/* CSS Variables */
:root {
    --navy: #0a192f;
    --light-navy: #112240;
    --lightest-navy: #233554;
    --navy-shadow: rgba(2, 12, 27, 0.7);
    --slate: #8892b0;
    --light-slate: #a8b2d1;
    --lightest-slate: #ccd6f6;
    --white: #e6f1ff;
    --green: #64ffda;
    --green-tint: rgba(100, 255, 218, 0.1);
    --font-sans: 'Inter', 'SF Pro Display', -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue', sans-serif;
    --fz-xxs: 12px;
    --fz-xs: 13px;
    --fz-sm: 14px;
    --fz-md: 16px;
    --fz-lg: 18px;
    --fz-xl: 20px;
    --fz-xxl: 22px;
    --fz-heading: 32px;
    --border-radius: 4px;
    --nav-height: 100px;
    --nav-scroll-height: 70px;
    --tab-height: 42px;
    --tab-width: 120px;
    --transition: all 0.25s cubic-bezier(0.645, 0.045, 0.355, 1);
}

/* Reset & Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    font-size: var(--fz-md);
    line-height: 1.6;
    color: var(--slate);
    background-color: var(--navy);
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    overflow-x: hidden;
}

/* 커서 블러 효과 */
.cursor-blur {
    position: fixed;
    width: 800px;
    height: 800px;
    border-radius: 50%;
    background: radial-gradient(circle, rgba(100, 255, 218, 0.15) 0%, transparent 70%);
    pointer-events: none;
    transform: translate(-50%, -50%);
    transition: width 0.3s ease, height 0.3s ease, opacity 0.3s ease;
    z-index: 9999;
    mix-blend-mode: normal;
    opacity: 0;
}

.cursor-blur.active {
    opacity: 1;
}

/* Sidebar Navigation */
.sidebar {
    position: fixed;
    left: 0;
    top: 0;
    width: 100px;
    height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: space-between;
    padding: 50px 0;
    z-index: 100;
    background-color: rgba(10, 25, 47, 0.85);
    backdrop-filter: blur(10px);
}

.language-switcher {
    display: flex;
    flex-direction: column;
    gap: 8px;
    margin-bottom: 30px;
}

.lang-btn {
    background-color: transparent;
    border: 1px solid var(--lightest-navy);
    color: var(--slate);
    padding: 6px 12px;
    font-size: var(--fz-xs);
    font-family: var(--font-sans);
    cursor: pointer;
    transition: var(--transition);
    border-radius: 3px;
    min-width: 50px;
}

.lang-btn:hover {
    border-color: var(--green);
    color: var(--green);
}

.lang-btn.active {
    background-color: var(--green-tint);
    border-color: var(--green);
    color: var(--green);
}

.logo {
    min-width: 60px;
    width: auto;
    padding: 10px 15px;
    height: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
    border: 2px solid var(--green);
    border-radius: 30px;
    transition: var(--transition);
}

.logo:hover {
    transform: translateY(-3px);
    box-shadow: 0 10px 30px -15px var(--green);
}

.logo a {
    color: var(--green);
    font-size: 14px;
    font-weight: 600;
    text-decoration: none;
    white-space: nowrap;
}

.nav-links {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.nav-link {
    writing-mode: vertical-rl;
    text-orientation: mixed;
    color: var(--light-slate);
    font-size: var(--fz-xs);
    letter-spacing: 0.1em;
    text-decoration: none;
    transition: var(--transition);
    padding: 10px;
    position: relative;
}

.nav-link:hover,
.nav-link.active {
    color: var(--green);
    transform: translateY(-3px);
}

.nav-link::after {
    content: '';
    position: absolute;
    left: -20px;
    top: 50%;
    transform: translateY(-50%);
    width: 2px;
    height: 0;
    background-color: var(--green);
    transition: var(--transition);
}

.nav-link.active::after {
    height: 100%;
}

/* Main Content */
.main-wrapper {
    margin-left: 100px;
    min-height: 100vh;
}

