/* ============================================================
   Hiroaki Tatsumi Research Website
   Design System
   ============================================================ */

/* ---------- Tokens ---------- */
:root {
  /* Light theme (default) */
  --bg: oklch(99% 0 0);
  --bg-elevated: oklch(96% 0 0);
  --bg-glass: oklch(100% 0 0 / 0.72);
  --surface: oklch(97% 0 0);
  --text: oklch(15% 0 0);
  --text-muted: oklch(40% 0 0);
  --text-subtle: oklch(55% 0 0);
  --border: oklch(90% 0 0);
  --border-strong: oklch(80% 0 0);
  --accent: oklch(48% 0.15 245);
  --accent-hover: oklch(55% 0.17 245);
  --accent-soft: oklch(94% 0.04 245);
  --accent-text: oklch(98% 0 0);
  --gold: oklch(70% 0.13 75);

  /* Layout */
  --max-w: 1240px;
  --max-w-text: 720px;
  --pad-x: clamp(20px, 5vw, 60px);
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 22px;
  --radius-xl: 32px;

  /* Type scale (modular) */
  --fs-xs: 0.78rem;
  --fs-sm: 0.9rem;
  --fs-base: 1rem;
  --fs-md: 1.13rem;
  --fs-lg: 1.4rem;
  --fs-xl: 1.85rem;
  --fs-2xl: 2.6rem;
  --fs-3xl: clamp(2.8rem, 6vw, 4.5rem);
  --fs-4xl: clamp(3.5rem, 9vw, 7rem);

  /* Easing */
  --ease-out: cubic-bezier(0.22, 1, 0.36, 1);
  --ease-in-out: cubic-bezier(0.65, 0, 0.35, 1);

  /* Shadow */
  --shadow-sm: 0 1px 2px oklch(0% 0 0 / 0.04), 0 1px 4px oklch(0% 0 0 / 0.04);
  --shadow-md: 0 4px 12px oklch(0% 0 0 / 0.06), 0 2px 6px oklch(0% 0 0 / 0.04);
  --shadow-lg: 0 24px 48px oklch(0% 0 0 / 0.10), 0 8px 16px oklch(0% 0 0 / 0.06);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: oklch(11% 0.005 250);
    --bg-elevated: oklch(16% 0.005 250);
    --bg-glass: oklch(11% 0.005 250 / 0.72);
    --surface: oklch(18% 0.005 250);
    --text: oklch(96% 0 0);
    --text-muted: oklch(70% 0 0);
    --text-subtle: oklch(55% 0 0);
    --border: oklch(24% 0.005 250);
    --border-strong: oklch(35% 0.005 250);
    --accent: oklch(72% 0.16 245);
    --accent-hover: oklch(80% 0.18 245);
    --accent-soft: oklch(25% 0.06 245);
    --accent-text: oklch(10% 0 0);
    --gold: oklch(80% 0.14 75);

    --shadow-sm: 0 1px 2px oklch(0% 0 0 / 0.4), 0 1px 4px oklch(0% 0 0 / 0.3);
    --shadow-md: 0 4px 12px oklch(0% 0 0 / 0.45), 0 2px 6px oklch(0% 0 0 / 0.3);
    --shadow-lg: 0 24px 48px oklch(0% 0 0 / 0.5), 0 8px 16px oklch(0% 0 0 / 0.35);
  }
}

/* Manual theme override */
:root[data-theme="light"] {
  color-scheme: light;
  --bg: oklch(99% 0 0);
  --bg-elevated: oklch(96% 0 0);
  --bg-glass: oklch(100% 0 0 / 0.72);
  --surface: oklch(97% 0 0);
  --text: oklch(15% 0 0);
  --text-muted: oklch(40% 0 0);
  --text-subtle: oklch(55% 0 0);
  --border: oklch(90% 0 0);
  --border-strong: oklch(80% 0 0);
  --accent: oklch(48% 0.15 245);
  --accent-hover: oklch(55% 0.17 245);
  --accent-soft: oklch(94% 0.04 245);
  --accent-text: oklch(98% 0 0);
  --gold: oklch(70% 0.13 75);
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --bg: oklch(11% 0.005 250);
  --bg-elevated: oklch(16% 0.005 250);
  --bg-glass: oklch(11% 0.005 250 / 0.72);
  --surface: oklch(18% 0.005 250);
  --text: oklch(96% 0 0);
  --text-muted: oklch(70% 0 0);
  --text-subtle: oklch(55% 0 0);
  --border: oklch(24% 0.005 250);
  --border-strong: oklch(35% 0.005 250);
  --accent: oklch(72% 0.16 245);
  --accent-hover: oklch(80% 0.18 245);
  --accent-soft: oklch(25% 0.06 245);
  --accent-text: oklch(10% 0 0);
  --gold: oklch(80% 0.14 75);
}

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

* {
  margin: 0;
  padding: 0;
}

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

body {
  font-family:
    "Inter", "Noto Sans JP", -apple-system, BlinkMacSystemFont, "Segoe UI",
    "Hiragino Sans", "Hiragino Kaku Gothic ProN", "Yu Gothic UI", Meiryo, sans-serif;
  font-feature-settings: "kern", "liga", "calt", "ss01", "cv11";
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  font-size: var(--fs-base);
  line-height: 1.6;
  color: var(--text);
  background: var(--bg);
  min-height: 100dvh;
  overflow-x: hidden;
  transition: background 0.3s var(--ease-out), color 0.3s var(--ease-out);
}

img,
picture,
svg,
video {
  max-width: 100%;
  display: block;
  height: auto;
}

a {
  color: var(--accent);
  text-decoration: none;
  transition: color 0.2s var(--ease-out);
}

