/* =============================================
   1. VARIABLES & RESET
   ============================================= */
:root {
    --primary-color: #2E7D6F;
    --secondary-color: #C88A3E;
    --accent-color: #4C6EF5;
    --light-color: #FFFFFF;
    --dark-color: #1a1a1a;
    --text-color: #2D2D2D;
    --background-color: #FAFAF8;
    --header-gradient: linear-gradient(180deg, #F7F8F6 0%, #FAFAF8 100%);
    --font-family: 'Inter', 'Segoe UI', -apple-system, sans-serif;
    --font-display: 'Cormorant Garamond', 'Georgia', serif;
    --link-color: var(--primary-color);
}

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

/* =============================================
   2. BASE TYPOGRAPHY
   ============================================= */
body {
    font-family: var(--font-family);
    line-height: 1.8;
    font-size: 1.1rem;
    font-weight: 400;
    background-color: var(--background-color);
    color: var(--text-color);
    scroll-behavior: smooth;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    overflow-x: hidden;
}

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

a { color: var(--link-color); }

/* =============================================
   3. LAYOUT
   ============================================= */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* =============================================
   4. HEADER
   ============================================= */
.header-section {
    background: var(--background-color);
    padding: 100px 0 80px 0;
    margin-bottom: 16px;
    color: var(--dark-color);
    position: relative;
    overflow: hidden;
}

.paper-title {
    font-family: var(--font-display);
    font-weight: 600;
    font-size: 3.4rem;
    line-height: 1.15;
    margin-bottom: 6px;
    position: relative;
    z-index: 1;
    display: block;
    text-align: center;
    letter-spacing: -0.5px;
}

.paper-subtitle {
    font-family: var(--font-display);
    font-weight: 400;
    font-size: 1.6rem;
    line-height: 1.4;
    margin-top: 8px;
    margin-bottom: 28px;
    color: #586069;
    text-align: center;
    letter-spacing: 0;
}

.author-line {
    font-size: 1.05rem;
    font-weight: 400;
    margin: 0.5rem 0;
    line-height: 1.6;
    letter-spacing: 0.01em;
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    align-items: center;
    position: relative;
    z-index: 1;
}

.author-line--middle {
    max-width: 760px;
    margin-left: auto;
    margin-right: auto;
}

.author-link {
    text-decoration: none;
    transition: all 0.2s ease;
    padding: 3px 6px;
    border-radius: 4px;
    color: var(--text-color);
}

.author-link:hover {
    color: var(--link-color);
    text-decoration: none;
    background-color: rgba(46, 125, 111, 0.05);
}

.author-link sup { font-weight: 400; color: #656565; }

.author-mark { font-weight: 700; font-size: 1.15em; color: #656565; }

.equal-contribution {
    font-size: 0.85rem;
    color: #656565;
    margin-top: 14px;
    margin-bottom: 0;
    text-align: center;
    position: relative;
    z-index: 1;
    letter-spacing: 0.01em;
}

.eq-separator { opacity: 0.3; }

.institution-line {
    font-size: 0.92rem;
    color: #586069;
    text-align: center;
    margin-top: 12px;
    line-height: 1.6;
}

/* Paper buttons */
.paper-btn-wrapper {
    display: flex;
    justify-content: center;
    gap: 12px;
    width: 100%;
    margin-top: 36px;
    flex-wrap: wrap;
}

.paper-btn {
    display: inline-flex;
    align-items: center;
    background-color: var(--primary-color);
    color: #FFFFFF !important;
    border: none;
    padding: 10px 26px;
    font-size: 1rem;
    font-weight: 500;
    letter-spacing: 0.03em;
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(46, 125, 111, 0.2);
    transition: all 0.25s ease;
    text-decoration: none;
}

.paper-btn:hover {
    background-color: #1F5C4F;
    color: #FFFFFF !important;
    box-shadow: 0 4px 16px rgba(46, 125, 111, 0.3);
    transform: translateY(-1px);
}

.paper-btn:active {
    transform: translateY(0);
    box-shadow: 0 2px 6px rgba(46, 125, 111, 0.2);
}

