/* ===== Sasamoto Daiki — Personal Homepage ===== */
:root {
  --bg: #0b0f1a;
  --bg-soft: #111827;
  --card: rgba(255, 255, 255, 0.04);
  --border: rgba(255, 255, 255, 0.09);
  --text: #e5e9f0;
  --text-dim: #9aa5b5;
  --accent1: #7c6cf6;
  --accent2: #38cfe0;
  --grad: linear-gradient(120deg, var(--accent1), var(--accent2));
  --radius: 16px;
  --maxw: 960px;
}

/* ===== Light theme ===== */
body.light {
  --bg: #f4f6fa;
  --bg-soft: #e9edf5;
  --card: rgba(15, 26, 55, 0.04);
  --border: rgba(15, 26, 55, 0.13);
  --text: #1c2433;
  --text-dim: #5b6678;
  --accent1: #6b5ce0;
  --accent2: #0d94a8;
}
body.light header { background: rgba(244, 246, 250, 0.78); }
body.light .bg-glow {
  background:
    radial-gradient(600px 400px at 15% 0%, rgba(107, 92, 224, 0.10), transparent 70%),
    radial-gradient(700px 500px at 90% 20%, rgba(13, 148, 168, 0.08), transparent 70%);
}
body.light details.book-group .group-body .card { background: rgba(15, 26, 55, 0.03); }

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

html { scroll-behavior: smooth; }

body {
  font-family: "Inter", "Noto Sans JP", -apple-system, "Hiragino Kaku Gothic ProN", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.8;
  -webkit-font-smoothing: antialiased;
}

/* --- Language toggle visibility --- */
body.lang-ja .en { display: none !important; }
/* 「おすすめ論文・おすすめ教科書・ノート」(#papers/#books/#notes)は
   見出し・タブ含めて英語モードでも日本語のまま表示する。
   英語コンテンツはHTMLに残っているので、下2行を
   「body.lang-en .ja { display: none !important; }」に戻せば英語表示が復活します。 */
body.lang-en .ja:not(:is(#papers, #books, #notes) .ja) { display: none !important; }
body.lang-en :is(#papers, #books, #notes) .en { display: none !important; }

/* --- Background glow --- */
.bg-glow {
  position: fixed; inset: 0; z-index: -1;
  background:
    radial-gradient(600px 400px at 15% 0%, rgba(124, 108, 246, 0.16), transparent 70%),
    radial-gradient(700px 500px at 90% 20%, rgba(56, 207, 224, 0.10), transparent 70%);
}

/* --- Header / Nav --- */
header {
  position: sticky; top: 0; z-index: 10;
  backdrop-filter: blur(14px);
  background: rgba(11, 15, 26, 0.7);
  border-bottom: 1px solid var(--border);
}
.nav {
  max-width: var(--maxw); margin: 0 auto;
  display: flex; align-items: center; justify-content: space-between;
  padding: 0.9rem 1.5rem;
}
.nav-logo {
  font-weight: 700; letter-spacing: 0.02em;
  background: var(--grad);
  -webkit-background-clip: text; background-clip: text; color: transparent;
  text-decoration: none; font-size: 1.05rem;
}
.nav-links { display: flex; align-items: center; gap: 1.4rem; list-style: none; }
.nav-links a {
  color: var(--text-dim); text-decoration: none; font-size: 0.92rem;
  transition: color 0.2s;
}
.nav-links a:hover { color: var(--text); }

.lang-btn {
  border: 1px solid var(--border);
  background: var(--card);
  color: var(--text);
  border-radius: 999px;
  padding: 0.35rem 0.95rem;
  font-size: 0.85rem;
  cursor: pointer;
  transition: border-color 0.2s, background 0.2s;
}
.lang-btn:hover { border-color: var(--accent2); }

/* --- Layout --- */
main { max-width: var(--maxw); margin: 0 auto; padding: 0 1.5rem; }
section { padding: 4.5rem 0 1rem; }

.section-title {
  font-size: 1.5rem; font-weight: 700; margin-bottom: 1.6rem;
  display: flex; align-items: center; gap: 0.7rem;
}
.section-title::before {
  content: ""; width: 26px; height: 3px; border-radius: 2px;
  background: var(--grad);
}