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

button {
  font: inherit;
  color: inherit;
  background: transparent;
  border: 0;
  cursor: pointer;
}

ul,
ol {
  list-style: none;
}

h1,
h2,
h3,
h4 {
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1.15;
  color: var(--text);
}

p {
  text-wrap: pretty;
}

::selection {
  background: var(--accent);
  color: var(--accent-text);
}

/* ---------- i18n ---------- */
:root[data-lang="ja"] [lang="en"] {
  display: none;
}
:root[data-lang="en"] [lang="ja"] {
  display: none;
}

/* ---------- Layout ---------- */
.container {
  max-width: var(--max-w);
  margin-inline: auto;
  padding-inline: var(--pad-x);
}

.container-narrow {
  max-width: var(--max-w-text);
  margin-inline: auto;
  padding-inline: var(--pad-x);
}

main {
  padding-top: 72px;
}

section {
  padding-block: clamp(64px, 9vw, 120px);
}

/* ---------- Site Nav ---------- */
.site-nav {
  position: fixed;
  top: 0;
  inset-inline: 0;
  z-index: 100;
  background: var(--bg-glass);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 1px solid var(--border);
  transition: border-color 0.3s var(--ease-out), background 0.3s var(--ease-out);
}

.site-nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
  max-width: var(--max-w);
  margin-inline: auto;
  padding-inline: var(--pad-x);
}

.site-nav__brand {
  font-weight: 700;
  letter-spacing: -0.01em;
  font-size: var(--fs-md);
  color: var(--text);
  display: inline-flex;
  align-items: center;
  gap: 10px;
}

.site-nav__brand:hover {
  color: var(--text);
}

.site-nav__brand-mark {
  width: 28px;
  height: 28px;
  border-radius: 8px;
  background: linear-gradient(135deg, var(--accent), oklch(60% 0.18 280));
  display: inline-grid;
  place-items: center;
  color: white;
  font-size: 13px;
  font-weight: 800;
  letter-spacing: 0;
}

.site-nav__menu {
  display: flex;
  align-items: center;
  gap: 6px;
}

.site-nav__menu a {
  position: relative;
  display: inline-flex;
  align-items: center;
  height: 36px;
  padding: 0 14px;
  border-radius: 10px;
  color: var(--text-muted);
  font-size: var(--fs-sm);
  font-weight: 500;
  transition: background 0.2s var(--ease-out), color 0.2s var(--ease-out);
}

.site-nav__menu a:hover,
.site-nav__menu a[aria-current="page"] {
  color: var(--text);
  background: var(--bg-elevated);
}

.site-nav__sub {
  position: relative;
}

.site-nav__sub-trigger {
  display: inline-flex;
  align-items: center;
  height: 36px;
  padding: 0 14px;
  border-radius: 10px;
  color: var(--text-muted);
  font-size: var(--fs-sm);
  font-weight: 500;
  transition: background 0.2s var(--ease-out), color 0.2s var(--ease-out);
}

.site-nav__sub-trigger::after {
  content: "";
  display: inline-block;
  width: 8px;
  height: 8px;
  margin-left: 6px;
  border-right: 1.5px solid currentColor;
  border-bottom: 1.5px solid currentColor;
  transform: rotate(45deg) translate(-2px, -2px);
}

.site-nav__sub-menu {
  position: absolute;
  top: calc(100% + 8px);
  left: 50%;
  transform: translateX(-50%) translateY(-4px);
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
  padding: 6px;
  min-width: 220px;
  opacity: 0;
  pointer-events: none;
  transition:
    opacity 0.2s var(--ease-out) 0.15s,
    transform 0.2s var(--ease-out) 0.15s;
}

/* Invisible "bridge" that fills the gap between the trigger and the menu
   so the cursor doesn't lose :hover when moving from one to the other. */
.site-nav__sub-menu::before {
  content: "";
  position: absolute;
  top: -12px;
  left: -16px;
  right: -16px;
  height: 14px;
}

.site-nav__sub:hover .site-nav__sub-menu,
.site-nav__sub:focus-within .site-nav__sub-menu {
  opacity: 1;
  pointer-events: auto;
  transform: translateX(-50%) translateY(0);
  transition-delay: 0s;
}

.site-nav__sub:hover .site-nav__sub-trigger,
.site-nav__sub:focus-within .site-nav__sub-trigger {
  color: var(--text);
  background: var(--bg-elevated);
}

.site-nav__sub-menu a {
  display: block;
  padding: 8px 12px;
  border-radius: 8px;
  color: var(--text-muted);
  font-size: var(--fs-sm);
  white-space: nowrap;
}

.site-nav__sub-menu a:hover {
  background: var(--bg-elevated);
  color: var(--text);
}

.site-nav__controls {
  display: flex;
  align-items: center;
  gap: 6px;
}

.site-nav__icon-btn {
  width: 36px;
  height: 36px;
  display: grid;
  place-items: center;
  border-radius: 10px;
  color: var(--text-muted);
  transition: background 0.2s var(--ease-out), color 0.2s var(--ease-out);
}

