:root {
    --bg:           #ffffff;
    --bg-alt:       #f7f7f5;
    --bg-card:      #ffffff;
    --accent:       #1a4a5e;
    --accent-light: rgba(26, 74, 94, 0.08);
    --text:         #111827;
    --muted:        #6b7280;
    --border:       rgba(0, 0, 0, 0.09);
    --border-soft:  rgba(0, 0, 0, 0.05);
    --card-shadow:  0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
    --card-hover:   0 8px 28px rgba(0,0,0,0.1);
    --nav-h:        64px;
    --radius:       10px;
    --max-w:        1080px;
}

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
    overflow-x: hidden;
}

#bg-canvas {
    position: fixed; inset: 0;
    z-index: 0; pointer-events: none;
}

/* ================================================================
   NAV
================================================================ */
nav {
    position: fixed; top: 0; left: 0; right: 0;
    height: var(--nav-h); z-index: 1000;
    transition: background 0.3s, box-shadow 0.3s;
}
nav.scrolled {
    background: rgba(255, 255, 255, 0.94);
    backdrop-filter: blur(14px);
    -webkit-backdrop-filter: blur(14px);
    box-shadow: 0 1px 0 var(--border);
}
.nav-inner {
    max-width: var(--max-w);
    margin: 0 auto; padding: 0 2rem; height: 100%;
    display: flex; align-items: center; justify-content: space-between;
}
.nav-logo {
    font-family: 'Playfair Display', Georgia, serif;
    font-size: 1.15rem; font-weight: 700;
    text-decoration: none; letter-spacing: 0.02em;
    color: var(--text);
}
.nav-links { display: flex; gap: 2.25rem; }
.nav-links a {
    text-decoration: none; color: var(--muted);
    font-size: 0.875rem; font-weight: 500;
    transition: color 0.2s; position: relative;
}
.nav-links a::after {
    content: ''; position: absolute;
    bottom: -3px; left: 0; right: 0;
    height: 1.5px; border-radius: 1px;
    background: var(--accent);
    transform: scaleX(0);
    transition: transform 0.25s ease;
}
.nav-links a:hover { color: var(--text); }
.nav-links a:hover::after { transform: scaleX(1); }

.nav-menu-btn {
    display: none; flex-direction: column; gap: 5px;
    background: none; border: none; cursor: pointer; padding: 6px;
}
.nav-menu-btn span {
    display: block; width: 22px; height: 1.5px;
    background: var(--muted); border-radius: 2px; transition: 0.3s;
}
.mobile-menu {
    display: none; position: fixed; top: var(--nav-h); left: 0; right: 0;
    background: rgba(255,255,255,0.98); backdrop-filter: blur(14px);
    z-index: 999; padding: 0.5rem 2rem 2rem;
    border-top: 1px solid var(--border);
    flex-direction: column;
}
.mobile-menu.open { display: flex; }
.mobile-link {
    text-decoration: none; color: var(--muted); font-size: 1rem;
    font-weight: 500; padding: 1rem 0; border-bottom: 1px solid var(--border-soft);
    transition: color 0.2s;
}
.mobile-link:last-child { border-bottom: none; }
.mobile-link:hover { color: var(--text); }

/* ================================================================
   HERO
================================================================ */
#hero {
    min-height: 100vh; display: flex; align-items: center;
    justify-content: center; gap: 5rem;
    max-width: var(--max-w); margin: 0 auto;
    padding: calc(var(--nav-h) + 4rem) 2rem 5rem;
    position: relative; z-index: 1;
}
.hero-text { flex: 1; min-width: 0; }

.hero-greeting {
    color: var(--accent); font-size: 0.8rem; font-weight: 600;
    letter-spacing: 0.22em; text-transform: uppercase; margin-bottom: 1rem;
    opacity: 0; animation: fadeUp 0.7s ease 0.1s forwards;
}
.hero-name {
    font-family: 'Playfair Display', Georgia, serif;
    font-size: clamp(2.8rem, 7vw, 5rem); font-weight: 700;
    line-height: 1.08; letter-spacing: -0.02em;
    color: var(--text); margin-bottom: 1.25rem;
    opacity: 0; animation: fadeUp 0.7s ease 0.2s forwards;
}
.hero-role {
    font-size: 1.05rem; font-weight: 400; color: var(--muted);
    min-height: 2rem; margin-bottom: 0.75rem;
    opacity: 0; animation: fadeUp 0.7s ease 0.35s forwards;
}
.cursor-blink {
    color: var(--accent); font-weight: 300;
    animation: blink 1s step-end infinite;
}
@keyframes blink { 0%,100%{opacity:1} 50%{opacity:0} }

