/* ===========================
   CSS Variables & Reset
   =========================== */
:root {
    --bg-dark: #222831;
    --bg-darker: #1a1e25;
    --bg-light: #EEEEEE;
    --bg-section: #101010;
    --color-primary: #00ADB5;
    --color-accent-green: #00FF94;
    --color-accent-blue: #001AFF;
    --color-accent-orange: #C84B31;
    --color-text: #EEEEEE;
    --color-text-dark: #393E46;
    --color-text-muted: #8b8b8b;
    --font-en: 'Montserrat', sans-serif;
    --font-kr: 'Noto Sans KR', sans-serif;
    --transition: all 0.3s ease;
}

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

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-kr);
    background-color: var(--bg-dark);
    color: var(--color-text);
    overflow-x: hidden;
    line-height: 1.6;
}

a {
    text-decoration: none;
    color: inherit;
    transition: var(--transition);
}

ul, ol {
    list-style: none;
}

img {
    max-width: 100%;
    display: block;
}

strong {
    color: var(--color-primary);
    font-weight: 700;
}

/* ===========================
   Common
   =========================== */
.section {
    min-height: 100vh;
    padding: 100px 80px;
    position: relative;
}

.section-title {
    font-family: var(--font-en);
    font-size: 3rem;
    font-weight: 800;
    color: var(--color-text);
    margin-bottom: 50px;
    position: relative;
    display: inline-block;
}

.section-title.center {
    display: block;
    text-align: center;
}

.title-dot {
    color: var(--color-primary);
}

/* ===========================
   Navigation
   =========================== */
.nav {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    padding: 20px 80px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    z-index: 1000;
    background: transparent;
    transition: var(--transition);
}

.nav.scrolled {
    background: rgba(34, 40, 49, 0.95);
    backdrop-filter: blur(10px);
    padding: 15px 80px;
    box-shadow: 0 2px 20px rgba(0, 0, 0, 0.3);
}

.nav-logo {
    font-family: var(--font-en);
    font-size: 1.8rem;
    font-weight: 900;
    color: var(--color-primary);
    letter-spacing: 2px;
}

.nav-links {
    display: flex;
    gap: 35px;
}

.nav-links li a {
    font-family: var(--font-en);
    font-size: 0.9rem;
    font-weight: 600;
    letter-spacing: 1px;
    text-transform: uppercase;
    color: var(--color-text);
    position: relative;
    padding-bottom: 4px;
}

.nav-links li a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--color-primary);
    transition: width 0.3s ease;
}

.nav-links li a:hover::after,
.nav-links li a.active::after {
    width: 100%;
}

.nav-hamburger {
    display: none;
    flex-direction: column;
    gap: 5px;
    cursor: pointer;
    z-index: 1001;
}

.nav-hamburger span {
    width: 28px;
    height: 2px;
    background: var(--color-text);
    transition: var(--transition);
}

.nav-hamburger.active span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
}

.nav-hamburger.active span:nth-child(2) {
    opacity: 0;
}

.nav-hamburger.active span:nth-child(3) {
    transform: rotate(-45deg) translate(5px, -5px);
}

/* ===========================
   Hero Section
   =========================== */
.hero {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    background: var(--bg-darker);
    overflow: hidden;
    padding-top: 0;
    padding-bottom: 0;
}

.hero-content {
    text-align: center;
    width: 100%;
}

.hero-text-slider {
    overflow: hidden;
    width: 100%;
    margin-bottom: 30px;
}

.hero-text-track {
    display: flex;
    gap: 60px;
    animation: textSlide 12s linear infinite;
    white-space: nowrap;
}

.hero-text-track span {
    font-family: var(--font-en);
    font-size: 7rem;
    font-weight: 900;
    color: transparent;
    -webkit-text-stroke: 2px var(--color-text);
    letter-spacing: 5px;
    flex-shrink: 0;
}

.hero-text-track span:nth-child(even) {
    -webkit-text-stroke: 2px var(--color-primary);
}

@keyframes textSlide {
    0% { transform: translateX(0); }
    100% { transform: translateX(-50%); }
}

