:root {
    --text: #1f2937;
    --muted: #4b5563;
    --accent: #0f4c81;
    --accent-strong: #0b3a63;
    --accent-bg: #e7f0fb;
    --border: #e5e7eb;
    --panel: #f8fafc;
    --content-max: 1120px;
    --gutter: clamp(1.25rem, 3.5vw, 3.25rem);
}

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

body {
    font-family: "Segoe UI", SegoeUI, -apple-system, BlinkMacSystemFont, "Helvetica Neue", Arial, sans-serif;
    margin: 0;
    line-height: 1.7;
    color: var(--text);
    background-color: #ffffff;
}

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

h1,
h2,
h3,
h4,
h5,
h6 {
    color: var(--accent-strong);
}

header {
    background: var(--accent-strong);
    color: #fff;
    padding: 20px 0;
    text-align: center;
}

header h1 {
    margin: 0;
    font-size: 2.5em;
}

nav {
    margin: 20px 0;
}

nav a {
    color: #fff;
    text-decoration: none;
    margin: 0 15px;
    font-weight: bold;
}

nav a:hover {
    text-decoration: underline;
}

section {
    padding: 10px 0;
}

footer {
    background: var(--accent-strong);
    color: #fff;
    text-align: center;
    padding: 10px 0;
    position: relative;
    bottom: 0;
    width: 100%;
}

.navbar {
    background-color: var(--accent-strong);
    color: white;
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav-container {
    max-width: var(--content-max);
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 var(--gutter);
    flex-wrap: wrap;
    gap: 0.75rem 1.25rem;
}

.logo {
    font-size: 1.5rem;
    font-weight: bold;
    line-height: 1.2;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
    margin: 0;
    padding: 0;
    flex-wrap: wrap;
}

.nav-toggle {
    display: none;
    align-items: center;
    justify-content: center;
    width: 44px;
    height: 40px;
    border: 1px solid rgba(255, 255, 255, 0.5);
    border-radius: 8px;
    background: transparent;
    color: #fff;
    cursor: pointer;
}

.nav-toggle .bar {
    display: block;
    width: 22px;
    height: 2px;
    background: #fff;
    border-radius: 999px;
    position: relative;
    transition: transform 0.2s ease, background 0.2s ease;
}

.nav-toggle .bar::before,
.nav-toggle .bar::after {
    content: "";
    position: absolute;
    left: 0;
    width: 22px;
    height: 2px;
    background: #fff;
    border-radius: 999px;
    transition: transform 0.2s ease, top 0.2s ease, opacity 0.2s ease;
}

.nav-toggle .bar::before {
    top: -7px;
}

.nav-toggle .bar::after {
    top: 7px;
}

.nav-toggle.is-open .bar {
    background: transparent;
}

.nav-toggle.is-open .bar::before {
    top: 0;
    transform: rotate(45deg);
}

.nav-toggle.is-open .bar::after {
    top: 0;
    transform: rotate(-45deg);
}

.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;
}

.nav-menu a {
    color: white;
    text-decoration: none;
    transition: opacity 0.3s;
}

.nav-menu a:hover {
    opacity: 0.8;
}

.social-icons {
    display: flex;
    gap: 15px;
    margin-top: 15px;
    flex-wrap: wrap;
}

.social-icons a {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    background-color: var(--accent-strong);
    color: white;
    border-radius: 50%;
    text-decoration: none;
    font-size: 18px;
    transition: transform 0.2s ease, box-shadow 0.2s ease, filter 0.2s ease;
    box-shadow: 0 6px 12px rgba(11, 58, 99, 0.2);
}

.social-icons a:hover {
    filter: brightness(0.95);
    transform: translateY(-2px);
    box-shadow: 0 10px 18px rgba(11, 58, 99, 0.25);
}

.social-icons a:focus-visible {
    outline: 2px solid var(--accent-strong);
    outline-offset: 3px;
}