.hero-tagline {
    color: var(--muted); font-size: 0.875rem; letter-spacing: 0.08em;
    margin-bottom: 2.5rem;
    opacity: 0; animation: fadeUp 0.7s ease 0.5s forwards;
}
.hero-btns {
    display: flex; gap: 1rem; flex-wrap: wrap; margin-bottom: 2rem;
    opacity: 0; animation: fadeUp 0.7s ease 0.65s forwards;
}
.social-row {
    display: flex; gap: 0.6rem;
    opacity: 0; animation: fadeUp 0.7s ease 0.8s forwards;
}
@keyframes fadeUp {
    from { opacity:0; transform:translateY(16px); }
    to   { opacity:1; transform:translateY(0); }
}

/* Buttons */
.btn-primary {
    display: inline-flex; align-items: center;
    padding: 0.72rem 1.6rem;
    background: var(--accent);
    color: #fff; text-decoration: none; border-radius: 8px;
    font-weight: 600; font-size: 0.875rem;
    transition: background 0.2s, transform 0.2s;
}
.btn-primary:hover {
    background: #153d50;
    transform: translateY(-2px);
}
.btn-outline {
    display: inline-flex; align-items: center;
    padding: 0.72rem 1.6rem;
    border: 1.5px solid var(--border); color: var(--text);
    text-decoration: none; border-radius: 8px;
    font-weight: 600; font-size: 0.875rem;
    transition: border-color 0.2s, color 0.2s, transform 0.2s;
}
.btn-outline:hover {
    border-color: var(--accent); color: var(--accent);
    transform: translateY(-2px);
}
.social-icon {
    display: flex; align-items: center; justify-content: center;
    width: 40px; height: 40px; border-radius: 8px;
    border: 1.5px solid var(--border); color: var(--muted);
    text-decoration: none;
    transition: color 0.2s, border-color 0.2s, transform 0.2s;
}
.social-icon:hover {
    color: var(--accent); border-color: var(--accent);
    transform: translateY(-2px);
}

/* Photo */
.hero-photo {
    flex: 0 0 auto; display: flex; align-items: center; justify-content: center;
    opacity: 0; animation: fadeUp 0.7s ease 0.25s forwards;
}
.photo-wrapper {
    width: 280px; height: 280px; border-radius: 50%;
    position: relative; overflow: hidden;
    border: 2px solid rgba(26, 74, 94, 0.2);
}
.photo-spin-ring { display: none; }
.photo-wrapper img {
    position: absolute; inset: 0;
    width: 100%; height: 100%;
    border-radius: 50%; object-fit: cover;
}

/* ================================================================
   STATS BAR
================================================================ */
.stats-bar {
    position: relative; z-index: 1;
    background: var(--bg-alt);
    border-top: 1px solid var(--border);
    border-bottom: 1px solid var(--border);
    display: flex; align-items: center; justify-content: center;
    gap: 0; padding: 2rem; flex-wrap: wrap;
}
.stat-item {
    display: flex; flex-direction: column; align-items: center;
    padding: 0.5rem 3rem; text-align: center;
}
.stat-num {
    font-family: 'Playfair Display', Georgia, serif;
    font-size: 1.9rem; font-weight: 700; color: var(--accent); line-height: 1;
    letter-spacing: -0.02em;
}
.stat-label {
    font-size: 0.71rem; font-weight: 500; color: var(--muted);
    letter-spacing: 0.12em; text-transform: uppercase; margin-top: 0.4rem;
}
.stat-divider {
    width: 1px; height: 36px; background: var(--border);
    flex: 0 0 auto;
}

