:root {
    --color-bg: #030712;
    --color-surface: #0f172a;
    --color-surface-muted: rgba(15, 23, 42, 0.72);
    --color-text: #f9fafb;
    --color-muted: #cbd5f5;
    --color-border: rgba(148, 163, 184, 0.35);
    --color-accent: #38bdf8;
    --color-accent-dark: #0ea5e9;
    --color-eyebrow: #38bdf8;
    --color-hero: linear-gradient(135deg, #020617 0%, #0f172a 100%);
    --shadow-soft: 0 25px 60px -20px rgba(2, 6, 23, 0.8);
    --shadow-card: 0 25px 50px -20px rgba(8, 47, 73, 0.6);
}

* {
    box-sizing: border-box;
}

body {
    font-family: 'Roboto', sans-serif;
    margin: 0;
    background: var(--color-bg);
    color: var(--color-text);
    line-height: 1.65;
    transition: background-color 0.4s ease, color 0.4s ease;
}

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

a {
    color: inherit;
}

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

.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 24px;
}

nav {
    position: sticky;
    top: 0;
    z-index: 1000;
    backdrop-filter: blur(12px);
    background: rgba(3, 7, 18, 0.85);
    border-bottom: 1px solid var(--color-border);
    transition: background-color 0.3s ease, border-color 0.3s ease;
}


.nav-container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 14px 24px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.brand {
    display: flex;
    align-items: center;
    gap: 12px;
    font-weight: 600;
    color: var(--color-text);
    text-decoration: none;
    letter-spacing: 0.02em;
}

.brand span {
    font-size: 1rem;
}

.logo {
    height: 56px;
    width: 56px;
    object-fit: contain;
}

.nav-links {
    list-style: none;
    display: flex;
    align-items: center;
    gap: 28px;
    margin: 0;
    padding: 0;
}

.nav-links a {
    font-weight: 500;
    color: var(--color-muted);
    text-decoration: none;
    position: relative;
    padding-bottom: 4px;
    transition: color 0.3s ease;
}

.nav-links a::after {
    content: '';
    position: absolute;
    left: 0;
    bottom: 0;
    width: 100%;
    height: 2px;
    background: var(--color-accent);
    transform: scaleX(0);
    transform-origin: left;
    transition: transform 0.3s ease;
}

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

.nav-links a:hover,
.nav-links a:focus-visible,
.nav-links a.active {
    color: var(--color-text);
}

.nav-toggle {
    display: none;
    background: none;
    border: none;
    color: var(--color-text);
    font-size: 1.5rem;
    cursor: pointer;
}


header#hero {
    background: var(--color-hero);
    color: #f8fafc;
    padding: 120px 0 80px;
    position: relative;
    overflow: hidden;
}

.hero-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 48px;
    align-items: center;
}

.hero-copy h1 {
    font-size: clamp(2.5rem, 5vw, 3.4rem);
    margin: 16px 0;
    line-height: 1.1;
    letter-spacing: -0.02em;
}

.eyebrow {
    text-transform: uppercase;
    letter-spacing: 0.32em;
    font-weight: 600;
    color: var(--color-eyebrow);
    margin: 0;
    font-size: 0.8rem;
}

.hero-tagline {
    font-size: 1.05rem;
    max-width: 560px;
    margin-bottom: 32px;
    color: rgba(248, 250, 252, 0.85);
}

.hero-cta {
    display: flex;
    flex-wrap: wrap;
    gap: 16px;
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    padding: 12px 28px;
    border-radius: 999px;
    font-weight: 600;
    text-decoration: none;
    cursor: pointer;
    transition: transform 0.2s ease, box-shadow 0.2s ease, background 0.3s ease;
}

.btn.primary {
    background: var(--color-accent);
    color: #0f172a;
    box-shadow: var(--shadow-soft);
}

.btn.primary:hover,
.btn.primary:focus-visible {
    background: var(--color-accent-dark);
    transform: translateY(-2px);
}

