/* ============================================
   DR. HYUNWOO CHO - PERSONAL WEBSITE STYLES
   Purple Gradient Theme
   ============================================
   
   수정 가이드:
   1. 색상 변경: :root 섹션의 CSS 변수를 수정하세요
   2. 폰트 변경: --font-primary 변수를 수정하세요
   3. 레이아웃 조정: 각 섹션별 padding, margin 조정
   
   주요 색상:
   - 퍼플 그라디언트: #667eea → #764ba2
   - 강조 색상: #8b5cf6 (보라색)
   - 텍스트: #1a202c (진한 회색)
============================================ */

/* ============================================
   CSS VARIABLES (색상, 폰트 등 한 곳에서 관리)
   수정 팁: 여기서 색상을 변경하면 전체 사이트에 적용됩니다
============================================ */
:root {
    /* Purple Gradient Theme */
    --primary-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --primary-color: #667eea;
    --primary-dark: #764ba2;
    --secondary-color: #8b5cf6;
    
    /* Text Colors */
    --text-dark: #1a202c;
    --text-medium: #2d3748;
    --text-light: #4a5568;
    --text-lighter: #718096;
    
    /* Background Colors */
    --bg-white: #ffffff;
    --bg-light: #f7fafc;
    --bg-lighter: #edf2f7;
    
    /* Accent Colors */
    --accent-orange: #f59e0b;
    --accent-gray: #6b7280;
    --accent-red: #dc2626;
    --accent-gold: #fbbf24;
    --accent-green: #10b981;
    
    /* Fonts */
    --font-primary: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    
    /* Spacing */
    --section-padding: 80px;
    --container-width: 1200px;
    
    /* Shadows */
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.12);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.15);
    
    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
}

/* ============================================
   RESET & BASE STYLES
============================================ */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

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

body {
    font-family: var(--font-primary);
    color: var(--text-dark);
    line-height: 1.7;
    background-color: var(--bg-white);
    overflow-x: hidden;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: 1.3;
    color: var(--text-dark);
}

p {
    margin-bottom: 1rem;
    color: var(--text-medium);
}

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

a:hover {
    color: var(--primary-dark);
}

/* Container */
.container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 20px;
}

/* Section */
.section {
    padding: var(--section-padding) 0;
    position: relative;
}

.section-alt {
    background-color: var(--bg-light);
}

.section-title {
    font-size: 2.5rem;
    text-align: center;
    margin-bottom: 3rem;
    position: relative;
    padding-bottom: 1rem;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 80px;
    height: 4px;
    background: var(--primary-gradient);
    border-radius: 2px;
}

/* ============================================
   NAVIGATION BAR
   수정 팁: navbar 높이, 배경색 등을 여기서 조정
============================================ */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: var(--bg-white);
    box-shadow: var(--shadow-md);
    z-index: 1000;
    transition: var(--transition-normal);
}

.navbar.scrolled {
    box-shadow: var(--shadow-lg);
}

.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 20px;
}

.nav-brand {
    font-size: 1.5rem;
    font-weight: 700;
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    text-decoration: none;
    cursor: pointer;
    transition: var(--transition-normal);
}

.nav-brand:hover {
    opacity: 0.8;
    transform: scale(1.05);
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
    margin: 0;
}

.nav-link {
    color: var(--text-dark);
    font-weight: 500;
    padding: 0.5rem 0;
    position: relative;
    transition: var(--transition-normal);
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary-gradient);
    transition: width var(--transition-normal);
}

.nav-link:hover::after,
.nav-link.active::after {
    width: 100%;
}

.nav-link.active {
    color: var(--primary-color);
}

/* Mobile Menu Toggle */
.nav-toggle {
    display: none;
    flex-direction: column;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0.5rem;
}

.nav-toggle span {
    width: 25px;
    height: 3px;
    background: var(--text-dark);
    margin: 3px 0;
    transition: var(--transition-normal);
    border-radius: 2px;
}