.hero-sub {
    margin-bottom: 40px;
}

.hero-sub p {
    font-family: var(--font-en);
    font-size: 1.3rem;
    font-weight: 400;
    letter-spacing: 8px;
    color: var(--color-text-muted);
}

.hero-progress {
    width: 200px;
    height: 3px;
    background: rgba(255, 255, 255, 0.1);
    margin: 0 auto;
    border-radius: 3px;
    overflow: hidden;
}

.hero-progress-bar {
    width: 30%;
    height: 100%;
    background: var(--color-primary);
    border-radius: 3px;
    animation: progress 4s ease-in-out infinite;
}

@keyframes progress {
    0% { transform: translateX(-100%); }
    50% { transform: translateX(250%); }
    100% { transform: translateX(-100%); }
}

.scroll-indicator {
    position: absolute;
    bottom: 40px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 10px;
}

.scroll-indicator span {
    font-family: var(--font-en);
    font-size: 0.7rem;
    letter-spacing: 3px;
    color: var(--color-text-muted);
}

.scroll-line {
    width: 1px;
    height: 40px;
    background: var(--color-text-muted);
    animation: scrollLine 2s ease-in-out infinite;
}

@keyframes scrollLine {
    0%, 100% { opacity: 0.3; transform: scaleY(0.5); }
    50% { opacity: 1; transform: scaleY(1); }
}

/* ===========================
   About Section
   =========================== */
.about {
    background: var(--bg-light);
    color: var(--color-text-dark);
    display: flex;
    align-items: center;
}

.about .section-title {
    color: var(--color-text-dark);
}

.about strong {
    color: var(--color-primary);
}

.about-container {
    display: flex;
    gap: 80px;
    align-items: center;
    max-width: 1200px;
    margin: 0 auto;
    width: 100%;
}

.about-left {
    flex: 0 0 350px;
}

.about-card {
    background: var(--bg-dark);
    border-radius: 20px;
    padding: 40px 30px;
    text-align: center;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
    transition: transform 0.3s ease;
}

.about-card:hover {
    transform: translateY(-10px);
}

.about-name {
    font-family: var(--font-kr);
    font-size: 2rem;
    font-weight: 900;
    color: var(--color-text);
    margin-bottom: 5px;
}

.about-role {
    font-family: var(--font-en);
    font-size: 1rem;
    font-weight: 600;
    color: var(--color-primary);
    margin-bottom: 25px;
    letter-spacing: 2px;
}

.about-info-list {
    text-align: left;
    margin-bottom: 25px;
}

.about-info-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 8px 0;
    color: var(--color-text);
    font-size: 0.9rem;
}

.about-info-item i {
    color: var(--color-primary);
    width: 20px;
    text-align: center;
    font-size: 0.9rem;
}

.about-links {
    display: flex;
    justify-content: center;
    gap: 15px;
    padding-top: 20px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
}

.about-links a {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    border: 1px solid rgba(255, 255, 255, 0.2);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-text);
    font-size: 1.1rem;
    transition: var(--transition);
}

.about-links a:hover {
    background: var(--color-primary);
    border-color: var(--color-primary);
    transform: translateY(-3px);
}

.about-right {
    flex: 1;
}

.about-description {
    font-size: 1rem;
    line-height: 1.8;
    margin-bottom: 20px;
    color: var(--color-text-dark);
}

.about-highlight {
    display: flex;
    gap: 40px;
    margin-top: 40px;
    padding-top: 30px;
    border-top: 1px solid rgba(0, 0, 0, 0.1);
}

.highlight-item {
    text-align: center;
}

.highlight-number {
    display: block;
    font-family: var(--font-en);
    font-size: 2.5rem;
    font-weight: 900;
    color: var(--color-primary);
    line-height: 1;
}

.highlight-label {
    font-family: var(--font-en);
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--color-text-muted);
    letter-spacing: 1px;
    margin-top: 5px;
    display: block;
}

/* ===========================
   Skills Section
   =========================== */
.skills {
    background: var(--bg-section);
    display: flex;
    flex-direction: column;
    justify-content: center;
}

.skills-container {
    max-width: 1000px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 40px;
}

.skill-category {
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid rgba(255, 255, 255, 0.08);
    border-radius: 16px;
    padding: 30px;
    transition: var(--transition);
}