/* ================================================================
   SECTIONS
================================================================ */
.section { position: relative; z-index: 1; padding: 6rem 2rem; }
.alt-bg   { background: var(--bg-alt); }
.section-inner { max-width: var(--max-w); margin: 0 auto; }
.section-header { margin-bottom: 3.5rem; }
.section-tag {
    display: inline-block; font-size: 0.71rem; font-weight: 700;
    letter-spacing: 0.22em; text-transform: uppercase;
    color: var(--accent); margin-bottom: 0.5rem;
}
.section-header h2 {
    font-family: 'Playfair Display', Georgia, serif;
    font-size: clamp(1.7rem, 3.5vw, 2.25rem); font-weight: 700;
    letter-spacing: -0.015em; color: var(--text);
    margin-bottom: 0.5rem;
}
.section-sub {
    color: var(--muted); font-size: 1rem; line-height: 1.7; max-width: 600px;
}

/* Scroll reveal */
.reveal {
    opacity: 0; transform: translateY(18px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}
.reveal.visible { opacity: 1; transform: translateY(0); }

/* ================================================================
   ABOUT & EDUCATION
================================================================ */
.about-grid {
    display: grid; grid-template-columns: 1fr 1fr;
    gap: 4rem; align-items: start;
}
.about-text p {
    color: var(--muted); font-size: 1rem; line-height: 1.85;
    margin-bottom: 1.1rem;
}
.edu-card-main {
    background: var(--bg-card); border: 1px solid var(--border);
    border-radius: var(--radius); padding: 2rem;
    box-shadow: var(--card-shadow);
}
.edu-card-header {
    display: flex; justify-content: space-between;
    align-items: flex-start; gap: 1rem; margin-bottom: 1.5rem;
}
.edu-school {
    font-size: 0.97rem; font-weight: 700; color: var(--text);
    margin-bottom: 0.2rem; line-height: 1.4;
}
.edu-dates { font-size: 0.8rem; color: var(--muted); }
.gpa-badge {
    flex: 0 0 auto;
    background: var(--accent);
    color: #fff; padding: 0.3rem 0.8rem; border-radius: 20px;
    font-size: 0.8rem; font-weight: 700; white-space: nowrap;
}
.degree-list { margin-bottom: 1.25rem; display: flex; flex-direction: column; gap: 0.5rem; }
.degree-row  { display: flex; gap: 0.5rem; flex-wrap: wrap; }
.degree-pill {
    display: inline-block; padding: 0.3rem 0.85rem;
    border-radius: 6px; font-size: 0.8rem; font-weight: 600;
}
.degree-pill.bs {
    background: var(--accent); color: #fff;
}
.degree-pill.minor {
    background: var(--accent-light); color: var(--accent);
    border: 1px solid rgba(26, 74, 94, 0.18);
}
.edu-honors { display: flex; flex-wrap: wrap; gap: 0.5rem; }
.honor-chip {
    background: var(--bg-alt); color: var(--muted);
    padding: 0.28rem 0.7rem; border-radius: 20px;
    font-size: 0.77rem; font-weight: 500;
    border: 1px solid var(--border-soft);
}

/* ================================================================
   RESEARCH CARDS
================================================================ */
.research-card {
    background: var(--bg-card); border: 1px solid var(--border);
    border-left: 3px solid var(--accent);
    border-radius: var(--radius); padding: 1.75rem 2rem;
    box-shadow: var(--card-shadow); margin-bottom: 1.25rem;
    transition: box-shadow 0.25s ease;
}
.research-card:hover { box-shadow: var(--card-hover); }
.research-card-header {
    display: flex; justify-content: space-between;
    align-items: flex-start; gap: 1rem; margin-bottom: 1rem; flex-wrap: wrap;
}
.research-meta { display: flex; align-items: center; gap: 0.75rem; flex-wrap: wrap; }
.research-org { font-size: 1rem; font-weight: 700; color: var(--text); }
.research-badge {
    display: inline-block; padding: 0.18rem 0.6rem;
    border-radius: 20px; font-size: 0.7rem; font-weight: 700;
    letter-spacing: 0.05em; text-transform: uppercase;
}
.research-badge.active { background: var(--accent-light); color: var(--accent); }
.research-badge.past   { background: rgba(0,0,0,0.05); color: var(--muted); }
.research-dates { font-size: 0.8rem; color: var(--muted); font-weight: 500; white-space: nowrap; }

.entry-summary {
    color: var(--muted); font-size: 0.95rem; line-height: 1.8; margin-bottom: 1.1rem;
}