.paper-btn .fa-arrow-right {
    transition: transform 0.25s ease;
    font-size: 0.8em;
    opacity: 0.7;
}

.paper-btn:hover .fa-arrow-right { transform: translateX(3px); }

.paper-btn--outline {
    background-color: transparent;
    color: var(--primary-color) !important;
    border: 1.5px solid var(--primary-color);
    box-shadow: none;
}

.paper-btn--outline:hover {
    background-color: var(--primary-color);
    color: #FFFFFF !important;
}

/* =============================================
   5. TL;DR SECTION
   ============================================= */
.tldr-box {
    background-color: rgba(46, 125, 111, 0.03);
    border: 1px solid rgba(46, 125, 111, 0.08);
    border-radius: 8px;
}

.tldr-headline {
    font-size: 1.5rem;
    text-align: center;
    color: var(--dark-color);
    line-height: 1.7;
    font-weight: 700;
}

.tldr-abstract {
    font-size: 1.15rem;
    font-weight: 400;
    text-align: left;
    line-height: 1.7;
}

/* TL;DR keyword tooltips */
.tldr-keyword {
    font-weight: 700;
    cursor: help;
    position: relative;
    transition: all 0.25s ease;
    padding: 0 2px;
    border-radius: 3px;
}

.tldr-keyword:hover { background-color: rgba(46, 125, 111, 0.08); }

.tldr-keyword[data-color="primary"] {
    color: var(--primary-color);
    border-bottom: 2px dashed var(--primary-color);
}

.tldr-keyword[data-color="secondary"] {
    color: var(--secondary-color);
    border-bottom: 2px dashed var(--secondary-color);
}

.tldr-keyword[data-color="accent"] {
    color: var(--accent-color);
    border-bottom: 2px dashed var(--accent-color);
}

.tldr-keyword .keyword-tooltip {
    visibility: hidden;
    opacity: 0;
    position: absolute;
    bottom: calc(100% + 12px);
    left: 50%;
    transform: translateX(-50%) translateY(5px);
    width: 360px;
    padding: 16px 20px;
    border-radius: 8px;
    font-size: 0.9rem;
    font-weight: 400;
    line-height: 1.7;
    color: #2D2D2D;
    background: #FFFFFF;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
    border: 1px solid rgba(0, 0, 0, 0.06);
    z-index: 100;
    pointer-events: none;
    transition: opacity 0.25s ease, transform 0.25s ease;
}

.tldr-keyword .keyword-tooltip::after {
    content: "";
    position: absolute;
    top: 100%;
    left: 50%;
    transform: translateX(-50%);
    border: 8px solid transparent;
    border-top-color: #FFFFFF;
}

.tldr-keyword:hover .keyword-tooltip,
.tldr-keyword.tooltip-active .keyword-tooltip {
    visibility: visible;
    opacity: 1;
    transform: translateX(-50%) translateY(0);
}

.tldr-keyword[data-color="primary"] .keyword-tooltip { border-top: 2px solid var(--primary-color); }
.tldr-keyword[data-color="secondary"] .keyword-tooltip { border-top: 2px solid var(--secondary-color); }
.tldr-keyword[data-color="accent"] .keyword-tooltip { border-top: 2px solid var(--accent-color); }

/* =============================================
   6. CONTENT SECTIONS
   ============================================= */
.section-title {
    font-family: var(--font-display);
    margin: 36px 0 28px 0;
    font-weight: 500;
    font-size: 2rem;
    color: var(--dark-color);
    padding-bottom: 10px;
    text-align: center;
    position: relative;
    letter-spacing: -0.2px;
}

.section-title::after {
    content: "";
    display: block;
    width: 80px;
    height: 2px;
    background-color: var(--secondary-color);
    margin: 18px auto 0 auto;
    opacity: 0.7;
}

.subsection-title {
    font-family: var(--font-display);
    margin: 36px 0 24px 0;
    font-weight: 500;
    font-size: 1.5rem;
    color: var(--dark-color);
    text-align: center;
    letter-spacing: -0.1px;
}