.skill-category:hover {
    border-color: var(--color-primary);
    box-shadow: 0 0 30px rgba(0, 173, 181, 0.1);
}

.skill-category-title {
    font-family: var(--font-en);
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--color-primary);
    margin-bottom: 20px;
    letter-spacing: 1px;
}

.skill-items {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.skill-item {
    display: flex;
    align-items: center;
    gap: 15px;
}

.skill-name {
    font-family: var(--font-en);
    font-size: 0.9rem;
    font-weight: 600;
    min-width: 90px;
    color: var(--color-text);
}

.skill-bar {
    flex: 1;
    height: 8px;
    background: rgba(255, 255, 255, 0.1);
    border-radius: 8px;
    overflow: hidden;
}

.skill-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--color-primary), var(--color-accent-green));
    border-radius: 8px;
    width: 0;
    transition: width 1.5s ease;
}

.skill-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}

.skill-tag {
    padding: 8px 18px;
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 25px;
    font-family: var(--font-en);
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--color-text);
    transition: var(--transition);
    cursor: default;
}

.skill-tag:hover {
    background: var(--color-primary);
    border-color: var(--color-primary);
    color: var(--bg-dark);
    transform: translateY(-2px);
}

/* ===========================
   Experience Section
   =========================== */
.experience {
    background: var(--bg-dark);
}

.exp-container {
    max-width: 1000px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 80px;
}

.timeline {
    position: relative;
    padding-left: 30px;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    bottom: 0;
    width: 2px;
    background: rgba(255, 255, 255, 0.1);
}

.timeline-item {
    position: relative;
    margin-bottom: 40px;
}

.timeline-item:last-child {
    margin-bottom: 0;
}

.timeline-dot {
    position: absolute;
    left: -35px;
    top: 5px;
    width: 12px;
    height: 12px;
    border-radius: 50%;
    background: var(--color-primary);
    border: 3px solid var(--bg-dark);
}

.timeline-content {
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid rgba(255, 255, 255, 0.08);
    border-radius: 12px;
    padding: 25px;
    transition: var(--transition);
}

.timeline-content:hover {
    border-color: var(--color-primary);
    transform: translateX(5px);
}

.timeline-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 8px;
}

.timeline-header h4 {
    font-size: 1.15rem;
    font-weight: 700;
    color: var(--color-text);
}

.timeline-badge {
    padding: 4px 12px;
    background: var(--color-primary);
    color: var(--bg-dark);
    border-radius: 20px;
    font-size: 0.75rem;
    font-weight: 700;
    white-space: nowrap;
}

.timeline-badge.edu {
    background: var(--color-accent-green);
}

.timeline-sub {
    display: block;
    font-size: 0.85rem;
    color: var(--color-text-muted);
    margin-bottom: 5px;
}

.timeline-date {
    display: block;
    font-family: var(--font-en);
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--color-primary);
    margin-bottom: 15px;
}

.timeline-list {
    list-style: none;
}

.timeline-list li {
    position: relative;
    padding-left: 15px;
    font-size: 0.9rem;
    line-height: 1.8;
    color: var(--color-text);
}

.timeline-list li::before {
    content: '·';
    position: absolute;
    left: 0;
    color: var(--color-primary);
    font-weight: 900;
    font-size: 1.2rem;
}

/* ===========================
   Projects Section
   =========================== */
.projects {
    background: var(--bg-section);
}

.projects-container {
    max-width: 1000px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    gap: 30px;
}

.project-card {
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid rgba(255, 255, 255, 0.08);
    border-radius: 16px;
    padding: 35px;
    transition: var(--transition);
    width: 75%;
}

.project-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.3);
}

.project-card.left {
    border-left: 4px solid var(--color-accent-green);
    align-self: flex-start;
}

.project-card.right {
    border-right: 4px solid var(--color-accent-blue);
    align-self: flex-end;
}

.project-card.full-width {
    width: 100%;
}

.project-card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 8px;
}

.project-card-header h4 {
    font-size: 1.4rem;
    font-weight: 800;
    color: var(--color-text);
}

