/* ==========================================================================
   Yi Wu — academic homepage
   Base layout; theme.css supplies the typefaces and colour palette.
   ========================================================================== */

:root {
    --page-width: 960px;
    --page-inline-space: 3rem;
    --topbar-height: 72px;

    --font-sans: "Manrope", -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", sans-serif;
    --font-serif: "EB Garamond", Georgia, "Songti SC", "Times New Roman", serif;
    --font-mono: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
    /* Ships a single weight (400). Display type asks for 700 anyway and lets the
       browser synthesise the bold — deliberate, so `font-synthesis-weight` must
       stay at its default (never set it to `none`, that silently kills this).
       Its cap-height runs ~17% taller and its descenders ~41% deeper than a
       typical script face, so hand-font sizes are set smaller and line-heights
       looser than usual. */
    --font-hand: "Annie Use Your Telescope", "Bradley Hand", "Segoe Script", cursive;

    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 14px;

    --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
}

:root,
:root[data-theme="light"] {
    --bg: #fbfbfd;
    --bg-elev: #ffffff;
    --bg-sunk: #f3f4f8;
    --ink: #15161c;
    --ink-soft: #555a68;
    --ink-faint: #626774;
    --rule: #e1e3ea;
    --rule-soft: #edeef3;
    --accent: #3f4fa8;
    --accent-hover: #33418d;
    --accent-wash: #ecedfa;
    --badge-ink: #805000;
    --badge-bg: #fff3ce;
    --badge-border: #e6c776;
    --shadow: 0 1px 2px rgba(21, 22, 28, 0.05), 0 10px 28px -18px rgba(21, 22, 28, 0.35);
}

:root[data-theme="dark"] {
    --bg: #121315;
    --bg-elev: #191a1d;
    --bg-sunk: #0b0c0f;
    --ink: #e8e9ee;
    --ink-soft: #9ba1b0;
    --ink-faint: #9296a0;
    --rule: #282b34;
    --rule-soft: #1e2027;
    --accent: #9aa6f0;
    --accent-hover: #b3bcf5;
    --accent-wash: #212540;
    --badge-ink: #f6d680;
    --badge-bg: #302714;
    --badge-border: #756030;
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.45), 0 10px 28px -18px rgba(0, 0, 0, 0.85);
}

/* --------------------------------------------------------------------------
   Base
   -------------------------------------------------------------------------- */

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

html {
    scroll-behavior: smooth;
    scroll-padding-top: calc(var(--topbar-height) + 24px);
    -webkit-text-size-adjust: 100%;
}

body {
    margin: 0;
    background: var(--bg);
    color: var(--ink);
    font-family: var(--font-serif);
    font-size: 1.1875rem;
    line-height: 1.66;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

img {
    max-width: 100%;
    height: auto;
}

a {
    color: var(--accent);
    text-decoration: none;
    text-underline-offset: 3px;
    transition: color 140ms var(--ease);
}

a:hover {
    color: var(--accent-hover);
    text-decoration: underline;
    text-decoration-thickness: 1px;
}

p {
    margin: 0 0 0.85em;
}

h1,
h2,
h3 {
    margin: 0;
    font-weight: 600;
    line-height: 1.25;
    text-wrap: balance;
}

p {
    text-wrap: pretty;
}

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

:focus-visible {
    outline: 2px solid var(--accent);
    outline-offset: 3px;
    border-radius: 3px;
}

.muted {
    color: var(--ink-faint);
}

.skip-link {
    position: absolute;
    inset-block-start: -100px;
    inset-inline-start: 12px;
    z-index: 100;
    padding: 0.5rem 0.9rem;
    border-radius: var(--radius-sm);
    background: var(--accent);
    color: #fff;
    font-family: var(--font-mono);
    font-size: 0.8rem;
}

.skip-link:focus {
    inset-block-start: 12px;
}

/* --------------------------------------------------------------------------
   Top bar
   -------------------------------------------------------------------------- */

.topbar {
    position: sticky;
    inset-block-start: 0;
    z-index: 3;
    border-block-end: 1px solid transparent;
    background: var(--bg);
    transition: border-color 200ms var(--ease);
}