/* Hero Section */
.hero-section {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 0 50px;
    max-width: 1400px;
    margin: 0 auto;
}

.hero-container {
    display: grid;
    grid-template-columns: 1.2fr 1fr;
    gap: 60px;
    align-items: center;
    width: 100%;
}

.hero-content {
    max-width: 900px;
    z-index: 1;
}

.hero-image-wrapper {
    display: flex;
    justify-content: center;
    align-items: center;
    position: relative;
}

.profile-image-container {
    position: relative;
    width: 400px;
    height: 400px;
    max-width: 90%;
    max-height: 90vh;
}

.profile-image-container::before {
    content: '';
    position: absolute;
    top: 20px;
    left: 20px;
    width: 100%;
    height: 100%;
    border: 2px solid var(--green);
    border-radius: 4px;
    transition: var(--transition);
    z-index: -1;
}

.profile-image-container:hover::before {
    top: 15px;
    left: 15px;
}

.profile-image {
    width: 100%;
    height: 100%;
    object-fit: cover;
    border-radius: 4px;
    filter: grayscale(100%) contrast(1.1);
    transition: var(--transition);
    position: relative;
    z-index: 1;
}

.profile-image-container:hover .profile-image {
    filter: grayscale(0%) contrast(1.1);
    transform: translateY(-5px);
}

.profile-image-container::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: var(--green-tint);
    border-radius: 4px;
    opacity: 0;
    transition: var(--transition);
    z-index: 2;
    mix-blend-mode: screen;
}

.profile-image-container:hover::after {
    opacity: 0.2;
}

.greeting {
    color: var(--green);
    font-family: var(--font-sans);
    font-size: var(--fz-lg);
    font-weight: 400;
    margin-bottom: 20px;
}

.hero-name {
    font-size: clamp(40px, 8vw, 80px);
    font-weight: 700;
    color: var(--lightest-slate);
    line-height: 1.1;
    margin-bottom: 15px;
}

.hero-name-en {
    font-size: clamp(12px, 2.4vw, 19.2px);
    font-weight: 400;
    color: var(--slate);
    margin-left: 10px;
}

.hero-title {
    font-size: clamp(24px, 5vw, 36px);
    font-weight: 600;
    color: var(--light-slate);
    line-height: 1.3;
    margin-bottom: 15px;
}

.hero-subtitle {
    color: var(--green);
    font-size: var(--fz-lg);
    font-weight: 500;
    margin-bottom: 10px;
    letter-spacing: 0.5px;
}

.hero-tags {
    color: var(--slate);
    font-size: var(--fz-md);
    font-weight: 400;
    margin-bottom: 0;
    opacity: 0.8;
}

.hero-tags + .hero-description {
    margin-top: 1.5em;
}

.hero-description {
    color: var(--slate);
    font-size: var(--fz-xl);
    line-height: 1.6;
    max-width: 600px;
    margin-bottom: 40px;
}

.cta-button {
    display: inline-block;
    color: var(--green);
    background-color: transparent;
    border: 1px solid var(--green);
    border-radius: var(--border-radius);
    padding: 1.25rem 1.75rem;
    font-size: var(--fz-sm);
    font-family: var(--font-sans);
    line-height: 1;
    text-decoration: none;
    cursor: pointer;
    transition: var(--transition);
    margin-top: 50px;
}

.cta-button:hover {
    background-color: var(--green-tint);
    transform: translateY(-3px);
}

/* Section Styles */
.section {
    max-width: 1200px;
    margin: 0 auto;
    padding: 100px 50px;
}

.section-heading {
    display: flex;
    align-items: center;
    position: relative;
    margin: 10px 0 40px;
    width: 100%;
    font-size: clamp(26px, 5vw, var(--fz-heading));
    white-space: nowrap;
    color: var(--lightest-slate);
    font-weight: 600;
}

.section-number {
    position: relative;
    counter-increment: item 1;
    margin-right: 10px;
    color: var(--green);
    font-family: var(--font-sans);
    font-size: clamp(16px, 3vw, 20px);
    font-weight: 400;
}