.project-role {
    padding: 4px 14px;
    background: rgba(0, 173, 181, 0.15);
    color: var(--color-primary);
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 600;
}

.project-date {
    display: block;
    font-family: var(--font-en);
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--color-primary);
    margin-bottom: 12px;
}

.project-team {
    font-size: 0.9rem;
    color: var(--color-text-muted);
    margin-bottom: 15px;
}

.project-detail {
    margin-bottom: 20px;
}

.project-detail li {
    position: relative;
    padding-left: 15px;
    font-size: 0.9rem;
    line-height: 1.9;
    color: var(--color-text);
}

.project-detail li::before {
    content: '·';
    position: absolute;
    left: 0;
    color: var(--color-primary);
    font-weight: 900;
    font-size: 1.2rem;
}

.project-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-bottom: 15px;
}

.project-tags span {
    padding: 5px 14px;
    background: rgba(0, 173, 181, 0.1);
    border: 1px solid rgba(0, 173, 181, 0.3);
    border-radius: 20px;
    font-family: var(--font-en);
    font-size: 0.78rem;
    font-weight: 600;
    color: var(--color-primary);
}

.project-links {
    display: flex;
    gap: 12px;
}

.project-links a {
    padding: 6px 16px;
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 8px;
    font-size: 0.8rem;
    font-weight: 500;
    color: var(--color-text);
    display: flex;
    align-items: center;
    gap: 6px;
    transition: var(--transition);
}

.project-links a:hover {
    background: var(--color-primary);
    border-color: var(--color-primary);
    color: var(--bg-dark);
}

.project-sub-list {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-bottom: 20px;
}

.project-sub-list span {
    padding: 5px 12px;
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: 6px;
    font-size: 0.8rem;
    color: var(--color-text-muted);
}

/* ===========================
   Cover Letter Section
   =========================== */
.coverletter {
    background: var(--bg-dark);
}

.cl-container {
    max-width: 900px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    gap: 30px;
}

.cl-block {
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid rgba(255, 255, 255, 0.08);
    border-radius: 16px;
    overflow: hidden;
    transition: var(--transition);
}

.cl-block:hover {
    border-color: var(--color-primary);
}

.cl-block-title {
    display: flex;
    align-items: center;
    gap: 20px;
    padding: 25px 30px;
    background: rgba(0, 173, 181, 0.08);
    cursor: pointer;
}

.cl-number {
    font-family: var(--font-en);
    font-size: 1.5rem;
    font-weight: 900;
    color: var(--color-primary);
}

.cl-block-title h4 {
    font-size: 1.2rem;
    font-weight: 700;
    color: var(--color-text);
}

.cl-block-content {
    padding: 25px 30px 30px;
}

.cl-block-content p {
    font-size: 0.95rem;
    line-height: 1.9;
    margin-bottom: 15px;
    color: rgba(238, 238, 238, 0.85);
}

.cl-block-content p:last-child {
    margin-bottom: 0;
}

/* ===========================
   Hobby Section
   =========================== */
.hobby {
    background: var(--bg-section);
    min-height: auto;
    padding: 80px;
}

.hobby-container {
    display: flex;
    justify-content: center;
    gap: 60px;
    max-width: 600px;
    margin: 0 auto;
}

.hobby-item {
    text-align: center;
    padding: 40px;
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid rgba(255, 255, 255, 0.08);
    border-radius: 16px;
    flex: 1;
    transition: var(--transition);
}

.hobby-item:hover {
    border-color: var(--color-primary);
    transform: translateY(-5px);
}

.hobby-item i {
    font-size: 2.5rem;
    color: var(--color-primary);
    margin-bottom: 15px;
}

.hobby-item h4 {
    font-size: 1.1rem;
    font-weight: 700;
    margin-bottom: 8px;
}

.hobby-item p {
    font-size: 0.85rem;
    color: var(--color-text-muted);
}

/* ===========================
   Footer
   =========================== */
.footer {
    background: var(--bg-darker);
    padding: 50px 80px;
    text-align: center;
    border-top: 1px solid rgba(255, 255, 255, 0.05);
}

.footer-logo {
    font-family: var(--font-en);
    font-size: 1.5rem;
    font-weight: 900;
    color: var(--color-primary);
    letter-spacing: 3px;
    margin-bottom: 20px;
}