.topbar.is-stuck {
    border-block-end-color: var(--rule-soft);
}

.topbar-inner {
    display: flex;
    align-items: center;
    gap: 2.5rem;
    width: min(100% - var(--page-inline-space), var(--page-width));
    height: var(--topbar-height);
    margin-inline: auto;
}

.topbar-name {
    flex-shrink: 0;
    color: var(--ink);
    font-family: var(--font-hand);
    font-size: 1.42rem;
    font-weight: 700;
    line-height: 1.2;
}

.topbar-name:hover {
    color: var(--accent);
    text-decoration: none;
}

.topbar-nav {
    flex: 1;
    min-width: 0;
}

.topbar-controls {
    display: flex;
    align-items: center;
    flex-shrink: 0;
    gap: 0.25rem;
}

.nav-links {
    display: flex;
    gap: 1.35rem;
    margin: 0;
    padding: 0;
    overflow-x: auto;
    list-style: none;
    scrollbar-width: none;
}

.nav-links::-webkit-scrollbar {
    display: none;
}

.nav-links a {
    position: relative;
    display: block;
    padding-block: 8px;
    color: var(--ink-soft);
    font-family: var(--font-mono);
    font-size: 0.79rem;
    font-weight: 500;
    white-space: nowrap;
}

.nav-links a::after {
    position: absolute;
    inset-block-end: 3px;
    inset-inline-start: 0;
    width: 100%;
    height: 1.5px;
    border-radius: 2px;
    background: var(--accent);
    content: "";
    transform: scaleX(0);
    transform-origin: 0 50%;
    transition: transform 220ms var(--ease);
}

.nav-links a:hover {
    color: var(--ink);
    text-decoration: none;
}

.nav-links a.active {
    color: var(--ink);
}

.nav-links a.active::after {
    transform: scaleX(1);
}

.theme-toggle {
    display: grid;
    flex-shrink: 0;
    place-items: center;
    width: 40px;
    height: 40px;
    padding: 0;
    border: 0;
    border-radius: 50%;
    background: transparent;
    color: var(--ink-soft);
    font-size: 0.76rem;
    cursor: pointer;
    transition: color 160ms var(--ease), border-color 160ms var(--ease),
        background-color 160ms var(--ease);
}

.theme-toggle:hover {
    border-color: var(--accent);
    background: var(--accent-wash);
    color: var(--accent);
}

/* --------------------------------------------------------------------------
   Page shell
   -------------------------------------------------------------------------- */

.page {
    position: relative;
    z-index: 1;
    width: min(100% - var(--page-inline-space), var(--page-width));
    margin-inline: auto;
    padding-block-end: 2rem;
}

/* --------------------------------------------------------------------------
   Hero
   -------------------------------------------------------------------------- */

.hero {
    display: flex;
    align-items: center;
    gap: clamp(1.5rem, 5vw, 3rem);
    padding-block: clamp(3.5rem, 8vw, 7rem) clamp(1.5rem, 3vw, 3rem);
}

.hero-text {
    flex: 1;
    min-width: 0;
}

.hero-name {
    font-family: var(--font-hand);
    font-size: clamp(3.4rem, 8vw, 5rem);
    font-weight: 700;
    line-height: 1.16;
    letter-spacing: 0.005em;
}

.hero-name-cn {
    margin-inline-start: 0.4rem;
    color: var(--ink-soft);
    font-family: var(--font-serif);
    font-size: 0.28em;
    font-weight: 400;
    letter-spacing: 0.02em;
}

.hero-role {
    margin-block: 0.75rem 0;
    color: var(--ink-soft);
    font-family: var(--font-mono);
    font-size: 0.83rem;
    line-height: 1.7;
}

.hero-motto {
    margin-block: 0.6rem 0;
    color: var(--ink-faint);
    font-family: var(--font-hand);
    font-size: 1.28rem;
    font-weight: 700;
    line-height: 1.35;
}

.hero-portrait {
    flex-shrink: 0;
    width: clamp(152px, 28vw, 224px);
}

.hero-portrait img {
    display: block;
    width: 100%;
    aspect-ratio: 1;
    border-radius: 8px;
    object-fit: cover;
    transition: transform 650ms var(--ease);
}

.hero-portrait:hover img {
    transform: translateY(-4px) rotate(-1deg);
}

.social-links {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-block-start: 1.3rem;
}

