:root {
    --bg-color: #ffffff;
    --text-color: #1a1a1a;
    --nav-link-color: #c4552f;
    --icon-color: #333;
    --shadow-color: rgba(0, 0, 0, 0.15);
}

[data-theme="dark"] {
    --bg-color: #1a1a1a;
    --text-color: #e0e0e0;
    --nav-link-color: #ff7a4d;
    --icon-color: #e0e0e0;
    --shadow-color: rgba(255, 255, 255, 0.1);
}

html {
    scroll-behavior: smooth;
}

body {
    margin: 0;
    font-family: -apple-system, BlinkMacSystemFont, Segoe UI, Roboto, sans-serif;
    background: var(--bg-color);
    color: var(--text-color);
    text-align: center;
    transition: background-color 0.3s ease, color 0.3s ease;
}

.nav {
    display: flex;
    justify-content: space-between;
    padding: 20px 60px;
    font-size: 15px;
}

.nav-right {
    display: flex;
    align-items: center;
}

.nav-right a {
    margin-left: 20px;
    text-decoration: none;
    color: var(--nav-link-color);
    transition: color 0.3s ease;
}

.theme-toggle {
    margin-left: 20px;
    background: transparent;
    border: none;
    font-size: 20px;
    cursor: pointer;
    padding: 5px 10px;
    border-radius: 5px;
    transition: background-color 0.3s ease;
}

.theme-toggle:hover {
    background-color: var(--shadow-color);
}

.avatar {
    width: 220px;
    height: 220px;
    border-radius: 50%;
    object-fit: cover;
    margin-top: 40px;
    box-shadow: 0 4px 18px var(--shadow-color);
    transition: box-shadow 0.3s ease;
}

.name {
    font-size: 32px;
    margin-top: 20px;
    font-weight: 600;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
}

.name-audio-btn {
    background: transparent;
    border: none;
    font-size: 20px;
    cursor: pointer;
    padding: 5px 8px;
    border-radius: 5px;
    transition: all 0.3s ease;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    opacity: 0.7;
}

[data-theme="dark"] .name-audio-btn {
    filter: brightness(0) invert(1);
}

.name-audio-btn:hover {
    opacity: 1;
    transform: scale(1.1);
    background-color: var(--shadow-color);
}

.name-audio-btn:active {
    transform: scale(0.95);
}

.subtitle {
    max-width: 600px;
    margin: 20px auto;
    font-size: 16px;
    line-height: 1.5;
}

.bio {
    max-width: 680px;
    margin: 10px auto 30px;
    font-size: 15px;
    line-height: 1.6;
}

.bio a {
    color: #000000;
    text-decoration: underline;
    transition: color 0.3s ease, opacity 0.3s ease;
}

[data-theme="dark"] .bio a {
    color: #ffffff;
}

.bio a:hover {
    opacity: 0.8;
}

.icons a {
    font-size: 22px;
    margin: 0 10px;
    text-decoration: none;
    color: var(--icon-color);
    transition: color 0.3s ease;
}

.icons a:hover {
    opacity: 0.7;
}

.research-section {
    max-width: 900px;
    margin: 80px auto;
    padding: 0 20px;
    text-align: left;
}

.research-image {
    max-width: 600px;
    width: 100%;
    max-height: 400px;
    object-fit: cover;
    border-radius: 12px;
    margin: 40px auto 60px;
    display: block;
    box-shadow: 0 8px 24px var(--shadow-color);
    transition: box-shadow 0.3s ease, transform 0.3s ease;
}

.research-image:hover {
    transform: translateY(-4px);
    box-shadow: 0 12px 32px var(--shadow-color);
}

.section-title {
    font-size: 36px;
    font-weight: 600;
    margin-bottom: 50px;
    text-align: center;
    color: var(--text-color);
}

.research-content {
    display: flex;
    flex-direction: column;
    gap: 50px;
}

.research-category {
    margin-bottom: 40px;
}

.category-title {
    font-size: 24px;
    font-weight: 600;
    margin-bottom: 20px;
    color: var(--nav-link-color);
}

.subsection-title {
    font-size: 20px;
    font-weight: 600;
    margin-top: 30px;
    margin-bottom: 15px;
    color: var(--text-color);
}

.research-list {
    max-width: 680px;
    margin: 15px auto 30px;
    padding-left: 30px;
    font-size: 15px;
    line-height: 1.8;
    color: var(--text-color);
}

.research-list li {
    margin-bottom: 10px;
}

.research-section .bio {
    text-align: left;
    margin-left: 0;
    margin-right: 0;
}

.research-section .bio strong {
    font-weight: 600;
}

/* Research Hero */
.research-hero {
    text-align: center;
    margin-bottom: 60px;
}

.research-hero h1 {
    font-size: 42px;
    margin-bottom: 10px;
}

.hero-subtitle {
    font-size: 17px;
    opacity: 0.8;
    max-width: 700px;
    margin: 0 auto;
}

/* Research Cards */
.research-card {
    background: transparent;
    padding: 30px 0;
    border-top: 1px solid var(--shadow-color);
}

.research-card h2 {
    font-size: 26px;
    margin-bottom: 15px;
    color: var(--nav-link-color);
}

.research-card h3 {
    margin-top: 30px;
    font-size: 20px;
}

.research-card p {
    max-width: 720px;
    line-height: 1.6;
}

.research-card ul {
    max-width: 720px;
    padding-left: 20px;
    line-height: 1.8;
}

.research-card a {
    text-decoration: none;
    color: var(--nav-link-color);
    transition: opacity 0.3s ease;
}

.research-card a:hover {
    opacity: 0.8;
}

/* Two-column grid */
.research-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 30px;
    margin: 30px 0;
}

