:root {
  --bg: #f7f8fb;
  --panel: #ffffff;
  --text: #1f2430;
  --muted: #5e6473;
  --accent: #2f5aa8;
  --border: #dbe0ea;
  --header-height: 72px;
  --mobile-nav-height: 0px;
}

* { box-sizing: border-box; }

html,
body {
  margin: 0;
  padding: 0;
  font-family: "Helvetica Neue", Arial, "Hiragino Kaku Gothic ProN", "Hiragino Sans", "Noto Sans JP", "Microsoft YaHei", sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.7;
}

.site-header {
  position: fixed;
  inset: 0 0 auto 0;
  height: var(--header-height);
  z-index: 100;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(4px);
  border-bottom: 1px solid var(--border);
}

.header-inner {
  position: relative;
  height: 100%;
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 1rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.top-nav,
.lang-switch { display: flex; gap: 0.5rem; flex-wrap: wrap; align-items: center; }

.lang-switch {
  padding: 0.25rem;
  border: 1px solid #ccd7ee;
  border-radius: 999px;
  background: #eef3ff;
}

.nav-btn,
.lang-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 2.2rem;
  border: 1px solid var(--border);
  background: var(--panel);
  color: var(--text);
  padding: 0.4rem 0.75rem;
  border-radius: 999px;
  font-weight: 600;
  cursor: pointer;
  text-decoration: none;
  font-size: 0.9rem;
  line-height: 1;
  font-family: inherit;
  appearance: none;
  -webkit-appearance: none;
}

.lang-btn {
  border-color: #9eb0da;
}

.nav-btn.active,
.lang-btn.active {
  color: #fff;
  border-color: var(--accent);
  background: var(--accent);
}

.menu-toggle {
  display: none;
  align-items: center;
  justify-content: center;
  width: 2.2rem;
  height: 2.2rem;
  border-radius: 0.4rem;
  border: 1px solid var(--border);
  background: var(--panel);
  color: var(--muted);
  font-size: 1.2rem;
  line-height: 1;
  padding: 0;
}

main {
  max-width: 1100px;
  margin: 0 auto;
  padding: calc(var(--header-height) + 1rem) 1rem 2rem;
}

.screen { display: block; }

.content-grid { display: grid; grid-template-columns: minmax(0, 1fr) 260px; gap: 1.5rem; }
.content-grid.single-column { grid-template-columns: 1fr; }

.profile-block,
.anchor-section,
.toc {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1rem 1.2rem;
}

.profile-block {
  display: grid;
  grid-template-columns: 1fr 200px;
  align-items: center;
  gap: 1rem;
}

.profile-photo { width: 100%; border-radius: 12px; border: 1px solid var(--border); }
.anchor-section { margin-top: 1rem; }
h1, h2, h3 { line-height: 1.3; }
h2 { color: var(--accent); }

.site-footer {
  display: flex;
  justify-content: center;
  width: 100%;
  text-align: center;
  color: #9aa3b2;
  font-size: 0.75rem;
  padding: 0.5rem 1rem 1.25rem;
}

@media (max-width: 900px) {
  .content-grid,
  .profile-block { grid-template-columns: 1fr; }
  .profile-photo-wrap { max-width: 220px; margin: 0 auto; }
}

@media (max-width: 720px) {
  .menu-toggle { display: inline-flex; margin-left: auto; }

  .top-nav,
  .lang-switch {
    display: none;
    position: absolute;
    right: 1rem;
    left: 1rem;
    background: var(--panel);
  }

  .header-inner.menu-open .top-nav,
  .header-inner.menu-open .lang-switch {
    display: flex;
    flex-direction: column;
    align-items: stretch;
    flex-wrap: nowrap;
    gap: 0.35rem;
    border: 1px solid var(--border);
    border-radius: 12px;
    padding: 0.6rem;
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.08);
  }

  .header-inner.menu-open .top-nav { top: calc(100% + 0.35rem); }
  .header-inner.menu-open .lang-switch { top: calc(100% + 0.7rem + var(--mobile-nav-height)); }

  .header-inner.menu-open .lang-switch {
    background: #eef3ff;
    border-color: #ccd7ee;
  }

  .header-inner.menu-open .nav-btn,
  .header-inner.menu-open .lang-btn {
    width: 100%;
    justify-content: flex-start;
    border-radius: 8px;
  }
}