.sec-gold .section-title::after { background-color: var(--secondary-color); }
.sec-teal .section-title::after { background-color: var(--primary-color); }
.sec-blue .section-title::after { background-color: var(--accent-color); }

.section-divider {
    border: none;
    height: 0;
    max-width: 280px;
    margin: 32px auto;
    position: relative;
}

.section-divider::before {
    content: "";
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 40px;
    height: 1.5px;
    background-color: rgba(0, 0, 0, 0.12);
}

.section-divider::after {
    content: "";
    position: absolute;
    top: -1px;
    left: 50%;
    transform: translateX(-50%);
    width: 6px;
    height: 6px;
    border: 1.5px solid rgba(0, 0, 0, 0.12);
    border-radius: 50%;
    background-color: var(--background-color);
}

.body-text {
    font-size: 1.05rem;
    line-height: 1.8;
    max-width: 860px;
    margin: 0 auto 28px auto;
}

/* Section figures */
.section-figure {
    max-width: 780px;
    margin: 0 auto 16px auto;
    text-align: center;
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 180px;
}

.section-figure img {
    max-width: 100%;
    max-height: 360px;
    width: auto;
    height: auto;
    border-radius: 6px;
    object-fit: contain;
}

.section-figure--tall img { max-height: 560px; }
.section-figure--wide { max-width: 1000px; }

.section-figure--framed img {
    background: #fff;
    padding: 12px;
    border: 1px solid rgba(0, 0, 0, 0.06);
}

.section-figure--wide img { max-height: 50%; }

/* Side-by-side figures */
.section-figure-row {
    display: flex;
    gap: 16px;
    max-width: 860px;
    margin: 0 auto 16px auto;
    align-items: center;
    justify-content: center;
}

.section-figure-col {
    flex: 1;
    min-width: 0;
    text-align: center;
}

.section-figure-col img {
    max-width: 100%;
    height: auto;
    border-radius: 6px;
    object-fit: contain;
}

@media (max-width: 576px) {
    .section-figure-row { flex-direction: column; gap: 12px; }
}

.section-caption {
    font-size: 0.88rem;
    color: #586069;
    text-align: center;
    max-width: 780px;
    margin: 0 auto 32px auto;
    line-height: 1.6;
}

.section-caption strong { color: #4B5563; }

/* Callout boxes */
.callout {
    max-width: 860px;
    margin: 0 auto;
    padding: 16px 24px;
    border-left: 2px solid;
    border-radius: 0 6px 6px 0;
}

.callout p { margin: 0; font-size: 1.0rem; line-height: 1.7; }

.callout--gold {
    border-left-color: var(--secondary-color);
    background: rgba(200, 138, 62, 0.03);
}

.callout--teal {
    border-left-color: var(--primary-color);
    background: rgba(46, 125, 111, 0.03);
}

.callout--blue {
    border-left-color: var(--accent-color);
    background: rgba(76, 110, 245, 0.03);
}

/* Math formula block */
.math-block {
    max-width: 860px;
    margin: 0 auto 24px auto;
    text-align: center;
    padding: 16px 24px;
    background: rgba(0, 0, 0, 0.02);
    border-radius: 8px;
    border: 1px solid rgba(0, 0, 0, 0.04);
    overflow-x: auto;
}

/* Case study grid */
.case-grid {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 12px;
    max-width: 960px;
    margin: 0 auto 16px auto;
}

.case-card {
    text-align: center;
    border: 1px solid rgba(0, 0, 0, 0.06);
    border-radius: 8px;
    padding: 10px;
    background: rgba(0, 0, 0, 0.01);
}

.case-card img {
    width: 100%;
    height: 100px;
    object-fit: contain;
    border-radius: 4px;
    margin-bottom: 6px;
    background-color: #FFFFFF;
}

.case-card__label {
    font-size: 0.72rem;
    font-weight: 600;
    color: var(--primary-color);
    margin-bottom: 4px;
}

.case-card__text {
    font-size: 0.75rem;
    line-height: 1.5;
    color: #586069;
    text-align: left;
}

