/* ===== CSS Variables ===== */
:root {
    --bg-primary: #ffffff;
    --bg-secondary: #f8f9fa;
    --text-primary: #1a1a1a;
    --text-secondary: #666;
    --border-color: #e0e0e0;
    --accent: #0066cc;
    --accent-hover: #0052a3;
    --spacing: 1rem;
    --max-width: 900px;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
    background-color: var(--bg-primary);
}

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

/* ===== NAVIGATION ===== */
.navbar {
    background-color: var(--bg-primary);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav-container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 1rem var(--spacing);
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.2rem;
    font-weight: 700;
    color: var(--text-primary);
    text-decoration: none;
}

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

.nav-menu a {
    color: var(--text-secondary);
    text-decoration: none;
    transition: color 0.3s;
}

.nav-menu a:hover {
    color: var(--accent);
}

/* ===== HEADER SECTION ===== */
.header {
    padding: 4rem var(--spacing);
    text-align: center;
    border-bottom: 1px solid var(--border-color);
}

.header h1 {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
    font-weight: 700;
}

.tagline {
    font-size: 1.2rem;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

.subtitle {
    font-size: 1rem;
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
}

.contact-info {
    display: flex;
    justify-content: center;
    gap: 2rem;
    flex-wrap: wrap;
    margin-bottom: 1.5rem;
    font-size: 0.95rem;
}

.contact-info a {
    color: var(--accent);
    text-decoration: none;
}

.contact-info a:hover {
    text-decoration: underline;
}

.social-links {
    display: flex;
    justify-content: center;
    gap: 1.5rem;
}

.social-links a {
    color: var(--accent);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s;
}

.social-links a:hover {
    color: var(--accent-hover);
}

/* ===== BIO SECTION ===== */
.bio {
    padding: 3rem var(--spacing);
    background-color: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
}

.bio h2 {
    font-size: 1.8rem;
    margin-bottom: 1.5rem;
}

.bio p {
    font-size: 1rem;
    line-height: 1.8;
    margin-bottom: 1.5rem;
    color: var(--text-secondary);
}

.bio h3 {
    font-size: 1.2rem;
    margin-bottom: 1rem;
    margin-top: 1.5rem;
}

.tech-stack {
    display: grid;
    gap: 1rem;
}

.tech-group {
    padding: 1rem;
    background-color: var(--bg-primary);
    border-left: 3px solid var(--accent);
    border-radius: 4px;
}

.tech-group strong {
    color: var(--text-primary);
    display: block;
    margin-bottom: 0.25rem;
}

/* ===== SECTIONS ===== */
.experience,
.projects,
.experiments,
.articles {
    padding: 3rem var(--spacing);
    border-bottom: 1px solid var(--border-color);
}

.experience:nth-child(even),
.projects:nth-child(even),
.experiments:nth-child(even),
.articles:nth-child(even) {
    background-color: var(--bg-secondary);
}

.experience h2,
.projects h2,
.experiments h2,
.articles h2 {
    font-size: 1.8rem;
    margin-bottom: 2rem;
}

.section-desc {
    color: var(--text-secondary);
    margin-bottom: 2rem;
}

/* ===== EXPERIENCE ITEMS ===== */
.experience-item {
    margin-bottom: 2.5rem;
    padding-bottom: 2rem;
    border-bottom: 1px solid var(--border-color);
}

.experience-item:last-child {
    border-bottom: none;
}

.exp-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 0.5rem;
    flex-wrap: wrap;
    gap: 1rem;
}

.exp-title {
    font-size: 1.1rem;
    font-weight: 700;
}

.exp-company {
    color: var(--accent);
    font-weight: 600;
}

.exp-date {
    color: var(--text-secondary);
    font-size: 0.9rem;
    white-space: nowrap;
}

.exp-description {
    color: var(--text-secondary);
    margin-bottom: 1rem;
}

.exp-points {
    list-style: none;
    padding-left: 0;
}

.exp-points li {
    padding: 0.4rem 0;
    padding-left: 1.5rem;
    position: relative;
    color: var(--text-secondary);
    line-height: 1.7;
}

.exp-points li:before {
    content: "•";
    position: absolute;
    left: 0;
    color: var(--accent);
    font-weight: bold;
}

/* ===== PROJECTS ===== */
.projects-list {
    display: grid;
    gap: 2.5rem;
}

.project-item {
    padding: 1.5rem;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    transition: all 0.3s;
}

.project-item:hover {
    border-color: var(--accent);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
}

/* Keep anchor-wrapped project cards visually identical to cards */
.project-card-link {
    display: block; /* ensure full-card clickable */
    text-decoration: none; /* remove link underline */
    color: inherit; /* preserve text color */
}
.project-card-link:focus {
    outline: none;
}
.project-card-link .project-item {
    /* keep same hover effect when wrapping with anchor */
}

.project-name {
    font-size: 1.1rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.project-desc {
    color: var(--text-secondary);
    margin-bottom: 1rem;
    line-height: 1.7;
}

.project-tech {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-top: 1rem;
}