/* --- Hero --- */
.hero { padding: 6.5rem 0 3rem; }
.hero-flex { display: flex; align-items: center; justify-content: space-between; gap: 2.5rem; }
.hero-main { min-width: 0; }
.hero-photo {
  flex: 0 0 auto;
  width: 235px; height: 357px;
  border-radius: 20px;
  object-fit: cover;
  border: 3px solid var(--border);
  box-shadow: 0 16px 40px rgba(0,0,0,0.22), 0 4px 12px rgba(0,0,0,0.12);
}
.hero-kicker {
  color: var(--accent2); font-size: 0.9rem; letter-spacing: 0.18em;
  text-transform: uppercase; margin-bottom: 1rem;
}
.hero h1 {
  font-size: clamp(2.2rem, 6vw, 3.4rem);
  font-weight: 800; line-height: 1.2; margin-bottom: 1.1rem;
}
.hero h1 .grad {
  background: var(--grad);
  -webkit-background-clip: text; background-clip: text; color: transparent;
}
.hero-sub { color: var(--text-dim); font-size: 1.05rem; max-width: 620px; }
.hero-links { color: var(--text-dim); font-size: 1.05rem; margin-top: 1.4rem; line-height: 1.9; }
.hero-links a { white-space: nowrap; }
.hero-links .hl-row { display: flex; align-items: baseline; }
.hero-links .hl-label { flex: 0 0 auto; white-space: nowrap; }
.hero-links .hl-body { min-width: 0; }
.hero-tags { display: flex; flex-wrap: wrap; gap: 0.6rem; margin-top: 1.6rem; }
.tag {
  font-size: 0.8rem; color: var(--text);
  border: 1px solid var(--border); background: var(--card);
  padding: 0.3rem 0.85rem; border-radius: 999px;
}

/* --- Cards --- */
.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.6rem 1.8rem;
  margin-bottom: 1.2rem;
  transition: transform 0.25s, border-color 0.25s;
}
.card:hover { transform: translateY(-3px); border-color: rgba(124, 108, 246, 0.5); }
.card h3 { font-size: 1.05rem; margin-bottom: 0.4rem; }
.card p { color: var(--text-dim); font-size: 0.95rem; }

.grid2 { display: grid; grid-template-columns: 1fr 1fr; gap: 1.2rem; }
@media (max-width: 700px) { .grid2 { grid-template-columns: 1fr; } }

/* --- Timeline (CV) --- */
.timeline { list-style: none; border-left: 2px solid var(--border); padding-left: 1.5rem; }
.timeline li { position: relative; padding-bottom: 1.4rem; }
.timeline li::before {
  content: ""; position: absolute; left: -1.85rem; top: 0.5em;
  width: 10px; height: 10px; border-radius: 50%;
  background: var(--grad);
}
.timeline .when { color: var(--accent2); font-size: 0.85rem; display: block; }

/* --- Publications --- */
.pub-list { list-style: none; counter-reset: pub; }
.pub-list li {
  padding: 1rem 0; border-bottom: 1px solid var(--border);
  color: var(--text-dim); font-size: 0.95rem;
}
.placeholder-note {
  color: var(--text-dim); font-style: italic; font-size: 0.92rem;
  border: 1px dashed var(--border); border-radius: var(--radius);
  padding: 1.2rem 1.5rem;
}

/* --- Blog list --- */
.post-list { list-style: none; }
.post-list li { margin-bottom: 1rem; }
.post-list a {
  display: block; text-decoration: none;
  background: var(--card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 1.2rem 1.5rem;
  transition: transform 0.25s, border-color 0.25s;
}
.post-list a:hover { transform: translateY(-3px); border-color: rgba(56, 207, 224, 0.5); }
.post-date { color: var(--accent2); font-size: 0.82rem; }
.post-title { color: var(--text); font-weight: 600; margin-top: 0.15rem; }
.post-excerpt { color: var(--text-dim); font-size: 0.9rem; margin-top: 0.3rem; }

/* --- Contact --- */
.contact-box { text-align: center; padding: 2.4rem 1.5rem; }
.email-link {
  font-size: 1.1rem; font-weight: 600; text-decoration: none;
  background: var(--grad);
  -webkit-background-clip: text; background-clip: text; color: transparent;
}