/* ============================================
   HERO SECTION
   수정 팁: 배경색, 텍스트 크기 등을 여기서 조정
============================================ */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--primary-gradient);
    color: white;
    text-align: center;
    padding: 120px 20px 80px;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1200 600"><path d="M0,300 Q300,200 600,300 T1200,300 L1200,600 L0,600 Z" fill="rgba(255,255,255,0.05)"/></svg>') no-repeat bottom center;
    background-size: cover;
    opacity: 0.5;
}

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

.hero-badge {
    display: inline-block;
    background: rgba(255, 255, 255, 0.2);
    padding: 0.5rem 1.5rem;
    border-radius: 50px;
    font-size: 0.9rem;
    font-weight: 600;
    letter-spacing: 0.5px;
    margin-bottom: 1.5rem;
    backdrop-filter: blur(10px);
}

.hero-title {
    font-size: 4rem;
    margin-bottom: 1rem;
    font-weight: 800;
    text-shadow: 0 2px 10px rgba(0, 0, 0, 0.2);
}

.hero-subtitle {
    font-size: 1.5rem;
    margin-bottom: 2rem;
    opacity: 0.95;
    font-weight: 400;
}

.hero-affiliation {
    font-size: 1.1rem;
    margin-bottom: 2.5rem;
    opacity: 0.9;
    line-height: 1.8;
}

.hero-affiliation i {
    margin-right: 0.5rem;
}

.hero-buttons {
    display: flex;
    gap: 1rem;
    justify-content: center;
    flex-wrap: wrap;
    margin-bottom: 3rem;
}

/* Statistics */
.hero-stats {
    display: flex;
    gap: 3rem;
    justify-content: center;
    margin-top: 3rem;
}

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

.stat-number {
    font-size: 3rem;
    font-weight: 800;
    display: block;
    margin-bottom: 0.5rem;
}

.stat-label {
    font-size: 1rem;
    opacity: 0.9;
    text-transform: uppercase;
    letter-spacing: 1px;
}

/* ============================================
   BUTTONS
   수정 팁: 버튼 스타일을 여기서 조정
============================================ */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 2rem;
    border-radius: 50px;
    font-weight: 600;
    font-size: 1rem;
    border: none;
    cursor: pointer;
    transition: var(--transition-normal);
    text-decoration: none;
}

.btn-primary {
    background: white;
    color: var(--primary-color);
    box-shadow: var(--shadow-md);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
    color: var(--primary-dark);
}

.btn-secondary {
    background: rgba(255, 255, 255, 0.2);
    color: white;
    backdrop-filter: blur(10px);
}

.btn-secondary:hover {
    background: rgba(255, 255, 255, 0.3);
    transform: translateY(-2px);
}

.btn-scholar {
    background: linear-gradient(135deg, #4285f4 0%, #34a853 100%);
    color: white;
    box-shadow: var(--shadow-md);
}

.btn-scholar:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
    color: white;
}

.btn-block {
    width: 100%;
    justify-content: center;
}

/* ============================================
   ABOUT SECTION
   수정 팁: About 텍스트 스타일과 하이라이트 색상 조정
============================================ */
.about-content {
    max-width: 900px;
    margin: 0 auto;
}

.about-text {
    font-size: 1.1rem;
    line-height: 1.9;
    text-align: justify;
}

/* 하이라이트 스타일 - 중요한 키워드 강조 */
.highlight {
    background: linear-gradient(120deg, rgba(102, 126, 234, 0.2) 0%, rgba(118, 75, 162, 0.2) 100%);
    padding: 2px 6px;
    border-radius: 3px;
    font-weight: 600;
    color: var(--primary-dark);
}

/* ============================================
   RESEARCH INTERESTS
   수정 팁: 연구 분야 카드 스타일 조정
============================================ */
.research-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.research-card {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow-md);
    transition: var(--transition-normal);
    border: 2px solid transparent;
}

.research-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary-color);
}

.research-icon {
    width: 60px;
    height: 60px;
    background: var(--primary-gradient);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 1.5rem;
}

.research-icon i {
    font-size: 1.8rem;
    color: white;
}

.research-card h3 {
    font-size: 1.3rem;
    margin-bottom: 1rem;
    color: var(--text-dark);
}