.case-card__text strong { color: var(--primary-color); }

@media (max-width: 768px) {
    .case-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 576px) {
    .case-grid { grid-template-columns: 1fr; }
}

/* Result tables */
.result-table-wrapper {
    max-width: 960px;
    margin: 0 auto 28px auto;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
}

.result-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.88rem;
    line-height: 1.5;
    text-align: center;
}

.result-table caption {
    font-size: 0.92rem;
    font-weight: 600;
    color: var(--dark-color);
    text-align: left;
    margin-bottom: 10px;
    line-height: 1.5;
}

.result-table thead th {
    font-weight: 600;
    padding: 8px 6px;
    border-bottom: 2px solid rgba(0, 0, 0, 0.15);
    white-space: nowrap;
    font-size: 0.82rem;
    color: var(--dark-color);
}

.result-table tbody td {
    padding: 5px 6px;
    border-bottom: 1px solid rgba(0, 0, 0, 0.06);
}

.result-table tbody tr:last-child td { border-bottom: 2px solid rgba(0, 0, 0, 0.15); }

.result-table .row-model { font-weight: 500; text-align: left; white-space: nowrap; }
.result-table .row-delta { font-size: 0.78rem; }
.result-table .row-delta td { padding-top: 0; }

.result-table .group-header td {
    font-weight: 500;
    font-style: italic;
    text-align: left;
    padding-top: 10px;
    border-bottom: none;
    color: #586069;
    font-size: 0.82rem;
}

.result-table .row-ours td {
    font-weight: 600;
    background-color: rgba(46, 125, 111, 0.04);
}

.result-table .row-ours .row-model { font-weight: 700; }

.result-table .val-best { font-weight: 700; }
.result-table .val-second { text-decoration: underline; }

.result-table .delta-pos { color: #008a00; font-size: 0.78rem; }
.result-table .delta-neg { color: #c00000; font-size: 0.78rem; }

.result-table .col-sep-left { border-left: 1px solid rgba(0, 0, 0, 0.08); }
.result-table .col-avg { font-weight: 600; }

.result-table .midrule td { border-bottom: 1.5px solid rgba(0, 0, 0, 0.12); }

.result-table-note {
    font-size: 0.78rem;
    color: #586069;
    max-width: 960px;
    margin: -20px auto 24px auto;
    line-height: 1.5;
}

/* Paper invite */
.paper-invite {
    font-size: 0.95rem;
    line-height: 1.8;
    max-width: 620px;
    margin: 60px auto 40px auto;
    text-align: center;
    color: #586069;
}

.paper-invite a {
    color: var(--primary-color);
    text-decoration: none;
    border-bottom: 1px solid rgba(46, 125, 111, 0.3);
}

.paper-invite a:hover { border-bottom-color: var(--primary-color); }

/* =============================================
   7. STICKY SECTION NAVIGATION
   ============================================= */
.section-nav {
    position: sticky;
    top: 0;
    z-index: 100;
    background-color: var(--background-color);
    border-bottom: 1px solid rgba(0, 0, 0, 0.1);
    padding: 0 20px;
    opacity: 0;
    transition: opacity 0.3s ease;
    pointer-events: none;
}

.section-nav.visible { opacity: 1; pointer-events: auto; }

.section-nav-inner {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 12px;
    max-width: 780px;
    margin: 0 auto;
    padding: 20px 0 18px 0;
}

.section-nav-link {
    position: relative;
    cursor: pointer;
    font-size: 1.06rem;
    font-weight: 400;
    color: #586069;
    text-decoration: none;
    transition: color 0.2s ease;
    white-space: nowrap;
    letter-spacing: 0.03em;
    padding-bottom: 14px;
    margin-bottom: -14px;
}

.section-nav-link::after {
    content: "";
    position: absolute;
    bottom: 4px;
    left: 0;
    right: 0;
    height: 2.5px;
    background-color: transparent;
    transition: background-color 0.2s ease;
}