/* --- Article --- */
.article { padding-top: 4rem; max-width: 720px; margin: 0 auto; }
.article h1 { font-size: 1.9rem; line-height: 1.4; margin: 0.4rem 0 1.6rem; }
.article p { margin-bottom: 1.2rem; color: var(--text); }
.back-link { color: var(--accent2); text-decoration: none; font-size: 0.9rem; }

/* --- Footer --- */
footer {
  margin-top: 5rem; padding: 2rem 1.5rem;
  border-top: 1px solid var(--border);
  text-align: center; color: var(--text-dim); font-size: 0.85rem;
}

/* --- Reveal animation --- */
.reveal { opacity: 0; transform: translateY(18px); transition: opacity 0.7s, transform 0.7s; }
.reveal.visible { opacity: 1; transform: none; }

/* --- Collapsible book groups (Textbooks tab) --- */
details.book-group {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--card);
  margin-bottom: 1rem;
}
details.book-group summary {
  cursor: pointer;
  padding: 1.2rem 1.6rem;
  font-weight: 600;
  font-size: 1.02rem;
  list-style: none;
  display: flex; justify-content: space-between; align-items: center;
  transition: color 0.2s;
}
details.book-group summary::-webkit-details-marker { display: none; }
details.book-group summary::after {
  content: "+";
  color: var(--accent2);
  font-size: 1.3rem; font-weight: 400;
  transition: transform 0.25s;
}
details.book-group[open] summary::after { transform: rotate(45deg); }
details.book-group summary:hover { color: var(--accent2); }
details.book-group .group-body { padding: 0.2rem 1.2rem 1.2rem; }
details.book-group .group-body .card { background: rgba(255,255,255,0.03); }

/* --- Book cards (cover image + text) --- */
.book-card { display: flex; gap: 1.5rem; align-items: flex-start; }
.book-cover {
  width: 110px; flex-shrink: 0; border-radius: 8px;
  border: 1px solid var(--border);
}
@media (max-width: 600px) { .book-card { flex-direction: column; } }

/* --- News list (Home) --- */
.news-list { list-style: none; margin-top: 1rem; }
.news-list li {
  display: flex; gap: 1.2rem; align-items: baseline;
  padding: 0.7rem 0.2rem; border-bottom: 1px solid var(--border);
  font-size: 0.93rem;
}
.news-list .news-date { color: var(--accent2); white-space: nowrap; font-size: 0.85rem; }
.news-list .news-body { color: var(--text-dim); }

/* --- Panel switching (tab-style sections) --- */
.panel { display: none; }
.panel.active { display: block; animation: fadeUp 0.45s ease both; }
@keyframes fadeUp {
  from { opacity: 0; transform: translateY(14px); }
  to { opacity: 1; transform: none; }
}
.nav-links a.current { color: var(--text); }
body.has-panels section.panel { padding-top: 3.5rem; min-height: 55vh; }

/* --- EN nav: keep labels on one line --- */
body.lang-en .nav-links a { white-space: nowrap; }
body.lang-en .nav-links { gap: 1.15rem; }

/* ---- mobile nav & type ---- */
@media (max-width: 640px) {
  .nav { padding: 0.7rem 0.8rem; gap: 0.55rem; }
  .nav-logo { font-size: 0.95rem; flex: 0 0 auto; }
  .nav-links {
    gap: 0.65rem; overflow-x: auto; -webkit-overflow-scrolling: touch;
    scrollbar-width: none; padding: 0; margin: 0; min-width: 0;
  }
  .nav-links::-webkit-scrollbar { display: none; }
  .nav-links a { font-size: 0.86rem; white-space: nowrap; }
  .nav-links li { white-space: nowrap; flex: 0 0 auto; }
  .lang-btn { padding: 0.32rem 0.65rem; font-size: 0.8rem; }
  .hero-sub { font-size: 0.98rem; }
  .hero-links { font-size: 0.98rem; }
  .hero-flex { flex-direction: column; align-items: flex-start; gap: 1.8rem; }
  .hero-photo { width: 170px; height: 258px; align-self: center; }
  .card { padding: 1.15rem 0.95rem; }
  .card img, .card canvas { max-width: 100%; height: auto; }
  .sim-canvas-box { max-width: 100%; }
}