.social-links a {
    display: grid;
    place-items: center;
    width: 40px;
    height: 40px;
    border: 0;
    border-radius: 50%;
    color: var(--ink-soft);
    font-size: 0.85rem;
    transition: color 160ms var(--ease), border-color 160ms var(--ease),
        background-color 160ms var(--ease), transform 160ms var(--ease);
}

.social-links a:hover {
    border-color: var(--accent);
    background: var(--accent-wash);
    color: var(--accent);
    text-decoration: none;
    transform: translateY(-2px);
}

.social-cv-mark {
    font-family: var(--font-mono);
    font-size: 0.7rem;
    font-weight: 500;
}

/* --------------------------------------------------------------------------
   Sections
   -------------------------------------------------------------------------- */

.section {
    padding-block: clamp(2.75rem, 6vw, 4.5rem) 0;
}

.section-title {
    display: flex;
    align-items: baseline;
    gap: 0.8rem;
    margin-block-end: 1.65rem;
    font-family: var(--font-sans);
    font-size: clamp(1.25rem, 2.5vw, 1.5rem);
    font-weight: 600;
    line-height: 1.2;
    letter-spacing: -0.03em;
}

.section-title::after {
    content: none;
}

.section-note {
    color: var(--ink-faint);
    font-family: var(--font-mono);
    font-size: 0.75rem;
    font-weight: 400;
}

.prose p:last-child {
    margin-block-end: 0;
}

.prose { width: 100%; }

.prose strong {
    font-weight: 600;
}

.inline-logo {
    height: 0.95em;
    vertical-align: -0.1em;
}

:root[data-theme="dark"] .inline-logo[src$="purdue.svg"] {
    filter: brightness(0) invert(0.9);
}

/* Research ---------------------------------------------------------------- */

.research-list {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2.5rem;
    margin: 0;
    padding: 0;
    list-style: none;
}

.research-list li {
    padding-block-start: 1.2rem;
    border-block-start: 1px solid var(--rule);
}

.interest-keyword {
    display: block;
    color: var(--ink);
    font-family: var(--font-sans);
    font-size: 1rem;
    font-weight: 600;
    line-height: 1.3;
}

.research-list p {
    margin-block: 0.6rem 0;
    color: var(--ink-soft);
    font-size: 1.02rem;
    line-height: 1.8;
}

.collab-invite {
    display: flex;
    align-items: baseline;
    gap: 0.6rem;
    margin-block: 1.5rem 0;
    padding: 0;
    color: var(--ink-soft);
    font-size: 1.02rem;
}

.collab-invite i {
    display: none;
}

/* News -------------------------------------------------------------------- */

.news-container {
    max-height: 330px;
    padding-inline-end: 0.5rem;
    overflow-y: auto;
    mask-image: linear-gradient(to bottom, #000 86%, transparent);
    -webkit-mask-image: linear-gradient(to bottom, #000 86%, transparent);
    scrollbar-width: thin;
    scrollbar-color: var(--rule) transparent;
}

.news-container::-webkit-scrollbar {
    width: 5px;
}

.news-container::-webkit-scrollbar-thumb {
    border-radius: 99px;
    background: var(--rule);
}

.news-list {
    margin: 0;
    padding: 0;
    list-style: none;
}

.news-item {
    display: grid;
    grid-template-columns: 5.4rem 1fr;
    gap: 1rem;
    padding-block: 0.45rem;
    border-block-end: 1px solid var(--rule-soft);
}

.news-item:last-child {
    border-block-end: 0;
}

.news-date {
    color: var(--ink-faint);
    font-family: var(--font-mono);
    font-size: 0.75rem;
    letter-spacing: -0.02em;
    line-height: 2.1;
    white-space: nowrap;
}

.news-item p {
    margin: 0;
    font-size: 1.04rem;
    line-height: 1.5;
}

/* Publications ------------------------------------------------------------ */

.publication-controls {
    display: flex;
    flex-wrap: wrap;
    gap: 0.35rem 1.5rem;
    margin-block: 0 0.75rem;
    border-block-end: 1px solid var(--rule);
}