.btn.secondary {
    border: 1px solid rgba(248, 250, 252, 0.6);
    color: #f8fafc;
    background: transparent;
}

.btn.secondary:hover,
.btn.secondary:focus-visible {
    border-color: #f8fafc;
    transform: translateY(-2px);
}

.hero-media {
    display: grid;
    gap: 24px;
    justify-items: center;
}

.hero-image-frame {
    padding: 12px;
    border-radius: 28px;
    background: rgba(15, 23, 42, 0.45);
    backdrop-filter: blur(14px);
    box-shadow: var(--shadow-card);
}

.hero-image {
    border-radius: 24px;
    width: min(320px, 80vw);
    object-fit: cover;
}

.hero-affiliations {
    display: flex;
    gap: 20px;
    align-items: center;
}

.header-link {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 10px;
    border-radius: 16px;
    background: rgba(15, 23, 42, 0.35);
    transition: transform 0.3s ease;
}

.header-link:hover,
.header-link:focus-visible {
    transform: translateY(-3px);
}

.header-logo_kcdh {
    height: 100px;
    width: 100px;
    object-fit: contain;
}

.header-logo_aide {
    height: 100px;
    width: 100px;
    object-fit: contain;
}

.hero-scroll-cue {
    position: absolute;
    bottom: 20px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 6px;
    font-size: 0.85rem;
    letter-spacing: 0.18em;
    text-transform: uppercase;
    color: rgba(248, 250, 252, 0.7);
    animation: bounce 2.8s infinite;
}

@keyframes bounce {
    0%, 100% { transform: translate(-50%, 0); }
    50% { transform: translate(-50%, -8px); }
}

main {
    padding: 80px 0 120px;
}

section {
    background: var(--color-surface);
    margin-bottom: 36px;
    padding: 48px;
    border-radius: 32px;
    border: 1px solid var(--color-border);
    box-shadow: var(--shadow-card);
    transition: background 0.4s ease, border-color 0.4s ease, box-shadow 0.4s ease;
}

section h2 {
    font-size: 1.9rem;
    margin-top: 0;
    margin-bottom: 24px;
    display: flex;
    align-items: center;
    gap: 12px;
}

section h2 i {
    font-size: 1.6rem;
    color: var(--color-accent);
}

.about-content {
    display: grid;
    grid-template-columns: minmax(0, 2fr) minmax(0, 1fr);
    gap: 36px;
    align-items: start;
}

.about-skills {
    padding: 24px;
    background: var(--color-surface-muted);
    border-radius: 24px;
    box-shadow: var(--shadow-soft);
}

.about-skills h3 {
    margin: 0 0 12px;
    font-size: 1.1rem;
}

.skill-list {
    list-style: none;
    padding: 0;
    margin: 0;
    display: grid;
    gap: 10px;
}

.skill-list li {
    background: var(--color-surface-muted);
    border-radius: 14px;
    padding: 12px 16px;
    display: flex;
    align-items: center;
    gap: 12px;
    color: var(--color-muted);
}

.skill-list i {
    color: var(--color-accent);
}

.experience-grid {
    display: grid;
    grid-template-columns: minmax(0, 300px) minmax(0, 1fr);
    gap: 36px;
    align-items: start;
}

.experience-list {
    display: flex;
    flex-direction: column;
    gap: 10px;
    padding: 16px;
    background: var(--color-surface-muted);
    border: 1px solid var(--color-border);
    border-radius: 24px;
}

.experience-item {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    gap: 6px;
    padding: 14px 18px;
    border-radius: 18px;
    border: 1px solid transparent;
    background: transparent;
    color: var(--color-muted);
    font: inherit;
    text-align: left;
    cursor: pointer;
    transition: border-color 0.3s ease, background 0.3s ease, color 0.3s ease, transform 0.2s ease;
}

