/*
 * styles.css
 *
 * This stylesheet provides the visual appearance of the personal website.  
 * It defines a colour palette using CSS custom properties, configures typography and layout,  
 * and implements responsive behaviour using flexible grids and media queries.  
 * Responsive design ensures the site looks good on both large and small screens【213253163178346†L180-L197】.  
 */

/* Colour palette variables for easy theming */
:root {
    --color-primary: #0f172a;
    --color-secondary: #1DBF73;
    --color-accent: #E36262;
    --color-dark: #0f172a;
    --color-light: #FFFFFF;
    --color-bg-hero: #f8fafc;
    --color-bg-light: #FFFFFF;
    --color-bg-pubs: #f8fafc;
    --color-bg-projects: #FFFFFF;
    --color-bg-talks: #f8fafc;
    --color-bg-card-dark: #f8fafc;
    --container-width: 1200px;
    --gutter: 1.5rem;
}


/* Base styles */
* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: 'Montserrat', 'Open Sans', sans-serif;
    line-height: 1.6;
    color: var(--color-dark);
    background-color: var(--color-light);
}

/* Smooth anchor scrolling for whole page */
html {
    scroll-behavior: auto;
}

h1, h2, h3 {
    margin-top: 0;
    font-weight: 600;
}

p {
    margin: 0.5rem 0 1rem;
}

/* Container to centre content and apply horizontal padding */
.container {
    width: 100%;
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 var(--gutter);
}

/* Hero section */
.hero {
    background-color: var(--color-bg-hero);
    padding: 3rem 0;
    border-bottom: 1px solid rgba(0, 0, 0, 0.05);
}

.hero-container {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: center;
    gap: 2rem;
}

.hero-image img {
    width: 220px;
    height: 220px;
    border-radius: 50%;
    object-fit: cover;
    object-position: 50% 10%;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

.hero-text h1 {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
    color: var(--color-primary);
}

.hero-text .tagline {
    font-size: 1.2rem;
    color: var(--color-dark);
}

/* for buttons in the hero section */
.hero-links {
    display: flex;
    gap: 0.8rem;
    margin-top: 1.2rem;
}

/* about section */
.about {
    background-color: var(--color-bg-light);
    padding: 4rem 0;
    border-bottom: 1px solid rgba(0, 0, 0, 0.05);
}

.about h2 {
    text-align: center;
    margin-bottom: 0.5rem;
    color: var(--color-primary);
}

.section-intro {
    max-width: 1000px;
    margin: 0.5rem auto 2rem;
    text-align: justify;
    color: #555;
}

.link-buttons {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 1rem;
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.8rem 1.2rem;
    border-radius: 0.4rem;
    text-decoration: none;
    font-weight: 600;
    border: none;
    color: var(--color-light);
    transition: background-color 0.3s ease, transform 0.2s ease;
}

.btn i {
    font-size: 1.0rem;
}

.btn.disabled {
    opacity: 0.5;
    pointer-events: none;
    cursor: not-allowed;
}

.btn-primary {
    background-color: var(--color-primary);
}

.btn-secondary {
    background-color: var(--color-secondary);
}

.btn-accent {
    background-color: var(--color-accent);
}

.btn-dark {
    background-color: var(--color-dark);
}

.btn-outline {
    background-color: transparent;
    color: var(--color-primary);
    border: 2px solid var(--color-primary);
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
    filter: brightness(1.05);
}

.btn-outline:hover {
    background-color: var(--color-primary);
    color: var(--color-light);
}

/* Section shared styles */
.publications, .projects, .talks {
    padding: 4rem 0;
}

.publications {
    background-color: var(--color-bg-pubs);
    border-bottom: 1px solid rgba(0, 0, 0, 0.05);
}

.projects {
    background-color: var(--color-bg-projects);
    border-bottom: 1px solid rgba(0, 0, 0, 0.05);
}

.talks {
    background-color: var(--color-bg-talks);
    border-bottom: 1px solid rgba(0, 0, 0, 0.05);
}

.publications h2, .projects h2, .talks h2 {
    text-align: center;
    margin-bottom: 0.5rem;
    color: var(--color-primary);
}

.card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.publication-tools {
    display: grid;
    grid-template-columns: minmax(280px, 1fr);
    gap: 1rem;
    margin: 0 auto 1rem;
    max-width: 1000px;
}

.publication-search {
    display: block;
}

.publication-search span {
    display: block;
    margin-bottom: 0.35rem;
    color: var(--color-primary);
    font-size: 0.85rem;
    font-weight: 700;
    letter-spacing: 0.04em;
    text-transform: uppercase;
}