.research-card ul {
    list-style: none;
    padding: 0;
}

.research-card li {
    padding-left: 1.5rem;
    margin-bottom: 0.8rem;
    position: relative;
    color: var(--text-light);
    line-height: 1.6;
}

.research-card li::before {
    content: '▸';
    position: absolute;
    left: 0;
    color: var(--primary-color);
    font-weight: bold;
}

/* ============================================
   PUBLICATIONS SECTION
   수정 팁: 논문 항목 스타일, 배지 색상 등 조정
============================================ */
.scholar-button {
    text-align: center;
    margin-bottom: 3rem;
}

.pub-filter {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-bottom: 3rem;
    flex-wrap: wrap;
}

.filter-btn {
    padding: 0.6rem 1.5rem;
    border: 2px solid var(--primary-color);
    background: white;
    color: var(--primary-color);
    border-radius: 50px;
    cursor: pointer;
    font-weight: 600;
    transition: var(--transition-normal);
}

.filter-btn:hover,
.filter-btn.active {
    background: var(--primary-gradient);
    color: white;
    border-color: transparent;
}

.publications-container {
    max-width: 1000px;
    margin: 0 auto;
}

.pub-category-title {
    font-size: 1.8rem;
    color: var(--text-dark);
    margin-bottom: 2rem;
    padding-bottom: 0.8rem;
    border-bottom: 3px solid var(--primary-color);
    display: flex;
    align-items: center;
    gap: 0.8rem;
}

.pub-category-title i {
    color: var(--primary-color);
}

/* Publication Item */
.publication-item {
    background: white;
    padding: 1.8rem;
    margin-bottom: 1.5rem;
    border-radius: 10px;
    border-left: 4px solid var(--text-lighter);
    box-shadow: var(--shadow-sm);
    transition: var(--transition-normal);
    position: relative;
}

.publication-item:hover {
    transform: translateX(5px);
    box-shadow: var(--shadow-md);
}

/* First Author 논문 강조 - 퍼플 그라디언트 */
.publication-item.first-author {
    border-left: 5px solid var(--primary-color);
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.03) 0%, rgba(118, 75, 162, 0.03) 100%);
    box-shadow: var(--shadow-md);
}

.publication-item.first-author:hover {
    box-shadow: var(--shadow-lg);
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.06) 0%, rgba(118, 75, 162, 0.06) 100%);
}

.pub-year {
    position: absolute;
    top: 1rem;
    right: 1rem;
    font-size: 0.85rem;
    color: var(--text-lighter);
    font-weight: 600;
}

/* 저자 역할 배지 */
.pub-badges {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1rem;
    flex-wrap: wrap;
}

.badge {
    display: inline-block;
    padding: 0.3rem 0.8rem;
    border-radius: 20px;
    font-size: 0.75rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.badge-first {
    background: var(--primary-gradient);
    color: white;
}

.badge-cofirst {
    background: var(--accent-orange);
    color: white;
}

.badge-coauthor {
    background: var(--accent-gray);
    color: white;
}

.badge-corresponding {
    background: var(--accent-red);
    color: white;
}

/* JCR Top 25% 배지 - 골드 색상으로 강조 */
.badge-jcr {
    background: linear-gradient(135deg, #fbbf24 0%, #f59e0b 100%);
    color: white;
    font-weight: 800;
    box-shadow: 0 2px 8px rgba(251, 191, 36, 0.3);
}

.badge-preprint {
    background: var(--accent-green);
    color: white;
}

.pub-authors {
    font-size: 0.95rem;
    color: var(--text-light);
    margin-bottom: 0.8rem;
    line-height: 1.6;
}

.pub-authors strong {
    color: var(--primary-dark);
    font-weight: 700;
}

.pub-title {
    font-size: 1.05rem;
    font-weight: 600;
    color: var(--text-dark);
    margin-bottom: 0.8rem;
    line-height: 1.5;
}

.pub-journal {
    font-size: 0.95rem;
    color: var(--text-light);
    font-style: italic;
    margin-bottom: 0.5rem;
}