.experience-item:hover,
.experience-item:focus-visible {
    border-color: rgba(14, 165, 233, 0.4);
    background: rgba(14, 165, 233, 0.08);
    color: var(--color-text);
    transform: translateX(4px);
}

.experience-item.active {
    border-color: var(--color-accent);
    background: rgba(14, 165, 233, 0.12);
    color: var(--color-text);
}

.experience-role {
    font-weight: 600;
}

.experience-meta {
    font-size: 0.9rem;
    color: var(--color-muted);
}

.experience-detail {
    background: var(--color-surface-muted);
    border-radius: 28px;
    border: 1px solid var(--color-border);
    padding: 32px;
    box-shadow: var(--shadow-soft);
    min-height: 100%;
}

.experience-panel {
    display: none;
    opacity: 0;
    transform: translateY(10px);
}

.experience-panel.active {
    display: block;
    animation: experienceFade 0.4s ease forwards;
}

@keyframes experienceFade {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.experience-header h3 {
    margin: 0;
    font-size: 1.4rem;
}

.experience-header p {
    margin: 8px 0 0;
    color: var(--color-muted);
}

.experience-duration {
    display: inline-block;
    margin-top: 12px;
    font-size: 0.9rem;
    color: var(--color-accent);
    font-weight: 600;
}

.experience-subsection {
    margin-top: 24px;
}

.experience-subsection h4 {
    margin: 0 0 10px;
    font-size: 1.05rem;
    color: var(--color-text);
}

.experience-detail ul {
    padding-left: 20px;
    margin: 0;
    display: grid;
    gap: 8px;
}

.section-placeholder {
    margin: 0;
    padding: 32px;
    text-align: center;
    font-size: 1.1rem;
    color: var(--color-muted);
    background: var(--color-surface-muted);
    border-radius: 24px;
    border: 1px dashed var(--color-border);
}

.publications-grid {
    display: grid;
    grid-template-columns: minmax(0, 260px) minmax(0, 1fr);
    gap: 32px;
    align-items: start;
}

.publication-tabs {
    display: flex;
    flex-direction: column;
    gap: 10px;
    padding: 16px;
    background: var(--color-surface-muted);
    border-radius: 24px;
    border: 1px solid var(--color-border);
}

.publication-tab {
    border: 1px solid transparent;
    border-radius: 16px;
    padding: 12px 16px;
    background: transparent;
    color: var(--color-muted);
    font: inherit;
    text-align: left;
    cursor: pointer;
    transition: border-color 0.3s ease, background 0.3s ease, color 0.3s ease, transform 0.2s ease;
}

.publication-tab:hover,
.publication-tab:focus-visible {
    border-color: rgba(14, 165, 233, 0.4);
    background: rgba(14, 165, 233, 0.08);
    color: var(--color-text);
    transform: translateX(4px);
}

.publication-tab.active {
    border-color: var(--color-accent);
    background: rgba(14, 165, 233, 0.12);
    color: var(--color-text);
}

.publication-panels {
    background: var(--color-surface-muted);
    border-radius: 28px;
    border: 1px solid var(--color-border);
    padding: 32px;
    box-shadow: var(--shadow-soft);
}

.publication-panel {
    display: none;
    opacity: 0;
    transform: translateY(10px);
}

.publication-panel.active {
    display: block;
    animation: publicationFade 0.4s ease forwards;
}

@keyframes publicationFade {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.publication-panel h3 {
    margin-top: 0;
    font-size: 1.3rem;
}

.publication-year-list {
    list-style: none;
    padding: 0;
    margin: 24px 0 0;
    display: grid;
    gap: 16px;
}

.publication-year-list li {
    border: 1px solid var(--color-border);
    border-radius: 18px;
    padding: 18px 20px;
    background: rgba(8, 47, 73, 0.4);
}

