/* ================================================================
   xMath Lab — style.css
   デザイン変更は :root の変数だけ編集すればOK
   ================================================================ */
:root {
  --color-bg: #faf9f7;
  --color-text: #1a1a1a;
  --color-muted: #888;
  --color-line: #e0e0e0;

  --nav-bg: #111;
  --nav-text: #ffffff;
  --nav-muted: #969696;
  --nav-border: rgba(255, 255, 255, 0.1);
  --nav-height: 60px;

  --font: 'Noto Sans JP', 'Noto Sans', sans-serif;
  --font-size: 15px;
  --line-height: 1.95;
  --max-width: 760px;
  --pad: 2rem;
  --gap: 3rem;

  /* Markdown 本文フォントサイズ（ここを変えると各要素に反映） */
  --md-h2: 1.0rem;
  /* ## 見出し */
  --md-p: 1.1rem;
  /* 段落 */
  --md-li: 1.1rem;
  /* リスト項目（テーマ行） */
  --md-li-sub: 1.10rem;
  /* ネストしたリスト項目 */
  --md-li-plain: 1.0rem;
  /* 箇条書きリスト */
  --md-pub: 1.2rem;
  /* Publication 論文行 */
  --md-pub-strong: 600;
  /* Publication 太字の font-weight */
}

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

html {
  scroll-behavior: smooth;
}

body {
  background: var(--color-bg);
  color: var(--color-text);
  font-family: var(--font);
  font-size: var(--font-size);
  font-weight: 400;
  line-height: var(--line-height);
}

a {
  color: var(--color-text);
  text-underline-offset: 3px;
}

a:hover {
  opacity: 0.55;
}

strong {
  font-weight: 600;
}

/* --- Nav --- */
.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--nav-bg);
  border-bottom: 1px solid var(--nav-border);
}

.nav__inner {
  max-width: calc(var(--max-width) + var(--pad) * 2);
  margin: 0 auto;
  padding: 0 var(--pad);
  height: var(--nav-height);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav__logo {
  font-size: 1.2rem;
  font-weight: 400;
  letter-spacing: 0.13em;
  text-transform: uppercase;
  color: var(--nav-text);
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.nav__logo-sep {
  font-size: 0.8rem;
  font-weight: 300;
  letter-spacing: 0.16em;
  color: var(--nav-muted);
  border-left: 1px solid rgba(255, 255, 255, 0.2);
  padding-left: 0.75rem;
}

.nav__links {
  list-style: none;
  display: flex;
}

.nav__links a {
  display: block;
  height: var(--nav-height);
  line-height: var(--nav-height);
  padding: 0 1.1rem;
  font-size: 0.9rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--nav-muted);
  text-decoration: none;
  transition: color 0.2s;
  position: relative;
}

.nav__links a::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 1.1rem;
  right: 1.1rem;
  height: 1px;
  background: var(--nav-text);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.25s ease;
}

.nav__links a:hover,
.nav__links a.active {
  color: var(--nav-text);
  opacity: 1;
}

.nav__links a:hover::after,
.nav__links a.active::after {
  transform: scaleX(1);
}

/* --- Page --- */
.page {
  max-width: calc(var(--max-width) + var(--pad) * 2);
  margin: 0 auto;
  padding: 5rem var(--pad) 7rem;
}

/* --- Page header --- */
.page-header {
  margin-bottom: var(--gap);
  padding-bottom: var(--gap);
  border-bottom: 1px solid var(--color-line);
}

.page-header h1 {
  font-size: clamp(2rem, 6vw, 3rem);
  font-weight: 300;
  letter-spacing: -0.01em;
  line-height: 1.12;
  margin-bottom: 0.8rem;
}

.lang-switch a {
  font-size: 1.2rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--color-muted);
  text-decoration: none;
  border-bottom: 1px solid var(--color-line);
  padding-bottom: 0.15rem;
  transition: color 0.2s, border-color 0.2s;
}

.lang-switch a:hover {
  color: var(--color-text);
  border-color: var(--color-text);
  opacity: 1;
}

/* --- Rendered Markdown body --- */
.md-body h2 {
  font-size: var(--md-h2);
  font-weight: 400;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--color-muted);
  margin-top: var(--gap);
  margin-bottom: 1.2rem;
  display: flex;
  align-items: center;
  gap: 0.9rem;
}

.md-body h2::after {
  content: '';
  flex: 1;
  height: 1px;
  background: var(--color-line);
}

.md-body p {
  font-size: var(--md-p);
  color: #444;
  margin-bottom: 1rem;
  max-width: 760px;
}

.md-body p:last-child {
  margin-bottom: 0;
}

.md-body strong {
  color: var(--color-text);
}

.md-body a {
  color: var(--color-text);
}

.md-body em {
  font-style: italic;
}

/* top-level list → theme rows */
.md-body>ul {
  list-style: none;
  border-top: 1px solid var(--color-line);
}

.md-body>ul>li {
  display: grid;
  grid-template-columns: 160px 1fr;
  gap: 1.5rem;
  padding: 1.4rem 0;
  border-bottom: 1px solid var(--color-line);
  font-size: var(--md-li);
  font-weight: 400;
}

/* nested list inside li */
.md-body>ul>li>ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

.md-body>ul>li>ul>li {
  font-size: var(--md-li-sub);
  color: #555;
  font-weight: 300;
  padding-left: 1rem;
  position: relative;
  line-height: 1.65;
}