.pub-journal i {
    margin-right: 0.5rem;
    color: var(--primary-color);
}

/* JCR 정보 강조 */
.pub-details {
    margin-top: 0.8rem;
}

.jcr-info {
    display: inline-block;
    background: linear-gradient(135deg, rgba(251, 191, 36, 0.1) 0%, rgba(245, 158, 11, 0.1) 100%);
    padding: 0.4rem 0.8rem;
    border-radius: 6px;
    font-size: 0.85rem;
    font-weight: 600;
    color: #b45309;
    border: 1px solid rgba(251, 191, 36, 0.3);
}

.pub-link {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    margin-top: 0.8rem;
    color: var(--primary-color);
    font-weight: 600;
    font-size: 0.9rem;
    transition: var(--transition-normal);
}

.pub-link:hover {
    color: var(--primary-dark);
    text-decoration: underline;
}

.pub-notice {
    padding: 1.5rem;
    background: var(--bg-lighter);
    border-radius: 8px;
    color: var(--text-light);
    font-style: italic;
    text-align: center;
}

.pub-notice i {
    margin-right: 0.5rem;
    color: var(--primary-color);
}

/* ============================================
   CONFERENCE PRESENTATIONS
   수정 팁: Conference 항목 스타일 조정
============================================ */
.conference-item {
    background: white;
    padding: 1.5rem;
    margin-bottom: 1.2rem;
    border-radius: 10px;
    border-left: 4px solid var(--secondary-color);
    box-shadow: var(--shadow-sm);
    transition: var(--transition-normal);
}

.conference-item:hover {
    transform: translateX(5px);
    box-shadow: var(--shadow-md);
}

.conf-year {
    display: inline-block;
    background: var(--secondary-color);
    color: white;
    padding: 0.3rem 0.8rem;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 700;
    margin-bottom: 0.8rem;
}

.conf-title {
    font-size: 1rem;
    color: var(--text-dark);
    margin-bottom: 0.8rem;
    line-height: 1.6;
}

/* Cho, H. 이름 언더라인 강조 */
.conf-title strong {
    color: var(--primary-dark);
    font-weight: 700;
    text-decoration: underline;
    text-decoration-color: var(--primary-color);
    text-decoration-thickness: 2px;
    text-underline-offset: 2px;
}

.conf-venue {
    font-size: 0.9rem;
    color: var(--text-light);
    font-style: italic;
}

.conf-venue i {
    margin-right: 0.5rem;
    color: var(--secondary-color);
}

.conf-type {
    display: inline-block;
    padding: 0.2rem 0.6rem;
    border-radius: 12px;
    font-size: 0.75rem;
    font-weight: 600;
    margin-left: 0.8rem;
    font-style: normal;
}

.conf-type.oral {
    background: #ec4899;
    color: white;
}

.conf-type.invited {
    background: linear-gradient(135deg, #f59e0b 0%, #d97706 100%);
    color: white;
    font-weight: 700;
    box-shadow: 0 2px 6px rgba(245, 158, 11, 0.3);
}

/* ============================================
   EDUCATION & EXPERIENCE - DUAL COLUMN
   수정 팁: 타임라인 색상, 스타일 조정
============================================ */
.edu-exp-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(450px, 1fr));
    gap: 3rem;
    max-width: 1100px;
    margin: 0 auto;
}

.edu-exp-column {
    position: relative;
}

.column-title {
    font-size: 1.8rem;
    color: var(--text-dark);
    margin-bottom: 2rem;
    display: flex;
    align-items: center;
    gap: 0.8rem;
    padding-bottom: 0.8rem;
    border-bottom: 3px solid var(--primary-color);
}

.column-title i {
    color: var(--primary-color);
    font-size: 1.5rem;
}

.timeline {
    position: relative;
    padding-left: 50px;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 20px;
    top: 0;
    bottom: 0;
    width: 3px;
    background: var(--primary-gradient);
}