/* ================================================================
   TAGS
================================================================ */
.research-tags, .exp-tags, .skill-tags { display: flex; flex-wrap: wrap; gap: 0.4rem; }
.tag {
    background: var(--bg-alt); color: var(--muted);
    padding: 0.25rem 0.7rem; border-radius: 4px;
    font-size: 0.76rem; font-weight: 500;
    border: 1px solid var(--border);
}
.tag.sm { font-size: 0.71rem; padding: 0.2rem 0.6rem; }

/* ================================================================
   PUBLICATIONS
================================================================ */
.pub-list {
    display: flex; flex-direction: column;
    border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden;
}
.pub-item {
    display: flex; align-items: center; gap: 1.75rem;
    background: var(--bg-card);
    padding: 1.5rem 1.75rem;
    border-bottom: 1px solid var(--border-soft);
    transition: background 0.2s;
}
.pub-item:last-child { border-bottom: none; }
.pub-item:hover { background: var(--bg-alt); }
.pub-number {
    font-family: 'Playfair Display', Georgia, serif;
    font-size: 1.5rem; font-weight: 700; color: rgba(0,0,0,0.12);
    flex: 0 0 auto; line-height: 1; min-width: 2rem;
}
.pub-body { flex: 1; }
.pub-body h3 { font-size: 0.97rem; font-weight: 700; color: var(--text); margin-bottom: 0.3rem; }
.pub-meta { font-size: 0.82rem; color: var(--muted); display: flex; align-items: center; gap: 0.4rem; flex-wrap: wrap; }
.pub-role {
    display: inline-block; padding: 0.12rem 0.55rem; border-radius: 4px;
    font-weight: 600; font-size: 0.73rem;
}
.pub-role.first-author { background: var(--accent-light); color: var(--accent); }
.pub-role.co-author    { background: rgba(0,0,0,0.05); color: var(--muted); }
.pub-status {
    flex: 0 0 auto; background: var(--bg-alt);
    color: var(--muted); padding: 0.3rem 0.8rem;
    border-radius: 20px; font-size: 0.73rem; font-weight: 600;
    border: 1px solid var(--border); white-space: nowrap;
}

/* ================================================================
   PRESENTATIONS
================================================================ */
.pres-list { display: flex; flex-direction: column; }
.pres-item {
    display: flex; gap: 2.5rem; align-items: flex-start;
    padding: 1.5rem 0;
    border-bottom: 1px solid var(--border-soft);
}
.pres-item:first-child { border-top: 1px solid var(--border-soft); }
.pres-date {
    flex: 0 0 auto; font-size: 0.8rem; font-weight: 700;
    color: var(--accent); min-width: 4.5rem; padding-top: 0.1rem;
}
.pres-body h3 { font-size: 0.95rem; font-weight: 700; color: var(--text); margin-bottom: 0.3rem; }
.pres-body p  { font-size: 0.84rem; color: var(--muted); margin-bottom: 0.5rem; }
.pres-type-group { display: flex; gap: 0.4rem; flex-wrap: wrap; margin-top: 0.25rem; }
.pres-type {
    display: inline-block; background: var(--bg-alt);
    color: var(--muted); padding: 0.18rem 0.6rem;
    border-radius: 4px; font-size: 0.73rem; font-weight: 600;
    border: 1px solid var(--border);
}

/* ================================================================
   EXPERIENCE GRID
================================================================ */
.exp-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 1.25rem; }
.exp-card {
    background: var(--bg-card); border: 1px solid var(--border);
    border-radius: var(--radius); padding: 1.5rem 1.75rem;
    box-shadow: var(--card-shadow);
    transition: box-shadow 0.25s ease;
    display: flex; flex-direction: column; gap: 0.85rem;
}
.exp-card:hover { box-shadow: var(--card-hover); }
.exp-card-top {
    display: flex; justify-content: space-between;
    align-items: flex-start; gap: 1rem;
}
.exp-card-top h3 { font-size: 0.97rem; font-weight: 700; color: var(--text); }
.exp-role { font-size: 0.8rem; color: var(--muted); font-weight: 500; margin-top: 0.2rem; }
.exp-date {
    font-size: 0.76rem; color: var(--muted); white-space: nowrap; flex: 0 0 auto;
}