.md-body>ul>li>ul>li::before {
  content: '–';
  position: absolute;
  left: 0;
  color: var(--color-line);
}

/* list after a <p> → plain bullet list */
.md-body>p+ul>li {
  display: flex;
  gap: 0.8rem;
  grid-template-columns: unset;
  font-size: var(--md-li-plain);
  font-weight:400;
  color: #444;
  padding: 0.72rem 0;
  border-bottom: 1px solid var(--color-line);
}

.md-body>p+ul>li::before {
  content: '—';
  color: var(--color-line);
  flex-shrink: 0;
}

.md-body>p+ul>li>ul {
  display: none;
}

.last-updated {
  font-size: 1.0rem;
  letter-spacing: 0.08em;
  color: var(--color-muted);
  margin-top: 0.6rem;
}

/* --- Footer --- */
.footer {
  border-top: 1px solid var(--color-line);
  max-width: calc(var(--max-width) + var(--pad) * 2);
  margin: 0 auto;
  padding: 2rem var(--pad);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.footer__logo {
  font-size: 0.82rem;
  font-weight: 400;
  letter-spacing: 0.11em;
  text-transform: uppercase;
}

.footer__copy {
  font-size: 0.63rem;
  color: var(--color-muted);
}

/* --- External nav link --- */
.nav__links a[target="_blank"]::after {
  display: none;
}

.nav__links a[target="_blank"] {
  color: var(--nav-muted);
}

.nav__links a[target="_blank"]:hover {
  color: var(--nav-text);
}

/* --- Publication page --- */
.pub-year {
  font-size: 1.1rem !important;
  font-weight: 400;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--color-muted);
  margin-top: var(--gap) !important;
  margin-bottom: 0 !important;
  display: flex;
  align-items: center;
  gap: 0.9rem;
}

.pub-year::after {
  content: '';
  flex: 1;
  height: 1px;
  background: var(--color-line);
}

.pub-list {
  list-style: none;
  border-top: none !important;
  margin-top: 0 !important;
}

.pub-item {
  display: block !important;
  grid-template-columns: unset !important;
  font-size: var(--md-pub);
  font-weight: 300;
  color: #333;
  padding: 1rem 0 !important;
  border-bottom: 1px solid var(--color-line);
  line-height: 1.7;
}

.pub-item em {
  color: var(--color-muted);
  font-style: italic;
}

.pub-item strong {
  font-weight: var(--md-pub-strong);
  color: var(--color-text);
}

.pub-item a {
  font-size: 0.68rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--color-muted);
  text-decoration: none;
  border: 1px solid var(--color-line);
  padding: 0.15rem 0.5rem;
  margin-left: 0.5rem;
  transition: all 0.2s;
  white-space: nowrap;
}

.pub-item a:hover {
  color: var(--color-text);
  border-color: var(--color-text);
  opacity: 1;
}

/* --- Hamburger button --- */
.nav__hamburger {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 32px;
  height: 32px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}

.nav__hamburger span {
  display: block;
  width: 100%;
  height: 1px;
  background: var(--nav-text);
  transition: transform 0.25s ease, opacity 0.25s ease;
}

.nav__hamburger[aria-expanded="true"] span:nth-child(1) {
  transform: translateY(6px) rotate(45deg);
}

.nav__hamburger[aria-expanded="true"] span:nth-child(2) {
  opacity: 0;
}

.nav__hamburger[aria-expanded="true"] span:nth-child(3) {
  transform: translateY(-6px) rotate(-45deg);
}

/* --- Mobile drawer --- */
.nav__drawer {
  display: none;
  flex-direction: column;
  background: var(--nav-bg);
  border-top: 1px solid var(--nav-border);
  padding: 0.5rem 0;
  list-style: none;
}

.nav__drawer li {
  list-style: none;
}

.nav__drawer a {
  display: block;
  padding: 0.85rem var(--pad);
  font-size: 0.72rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--nav-muted);
  text-decoration: none;
  border-bottom: 1px solid var(--nav-border);
  transition: color 0.2s;
}

.nav__drawer a:last-child {
  border-bottom: none;
}

.nav__drawer a:hover,
.nav__drawer a.active {
  color: var(--nav-text);
  opacity: 1;
}

.nav.is-open .nav__drawer {
  display: flex;
}

/* --- Publication: title as link --- */
.pub-title {
  font-size: var(--md-pub) !important;
  font-weight: 400 !important;
  color: var(--color-text) !important;
  text-decoration: none !important;
  border-bottom: 1px solid var(--color-line) !important;
  padding-bottom: 0.05rem !important;
  transition: border-color 0.2s !important;
  letter-spacing: 0 !important;
  text-transform: none !important;
  border: none !important;
  padding: 0 !important;
  margin: 0 !important;
}

.pub-title:hover {
  opacity: 0.6 !important;
  border-color: var(--color-text) !important;
}

/* --- Responsive --- */
@media (max-width: 0px) {
  .nav__links {
    display: none;
  }

  .nav__hamburger {
    display: flex;
  }

  .md-body>ul>li {
    grid-template-columns: 1fr;
    gap: 0.5rem;
  }

  .footer {
    flex-direction: column;
    gap: 0.6rem;
    text-align: center;
  }
}