.publication-search input {
    width: 100%;
    border: 1px solid rgba(15, 23, 42, 0.2);
    border-radius: 0.5rem;
    padding: 0.85rem 1rem;
    color: var(--color-primary);
    font: inherit;
    background: var(--color-light);
    box-shadow: 0 2px 8px rgba(15, 23, 42, 0.05);
}

.publication-search input:focus {
    outline: 3px solid rgba(29, 191, 115, 0.22);
    border-color: var(--color-secondary);
}

.publication-filters {
    display: flex;
    flex-wrap: wrap;
    gap: 0.6rem;
}

.filter-chip {
    border: 1px solid rgba(15, 23, 42, 0.18);
    border-radius: 999px;
    padding: 0.45rem 0.8rem;
    color: var(--color-primary);
    background: var(--color-light);
    font: inherit;
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.2s ease, color 0.2s ease, border-color 0.2s ease;
}

.filter-chip:hover,
.filter-chip.active {
    color: var(--color-light);
    background: var(--color-primary);
    border-color: var(--color-primary);
}

.publication-count,
.publication-empty {
    max-width: 1000px;
    margin: 0 auto 1.5rem;
    color: #555;
    font-size: 0.95rem;
}

.publication-empty {
    padding: 1.25rem;
    text-align: center;
    border: 1px dashed rgba(15, 23, 42, 0.25);
    border-radius: 0.5rem;
}

.publication-card.is-hidden {
    display: none;
}

.card {
    background-color: var(--color-light);
    border-radius: 0.5rem;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
    padding: 2rem;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
}

.card.dark {
    background-color: var(--color-bg-card-dark);
}

.card h3 {
    margin-top: 0;
    margin-bottom: 0.5rem;
    color: var(--color-secondary);
}

.card p {
    flex-grow: 1;
    color: #555;
}

.card-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    margin-top: 1rem;
}

.card.has-badge {
    border: 2px solid var(--color-secondary);
    position: relative;
}

.card-badge {
    position: absolute;
    top: -10px;
    left: 16px;
    background: var(--color-secondary);
    color: white;
    font-size: 0.7rem;
    font-weight: 700;
    padding: 3px 8px;
    border-radius: 4px;
    letter-spacing: 0.5px;
    text-transform: uppercase;
}

.card-badge-accepted {
    background: var(--color-secondary);
}

.card-badge-published {
    background: var(--color-secondary);
}

.card-badge-upcoming {
    background: var(--color-secondary);
}

.modal-overlay {
    position: fixed;
    inset: 0;
    background: rgba(15, 23, 42, 0.7);
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 2rem;
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    transition: opacity 0.25s ease, visibility 0.25s ease;
    z-index: 2000;
}

.modal-overlay.open {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
}

.modal {
    position: relative;
    width: min(1400px, calc(100vw - 5rem));
    max-height: min(95vh, 1100px);
    overflow: auto;
    background: var(--color-light);
    border-radius: 0.9rem;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.2);
    padding: 2.5rem;
}

.modal-close {
    position: absolute;
    top: 1rem;
    right: 1rem;
    border: none;
    background: transparent;
    width: 2.2rem;
    height: 2.2rem;
    border-radius: 999px;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    font-size: 1.3rem;
    cursor: pointer;
    color: var(--color-dark);
    transition: background-color 0.2s ease, transform 0.2s ease;
}

.modal-close i {
    transition: transform 0.2s ease, color 0.2s ease;
}

.modal-close:hover {
    background-color: var(--color-dark);
    transform: scale(1.05);
}

.modal-close:hover i {
    transform: rotate(90deg);
    color: var(--color-light);
}

.modal-content {
    display: grid;
    grid-template-columns: minmax(280px, 360px) minmax(0, 1fr);
    gap: 2.5rem;
    align-items: start;
    min-width: 0;
}

.modal-image {
    max-width: 100%;
    min-width: 0;
}

.modal-image img {
    display: block;
    width: 100%;
    max-width: 100%;
    height: auto;
    border-radius: 0.5rem;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.08);
}

.modal-body {
    min-width: 0;
}

.modal-body h3 {
    color: var(--color-primary);
    margin-bottom: 0.5rem;
}

.modal-body h4 {
    margin-bottom: 0.1rem;
}

.modal-authors,
.modal-venue {
    color: var(--color-primary);
    margin-bottom: 0.5rem;
}

.modal-abstract {
    margin-top: 0;
    text-align: justify;
}

.modal-links {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
    margin: 1.25rem 0 1.5rem;
}