.site-nav__icon-btn:hover {
  background: var(--bg-elevated);
  color: var(--text);
}

.site-nav__lang {
  height: 36px;
  padding: 0 12px;
  border-radius: 10px;
  font-size: var(--fs-xs);
  font-weight: 600;
  letter-spacing: 0.06em;
  color: var(--text-muted);
  transition: background 0.2s var(--ease-out), color 0.2s var(--ease-out);
  display: inline-flex;
  align-items: center;
  gap: 4px;
}

.site-nav__lang:hover {
  background: var(--bg-elevated);
  color: var(--text);
}

.site-nav__lang-active {
  color: var(--text);
}

.site-nav__lang-divider {
  color: var(--border-strong);
}

.site-nav__burger {
  display: none;
}

@media (max-width: 920px) {
  .site-nav__menu {
    position: fixed;
    inset: 64px 0 0 0;
    flex-direction: column;
    align-items: stretch;
    background: var(--bg);
    padding: 24px var(--pad-x);
    gap: 4px;
    transform: translateY(-110%);
    transition: transform 0.3s var(--ease-out);
    overflow-y: auto;
    height: calc(100dvh - 64px);
    border-top: 1px solid var(--border);
  }

  .site-nav[data-open="true"] .site-nav__menu {
    transform: translateY(0);
  }

  .site-nav__menu a,
  .site-nav__sub-trigger {
    height: 48px;
    font-size: var(--fs-md);
  }

  .site-nav__sub-menu {
    position: static;
    transform: none;
    opacity: 1;
    pointer-events: auto;
    background: transparent;
    border: 0;
    box-shadow: none;
    padding: 0 0 0 16px;
    min-width: 0;
  }

  .site-nav__sub-trigger::after {
    display: none;
  }

  .site-nav__burger {
    display: grid;
    place-items: center;
    width: 36px;
    height: 36px;
    border-radius: 10px;
    color: var(--text);
    transition: background 0.2s var(--ease-out);
  }

  .site-nav__burger:hover {
    background: var(--bg-elevated);
  }
}

/* ---------- Hero (top page) ---------- */
.hero {
  position: relative;
  min-height: calc(100dvh - 72px);
  display: grid;
  align-items: center;
  padding-block: clamp(60px, 10vw, 120px);
  overflow: hidden;
  isolation: isolate;
}

.hero__layout {
  display: grid;
  grid-template-columns: minmax(0, 1.05fr) minmax(0, 1fr);
  gap: clamp(32px, 5vw, 80px);
  align-items: center;
}

@media (max-width: 980px) {
  .hero__layout {
    grid-template-columns: 1fr;
  }
}

.hero__visual {
  position: relative;
  aspect-ratio: 4 / 5;
  max-width: 540px;
  margin-inline: auto;
  width: 100%;
  border-radius: var(--radius-xl);
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  overflow: hidden;
  isolation: isolate;
  box-shadow: var(--shadow-lg);
}

@media (max-width: 980px) {
  .hero__visual {
    aspect-ratio: 16 / 11;
    max-width: 720px;
  }
}

.hero__visual img {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 8s var(--ease-out);
}

.hero__visual:hover img {
  transform: scale(1.04);
}

.hero__visual::after {
  content: "";
  position: absolute;
  inset: 0;
  background:
    linear-gradient(180deg, transparent 50%, oklch(0% 0 0 / 0.5) 100%),
    linear-gradient(120deg, oklch(from var(--accent) l c h / 0.12) 0%, transparent 60%);
  pointer-events: none;
  z-index: 1;
}

.hero__visual-label {
  position: absolute;
  bottom: 22px;
  left: 24px;
  right: 24px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-family: "Inter", monospace;
  font-size: var(--fs-xs);
  font-weight: 600;
  letter-spacing: 0.06em;
  color: oklch(98% 0 0);
  z-index: 2;
  text-shadow: 0 1px 6px oklch(0% 0 0 / 0.4);
}

.hero__visual-label::before {
  content: "";
  display: inline-block;
  width: 6px;
  height: 6px;
  border-radius: 999px;
  background: oklch(80% 0.2 150);
  margin-right: 8px;
  box-shadow: 0 0 0 4px oklch(80% 0.2 150 / 0.2);
  animation: pulse-dot 2s ease-in-out infinite;
}

@keyframes pulse-dot {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.55; }
}

.hero__visual-label-right {
  font-variant-numeric: tabular-nums;
  letter-spacing: 0;
}

.hero__grid-bg {
  position: absolute;
  inset: 0;
  z-index: -1;
  background:
    radial-gradient(ellipse 80% 60% at 50% 0%, var(--accent-soft), transparent 70%),
    radial-gradient(ellipse 60% 40% at 90% 100%, oklch(from var(--gold) l c h / 0.15), transparent 70%);
  opacity: 0.9;
}

.hero__grid-bg::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(var(--border) 1px, transparent 1px),
    linear-gradient(90deg, var(--border) 1px, transparent 1px);
  background-size: 80px 80px;
  mask-image: radial-gradient(ellipse 70% 60% at 50% 50%, black, transparent 80%);
  -webkit-mask-image: radial-gradient(ellipse 70% 60% at 50% 50%, black, transparent 80%);
  opacity: 0.4;
}

.hero__eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 14px;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: var(--fs-xs);
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.hero__eyebrow::before {
  content: "";
  width: 6px;
  height: 6px;
  border-radius: 999px;
  background: var(--accent);
}