.section-title {
    position: relative;
}

.section-heading::after {
    content: '';
    display: block;
    position: relative;
    top: -5px;
    width: 300px;
    height: 1px;
    margin-left: 20px;
    background-color: var(--lightest-navy);
}

/* About Section */
.about-content {
    max-width: 1200px;
}

.about-wrapper {
    display: grid;
    grid-template-columns: 1.2fr 1fr;
    gap: 60px;
    align-items: center;
}

.about-text {
    color: var(--light-slate);
    font-size: var(--fz-lg);
    line-height: 1.8;
}

.about-image-wrapper {
    display: flex;
    justify-content: center;
    align-items: center;
}

.about-image-container {
    position: relative;
    width: 300px;
    height: 300px;
    max-width: 100%;
}

.about-image-container::before {
    content: '';
    position: absolute;
    top: 20px;
    left: 20px;
    width: 100%;
    height: 100%;
    border: 2px solid var(--green);
    border-radius: 4px;
    transition: var(--transition);
    z-index: -1;
}

.about-image-container:hover::before {
    top: 15px;
    left: 15px;
}

.about-profile-image {
    width: 100%;
    height: 100%;
    object-fit: cover;
    border-radius: 4px;
    filter: grayscale(100%) contrast(1.1);
    transition: var(--transition);
    position: relative;
    z-index: 1;
}

.about-image-container:hover .about-profile-image {
    filter: grayscale(0%) contrast(1.1);
    transform: translateY(-5px);
}

.about-image-container::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: var(--green-tint);
    border-radius: 4px;
    opacity: 0;
    transition: var(--transition);
    z-index: 2;
    mix-blend-mode: screen;
}

.about-image-container:hover::after {
    opacity: 0.2;
}

.about-text p {
    margin-bottom: 20px;
}

.tech-list {
    display: grid;
    grid-template-columns: repeat(2, minmax(140px, 200px));
    gap: 10px;
    padding: 0;
    margin: 20px 0 0;
    overflow: hidden;
    list-style: none;
}

.tech-list li {
    position: relative;
    margin-bottom: 10px;
    padding-left: 20px;
    color: var(--slate);
    font-size: var(--fz-sm);
}

.tech-list li::before {
    content: '▹';
    position: absolute;
    left: 0;
    color: var(--green);
    font-size: var(--fz-sm);
    line-height: 1.8;
}

.education-info {
    margin-top: 40px;
    padding-top: 30px;
    border-top: 1px solid var(--lightest-navy);
}

.education-note {
    color: var(--slate);
    font-size: var(--fz-xs);
    line-height: 1.6;
    opacity: 0.7;
    font-style: italic;
}

/* Experience Section */
.experience-container {
    display: flex;
    gap: 50px;
    margin-top: 30px;
}

.tab-list {
    display: flex;
    flex-direction: column;
    gap: 0;
    position: relative;
    z-index: 3;
    width: max-content;
    padding: 0;
    margin: 0;
    list-style: none;
}

.tab-button {
    display: flex;
    align-items: center;
    width: 120px;
    height: var(--tab-height);
    padding: 0 20px 2px;
    border-left: 2px solid var(--lightest-navy);
    background-color: transparent;
    color: var(--slate);
    font-family: var(--font-sans);
    font-size: var(--fz-xs);
    text-align: left;
    white-space: nowrap;
    cursor: pointer;
    transition: var(--transition);
    border-top: 0;
    border-right: 0;
    border-bottom: 0;
}

.tab-button:hover,
.tab-button.active {
    color: var(--green);
    background-color: var(--light-navy);
    border-left: 2px solid var(--green);
}

.tab-content {
    flex: 1;
}

.tab-panel {
    display: none;
    width: 100%;
    height: auto;
    animation: fadeIn 0.5s;
}

.tab-panel.active {
    display: block;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.job {
    margin-bottom: 40px;
}

.job-title {
    color: var(--lightest-slate);
    font-size: var(--fz-xl);
    font-weight: 600;
    margin-bottom: 5px;
}