.publication-details {
    font-size: 0.98rem;
}

.paper-link {
    color: var(--color-text);
    text-decoration: none;
}

.paper-link:hover,
.paper-link:focus-visible {
    color: var(--color-accent);
}

.contact-cta {
    font-size: 1.15rem;
    font-weight: 600;
    margin: 0 0 24px;
}

.contact-card i:first-child {
    font-size: 1.8rem;
    color: var(--color-accent);
}

.contact-card i:last-child {
    font-size: 1rem;
    color: var(--color-muted);
}

.contact-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 28px;
}

.contact-group {
    background: var(--color-surface-muted);
    border-radius: 24px;
    border: 1px solid var(--color-border);
    padding: 28px;
    box-shadow: var(--shadow-soft);
}

.contact-group h3 {
    margin: 0 0 18px;
    font-size: 1.2rem;
}

.contact-card-list {
    display: grid;
    gap: 16px;
}

.contact-card {
    display: grid;
    grid-template-columns: auto 1fr auto;
    gap: 18px;
    align-items: center;
    padding: 18px 22px;
    border-radius: 18px;
    border: 1px solid transparent;
    background: rgba(8, 47, 73, 0.35);
    color: inherit;
    text-decoration: none;
    transition: border-color 0.3s ease, background 0.3s ease, transform 0.2s ease;
}

.contact-card span {
    font-weight: 600;
    display: block;
}

.contact-card:hover,
.contact-card:focus-visible {
    border-color: var(--color-accent);
    background: rgba(14, 165, 233, 0.14);
    transform: translateY(-3px);
}

footer {
    background: var(--color-hero);
    padding: 40px 0;
    color: rgba(248, 250, 252, 0.85);
}

.footer-content {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: center;
    gap: 12px;
}

.fade-in {
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
    opacity: 1;
    transform: translateY(0);
}

@media (max-width: 900px) {
    .about-content {
        grid-template-columns: 1fr;
    }

    .hero-content {
        grid-template-columns: 1fr;
    }

    .hero-media {
        order: -1;
    }

    .experience-grid {
        grid-template-columns: 1fr;
    }

    .experience-list {
        flex-direction: row;
        overflow-x: auto;
        padding: 12px;
        gap: 12px;
    }

    .experience-item {
        min-width: 220px;
    }

    .experience-detail {
        padding: 28px;
    }

    .publications-grid {
        grid-template-columns: 1fr;
    }

    .publication-tabs {
        flex-direction: row;
        overflow-x: auto;
        padding: 12px;
    }

    .publication-tab {
        min-width: 160px;
    }

    .publication-panels {
        padding: 28px;
    }
}

@media (max-width: 768px) {
    .nav-links {
        position: absolute;
        inset: 72px 24px auto;
        flex-direction: column;
        gap: 18px;
        background: var(--color-surface);
        border-radius: 20px;
        border: 1px solid var(--color-border);
        padding: 24px;
        box-shadow: var(--shadow-soft);
        display: none;
    }

    .nav-links.open {
        display: flex;
    }

    .nav-toggle {
        display: block;
    }

    section {
        padding: 36px;
    }

    .experience-list {
        flex-direction: column;
        overflow: visible;
    }

    .experience-item {
        min-width: auto;
    }

    .publication-tabs {
        flex-direction: column;
        overflow: visible;
    }

    .publication-tab {
        min-width: auto;
    }

    .contact-group {
        padding: 24px;
    }

    .contact-card {
        grid-template-columns: auto 1fr;
        gap: 14px;
    }
}

@media (max-width: 520px) {
    .hero-cta {
        flex-direction: column;
        align-items: stretch;
    }

    section {
        padding: 28px;
    }

    header#hero {
        padding: 100px 0 60px;
    }

    .footer-content {
        flex-direction: column;
        align-items: flex-start;
    }

    .contact-group {
        padding: 20px;
    }

    .contact-card {
        grid-template-columns: auto 1fr;
        gap: 12px;
        padding: 16px 18px;
    }
}

@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;
    }
}