.hero__title {
  font-size: var(--fs-4xl);
  font-weight: 800;
  letter-spacing: -0.035em;
  line-height: 0.98;
  margin-top: 28px;
  background: linear-gradient(180deg, var(--text) 50%, oklch(from var(--text) l c h / 0.65));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.hero__title-rotator {
  display: inline-block;
  /* opacity / transform / blur transitions live here; no bg-clip:text on
     this element to avoid Safari mis-rendering the clipped gradient
     during fades. */
  will-change: opacity, transform, filter;
}
.hero__title-rotator__inner {
  display: inline-block;
  background: linear-gradient(120deg, var(--accent), oklch(60% 0.18 280));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  -webkit-text-fill-color: transparent;
}

.hero__subtitle {
  margin-top: 28px;
  max-width: 640px;
  font-size: var(--fs-md);
  color: var(--text-muted);
  line-height: 1.65;
}

.hero__meta {
  margin-top: 32px;
  display: flex;
  flex-wrap: wrap;
  gap: 8px 16px;
  font-size: var(--fs-sm);
  color: var(--text-muted);
}

.hero__meta a {
  color: var(--text-muted);
  text-decoration: underline;
  text-decoration-color: var(--border-strong);
  text-underline-offset: 4px;
}

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

.hero__cta {
  margin-top: 44px;
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  height: 48px;
  padding: 0 22px;
  border-radius: 999px;
  font-size: var(--fs-sm);
  font-weight: 600;
  letter-spacing: 0;
  transition:
    transform 0.2s var(--ease-out),
    background 0.2s var(--ease-out),
    color 0.2s var(--ease-out),
    border-color 0.2s var(--ease-out),
    box-shadow 0.2s var(--ease-out);
}

.btn-primary {
  background: var(--text);
  color: var(--bg);
}

.btn-primary:hover {
  background: var(--accent);
  color: var(--accent-text);
  transform: translateY(-1px);
}

.btn-secondary {
  background: transparent;
  color: var(--text);
  border: 1px solid var(--border-strong);
}

.btn-secondary:hover {
  background: var(--bg-elevated);
  color: var(--text);
  transform: translateY(-1px);
}

.btn .arrow {
  transition: transform 0.2s var(--ease-out);
}

.btn:hover .arrow {
  transform: translateX(3px);
}

/* ---------- Section Headings ---------- */
.section-head {
  margin-bottom: clamp(40px, 6vw, 72px);
  max-width: var(--max-w-text);
}

.section-head__eyebrow {
  font-size: var(--fs-xs);
  font-weight: 600;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 16px;
}

.section-head__title {
  font-size: var(--fs-3xl);
  letter-spacing: -0.03em;
  font-weight: 800;
  line-height: 1.05;
}

.section-head__lede {
  margin-top: 20px;
  font-size: var(--fs-md);
  color: var(--text-muted);
  line-height: 1.7;
}

/* ---------- News (top page) ---------- */
.news-list {
  display: grid;
  gap: 0;
  border-top: 1px solid var(--border);
}

.news-item {
  display: grid;
  grid-template-columns: 140px 1fr;
  gap: 24px;
  padding-block: 22px;
  border-bottom: 1px solid var(--border);
  align-items: start;
}

@media (max-width: 720px) {
  .news-item {
    grid-template-columns: 1fr;
    gap: 8px;
  }
}

.news-item__date {
  font-variant-numeric: tabular-nums;
  font-size: var(--fs-sm);
  color: var(--text-subtle);
  font-weight: 600;
  letter-spacing: 0.02em;
  padding-top: 4px;
}

.news-item__body {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.news-item__tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.tag {
  display: inline-flex;
  align-items: center;
  height: 22px;
  padding: 0 10px;
  border-radius: 999px;
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.tag-new {
  background: var(--accent-soft);
  color: var(--accent);
}

.tag-published {
  background: oklch(95% 0.05 160);
  color: oklch(38% 0.13 160);
}

.tag-award {
  background: oklch(95% 0.06 75);
  color: oklch(40% 0.14 75);
}

.tag-talk {
  background: oklch(95% 0.05 290);
  color: oklch(40% 0.14 290);
}

@media (prefers-color-scheme: dark) {
  .tag-published {
    background: oklch(28% 0.08 160);
    color: oklch(85% 0.13 160);
  }
  .tag-award {
    background: oklch(28% 0.08 75);
    color: oklch(85% 0.13 75);
  }
  .tag-talk {
    background: oklch(28% 0.08 290);
    color: oklch(85% 0.13 290);
  }
}

:root[data-theme="dark"] .tag-published {
  background: oklch(28% 0.08 160);
  color: oklch(85% 0.13 160);
}
:root[data-theme="dark"] .tag-award {
  background: oklch(28% 0.08 75);
  color: oklch(85% 0.13 75);
}
:root[data-theme="dark"] .tag-talk {
  background: oklch(28% 0.08 290);
  color: oklch(85% 0.13 290);
}

.news-item__text {
  font-size: var(--fs-base);
  line-height: 1.65;
  color: var(--text);
}

.news-item__text a {
  text-decoration: underline;
  text-underline-offset: 3px;
  text-decoration-color: var(--border-strong);
}