.company {
    color: var(--green);
}

.job-period {
    color: var(--light-slate);
    font-family: var(--font-sans);
    font-size: var(--fz-sm);
    margin-bottom: 20px;
}

.job-description {
    padding: 0;
    margin: 0;
    list-style: none;
}

.job-description li {
    position: relative;
    padding-left: 30px;
    margin-bottom: 10px;
    color: var(--slate);
}

.job-description li::before {
    content: '▹';
    position: absolute;
    left: 0;
    color: var(--green);
    font-size: var(--fz-md);
    line-height: 1.8;
}

.job-description-sub {
    margin-top: 8px;
    margin-left: 20px;
    padding-left: 0;
    list-style: none;
}

.job-description-sub li {
    position: relative;
    padding-left: 25px;
    margin-bottom: 6px;
    color: var(--slate);
    font-size: var(--fz-sm);
}

.job-description-sub li::before {
    content: '▸';
    position: absolute;
    left: 5px;
    color: var(--green);
    font-size: var(--fz-sm);
}

/* Skills Section */
.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
    margin-top: 30px;
}

.skill-category {
    padding: 25px;
    background-color: var(--light-navy);
    border-radius: var(--border-radius);
    transition: var(--transition);
}

.skill-category:hover {
    transform: translateY(-5px);
}

.skill-category h3 {
    color: var(--lightest-slate);
    margin-bottom: 15px;
    font-size: var(--fz-lg);
}

.skill-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    list-style: none;
    padding: 0;
    margin: 0;
}

.skill-tags li {
    color: var(--slate);
    background-color: var(--green-tint);
    border: 1px solid var(--green);
    border-radius: 3px;
    padding: 6px 12px;
    font-size: var(--fz-xs);
    transition: var(--transition);
}

.skill-tags li:hover {
    background-color: var(--green);
    color: var(--navy);
    transform: translateY(-2px);
}

/* Research Section */
.research-container {
    display: grid;
    gap: 25px;
    margin-top: 30px;
}

.research-item {
    position: relative;
    padding: 25px;
    background-color: var(--light-navy);
    border-radius: var(--border-radius);
    transition: var(--transition);
}

.research-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 30px -15px var(--navy-shadow);
}

.research-header {
    display: flex;
    align-items: center;
    gap: 15px;
    margin-bottom: 15px;
}

.research-header svg {
    width: 20px;
    height: 20px;
    color: var(--green);
    flex-shrink: 0;
}

.research-title {
    color: var(--lightest-slate);
    font-size: var(--fz-lg);
    font-weight: 600;
    margin: 0;
    line-height: 1.3;
}

.research-meta {
    display: flex;
    gap: 15px;
    margin-bottom: 10px;
}

.research-year {
    color: var(--green);
    font-family: var(--font-sans);
    font-size: var(--fz-sm);
    font-weight: 600;
}

.research-venue {
    color: var(--light-slate);
    font-size: var(--fz-sm);
}

.research-authors {
    color: var(--slate);
    font-size: var(--fz-sm);
    margin-bottom: 10px;
}

.research-description {
    color: var(--slate);
    font-size: var(--fz-sm);
    line-height: 1.6;
}

/* Lectures Section */
.lectures-container {
    margin-top: 30px;
}

.lecture-group {
    margin-bottom: 40px;
}

.lecture-group h3 {
    color: var(--lightest-slate);
    font-size: var(--fz-lg);
    margin-bottom: 15px;
}

.lecture-item {
    padding: 20px;
    background-color: var(--light-navy);
    border-radius: var(--border-radius);
    border-left: 2px solid var(--green);
    margin-bottom: 15px;
    transition: var(--transition);
}

.lecture-item:hover {
    transform: translateX(5px);
}

.institution {
    color: var(--green);
    font-weight: 600;
    display: block;
    margin-bottom: 8px;
}

.lecture-item p {
    color: var(--slate);
    margin: 0;
}

/* Contact Section */
.contact-content {
    max-width: 700px;
    margin: 0 auto;
    text-align: center;
}