.section-nav-link:hover { color: var(--dark-color); }
.section-nav-link.active { font-weight: 600; color: var(--dark-color); }
.section-nav-link.active::after { background-color: var(--dark-color); }

.nav-color-gold.active { color: var(--secondary-color); }
.nav-color-gold.active::after { background-color: var(--secondary-color); }

.nav-color-teal.active { color: var(--primary-color); }
.nav-color-teal.active::after { background-color: var(--primary-color); }

.nav-color-blue.active { color: var(--accent-color); }
.nav-color-blue.active::after { background-color: var(--accent-color); }

.nav-top-link::after { display: none; }
.nav-top-link.active { font-weight: 400; }

.section-nav-sep {
    color: rgba(0, 0, 0, 0.15);
    font-size: 0.7rem;
    user-select: none;
    padding-bottom: 11px;
    margin-bottom: -12px;
}

/* Mobile nav header */
.nav-mobile-header {
    display: none;
    align-items: center;
    gap: 12px;
    padding: 12px 16px;
}

.nav-mobile-title {
    font-family: var(--font-display);
    font-size: 1rem;
    font-weight: 600;
    color: var(--dark-color);
    letter-spacing: -0.2px;
}

.nav-hamburger {
    background: none;
    border: none;
    cursor: pointer;
    padding: 6px;
    z-index: 10;
}

.nav-hamburger span {
    display: block;
    width: 20px;
    height: 2px;
    background-color: var(--dark-color);
    margin: 4px 0;
    border-radius: 1px;
    transition: all 0.25s ease;
}

.nav-hamburger.open span:nth-child(1) { transform: rotate(45deg) translate(4px, 4px); }
.nav-hamburger.open span:nth-child(2) { opacity: 0; }
.nav-hamburger.open span:nth-child(3) { transform: rotate(-45deg) translate(4px, -4px); }

/* =============================================
   8. CITATION
   ============================================= */
.citation-block {
    position: relative;
    background-color: rgba(0, 0, 0, 0.03);
    border: 1px solid rgba(0, 0, 0, 0.07);
    border-radius: 8px;
    padding: 24px 28px;
    max-width: 760px;
    margin-left: auto;
    margin-right: auto;
}

.citation-block pre {
    margin: 0;
    font-size: 0.85rem;
    line-height: 1.6;
    white-space: pre-wrap;
    word-break: break-word;
}

.copy-citation-btn {
    position: absolute;
    top: 12px;
    right: 12px;
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 6px 14px;
    font-size: 0.78rem;
    font-weight: 500;
    color: #586069;
    background: transparent;
    border: 1px solid rgba(0, 0, 0, 0.08);
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.2s ease;
    letter-spacing: 0.02em;
}

.copy-citation-btn:hover {
    color: var(--primary-color);
    border-color: var(--primary-color);
    background-color: rgba(46, 125, 111, 0.04);
}

.copy-citation-btn.copied {
    color: var(--primary-color);
    border-color: var(--primary-color);
    background-color: rgba(46, 125, 111, 0.06);
}

.copy-citation-btn i { font-size: 0.82rem; }

/* =============================================
   9. IMAGE LIGHTBOX
   ============================================= */
.lightbox {
    display: none;
    position: fixed;
    inset: 0;
    z-index: 2000;
    background: rgba(0, 0, 0, 0.85);
    cursor: zoom-out;
    align-items: center;
    justify-content: center;
    padding: 40px;
}

.lightbox.open { display: flex; }

.lightbox img {
    max-width: 90vw;
    max-height: 90vh;
    object-fit: contain;
    border-radius: 4px;
    box-shadow: 0 8px 40px rgba(0, 0, 0, 0.3);
    background-color: #FFFFFF;
}

.section-figure img,
.section-figure-col img,
.section-figure--tall img { cursor: zoom-in; }

/* =============================================
   10. FOOTER
   ============================================= */
.site-footer {
    margin-top: 80px;
    padding: 40px 0;
    border-top: 1px solid rgba(0, 0, 0, 0.06);
    text-align: center;
    color: #586069;
    font-size: 0.9rem;
}