.news-item__text a:hover {
  text-decoration-color: var(--accent);
}

.news-more {
  margin-top: 36px;
  text-align: center;
}

.news-year {
  margin-bottom: clamp(40px, 6vw, 64px);
}

.news-year__label {
  font-family: "Inter", sans-serif;
  font-variant-numeric: tabular-nums;
  font-size: var(--fs-2xl);
  font-weight: 800;
  letter-spacing: -0.025em;
  color: var(--text);
  margin-bottom: 16px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--border-strong);
}

/* ---------- Featured Papers (top page) ---------- */
.featured-papers {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 18px;
}

.paper-card {
  display: flex;
  flex-direction: column;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  text-decoration: none;
  color: var(--text);
  transition: transform 0.3s var(--ease-out), border-color 0.3s var(--ease-out), box-shadow 0.3s var(--ease-out);
}

.paper-card:hover {
  transform: translateY(-4px);
  border-color: var(--border-strong);
  box-shadow: var(--shadow-lg);
  color: var(--text);
}

.paper-card__thumb {
  aspect-ratio: 4 / 3;
  background: linear-gradient(135deg, var(--accent-soft), oklch(from var(--gold) l c h / 0.08)) var(--bg);
  background-size: cover;
  background-position: center;
  position: relative;
  overflow: hidden;
}

.paper-card__thumb img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.5s var(--ease-out);
}

.paper-card:hover .paper-card__thumb img {
  transform: scale(1.04);
}

.paper-card__body {
  padding: 18px 20px 20px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  flex: 1;
}

.paper-card__journal {
  font-size: var(--fs-xs);
  font-weight: 600;
  color: var(--accent);
  letter-spacing: 0.04em;
  text-transform: uppercase;
  font-style: normal;
}

.paper-card__title {
  font-size: var(--fs-sm);
  font-weight: 600;
  line-height: 1.4;
  letter-spacing: -0.005em;
  color: var(--text);
  flex: 1;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  line-clamp: 3;
  overflow: hidden;
}

.paper-card__meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: var(--fs-xs);
  color: var(--text-muted);
  margin-top: 4px;
}

.paper-card__year {
  font-variant-numeric: tabular-nums;
  font-weight: 600;
}

.paper-card__role {
  display: inline-flex;
  align-items: center;
  height: 20px;
  padding: 0 9px;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

/* ---------- Stats strip ---------- */
.stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 4px;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  padding: 4px;
}

.stat {
  padding: 28px 24px;
  border-radius: calc(var(--radius-xl) - 4px);
  background: var(--bg);
  text-align: left;
}

.stat__number {
  font-family: "Inter", sans-serif;
  font-size: var(--fs-2xl);
  font-weight: 800;
  letter-spacing: -0.04em;
  line-height: 1;
  background: linear-gradient(120deg, var(--text), var(--accent));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  font-variant-numeric: tabular-nums;
}

.stat__label {
  margin-top: 8px;
  font-size: var(--fs-xs);
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--text-muted);
}

/* ---------- Pickup grid ---------- */
.pickup-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 20px;
}

.pickup-card {
  position: relative;
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  min-height: 280px;
  padding: 28px;
  border-radius: var(--radius-lg);
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  overflow: hidden;
  isolation: isolate;
  transition: transform 0.3s var(--ease-out), border-color 0.3s var(--ease-out), box-shadow 0.3s var(--ease-out);
}

.pickup-card::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  background: var(--bg-image, linear-gradient(135deg, var(--accent-soft), transparent));
  background-size: cover;
  background-position: center;
  opacity: 0.5;
  transition: opacity 0.3s var(--ease-out), transform 0.6s var(--ease-out);
}

.pickup-card:hover {
  transform: translateY(-3px);
  border-color: var(--border-strong);
  box-shadow: var(--shadow-lg);
}

.pickup-card:hover::before {
  opacity: 0.7;
  transform: scale(1.04);
}

.pickup-card__label {
  font-size: var(--fs-xs);
  font-weight: 600;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--accent);
}

.pickup-card__title {
  margin-top: 8px;
  font-size: var(--fs-xl);
  font-weight: 700;
  letter-spacing: -0.02em;
}

.pickup-card__desc {
  margin-top: 8px;
  font-size: var(--fs-sm);
  color: var(--text-muted);
}

/* ---------- About page ---------- */
.profile {
  display: grid;
  grid-template-columns: 320px 1fr;
  gap: clamp(28px, 5vw, 60px);
  align-items: start;
}

@media (max-width: 820px) {
  .profile {
    grid-template-columns: 1fr;
  }
}

.profile__photo {
  border-radius: var(--radius-lg);
  overflow: hidden;
  aspect-ratio: 1 / 1.15;
  background: var(--bg-elevated);
}

.profile__photo img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  filter: grayscale(0.04) contrast(1.02);
}

.profile__name {
  font-size: var(--fs-2xl);
  letter-spacing: -0.025em;
}

.profile__role {
  margin-top: 12px;
  font-size: var(--fs-md);
  color: var(--text-muted);
  line-height: 1.65;
}

.profile__links {
  margin-top: 22px;
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.profile__links a {
  display: inline-flex;
  align-items: center;
  height: 32px;
  padding: 0 14px;
  border-radius: 999px;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  font-size: var(--fs-xs);
  font-weight: 600;
  color: var(--text-muted);
  letter-spacing: 0.02em;
  transition: background 0.2s var(--ease-out), color 0.2s var(--ease-out), border-color 0.2s var(--ease-out);
}

.profile__links a:hover {
  background: var(--surface);
  color: var(--text);
  border-color: var(--border-strong);
}