.footer-links {
    display: flex;
    justify-content: center;
    gap: 20px;
    margin-bottom: 20px;
}

.footer-links a {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    border: 1px solid rgba(255, 255, 255, 0.15);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-text-muted);
    font-size: 1rem;
    transition: var(--transition);
}

.footer-links a:hover {
    background: var(--color-primary);
    border-color: var(--color-primary);
    color: var(--bg-dark);
}

.footer-copy {
    font-family: var(--font-en);
    font-size: 0.8rem;
    color: var(--color-text-muted);
    letter-spacing: 1px;
}

/* ===========================
   Scroll Top Button
   =========================== */
.scroll-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 48px;
    height: 48px;
    border-radius: 50%;
    background: var(--color-primary);
    color: var(--bg-dark);
    border: none;
    cursor: pointer;
    font-size: 1.1rem;
    display: flex;
    align-items: center;
    justify-content: center;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition);
    z-index: 999;
    box-shadow: 0 4px 15px rgba(0, 173, 181, 0.4);
}

.scroll-top.visible {
    opacity: 1;
    visibility: visible;
}

.scroll-top:hover {
    transform: translateY(-3px);
    box-shadow: 0 6px 20px rgba(0, 173, 181, 0.6);
}

/* ===========================
   Responsive - Tablet (1024px)
   =========================== */
@media (max-width: 1024px) {
    .section {
        padding: 80px 40px;
    }

    .nav {
        padding: 20px 40px;
    }

    .nav.scrolled {
        padding: 15px 40px;
    }

    .hero-text-track span {
        font-size: 5rem;
    }

    .about-container {
        flex-direction: column;
        gap: 50px;
    }

    .about-left {
        flex: none;
        width: 100%;
        max-width: 400px;
        margin: 0 auto;
    }

    .exp-container {
        grid-template-columns: 1fr;
        gap: 60px;
    }

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

    .project-card {
        width: 100%;
    }
}

/* ===========================
   Responsive - Mobile (768px)
   =========================== */
@media (max-width: 768px) {
    .section {
        padding: 80px 20px;
        min-height: auto;
    }

    .nav {
        padding: 15px 20px;
    }

    .nav.scrolled {
        padding: 12px 20px;
    }

    .nav-links {
        position: fixed;
        top: 0;
        right: -100%;
        width: 70%;
        height: 100vh;
        background: rgba(34, 40, 49, 0.98);
        backdrop-filter: blur(10px);
        flex-direction: column;
        justify-content: center;
        align-items: center;
        gap: 30px;
        transition: right 0.4s ease;
    }

    .nav-links.open {
        right: 0;
    }

    .nav-links li a {
        font-size: 1.1rem;
    }

    .nav-hamburger {
        display: flex;
    }

    .hero-text-track span {
        font-size: 3rem;
    }

    .hero-sub p {
        font-size: 0.9rem;
        letter-spacing: 4px;
    }

    .section-title {
        font-size: 2.2rem;
    }

    .about-container {
        gap: 40px;
    }

    .about-highlight {
        gap: 20px;
    }

    .highlight-number {
        font-size: 2rem;
    }

    .project-card-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 8px;
    }

    .project-card-header h4 {
        font-size: 1.2rem;
    }

    .timeline-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 8px;
    }

    .hobby {
        padding: 60px 20px;
    }

    .hobby-container {
        flex-direction: column;
        gap: 20px;
    }

    .footer {
        padding: 40px 20px;
    }

    .cl-block-title {
        padding: 20px;
    }

    .cl-block-content {
        padding: 20px;
    }

    .cl-number {
        font-size: 1.2rem;
    }

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

/* ===========================
   Responsive - Small Mobile (480px)
   =========================== */
@media (max-width: 480px) {
    .hero-text-track span {
        font-size: 2.2rem;
    }

    .section-title {
        font-size: 1.8rem;
    }

    .about-card {
        padding: 30px 20px;
    }

    .about-name {
        font-size: 1.6rem;
    }

    .skill-category {
        padding: 20px;
    }

    .project-card {
        padding: 25px;
    }
}