.timeline-item {
    position: relative;
    margin-bottom: 3rem;
}

.timeline-dot {
    position: absolute;
    left: -38px;
    top: 5px;
    width: 18px;
    height: 18px;
    border-radius: 50%;
    background: white;
    border: 4px solid var(--primary-color);
    box-shadow: 0 0 0 4px rgba(102, 126, 234, 0.1);
}

.timeline-content {
    background: white;
    padding: 1.8rem;
    border-radius: 10px;
    box-shadow: var(--shadow-md);
    transition: var(--transition-normal);
}

.timeline-content:hover {
    transform: translateX(5px);
    box-shadow: var(--shadow-lg);
}

.timeline-date {
    display: inline-block;
    background: var(--primary-gradient);
    color: white;
    padding: 0.4rem 1rem;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

.timeline-content h3 {
    font-size: 1.3rem;
    margin-bottom: 0.8rem;
    color: var(--text-dark);
}

.timeline-location {
    color: var(--text-light);
    font-size: 0.95rem;
    line-height: 1.7;
}

.timeline-location i {
    margin-right: 0.5rem;
    color: var(--primary-color);
}

.timeline-thesis {
    margin-top: 1rem;
    padding-top: 1rem;
    border-top: 1px solid var(--bg-lighter);
    color: var(--text-light);
    font-size: 0.9rem;
}

.timeline-thesis i {
    margin-right: 0.5rem;
    color: var(--secondary-color);
}

/* ============================================
   AWARDS & HONORS
   수정 팁: 수상 카드 스타일 조정
============================================ */
.awards-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
    margin-bottom: 4rem;
}

.award-card {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow-md);
    border-left: 4px solid var(--accent-gold);
    transition: var(--transition-normal);
    text-align: center;
}

.award-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
}

/* 주요 수상 강조 */
.award-card.award-highlight {
    border-left-color: var(--primary-color);
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.03) 0%, rgba(118, 75, 162, 0.03) 100%);
}

.award-year {
    display: inline-block;
    background: var(--accent-gold);
    color: white;
    padding: 0.4rem 1rem;
    border-radius: 20px;
    font-weight: 700;
    font-size: 0.9rem;
    margin-bottom: 1rem;
}

.award-card.award-highlight .award-year {
    background: var(--primary-gradient);
}

.award-icon {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.award-icon i {
    color: var(--accent-gold);
}

.award-card.award-highlight .award-icon i {
    background: var(--primary-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.award-title {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--text-dark);
    margin-bottom: 0.5rem;
    line-height: 1.4;
}

.award-org {
    font-size: 0.9rem;
    color: var(--text-light);
    line-height: 1.5;
}

/* Professional Service */
.service-section {
    margin-top: 4rem;
    padding-top: 3rem;
    border-top: 2px solid var(--bg-lighter);
}

.service-title {
    font-size: 1.8rem;
    margin-bottom: 2rem;
    display: flex;
    align-items: center;
    gap: 0.8rem;
    color: var(--text-dark);
}

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

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

.service-item {
    display: flex;
    align-items: center;
    gap: 0.8rem;
    padding: 1rem;
    background: white;
    border-radius: 8px;
    box-shadow: var(--shadow-sm);
    transition: var(--transition-normal);
}

.service-item:hover {
    transform: translateX(5px);
    box-shadow: var(--shadow-md);
}

.service-item i {
    color: var(--primary-color);
    font-size: 1.2rem;
}

.service-item span {
    color: var(--text-medium);
    font-size: 0.95rem;
}

/* ============================================
   CONTACT SECTION
   수정 팁: 연락처 정보 스타일 조정
============================================ */
.contact-container {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 3rem;
    max-width: 1100px;
    margin: 0 auto;
}

.contact-info {
    display: grid;
    gap: 1.5rem;
}

.contact-card {
    background: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow-md);
    text-align: center;
    transition: var(--transition-normal);
}

.contact-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-xl);
}

.contact-icon {
    width: 60px;
    height: 60px;
    background: var(--primary-gradient);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1rem;
}

.contact-icon i {
    font-size: 1.5rem;
    color: white;
}

.contact-card h3 {
    font-size: 1.2rem;
    margin-bottom: 0.8rem;
    color: var(--text-dark);
}