.profile__expertise {
  margin-top: 28px;
  display: grid;
  gap: 12px;
}

.profile__expertise li {
  display: flex;
  gap: 10px;
  font-size: var(--fs-sm);
  color: var(--text);
  line-height: 1.6;
}

.profile__expertise li::before {
  content: "";
  flex-shrink: 0;
  width: 6px;
  height: 6px;
  border-radius: 999px;
  background: var(--accent);
  margin-top: 9px;
}

.bio {
  margin-top: clamp(48px, 7vw, 80px);
  max-width: var(--max-w-text);
}

.bio h3 {
  font-size: var(--fs-lg);
  margin-bottom: 12px;
  letter-spacing: -0.02em;
}

.bio p {
  font-size: var(--fs-base);
  color: var(--text);
  line-height: 1.8;
}

.bio p + p {
  margin-top: 1em;
}

/* Timeline */
.timeline {
  margin-top: 24px;
  position: relative;
  padding-left: 28px;
}

.timeline::before {
  content: "";
  position: absolute;
  left: 7px;
  top: 8px;
  bottom: 8px;
  width: 2px;
  background: var(--border);
  border-radius: 2px;
}

.timeline__item {
  position: relative;
  padding-bottom: 28px;
}

.timeline__item:last-child {
  padding-bottom: 0;
}

.timeline__item::before {
  content: "";
  position: absolute;
  left: -28px;
  top: 8px;
  width: 16px;
  height: 16px;
  border-radius: 999px;
  background: var(--bg);
  border: 2px solid var(--accent);
}

.timeline__year {
  font-variant-numeric: tabular-nums;
  font-size: var(--fs-sm);
  color: var(--accent);
  font-weight: 700;
  letter-spacing: 0.02em;
}

.timeline__role {
  margin-top: 4px;
  font-size: var(--fs-base);
  font-weight: 600;
  color: var(--text);
}

.timeline__org {
  margin-top: 2px;
  font-size: var(--fs-sm);
  color: var(--text-muted);
  line-height: 1.5;
}

/* Awards list */
.awards {
  margin-top: 24px;
  display: grid;
  gap: 16px;
}

.award {
  display: grid;
  grid-template-columns: 64px 1fr;
  gap: 18px;
  padding: 18px 0;
  border-top: 1px solid var(--border);
}

.award:last-child {
  border-bottom: 1px solid var(--border);
}

.award__year {
  font-variant-numeric: tabular-nums;
  font-size: var(--fs-md);
  color: var(--gold);
  font-weight: 700;
  letter-spacing: 0;
}

.award__body {
  font-size: var(--fs-sm);
  color: var(--text);
  line-height: 1.65;
}

.award__title {
  font-weight: 600;
  color: var(--text);
}

.award__sub {
  color: var(--text-muted);
  font-style: italic;
  margin-top: 2px;
}

/* ---------- Research page ---------- */
.research-intro {
  display: grid;
  gap: 28px;
  max-width: 880px;
}

.research-intro__tagline {
  font-size: clamp(2.1rem, 4.6vw, 3.6rem);
  font-weight: 800;
  letter-spacing: -0.035em;
  line-height: 1.08;
  color: var(--text);
}

.research-intro__tagline .line-1,
.research-intro__tagline .line-2 {
  display: block;
}

.research-intro__tagline .line-2 {
  background: linear-gradient(120deg, var(--accent), oklch(60% 0.18 280));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.research-intro__lede {
  font-size: var(--fs-lg);
  line-height: 1.55;
  letter-spacing: -0.01em;
  color: var(--text-muted);
  max-width: var(--max-w-text);
}

.research-intro__lede strong {
  color: var(--text);
  font-weight: 600;
}

.theme-list {
  display: grid;
  gap: clamp(36px, 5vw, 64px);
  margin-top: clamp(60px, 8vw, 100px);
}

.theme {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: clamp(24px, 4vw, 56px);
  align-items: center;
  padding: clamp(28px, 4vw, 48px);
  border-radius: var(--radius-xl);
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  position: relative;
  overflow: hidden;
  isolation: isolate;
}

.theme::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  background: radial-gradient(ellipse 60% 80% at var(--gx, 100%) var(--gy, 0%), var(--accent-soft), transparent 70%);
  opacity: 0.6;
  pointer-events: none;
}

@media (max-width: 880px) {
  .theme {
    grid-template-columns: 1fr;
  }
}

.theme:nth-child(even) {
  --gx: 0%;
}

.theme:nth-child(even) .theme__visual {
  order: 2;
}

@media (max-width: 880px) {
  .theme:nth-child(even) .theme__visual {
    order: 0;
  }
}

.theme__num {
  font-size: var(--fs-xs);
  font-weight: 600;
  letter-spacing: 0.18em;
  color: var(--accent);
}

.theme__title {
  margin-top: 12px;
  font-size: var(--fs-xl);
  letter-spacing: -0.025em;
  line-height: 1.15;
}

.theme__desc {
  margin-top: 18px;
  font-size: var(--fs-base);
  color: var(--text-muted);
  line-height: 1.75;
}

.theme__keywords {
  margin-top: 22px;
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.theme__keywords span {
  display: inline-flex;
  align-items: center;
  height: 26px;
  padding: 0 12px;
  border-radius: 999px;
  background: var(--bg);
  border: 1px solid var(--border);
  font-size: var(--fs-xs);
  font-weight: 500;
  color: var(--text-muted);
}