.publication-controls[hidden],
.pub[hidden] {
    display: none;
}

.publication-controls button {
    min-height: 44px;
    padding: 0.6rem 0;
    border: 0;
    border-block-end: 2px solid transparent;
    background: transparent;
    color: var(--ink-soft);
    font-family: var(--font-mono);
    font-size: 0.8rem;
    cursor: pointer;
}

.publication-controls button[aria-pressed="true"] {
    border-block-end-color: var(--accent);
    color: var(--accent);
}

.publication-controls button:hover {
    color: var(--accent-hover);
}

.publication-count {
    margin-inline-start: 0.3rem;
    color: var(--ink-faint);
    font-size: 0.72rem;
}

.publication-status {
    margin: 0 0 1.5rem;
    color: var(--ink-soft);
    font-size: 1rem;
}

.publication-list {
    display: grid;
}

.pub {
    display: grid;
    grid-template-columns: 184px 1fr;
    gap: 2rem;
    align-items: start;
    padding-block: 0 2rem;
}

/* Only visible preceding papers add a separator and space above the next row. */
.pub:not([hidden]) ~ .pub {
    padding-block-start: 2rem;
    border-block-start: 1px solid var(--rule-soft);
}

/* Bare figure: fixed width, natural height, no frame or backdrop. */
.pub-thumb img {
    display: block;
    width: 100%;
    height: auto;
    border-radius: 4px;
    transition: transform 650ms var(--ease);
}

.pub:hover .pub-thumb img {
    transform: translateY(-3px);
}

.pub-body {
    min-width: 0;
}

/* Reusable publication distinctions: rankings, Spotlight, Oral, etc.
   Use an anchor when there is a source link; otherwise use a span. */
.pub-meta {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 0.4rem 0.75rem;
}

.pub-badge {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    max-width: 100%;
    padding: 0.24rem 0.6rem;
    border: 1px solid var(--badge-border);
    border-radius: var(--radius-sm);
    background: var(--badge-bg);
    color: var(--badge-ink);
    font-family: var(--font-mono);
    font-size: 0.75rem;
    font-weight: 500;
    line-height: 1.65;
}

.pub-badge strong {
    font-weight: 700;
}

.pub-badge time {
    white-space: nowrap;
    font-size: 0.7rem;
}

a.pub-badge:hover {
    color: var(--badge-ink);
    border-color: currentColor;
    text-decoration: underline;
}

a.pub-badge:focus-visible {
    outline: 2px solid var(--badge-ink);
    outline-offset: 3px;
}

.pub-venue {
    display: inline-block;
    color: var(--accent);
    font-family: var(--font-mono);
    font-size: 0.75rem;
    font-weight: 500;
    letter-spacing: 0.02em;
    text-transform: uppercase;
}

.pub-title {
    margin-block: 0.3rem 0;
    font-size: 1.26rem;
    line-height: 1.45;
    letter-spacing: -0.02em;
    text-wrap: pretty;
}

.pub-authors {
    margin-block: 0.32rem 0;
    color: var(--ink-soft);
    font-size: 1rem;
    line-height: 1.75;
}

.highlight-name {
    color: var(--ink);
    font-weight: 600;
}

.pub-tldr {
    margin-block: 0.5rem 0;
    color: var(--ink-soft);
    font-size: 0.99rem;
    line-height: 1.8;
}

.pub-links {
    display: flex;
    flex-wrap: wrap;
    gap: 1.1rem;
    margin-block-start: 0.7rem;
}

.pub-links a,
.pub-bibtex {
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    padding: 0.4rem 0;
    border: 0;
    color: var(--accent);
    font-family: var(--font-mono);
    font-size: 0.77rem;
    transition: color 160ms var(--ease), border-color 160ms var(--ease),
        background-color 160ms var(--ease);
}

.pub-bibtex {
    background: none;
    cursor: pointer;
}

.pub-links a:hover,
.pub-bibtex:hover {
    border-color: var(--accent);
    color: var(--accent);
    text-decoration: underline;
}

.pub-links i {
    font-size: 0.64rem;
}

/* Education --------------------------------------------------------------- */

.education-list {
    display: grid;
}

.education-item {
    display: grid;
    grid-template-columns: 1fr auto;
    gap: 1.1rem;
    align-items: center;
    padding-block: 0.85rem;
    border-block-end: 1px solid var(--rule-soft);
}