.social-icons a.linkedin {
    background-color: #0a66c2;
}

.social-icons a.scholar {
    background-color: #4285f4;
}

.social-icons a.orcid {
    background-color: #a6ce39;
    color: #1b1b1b;
}

.social-icons a.researchgate {
    background-color: #00ccbb;
    color: #0b1a1a;
}

.social-icons a.github {
    background-color: #24292f;
}

.container {
    max-width: var(--content-max);
    margin: 0 auto;
    padding: 0 var(--gutter);
}

.wide-margins {
    padding-left: clamp(1.75rem, 5vw, 4.5rem);
    padding-right: clamp(1.75rem, 5vw, 4.5rem);
}

.section {
    margin: 0.35rem 0 1.1rem;
}

.about-content {
    background: #fff;
    border-radius: 18px;
    padding: clamp(1.2rem, 2.5vw, 2.2rem);
    padding-top: 0.9rem;
    box-shadow: 0 18px 40px rgba(11, 58, 99, 0.08);
}

.about-section {
    display: flex;
}

.about-content {
    display: grid;
    grid-template-columns: 250px 1fr;
    gap: 3rem;
    align-items: start;
}

.research-content {
    display: block;
    max-width: 900px;
    margin: 0 auto;
    text-align: left;
}

.research-content h1 {
    font-size: 2.25rem;
    letter-spacing: 0.01em;
    margin-bottom: 0.75rem;
}

.research-content h2 {
    font-size: 1.5rem;
    margin-top: 2rem;
    margin-bottom: 0.75rem;
    position: relative;
}

.research-content h2::after {
    content: "";
    display: block;
    width: 100%;
    height: 3px;
    background: var(--accent-strong);
    margin: 0.6rem 0 0;
    border-radius: 999px;
}

.full-underline::after {
    content: "";
    display: block;
    width: 100%;
    height: 3px;
    background: var(--accent-strong);
    margin: 0.6rem 0 0;
    border-radius: 999px;
}

.course {
    border-left: 3px solid rgba(15, 76, 129, 0.35);
    padding-left: 1.2rem;
    margin: 1.25rem 0;
}

.course h3 {
    color: var(--accent-strong);
    margin-bottom: 0.35rem;
}

.course-details {
    padding-left: 0.6rem;
}

.course-details h4 {
    color: var(--accent-strong);
    margin: 0.35rem 0 0.4rem;
}

.course-eval {
    color: var(--accent);
    margin: 0.2rem 0 0.4rem;
}

.course-period {
    color: var(--muted);
    font-style: italic;
    margin: 0 0 0.6rem;
}

.cv-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1rem;
    text-align: center;
}

.cv-content h1 {
    margin: 0.2rem 0 0.4rem;
}

.cv-download {
    display: inline-flex;
    align-items: center;
    gap: 0.6rem;
    padding: 0.6rem 1rem;
    border: 1px solid var(--accent-strong);
    border-radius: 10px;
    color: #fff;
    text-decoration: none;
    background: var(--accent-strong);
    transition: transform 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
}

.cv-download i {
    font-size: 1rem;
    color: #fff;
}

.cv-download:hover {
    border-color: rgba(11, 58, 99, 0.6);
    box-shadow: 0 8px 18px rgba(11, 58, 99, 0.15);
    transform: translateY(-1px);
}

.cv-viewer {
    width: 100%;
    max-width: 900px;
    height: 800px;
    border: 1px solid rgba(15, 76, 129, 0.2);
    border-radius: 12px;
    overflow: hidden;
    background: #fff;
}

.cv-viewer iframe {
    width: 100%;
    height: 100%;
    border: 0;
}

.research-content h3 {
    font-size: 1.15rem;
    margin-top: 1.5rem;
    margin-bottom: 0.5rem;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    color: var(--muted);
}

