html {
    scroll-behavior: smooth;
}
* {
    box-sizing: border-box;
}

body {
    margin: 0;
    font-family: Arial, sans-serif;
    background-color: #f7f7f7;
    color: #222;
}


/* 상단 메뉴 */

header {
    width: 100%;
    background-color: white;
    border-bottom: 1px solid #eeeeee;
    position: sticky;
top: 0;
z-index: 1000;
}


nav {
    max-width: 1200px;
    margin: auto;

    display: flex;
    justify-content: space-between;
    align-items: center;

    padding: 25px 40px;
}

.logo {
    font-size: 22px;
    font-weight: bold;
}

.menu {
    display: flex;
    gap: 30px;
}

.menu a {
    text-decoration: none;
    color: #333;
    font-size: 15px;
}

.menu a:hover {
    color: #777;
}


/* 첫 화면 */

.hero {
    max-width: 1200px;
    margin: auto;

    padding: 110px 40px;

    display: flex;
    justify-content: space-between;
    align-items: center;

    gap: 80px;
}

.small-title {
    font-size: 14px;
    letter-spacing: 2px;
    color: #777;
}

.hero h1 {
    font-size: 70px;

    margin-top: 20px;
    margin-bottom: 15px;
}

.hero h2 {
    font-size: 25px;
    font-weight: normal;

    color: #555;

    margin-bottom: 30px;
}

.description {
    font-size: 19px;
    line-height: 1.7;

    max-width: 650px;

    color: #555;
}


/* 버튼 */

.buttons {
    margin-top: 40px;

    display: flex;
    gap: 15px;
}

.buttons a {
    text-decoration: none;

    padding: 14px 24px;

    border-radius: 6px;
}

.primary-button {
    background-color: #222;
    color: white;
}

.secondary-button {
    border: 1px solid #222;
    color: #222;
}.hero-text {
    flex: 1;
}

.hero-image {
    flex: 0 0 340px;
}

.hero-image img {
    width: 100%;
    display: block;

    border-radius: 12px;
}/* About */

.about {
    background-color: white;
    padding: 120px 40px;
}

.about > * {
    max-width: 1200px;
    margin-left: auto;
    margin-right: auto;
}

.section-title p {
    font-size: 13px;
    letter-spacing: 2px;
    color: #888;
    margin-bottom: 10px;
}

.section-title h2 {
    font-size: 40px;
    margin-top: 0;
    margin-bottom: 60px;
}

.about-content {
    display: grid;
    grid-template-columns: 1.5fr 1fr;
    gap: 100px;
}

.about-text {
    font-size: 18px;
    line-height: 1.8;
    color: #444;
}

.about-info > div {
    margin-bottom: 30px;
}

.about-info span {
    font-size: 12px;
    letter-spacing: 1.5px;
    color: #888;
}

.about-info p {
    margin-top: 8px;
    font-size: 16px;
}/* Research */

.research {
    max-width: 1200px;
    margin: auto;

    padding: 120px 40px;
}


.research-grid {
    display: grid;

    grid-template-columns: repeat(3, 1fr);

    gap: 25px;
}


.research-card {
    background-color: white;

    padding: 40px;

    border: 1px solid #e8e8e8;

    border-radius: 10px;

    min-height: 350px;

    transition: 0.3s;
}


.research-card:hover {
    transform: translateY(-8px);

    box-shadow: 0 15px 35px rgba(0, 0, 0, 0.08);
}


.research-number {
    font-size: 13px;

    color: #999;

    letter-spacing: 2px;

    margin-bottom: 40px;
}


.research-card h3 {
    font-size: 24px;

    line-height: 1.3;

    margin-bottom: 25px;
}


.research-card > p:not(.research-number) {
    font-size: 16px;

    line-height: 1.7;

    color: #555;
}


.research-card span {
    display: block;

    margin-top: 35px;

    font-size: 13px;

    color: #888;
}/* Research Images */

.research-image {
    width: 100%;
    height: 180px;

    object-fit: contain;

    background-color: #ffffff;

    border-radius: 6px;

    margin-bottom: 25px;
}/* Publications */

.publications {
    background-color: white;
    padding: 120px 40px;
}

.publications > * {
    max-width: 1200px;
    margin-left: auto;
    margin-right: auto;
}

.publication-list {
    border-top: 1px solid #dddddd;
}

.publication-item {
    display: grid;

    grid-template-columns: 120px 1fr;

    gap: 40px;

    padding: 45px 0;

    border-bottom: 1px solid #dddddd;
}

.publication-year {
    font-size: 15px;

    color: #888;

    padding-top: 5px;
}

.publication-content h3 {
    font-size: 23px;

    line-height: 1.45;

    margin-top: 0;

    margin-bottom: 18px;

    max-width: 850px;
}

.authors {
    font-size: 15px;

    line-height: 1.7;

    color: #555;

    margin-bottom: 10px;
}

.journal {
    font-size: 15px;

    font-style: italic;

    margin-bottom: 12px;
}

.publication-note {
    display: inline-block;

    font-size: 12px;

    letter-spacing: 1px;

    color: #888;
}/* Publication Links */

.publication-links {
    display: flex;
    gap: 12px;
    margin-top: 20px;
}

.publication-links a {
    text-decoration: none;
    color: #222;

    font-size: 13px;
    font-weight: 600;

    border: 1px solid #cccccc;
    border-radius: 5px;

    padding: 8px 14px;

    transition: 0.2s;
}

.publication-links a:hover {
    background-color: #222;
    color: white;
    border-color: #222;
}/* All Publications */