/* ================================================================
   SKILLS
================================================================ */
.skills-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 1.25rem; }
.skill-group {
    background: var(--bg-card); border: 1px solid var(--border);
    border-radius: var(--radius); padding: 1.5rem;
    box-shadow: var(--card-shadow);
}
.skill-group h4 {
    font-size: 0.73rem; font-weight: 700; letter-spacing: 0.16em;
    text-transform: uppercase; color: var(--accent); margin-bottom: 1rem;
}

/* ================================================================
   HONORS
================================================================ */
.honors-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 1rem; }
.honor-card {
    background: var(--bg-card); border: 1px solid var(--border);
    border-radius: var(--radius); padding: 1.25rem;
    box-shadow: var(--card-shadow);
    transition: box-shadow 0.25s ease;
}
.honor-card:hover { box-shadow: var(--card-hover); }
.honor-year {
    display: inline-block;
    font-size: 0.76rem; font-weight: 700; color: var(--accent);
    margin-bottom: 0.5rem; letter-spacing: 0.05em;
}
.honor-card h4 { font-size: 0.88rem; font-weight: 700; color: var(--text); margin-bottom: 0.2rem; }
.honor-card p  { font-size: 0.78rem; color: var(--muted); }

/* ================================================================
   FUN FACTS
================================================================ */
.funfacts-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 1.25rem; }
.funfact-card {
    background: var(--bg-card); border: 1px solid var(--border);
    border-radius: var(--radius); padding: 1.5rem;
    text-align: center; box-shadow: var(--card-shadow);
    transition: box-shadow 0.25s ease;
}
.funfact-card:hover { box-shadow: var(--card-hover); }
.funfact-icon { display: block; font-size: 2rem; margin-bottom: 0.75rem; }
.funfact-card h4 { font-size: 0.92rem; font-weight: 700; color: var(--text); margin-bottom: 0.4rem; }
.funfact-card p  { font-size: 0.85rem; color: var(--muted); line-height: 1.7; }

/* ================================================================
   RESEARCH PROJECT TITLE
================================================================ */
.research-title {
    font-size: 0.97rem; font-weight: 700; color: var(--text);
    margin-bottom: 0.75rem;
}

/* ================================================================
   CONTACT
================================================================ */
.contact-layout {
    display: grid; grid-template-columns: 1fr;
    max-width: 32rem;
}
.contact-heading {
    font-family: 'Playfair Display', Georgia, serif;
    font-size: clamp(1.7rem, 3.5vw, 2.25rem); font-weight: 700;
    letter-spacing: -0.015em; color: var(--text);
    margin: 0.5rem 0 1.25rem;
}
.contact-info p {
    color: var(--muted); font-size: 1rem; line-height: 1.8; margin-bottom: 2rem;
}
.contact-links { display: flex; flex-direction: column; gap: 0.85rem; }
.contact-link {
    display: flex; align-items: center; gap: 0.7rem;
    color: var(--muted); text-decoration: none; font-size: 0.9rem; font-weight: 500;
    transition: color 0.2s;
}
.contact-link:hover { color: var(--accent); }

/* ================================================================
   FOOTER
================================================================ */
footer {
    position: relative; z-index: 1; text-align: center;
    padding: 2rem; color: var(--muted); font-size: 0.8rem;
    border-top: 1px solid var(--border);
}

/* ================================================================
   RESPONSIVE
================================================================ */
@media (max-width: 900px) {
    .honors-grid { grid-template-columns: repeat(2, 1fr); }
    .exp-grid     { grid-template-columns: 1fr; }
}
@media (max-width: 820px) {
    #hero {
        flex-direction: column-reverse; text-align: center;
        gap: 2.5rem; padding-top: calc(var(--nav-h) + 2rem);
    }
    .hero-btns  { justify-content: center; }
    .social-row { justify-content: center; }
    .photo-wrapper { width: 200px; height: 200px; }
    .about-grid  { grid-template-columns: 1fr; gap: 2.5rem; }
    .skills-grid { grid-template-columns: 1fr; }
    .nav-links    { display: none; }
    .nav-menu-btn { display: flex; }
    .stat-divider { display: none; }
    .stat-item    { padding: 0.5rem 1.25rem; }
    .funfacts-grid { grid-template-columns: repeat(2, 1fr); }
    .pres-item    { flex-direction: column; gap: 0.5rem; }
}
@media (max-width: 520px) {
    .honors-grid   { grid-template-columns: 1fr; }
    .funfacts-grid { grid-template-columns: 1fr; }
    .section { padding: 4rem 1.25rem; }
    .research-card-header { flex-direction: column; }
}