.research-content ul {
    margin: 0.75rem 0 1.5rem;
    padding-left: 1.1rem;
}

.research-content li {
    margin-bottom: 0.9rem;
    line-height: 1.6;
}

.research-content li strong {
    font-weight: 700;
}

.research-content a {
    color: var(--accent-strong);
    text-decoration: none;
    border-bottom: 1px solid rgba(11, 58, 99, 0.25);
}

.research-content a:hover {
    border-bottom-color: rgba(11, 58, 99, 0.65);
}

.research-content a:focus-visible {
    outline: 2px solid var(--accent-strong);
    outline-offset: 3px;
}

.about-photo img {
    max-width: 100%;
    height: auto;
    display: block;
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    margin-top: 4rem;
}

.center-headers h1,
.center-headers h2 {
    text-align: center;
}

.center-headers p {
    text-align: center;
}

.center-text {
    text-align: center;
}

.center-text ul {
    list-style-position: inside;
    padding-left: 0;
}

.skills-container {
    display: flex;
    gap: 2rem;
    justify-content: center;
    flex-wrap: wrap;
    margin: 2rem 0;
}

#skills h2 {
    text-align: center;
}

.skills-full {
    grid-column: 1 / -1;
    text-align: center;
    margin-top: 0.2rem;
    padding-top: 0.4rem;
    border-top: 1px solid rgba(15, 76, 129, 0.12);
}

.skills-full .skills-container {
    justify-content: center;
}

.skill-item {
    text-align: center;
    min-width: 110px;
}

.skill-item p {
    margin-top: 0.75rem;
}

.skill-icon {
    width: 64px;
    height: 64px;
    border-radius: 18px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    color: #fff;
    font-size: 1.75rem;
    box-shadow: 0 10px 20px rgba(11, 58, 99, 0.15);
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.skill-icon img {
    width: 44px;
    height: 44px;
    object-fit: contain;
    display: block;
}

.skill-item:hover .skill-icon {
    transform: translateY(-3px);
    box-shadow: 0 14px 24px rgba(11, 58, 99, 0.2);
}

.skill-icon.latex,
.skill-icon.python,
.skill-icon.rstudio,
.skill-icon.matlab,
.skill-icon.stata,
.skill-icon.vscode {
    background: #ffffff;
    border: 1px solid var(--border);
}

.latex-mark {
    font-size: 1.6rem;
    font-weight: 700;
    font-style: italic;
    letter-spacing: 0.02em;
}

.latex-mark span {
    position: relative;
    left: -0.32em;
    top: 0.32em;
}

@media (max-width: 1024px) {
    .about-content {
        grid-template-columns: 220px 1fr;
        gap: 2rem;
    }

    .cv-viewer {
        height: 640px;
    }
}

@media (max-width: 768px) {
    header h1 {
        font-size: 2em;
    }

    .navbar {
        position: sticky;
    }

    .nav-container {
        flex-direction: column;
        align-items: flex-start;
    }

    .nav-menu {
        display: none;
        width: 100%;
        gap: 0.75rem 1.25rem;
        padding-top: 0.5rem;
        flex-direction: column;
    }

    .nav-menu.is-open {
        display: flex;
    }

    .nav-toggle {
        display: inline-flex;
    }

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

    .about-photo img {
        margin-top: 0.75rem;
        max-width: 220px;
        margin-left: auto;
        margin-right: auto;
    }

    .skills-container {
        gap: 1.25rem;
    }

    .skill-item {
        min-width: 96px;
    }

    .cv-viewer {
        height: 520px;
    }
}

@media (max-width: 480px) {
    .logo {
        font-size: 1.25rem;
    }

    .nav-menu {
        flex-direction: column;
        align-items: flex-start;
        width: 100%;
    }

    .about-photo img {
        max-width: 180px;
    }

    .social-icons {
        justify-content: center;
    }

    .cv-download {
        width: 100%;
        justify-content: center;
    }

    .cv-viewer {
        height: 420px;
    }
}