.education-item:last-child {
    border-block-end: 0;
}

.edu-year {
    color: var(--ink-faint);
    font-family: var(--font-mono);
    font-size: 0.75rem;
    letter-spacing: -0.02em;
}

.edu-content h3 {
    font-size: 1.14rem;
}

.edu-content p {
    margin: 0.15rem 0 0;
    color: var(--ink-soft);
    font-size: 1rem;
}

.edu-logo img {
    display: block;
    width: 100%;
    max-height: 38px;
    object-fit: contain;
}

/* Services ---------------------------------------------------------------- */

.services {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 0.7rem;
}

.services-label {
    color: var(--ink-faint);
    font-family: var(--font-mono);
    font-size: 0.75rem;
    text-transform: uppercase;
}

.services-venues {
    display: flex;
    flex-wrap: wrap;
    gap: 0.4rem;
}

.venue-tag {
    padding: 0.2rem 0.65rem;
    border: 1px solid var(--rule);
    border-radius: 99px;
    color: var(--ink-soft);
    font-family: var(--font-mono);
    font-size: 0.75rem;
}

/* Earlier, thumbnail-free publications. */
.pub-subhead {
    margin-block: 2.5rem 0.4rem;
    color: var(--ink-faint);
    font-family: var(--font-mono);
    font-size: 0.75rem;
    font-weight: 500;
    letter-spacing: 0.04em;
    text-transform: uppercase;
}

.pub-compact {
    margin: 0;
    padding: 0;
    list-style: none;
}

.pub-compact li {
    padding-block: 1rem;
    border-block-end: 1px solid var(--rule-soft);
}

.pub-compact li:last-child {
    border-block-end: 0;
}

.pub-compact p {
    margin: 0.35rem 0 0;
    color: var(--ink-soft);
    font-size: 1rem;
    line-height: 1.7;
}

.pub-compact strong {
    color: var(--ink);
    font-weight: 600;
}

.pub-compact .pub-links {
    margin-block-start: 0.3rem;
}

/* Footer ------------------------------------------------------------------ */

.site-footer {
    margin-block-start: clamp(2.5rem, 6vw, 3.5rem);
    padding-block-start: 1.35rem;
    border-block-start: 1px solid var(--rule-soft);
    color: var(--ink-faint);
    font-family: var(--font-mono);
    font-size: 0.75rem;
    text-align: center;
}

/* --------------------------------------------------------------------------
   Responsive
   -------------------------------------------------------------------------- */

@media (min-width: 721px) and (max-width: 1100px) {
    :root { --page-inline-space: 8rem; }
}

@media (max-width: 720px) {
    :root {
        --topbar-height: 60px;
    }

    .topbar-inner,
    .page {
        width: min(100% - 2rem, var(--page-width));
    }

    .topbar-name {
        display: none;
    }

    .hero {
        flex-direction: column-reverse;
        align-items: flex-start;
        gap: 1.4rem;
    }

    .topbar-inner { gap: 0.5rem; }

    .research-list { grid-template-columns: 1fr; gap: 1.3rem; }

    .nav-links a { min-height: 44px; display: flex; align-items: center; }

    .social-links a,
    .theme-toggle { width: 44px; height: 44px; }

    .pub-links a, .pub-bibtex { min-height: 44px; }

    .pub {
        grid-template-columns: 1fr;
        gap: 0.9rem;
    }

    .pub-thumb img {
        max-width: 280px;
    }

    .news-item {
        grid-template-columns: 1fr;
        gap: 0.1rem;
    }

    .news-date {
        line-height: 1.5;
    }

    .education-item {
        grid-template-columns: 1fr;
        gap: 0.2rem;
    }

    .edu-year {
        grid-column: 1 / -1;
    }
}

@media (prefers-reduced-motion: reduce) {
    html {
        scroll-behavior: auto;
    }

    *,
    *::before,
    *::after {
        animation-duration: 0.001ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.001ms !important;
    }

}

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    overflow: hidden;
    clip: rect(0 0 0 0);
    white-space: nowrap;
}

.edu-content .edu-org {
    display: inline;
}

.edu-role {
    color: var(--ink-soft);
    font-size: 1.14rem;
    font-weight: 400;
}

.edu-content .edu-location {
    color: var(--ink-faint);
    font-size: 0.95rem;
    opacity: 0.75;
}