.googleapis.com/css2?family=Noto+Serif+JP:wght@400;700&family=Noto+Sans+JP:wght@400;500;600&display=swap');