.site-footer a { color: var(--primary-color); text-decoration: none; }
.site-footer a:hover { text-decoration: underline; }

/* =============================================
   12. RESPONSIVE -- TABLET
   ============================================= */
@media (max-width: 1200px) {
    .section-nav-link { font-size: 0.8rem; }
    .section-nav-inner { gap: 5px; }
}

/* =============================================
   13. RESPONSIVE -- MOBILE
   ============================================= */
@media (max-width: 768px) {
    body { font-size: 1rem; }
    .container { padding-left: 16px; padding-right: 16px; }
    .header-section { padding: 60px 0 40px 0; }
    .paper-title { font-size: 2.4rem; }
    .paper-subtitle { font-size: 1.3rem; margin-bottom: 20px; }
    .author-line { font-size: 0.92rem; gap: 4px 8px; }
    .paper-btn { padding: 12px 24px; font-size: 0.95rem; }

    .section-title { font-size: 2.2rem; margin: 36px 0 24px 0; }
    .subsection-title { font-size: 2rem; margin: 28px 0 20px 0; }
    .body-text { font-size: 1rem; }
    .section-figure { min-height: 120px; }
    .section-figure img { max-height: 280px; }
    .section-figure--tall img { max-height: 440px; }
    .callout { padding: 14px 18px; }

    .tldr-headline { font-size: 1.25rem; }
    .tldr-abstract { font-size: 1.05rem; }

    .tldr-keyword .keyword-tooltip {
        width: 260px;
        font-size: 0.85rem;
        padding: 12px 14px;
    }

    .nav-mobile-header { display: flex; }

    .section-nav-inner {
        display: none;
        flex-direction: column;
        align-items: stretch;
        gap: 0;
        padding: 0 0 8px 0;
        border-top: 1px solid rgba(0, 0, 0, 0.06);
    }

    .section-nav.menu-open .section-nav-inner { display: flex; }

    .section-nav-link {
        font-size: 0.92rem;
        padding: 10px 16px 10px 20px;
        margin-bottom: 0;
        text-align: left;
    }

    .section-nav-link::after { display: none; }

    .section-nav-link.active {
        background-color: rgba(0, 0, 0, 0.03);
        border-left: 2.5px solid;
    }

    .nav-color-gold.active { border-left-color: var(--secondary-color); }
    .nav-color-teal.active { border-left-color: var(--primary-color); }
    .nav-color-blue.active { border-left-color: var(--accent-color); }

    .section-nav-sep { display: none; }

    .citation-block { padding: 18px 16px; }
    .citation-block pre { font-size: 0.78rem; }
    .copy-citation-btn { position: relative; top: auto; right: auto; margin-bottom: 12px; }

        
}

/* =============================================
   14. RESPONSIVE -- SMALL MOBILE
   ============================================= */
@media (max-width: 576px) {
    body { font-size: 0.9rem; }
    .container { padding-left: 12px; padding-right: 12px; }
    .header-section { padding: 40px 0 30px 0; }
    .paper-title { font-size: 2.1rem; }
    .paper-subtitle { font-size: 1.1rem; margin-bottom: 30px; }
    .author-line { font-size: 0.85rem; }

    .section-title { font-size: 1.8rem; margin: 32px 0 20px 0; }
    .subsection-title { font-size: 1.6rem; margin: 24px 0 16px 0; }
    .section-figure img { max-height: 220px; }
    .section-figure--tall img { max-height: 360px; }

    .tldr-headline { font-size: 1.15rem; }
    .tldr-keyword .keyword-tooltip { width: 220px; font-size: 0.82rem; padding: 10px 12px; }

    .section-nav-link { font-size: 0.88rem; padding: 9px 14px; }
    .paper-invite { font-size: 0.88rem; margin: 40px auto 30px auto; }
}

/* =============================================
   15. TOUCH DEVICE OPTIMIZATIONS
   ============================================= */
@media (hover: none) {
    .author-link:hover, .paper-btn:hover, .section-figure img:hover { transform: none; }
    a, button, .btn { min-height: 44px; }
}