.contact-content p {
    color: var(--slate);
    font-size: var(--fz-lg);
    line-height: 1.8;
    margin-bottom: 40px;
}

.contact-button {
    display: inline-block;
    color: var(--green);
    background-color: transparent;
    border: 1px solid var(--green);
    border-radius: var(--border-radius);
    padding: 1.25rem 1.75rem;
    font-size: var(--fz-sm);
    font-family: var(--font-sans);
    line-height: 1;
    text-decoration: none;
    cursor: pointer;
    transition: var(--transition);
    margin-bottom: 50px;
}

.contact-button:hover {
    background-color: var(--green-tint);
    transform: translateY(-3px);
}

.contact-info {
    display: flex;
    flex-direction: column;
    gap: 20px;
    margin-top: 40px;
}

.contact-item {
    display: flex;
    flex-direction: column;
    gap: 5px;
}

.contact-label {
    color: var(--green);
    font-size: var(--fz-xs);
    text-transform: uppercase;
    letter-spacing: 1px;
}

.contact-value {
    color: var(--lightest-slate);
    font-size: var(--fz-lg);
    text-decoration: none;
    transition: var(--transition);
}

.contact-value:hover {
    color: var(--green);
}

/* Footer */
.footer {
    text-align: center;
    padding: 40px 50px;
    color: var(--slate);
    font-size: var(--fz-xs);
}

.footer-note {
    margin-top: 10px;
    color: var(--lightest-navy);
}

/* Responsive Design */
@media (max-width: 768px) {
    .sidebar {
        bottom: 0;
        top: auto;
        width: 100%;
        height: auto;
        flex-direction: row;
        padding: 10px 20px;
        justify-content: space-around;
    }

    .logo {
        min-width: 50px;
        width: auto;
        padding: 8px 12px;
        height: 40px;
    }

    .logo a {
        font-size: 11px;
    }

    .nav-links {
        flex-direction: row;
        gap: 15px;
    }

    .nav-link {
        writing-mode: horizontal-tb;
        text-orientation: mixed;
        font-size: 11px;
    }

    .nav-link::after {
        display: none;
    }

    .language-switcher {
        flex-direction: row;
        gap: 5px;
        margin-bottom: 15px;
    }

    .lang-btn {
        padding: 4px 8px;
        font-size: 10px;
        min-width: 40px;
    }

    .main-wrapper {
        margin-left: 0;
        margin-bottom: 60px;
    }

    .section {
        padding: 80px 30px;
    }

    .section-heading::after {
        width: 100px;
    }

    .hero-section {
        padding: 0 30px;
    }

    .hero-container {
        grid-template-columns: 1fr;
        gap: 40px;
    }

    .hero-image-wrapper {
        order: -1;
    }

    .profile-image-container {
        width: 300px;
        height: 300px;
    }

    .about-wrapper {
        grid-template-columns: 1fr;
        gap: 40px;
    }

    .about-image-wrapper {
        order: -1;
    }

    .about-image-container {
        width: 250px;
        height: 250px;
    }

    .experience-container {
        flex-direction: column;
        gap: 30px;
    }

    .tab-list {
        flex-direction: row;
        width: 100%;
        overflow-x: auto;
    }

    .tab-button {
        width: auto;
        min-width: 100px;
        border-left: 0;
        border-bottom: 2px solid var(--lightest-navy);
    }

    .tab-button:hover,
    .tab-button.active {
        border-left: 0;
        border-bottom: 2px solid var(--green);
    }

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

    .tech-list {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .section {
        padding: 60px 20px;
    }

    .hero-section {
        padding: 0 20px;
    }

    .hero-container {
        gap: 30px;
    }

    .profile-image-container {
        width: 250px;
        height: 250px;
    }

    .about-wrapper {
        gap: 30px;
    }

    .about-image-container {
        width: 200px;
        height: 200px;
    }

    .section-heading {
        flex-direction: column;
        align-items: flex-start;
    }

    .section-heading::after {
        display: none;
    }

    .section-number {
        margin-bottom: 5px;
    }
}