/* ================================================================
   PERSONAL PROJECTS
================================================================ */
.projects-list { display: flex; flex-direction: column; gap: 1.25rem; }
.project-card {
    background: var(--bg-card); border: 1px solid var(--border);
    border-left: 3px solid var(--accent);
    border-radius: var(--radius); padding: 1.75rem 2rem;
    box-shadow: var(--card-shadow);
    transition: box-shadow 0.25s ease;
}
.project-card:hover { box-shadow: var(--card-hover); }
.project-card-top { margin-bottom: 0.9rem; }
.project-title-row {
    display: flex; align-items: center; gap: 0.65rem; margin-bottom: 0.45rem;
}
.project-title-row h3 { font-size: 1.05rem; font-weight: 700; color: var(--text); }
.project-gh-link {
    display: flex; align-items: center; color: var(--muted);
    text-decoration: none; transition: color 0.2s;
    opacity: 0.55;
}
.project-gh-link:hover { color: var(--accent); opacity: 1; }
.project-meta-row { display: flex; align-items: center; gap: 0.65rem; }
.project-lang {
    display: inline-block; padding: 0.17rem 0.6rem;
    border-radius: 4px; font-size: 0.72rem; font-weight: 700;
    letter-spacing: 0.03em;
}
.lang-cpp { background: rgba(0, 89, 156, 0.1);  color: #00599c; }
.lang-ts  { background: rgba(49, 120, 198, 0.1); color: #3178c6; }
.lang-py  { background: rgba(55, 118, 171, 0.1); color: #3776ab; }
.project-date { font-size: 0.8rem; color: var(--muted); font-weight: 500; }
.project-tags { display: flex; flex-wrap: wrap; gap: 0.4rem; margin-top: 0.9rem; }

/* ================================================================
   PROGRESS BAR
================================================================ */
#progress-bar {
    position: fixed; top: 0; left: 0;
    height: 3px; width: 0%;
    background: linear-gradient(90deg, var(--accent), #3a9aba);
    z-index: 2000; pointer-events: none;
    transition: width 0.06s linear;
}

/* ================================================================
   HERO AMBIENT WASH
================================================================ */
#hero::before {
    content: ''; position: absolute;
    top: -10%; right: -8%;
    width: 55vmin; height: 55vmin; border-radius: 50%;
    background: radial-gradient(circle, rgba(26,74,94,0.07) 0%, transparent 65%);
    pointer-events: none; z-index: 0;
}

/* ================================================================
   STATS BAR — colored
================================================================ */
.stats-bar {
    background: linear-gradient(135deg, #1a4a5e 0%, #1e6e94 100%);
    border-top: none; border-bottom: none;
}
.stat-num   { color: #ffffff; }
.stat-label { color: rgba(255,255,255,0.7); }
.stat-divider { background: rgba(255,255,255,0.2); }

/* ================================================================
   SECTION TAG UNDERLINE
================================================================ */
.section-tag::after {
    content: ''; display: block;
    width: 28px; height: 2px;
    background: var(--accent);
    margin-top: 6px; border-radius: 2px;
}

/* ================================================================
   RESEARCH FILTER
================================================================ */
.research-filter {
    display: flex; gap: 0.5rem; margin-bottom: 1.5rem;
}
.filter-btn {
    padding: 0.35rem 1.1rem; border-radius: 20px;
    border: 1.5px solid var(--border);
    background: transparent; color: var(--muted);
    font-size: 0.8rem; font-weight: 600;
    cursor: pointer; transition: background 0.2s, color 0.2s, border-color 0.2s;
    font-family: inherit;
}
.filter-btn:hover { border-color: var(--accent); color: var(--accent); }
.filter-btn.active {
    background: var(--accent); color: #fff; border-color: var(--accent);
}
.research-card.hidden { display: none; }

/* ================================================================
   NAV SCROLL SPY
================================================================ */
.nav-links a.active-section { color: var(--text); }
.nav-links a.active-section::after { transform: scaleX(1); }

/* ================================================================
   SOCIAL ICONS — fill on hover
================================================================ */
.social-icon:hover {
    background: var(--accent); color: #fff; border-color: var(--accent);
    transform: translateY(-2px);
}