.tech-tag {
    background-color: var(--bg-secondary);
    color: var(--text-primary);
    padding: 0.3rem 0.75rem;
    border-radius: 3px;
    font-size: 0.85rem;
    border: 1px solid var(--border-color);
}

.project-tldr {
    background-color: #f0f7ff;
    border-left: 3px solid var(--accent);
    padding: 0.75rem 1rem;
    margin-bottom: 1rem;
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.6;
    border-radius: 2px;
}

.project-impact {
    color: var(--text-secondary);
    margin: 1rem 0;
    font-size: 0.95rem;
    line-height: 1.6;
}

.project-docs {
    margin-top: 1rem;
    display: flex;
    gap: 0.5rem;
}

.doc-link {
    display: inline-block;
    background-color: var(--accent);
    color: white;
    padding: 0.5rem 1rem;
    border-radius: 3px;
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 500;
    transition: background-color 0.3s;
}

.doc-link:hover {
    background-color: var(--accent-hover);
}

/* ===== EXPERIMENTS ===== */
.experiments-list {
    display: grid;
    gap: 2rem;
}

.experiment-item {
    padding: 1.5rem;
    border-left: 3px solid var(--accent);
    background-color: var(--bg-primary);
    border-radius: 4px;
}

.experiment-title {
    font-size: 1.1rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.experiment-authors {
    color: var(--text-secondary);
    font-size: 0.95rem;
    margin-bottom: 0.5rem;
}

.experiment-venue {
    color: var(--accent);
    font-weight: 500;
    margin-bottom: 1rem;
}

.experiment-links {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
}

.experiment-link {
    color: var(--accent);
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 500;
}

.experiment-link:hover {
    text-decoration: underline;
}

/* ===== AWARDS ===== */
.awards-list {
    display: grid;
    gap: 1.5rem;
}

.award-item {
    display: block;
    padding: 2rem;
    border: 2px solid var(--accent);
    border-radius: 6px;
    transition: all 0.3s ease;
    cursor: pointer;
    text-decoration: none;
    color: inherit;
    background-color: var(--bg-primary);
    text-align: center;
}

.award-item:hover {
    background-color: var(--bg-secondary);
    box-shadow: 0 6px 16px rgba(0, 102, 204, 0.2);
    transform: translateY(-4px);
}

.award-title {
    font-size: 1.3rem;
    font-weight: 700;
    color: var(--accent);
    margin-bottom: 1rem;
}

.award-description {
    color: var(--text-primary);
    font-size: 1rem;
    line-height: 1.7;
    margin-bottom: 1.5rem;
    font-weight: 500;
}

.award-link {
    color: var(--accent);
    font-size: 0.95rem;
    font-weight: 600;
    display: inline-block;
    transition: color 0.3s;
}

.award-item:hover .award-link {
    color: var(--accent-hover);
}

/* ===== ARTICLES ===== */
.articles-list {
    display: grid;
    gap: 1.5rem;
}

.article-item {
    padding: 1.5rem;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    transition: all 0.3s;
    cursor: pointer;
}

.article-item:hover {
    border-color: var(--accent);
    transform: translateX(5px);
}

.article-date {
    color: var(--accent);
    font-size: 0.85rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.article-title {
    font-size: 1rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.article-excerpt {
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.6;
}

.article-tags {
    display: flex;
    gap: 0.5rem;
    margin-top: 1rem;
    flex-wrap: wrap;
}

.article-tag {
    background-color: var(--bg-secondary);
    color: var(--accent);
    padding: 0.25rem 0.6rem;
    border-radius: 3px;
    font-size: 0.8rem;
}

/* ===== FOOTER ===== */
.footer {
    background-color: var(--bg-secondary);
    border-top: 1px solid var(--border-color);
    padding: 2rem var(--spacing);
    text-align: center;
    color: var(--text-secondary);
}

.footer a {
    color: var(--accent);
    text-decoration: none;
}

.footer a:hover {
    text-decoration: underline;
}

.footer p {
    margin: 0.5rem 0;
    font-size: 0.95rem;
}

/* ===== RESPONSIVE ===== */
@media (max-width: 768px) {
    .nav-menu {
        gap: 1rem;
        font-size: 0.9rem;
    }

    .header h1 {
        font-size: 1.8rem;
    }

    .tagline {
        font-size: 1rem;
    }

    .contact-info {
        gap: 1rem;
        flex-direction: column;
    }

    .exp-header {
        flex-direction: column;
    }

    .exp-date {
        order: -1;
    }

    .experience,
    .projects,
    .experiments,
    .awards,
    .articles {
        padding: 2rem var(--spacing);
    }

    h2 {
        font-size: 1.4rem;
    }

    .social-links {
        gap: 1rem;
    }
}

@media (max-width: 480px) {
    .nav-menu {
        gap: 0.8rem;
        font-size: 0.85rem;
    }

    .header h1 {
        font-size: 1.5rem;
    }

    .nav-container {
        padding: 0.75rem var(--spacing);
    }

    .contact-info {
        font-size: 0.85rem;
    }

    .exp-points li {
        padding-left: 1.2rem;
    }
}