.all-publications {
    max-width: 1200px;
    margin: 45px auto 0;
}

.all-publications summary {
    display: inline-block;

    cursor: pointer;

    font-size: 15px;
    font-weight: 600;

    padding: 12px 18px;

    border: 1px solid #cccccc;
    border-radius: 5px;

    transition: 0.2s;
}

.all-publications summary:hover {
    background-color: #222;
    color: white;
    border-color: #222;
}

.all-publications summary::marker {
    display: none;
}

.other-publications {
    margin-top: 35px;
    border-top: 1px solid #dddddd;
}

.other-publication-item {
    display: grid;
    grid-template-columns: 120px 1fr;

    gap: 40px;

    padding: 30px 0;

    border-bottom: 1px solid #dddddd;
}

.other-publication-item > span {
    font-size: 14px;
    color: #888;
}

.other-publication-item h4 {
    font-size: 18px;
    line-height: 1.5;

    margin: 0 0 8px 0;
}

.other-publication-item p {
    font-size: 14px;
    font-style: italic;

    color: #666;

    margin: 0;
}/* Contact */

.contact {
    max-width: 1200px;
    margin: auto;

    padding: 120px 40px 140px;
}

.contact-content {
    display: grid;
    grid-template-columns: 1fr 1.5fr;

    gap: 100px;
}

.contact-intro p {
    font-size: 20px;
    line-height: 1.7;

    color: #444;

    max-width: 420px;
}

.contact-links {
    border-top: 1px solid #dddddd;
}

.contact-links a {
    display: flex;
    justify-content: space-between;
    align-items: center;

    text-decoration: none;
    color: #222;

    padding: 25px 0;

    border-bottom: 1px solid #dddddd;

    transition: 0.2s;
}

.contact-links a:hover {
    padding-left: 10px;
}

.contact-links span {
    font-size: 12px;
    letter-spacing: 1.5px;

    color: #888;
}

.contact-links strong {
    font-size: 15px;
    font-weight: 500;
}
/* ========================================
   Mobile Responsive Design
   ======================================== */

@media (max-width: 768px) {

    /* 상단 메뉴 */

    nav {
        padding: 18px 20px;
        flex-direction: column;
        align-items: flex-start;
        gap: 15px;
    }

    .logo {
        font-size: 20px;
    }

    .menu {
        width: 100%;
        gap: 18px;
        overflow-x: auto;
        white-space: nowrap;
        padding-bottom: 5px;
    }

    .menu a {
        font-size: 14px;
    }


    /* 첫 화면 */

    .hero {
        padding: 70px 20px;

        flex-direction: column;
        align-items: flex-start;

        gap: 50px;
    }

    .hero h1 {
        font-size: 48px;
    }

    .hero h2 {
        font-size: 20px;
        line-height: 1.5;
    }

    .description {
        font-size: 17px;
    }

    .hero-image {
        width: 100%;
        max-width: 320px;

        flex: none;

        margin: auto;
    }


    /* 버튼 */

    .buttons {
        flex-wrap: wrap;
    }


    /* About */

    .about {
        padding: 80px 20px;
    }

    .about-content {
        grid-template-columns: 1fr;
        gap: 50px;
    }


    /* Research */

    .research {
        padding: 80px 20px;
    }

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

    .research-card {
        min-height: auto;
    }


    /* Publications */

    .publications {
        padding: 80px 20px;
    }

    .publication-item {
        grid-template-columns: 1fr;
        gap: 15px;

        padding: 35px 0;
    }

    .publication-content h3 {
        font-size: 20px;
    }

    .other-publication-item {
        grid-template-columns: 1fr;
        gap: 10px;
    }


    /* Contact */

    .contact {
        padding: 80px 20px;
    }

    .contact-content {
        grid-template-columns: 1fr;
        gap: 50px;
    }

    .contact-links a {
        flex-direction: column;
        align-items: flex-start;

        gap: 8px;
    }


    /* Section Titles */

    .section-title h2 {
        font-size: 34px;
        margin-bottom: 40px;
    }
}/* Footer */

footer {
    background-color: #222;
    color: white;

    padding: 35px 40px;
}

.footer-content {
    max-width: 1200px;
    width: 100%;
    margin: auto;

    display: flex;
    justify-content: space-between;
    align-items: center;
}

.footer-content p {
    font-size: 13px;
    color: #aaaaaa;
    margin: 0;
}

.footer-links {
    display: flex;
    gap: 25px;
}

.footer-links a {
    color: #dddddd;
    text-decoration: none;
    font-size: 13px;

    transition: 0.2s;
}

.footer-links a:hover {
    color: white;
/* Mobile Footer */

@media (max-width: 768px) {

    .footer-content {
        flex-direction: column;
        align-items: flex-start;
        gap: 20px;
    }

    .footer-links {
        flex-wrap: wrap;
    }

}