.theme__papers {
  margin-top: 28px;
  display: grid;
  gap: 8px;
}

.theme__papers-label {
  font-size: var(--fs-xs);
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-subtle);
  margin-bottom: 4px;
}

.theme__paper {
  display: block;
  padding: 14px 16px;
  border-radius: var(--radius-md);
  background: var(--bg);
  border: 1px solid var(--border);
  color: var(--text);
  transition: border-color 0.2s var(--ease-out), background 0.2s var(--ease-out), transform 0.2s var(--ease-out);
}

.theme__paper:hover {
  border-color: var(--accent);
  background: var(--bg);
  color: var(--text);
  transform: translateX(2px);
}

.theme__paper-title {
  font-size: var(--fs-sm);
  font-weight: 600;
  line-height: 1.4;
  letter-spacing: -0.005em;
}

.theme__paper-meta {
  margin-top: 6px;
  font-size: var(--fs-xs);
  color: var(--text-muted);
  display: flex;
  flex-wrap: wrap;
  gap: 6px 10px;
  align-items: center;
}

.theme__paper-journal {
  font-style: italic;
}

.theme__paper-year {
  font-variant-numeric: tabular-nums;
}

.theme__paper-tag {
  display: inline-flex;
  align-items: center;
  height: 18px;
  padding: 0 8px;
  border-radius: 999px;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.06em;
  background: var(--accent-soft);
  color: var(--accent);
}

.theme__visual {
  position: relative;
  aspect-ratio: 4 / 3;
  border-radius: var(--radius-lg);
  background: var(--bg);
  overflow: hidden;
  isolation: isolate;
  box-shadow: var(--shadow-md);
}

.theme__visual img {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.8s var(--ease-out);
}

.theme:hover .theme__visual img {
  transform: scale(1.03);
}

.theme__visual::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(180deg, transparent 60%, oklch(0% 0 0 / 0.18) 100%);
  pointer-events: none;
}

.theme__visual-tag {
  position: absolute;
  top: 14px;
  left: 14px;
  z-index: 2;
  display: inline-flex;
  align-items: center;
  height: 26px;
  padding: 0 12px;
  border-radius: 999px;
  background: oklch(100% 0 0 / 0.92);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  font-size: var(--fs-xs);
  font-weight: 600;
  letter-spacing: 0.05em;
  color: oklch(15% 0 0);
}

/* ---------- Page header ---------- */
.page-header {
  padding-top: clamp(60px, 9vw, 110px);
  padding-bottom: clamp(40px, 6vw, 70px);
  border-bottom: 1px solid var(--border);
  background: var(--bg);
  position: relative;
  isolation: isolate;
  overflow: hidden;
}

.page-header::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: -1;
  background: radial-gradient(ellipse 50% 80% at 100% 0%, var(--accent-soft), transparent 60%);
  opacity: 0.7;
}

.page-header__crumbs {
  font-size: var(--fs-xs);
  font-weight: 500;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-subtle);
  margin-bottom: 16px;
}

.page-header__crumbs a {
  color: var(--text-muted);
}

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

.page-header__title {
  font-size: var(--fs-3xl);
  letter-spacing: -0.03em;
  font-weight: 800;
}

.page-header__lede {
  margin-top: 18px;
  max-width: var(--max-w-text);
  font-size: var(--fs-md);
  color: var(--text-muted);
  line-height: 1.65;
}

/* ---------- Achievement list pages (publications/conferences/patents/projects) ---------- */
.achievements {
  display: grid;
  gap: clamp(40px, 6vw, 72px);
}

.ach-section__head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
  padding-bottom: 16px;
  margin-bottom: 24px;
  border-bottom: 1px solid var(--border-strong);
  flex-wrap: wrap;
}

.ach-section__title {
  font-size: var(--fs-xl);
  letter-spacing: -0.02em;
  font-weight: 700;
}

.ach-section__count {
  font-size: var(--fs-sm);
  color: var(--text-subtle);
  font-variant-numeric: tabular-nums;
  font-weight: 500;
  letter-spacing: 0.04em;
}

.ach-year {
  display: grid;
  grid-template-columns: 80px 1fr;
  gap: 24px;
  padding-block: 28px 8px;
  border-top: 1px solid var(--border);
  align-items: start;
}

.ach-year:first-of-type {
  border-top: 0;
  padding-top: 0;
}

@media (max-width: 720px) {
  .ach-year {
    grid-template-columns: 1fr;
    gap: 8px;
  }
}

.ach-year__label {
  position: sticky;
  top: 80px;
  font-family: "Inter", sans-serif;
  font-variant-numeric: tabular-nums;
  font-size: var(--fs-xl);
  font-weight: 800;
  letter-spacing: -0.02em;
  color: var(--text);
}

.ach-year__items {
  display: grid;
  gap: 22px;
}

.ach-item {
  display: grid;
  gap: 8px;
}

.ach-item__title {
  font-size: var(--fs-base);
  font-weight: 600;
  letter-spacing: -0.005em;
  line-height: 1.4;
  color: var(--text);
}

.ach-item__authors {
  font-size: var(--fs-sm);
  color: var(--text-muted);
  line-height: 1.6;
}

.ach-item__authors u {
  text-decoration: none;
  font-weight: 700;
  color: var(--text);
}