.research-grid h4 {
    margin-bottom: 10px;
    font-size: 16px;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    opacity: 0.8;
}

/* Impact line */
.impact-line {
    margin-top: 20px;
    font-style: italic;
    opacity: 0.85;
}

/* CTA */
.research-cta {
    margin-top: 80px;
    text-align: center;
}

.cta-button {
    display: inline-block;
    margin-top: 10px;
    padding: 12px 24px;
    border-radius: 30px;
    background-color: var(--nav-link-color);
    color: white;
    text-decoration: none;
    font-weight: 500;
    transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.cta-button:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px var(--shadow-color);
}

/* Projects Section */
.projects-section {
    max-width: 1200px;
    margin: 80px auto;
    padding: 0 20px;
}

.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 30px;
    margin-top: 50px;
}

.project-card {
    background: var(--bg-color);
    border: 1px solid var(--shadow-color);
    border-radius: 12px;
    padding: 30px;
    transition: transform 0.3s ease, box-shadow 0.3s ease, border-color 0.3s ease;
    display: flex;
    flex-direction: column;
}

.project-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 24px var(--shadow-color);
    border-color: var(--nav-link-color);
}

.project-icon {
    font-size: 32px;
    margin-bottom: 15px;
}

.project-title {
    font-size: 22px;
    font-weight: 600;
    margin-bottom: 15px;
    color: var(--text-color);
    line-height: 1.3;
}

.project-description {
    font-size: 15px;
    line-height: 1.6;
    color: var(--text-color);
    opacity: 0.9;
    flex-grow: 1;
}

.project-note {
    font-size: 13px;
    font-style: italic;
    color: var(--text-color);
    opacity: 0.7;
    margin-top: 10px;
}

.project-links {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-top: 20px;
    padding-top: 20px;
    border-top: 1px solid var(--shadow-color);
}

.project-button {
    display: inline-block;
    padding: 8px 16px;
    border-radius: 6px;
    background-color: var(--nav-link-color);
    color: white;
    text-decoration: none;
    font-size: 14px;
    font-weight: 500;
    transition: transform 0.2s ease, box-shadow 0.2s ease, opacity 0.2s ease;
    border: none;
    cursor: pointer;
}

.project-button:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px var(--shadow-color);
    opacity: 0.9;
}

.projects-footer {
    text-align: center;
    margin-top: 60px;
    padding-top: 40px;
    border-top: 1px solid var(--shadow-color);
}

.projects-footer .find-more {
    padding: 12px 24px;
    font-size: 16px;
}

/* Ice Breaker Section */
.icebreaker-section {
    max-width: 800px;
    margin: 80px auto;
    padding: 0 20px;
    text-align: left;
}

.icebreaker-list {
    list-style: none;
    padding: 0;
    margin: 40px 0 0;
}

.icebreaker-list li {
    font-size: 16px;
    line-height: 1.8;
    margin-bottom: 30px;
    padding-bottom: 30px;
    border-bottom: 1px solid var(--shadow-color);
    color: var(--text-color);
}

.icebreaker-list li:last-child {
    border-bottom: none;
    margin-bottom: 0;
    padding-bottom: 0;
}

.icebreaker-list li strong {
    font-weight: 600;
    color: var(--nav-link-color);
}

.icebreaker-list li em {
    font-style: italic;
    opacity: 0.9;
}

.icebreaker-list li a {
    color: var(--nav-link-color);
    text-decoration: none;
    margin-left: 8px;
    transition: opacity 0.3s ease;
}

.icebreaker-list li a:hover {
    opacity: 0.8;
    text-decoration: underline;
}

/* Contact Modal */
.contact-modal {
    display: none;
    position: fixed;
    z-index: 1000;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    backdrop-filter: blur(4px);
    animation: fadeIn 0.3s ease;
}

.contact-modal.show {
    display: flex;
    align-items: center;
    justify-content: center;
}

.contact-modal-content {
    background-color: var(--bg-color);
    margin: auto;
    padding: 40px;
    border-radius: 12px;
    max-width: 500px;
    width: 90%;
    box-shadow: 0 8px 32px var(--shadow-color);
    position: relative;
    animation: slideUp 0.3s ease;
}

.contact-modal-close {
    position: absolute;
    top: 20px;
    right: 25px;
    font-size: 32px;
    font-weight: bold;
    color: var(--text-color);
    cursor: pointer;
    line-height: 1;
    transition: opacity 0.3s ease;
    opacity: 0.7;
}

.contact-modal-close:hover {
    opacity: 1;
}

.contact-modal-content h2 {
    margin: 0 0 30px 0;
    font-size: 28px;
    color: var(--text-color);
    text-align: center;
}

.contact-links {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.contact-link-item {
    display: flex;
    align-items: center;
    padding: 15px 20px;
    border: 1px solid var(--shadow-color);
    border-radius: 8px;
    text-decoration: none;
    color: var(--text-color);
    transition: all 0.3s ease;
    background-color: var(--bg-color);
}

.contact-link-item:hover {
    transform: translateX(5px);
    border-color: var(--nav-link-color);
    box-shadow: 0 4px 12px var(--shadow-color);
}

.contact-icon {
    font-size: 24px;
    margin-right: 15px;
    width: 30px;
    text-align: center;
}

.contact-label {
    font-weight: 600;
    font-size: 16px;
    flex: 1;
    text-align: left;
}

.contact-value {
    font-size: 14px;
    opacity: 0.7;
    text-align: right;
}

@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

@keyframes slideUp {
    from {
        transform: translateY(30px);
        opacity: 0;
    }
    to {
        transform: translateY(0);
        opacity: 1;
    }
}