.bibtex-block {
    margin-top: 1.5rem;
}

.bibtex-block h4 {
    margin-bottom: 0.75rem;
}

.bibtex-wrapper {
    position: relative;
}

.bibtex-wrapper pre {
    margin: 0;
    padding: 1.25rem 1.25rem 1.25rem 1.25rem;
    padding-top: 3.2rem;
    background: var(--color-dark);
    color: #e2e8f0;
    border-radius: 0.5rem;
    overflow-x: auto;
    font-size: 0.9rem;
    line-height: 1.5;
}

.bibtex-wrapper code {
    display: block;
    font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
    white-space: pre;
}

.copy-bibtex-btn {
    position: absolute;
    top: 0.75rem;
    right: 0.75rem;
    padding: 0.3rem 0.65rem;
    font-size: 0.78rem;
    z-index: 10;
    border: 1px solid var(--color-light);
}

.copy-bibtex-btn:hover {
    border-color: var(--color-light);
    background-color: var(--color-light);
    color: var(--color-dark);
}

body.modal-open {
    overflow: hidden;
}

.page-up-btn {
    position: fixed;
    right: 1.25rem;
    bottom: 1.25rem;
    width: 2.8rem;
    height: 2.8rem;
    border: none;
    border-radius: 999px;
    background-color: var(--color-primary);
    color: var(--color-light);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.18);
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    transform: translateY(10px);
    transition: opacity 0.2s ease, transform 0.2s ease, visibility 0.2s ease, background-color 0.2s ease, color 0.2s ease;
    z-index: 1500;
}

.page-up-btn.visible {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
    transform: translateY(0);
}

.page-up-btn:hover {
    transform: translateY(-2px);
    background-color: var(--color-secondary);
}

.page-up-btn.in-footer {
    background-color: var(--color-light);
    color: var(--color-dark);
}

.page-up-btn.in-footer:hover {
    background-color: var(--color-secondary);
    color: var(--color-light);
}

.page-up-btn i {
    font-size: 1rem;
}

@media (max-width: 900px) {
    .modal-overlay {
        align-items: stretch;
        padding: 1rem;
    }

    .modal {
        width: 100%;
        max-width: 100%;
        max-height: calc(100dvh - 2rem);
        padding: 1.5rem;
        overflow-x: hidden;
    }

    .modal-close {
        position: sticky;
        top: 0;
        margin-left: auto;
        background: rgba(255, 255, 255, 0.95);
        z-index: 5;
    }

    .modal-content {
        grid-template-columns: 1fr;
        gap: 1.25rem;
    }

    .modal-image {
        width: min(100%, 340px);
        justify-self: center;
    }

    .modal-image img {
        max-height: 210px;
        object-fit: contain;
    }

    .modal-links {
        display: grid;
        grid-template-columns: 1fr;
    }

    .modal-links .btn {
        justify-content: center;
    }
}

/* Footer */
footer {
    background-color: var(--color-dark);
    color: var(--color-light);
    text-align: center;
    padding: 1rem 0;
}

/* Responsive breakpoints */
@media (max-width: 768px) {
    .hero-container {
        flex-direction: column;
    }
    .hero-image img {
        width: 160px;
        height: 160px;
    }
    .hero-text h1 {
        font-size: 2rem;
    }
    .btn {
        padding: 0.6rem 1rem;
    }

    .card-grid {
        grid-template-columns: 1fr;
        gap: 1.25rem;
    }

    .card {
        padding: 1.35rem;
    }
}

@media (max-width: 560px) {
    :root {
        --gutter: 1rem;
    }

    .hero,
    .about,
    .publications,
    .projects,
    .talks {
        padding: 2.5rem 0;
    }

    .hero-links,
    .link-buttons {
        display: grid;
        grid-template-columns: 1fr;
    }

    .section-intro,
    .modal-abstract {
        text-align: left;
    }

    .modal-overlay {
        padding: 0;
    }

    .modal {
        width: 100vw;
        max-width: 100vw;
        max-height: 100dvh;
        min-height: 100dvh;
        border-radius: 0;
        padding: 1rem;
        overflow-x: hidden;
    }

    .modal-image {
        width: min(100%, 280px);
    }

    .modal-image img {
        max-height: 150px;
    }

    .modal-body h3 {
        font-size: 1.2rem;
        line-height: 1.35;
    }

    .bibtex-wrapper pre {
        padding: 3rem 1rem 1rem;
        font-size: 0.78rem;
    }

    .copy-bibtex-btn {
        top: 0.6rem;
        right: 0.6rem;
    }

    .publication-filters {
        gap: 0.45rem;
    }

    .filter-chip {
        flex: 1 1 auto;
        text-align: center;
    }
}