.ach-item__meta {
  display: flex;
  flex-wrap: wrap;
  gap: 6px 12px;
  align-items: center;
  font-size: var(--fs-xs);
  color: var(--text-muted);
  margin-top: 2px;
}

.ach-item__meta i {
  font-style: italic;
}

.ach-item__role {
  display: inline-flex;
  align-items: center;
  height: 20px;
  padding: 0 9px;
  border-radius: 999px;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  /* Default = First — solid blue */
  background: oklch(50% 0.15 245);
  color: oklch(98% 0 0);
}

/* Corresponding (not first) — solid purple */
.ach-item__role--corresp {
  background: oklch(50% 0.18 290);
}

/* First & corresp. — gradient blend (most prominent) */
.ach-item__role--lead {
  background: linear-gradient(135deg, oklch(50% 0.15 245), oklch(50% 0.18 290));
  box-shadow: 0 1px 4px oklch(50% 0.15 245 / 0.35);
}

.ach-item__tag {
  display: inline-flex;
  align-items: center;
  height: 20px;
  padding: 0 9px;
  border-radius: 999px;
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.ach-item__tag--invited {
  background: oklch(95% 0.06 75);
  color: oklch(40% 0.14 75);
}
.ach-item__tag--intl {
  background: oklch(95% 0.05 290);
  color: oklch(40% 0.14 290);
}
.ach-item__tag--pi {
  background: var(--accent-soft);
  color: var(--accent);
}
.ach-item__tag--co {
  background: var(--bg-elevated);
  color: var(--text-muted);
  border: 1px solid var(--border);
}

@media (prefers-color-scheme: dark) {
  .ach-item__tag--invited {
    background: oklch(28% 0.08 75);
    color: oklch(85% 0.13 75);
  }
  .ach-item__tag--intl {
    background: oklch(28% 0.08 290);
    color: oklch(85% 0.13 290);
  }
}
:root[data-theme="dark"] .ach-item__tag--invited {
  background: oklch(28% 0.08 75);
  color: oklch(85% 0.13 75);
}
:root[data-theme="dark"] .ach-item__tag--intl {
  background: oklch(28% 0.08 290);
  color: oklch(85% 0.13 290);
}

.ach-item__doi {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-size: var(--fs-xs);
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: border-color 0.2s var(--ease-out);
}

.ach-item__doi:hover {
  border-color: var(--accent);
}

.ach-item__thumb {
  margin-top: 8px;
  width: 100%;
  max-width: 280px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border);
  overflow: hidden;
}

.ach-item__thumb img {
  width: 100%;
  height: auto;
  display: block;
}

/* ---------- Filter bar ---------- */
.filter-bar {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 32px;
  padding: 8px;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: 999px;
  width: fit-content;
}

.filter-bar button {
  height: 32px;
  padding: 0 16px;
  border-radius: 999px;
  font-size: var(--fs-xs);
  font-weight: 600;
  letter-spacing: 0.02em;
  color: var(--text-muted);
  transition: background 0.2s var(--ease-out), color 0.2s var(--ease-out);
}

.filter-bar button:hover {
  color: var(--text);
}

.filter-bar button[aria-pressed="true"] {
  background: var(--text);
  color: var(--bg);
}

/* ---------- Footer ---------- */
.site-footer {
  border-top: 1px solid var(--border);
  background: var(--bg-elevated);
  padding-block: 48px;
  margin-top: clamp(48px, 8vw, 100px);
}

.site-footer__inner {
  max-width: var(--max-w);
  margin-inline: auto;
  padding-inline: var(--pad-x);
  display: grid;
  gap: 28px;
  grid-template-columns: 1fr auto;
  align-items: end;
}

@media (max-width: 720px) {
  .site-footer__inner {
    grid-template-columns: 1fr;
  }
}

.site-footer__brand {
  font-weight: 700;
  letter-spacing: -0.01em;
  font-size: var(--fs-md);
  color: var(--text);
}

.site-footer__brand-sub {
  margin-top: 6px;
  font-size: var(--fs-sm);
  color: var(--text-muted);
}

.site-footer__copy {
  margin-top: 14px;
  font-size: var(--fs-xs);
  color: var(--text-subtle);
}

.site-footer__links {
  display: flex;
  gap: 16px;
  font-size: var(--fs-xs);
}

.site-footer__links a {
  color: var(--text-muted);
}

.site-footer__links a:hover {
  color: var(--text);
}

/* ---------- Reveal animation (scroll-driven) ---------- */
@supports (animation-timeline: view()) {
  .reveal {
    animation: reveal-fade linear both;
    animation-timeline: view();
    animation-range: entry 0% cover 25%;
  }
}

@keyframes reveal-fade {
  from {
    opacity: 0;
    transform: translateY(24px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Fallback for browsers without scroll-driven animations */
@media (prefers-reduced-motion: no-preference) {
  @supports not (animation-timeline: view()) {
    .reveal {
      opacity: 0;
      transform: translateY(24px);
      transition: opacity 0.6s var(--ease-out), transform 0.6s var(--ease-out);
    }
    .reveal.is-in {
      opacity: 1;
      transform: translateY(0);
    }
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

/* ---------- View transitions ---------- */
@view-transition {
  navigation: auto;
}

::view-transition-old(root),
::view-transition-new(root) {
  animation-duration: 0.3s;
  animation-timing-function: var(--ease-out);
}

/* ---------- Utility ---------- */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}