.contact-card p {
    color: var(--text-light);
    margin-bottom: 0.5rem;
}

.contact-card a {
    color: var(--primary-color);
    font-weight: 600;
}

.contact-card a:hover {
    color: var(--primary-dark);
    text-decoration: underline;
}

/* Contact Form */
.contact-form-wrapper {
    background: white;
    padding: 2.5rem;
    border-radius: 12px;
    box-shadow: var(--shadow-md);
}

.contact-form-wrapper h3 {
    font-size: 1.5rem;
    margin-bottom: 1.5rem;
    color: var(--text-dark);
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 0.9rem;
    border: 2px solid var(--bg-lighter);
    border-radius: 8px;
    font-family: var(--font-primary);
    font-size: 1rem;
    transition: var(--transition-normal);
    color: var(--text-dark);
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.form-group textarea {
    resize: vertical;
    min-height: 120px;
}

/* ============================================
   FOOTER
============================================ */
.footer {
    background: var(--text-dark);
    color: white;
    text-align: center;
    padding: 2rem 20px;
}

.footer p {
    color: rgba(255, 255, 255, 0.8);
    margin-bottom: 0.5rem;
}

/* ============================================
   SCROLL TO TOP BUTTON
============================================ */
.scroll-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background: var(--primary-gradient);
    color: white;
    border: none;
    border-radius: 50%;
    cursor: pointer;
    display: none;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
    box-shadow: var(--shadow-lg);
    transition: var(--transition-normal);
    z-index: 999;
}

.scroll-top:hover {
    transform: translateY(-3px);
    box-shadow: var(--shadow-xl);
}

.scroll-top.show {
    display: flex;
}

/* ============================================
   ANIMATIONS
============================================ */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.fade-in-up {
    animation: fadeInUp 0.6s ease-out;
}

/* ============================================
   RESPONSIVE DESIGN (모바일 최적화)
============================================ */
@media (max-width: 768px) {
    /* Navigation */
    .nav-toggle {
        display: flex;
    }
    
    .nav-menu {
        position: fixed;
        top: 70px;
        left: -100%;
        width: 100%;
        background: white;
        flex-direction: column;
        padding: 2rem;
        box-shadow: var(--shadow-lg);
        transition: left var(--transition-normal);
        gap: 0;
    }
    
    .nav-menu.active {
        left: 0;
    }
    
    .nav-menu li {
        margin: 0;
        padding: 1rem 0;
        border-bottom: 1px solid var(--bg-lighter);
    }
    
    /* Hero */
    .hero {
        padding: 100px 20px 60px;
    }
    
    .hero-title {
        font-size: 2.5rem;
    }
    
    .hero-subtitle {
        font-size: 1.2rem;
    }
    
    .hero-stats {
        flex-direction: column;
        gap: 2rem;
    }
    
    .stat-number {
        font-size: 2.5rem;
    }
    
    /* Sections */
    :root {
        --section-padding: 60px;
    }
    
    .section-title {
        font-size: 2rem;
    }
    
    /* Research Grid */
    .research-grid {
        grid-template-columns: 1fr;
    }
    
    /* Education & Experience - Stack on Mobile */
    .edu-exp-container {
        grid-template-columns: 1fr;
        gap: 2rem;
    }
    
    .column-title {
        font-size: 1.5rem;
    }
    
    /* Timeline */
    .timeline {
        padding-left: 40px;
    }
    
    .timeline::before {
        left: 10px;
    }
    
    .timeline-dot {
        left: -28px;
    }
    
    /* Awards */
    .awards-grid {
        grid-template-columns: 1fr;
    }
    
    /* Contact */
    .contact-container {
        grid-template-columns: 1fr;
    }
    
    /* Scroll Top Button */
    .scroll-top {
        bottom: 20px;
        right: 20px;
        width: 45px;
        height: 45px;
    }
}

@media (max-width: 480px) {
    .hero-title {
        font-size: 2rem;
    }
    
    .hero-buttons {
        flex-direction: column;
        width: 100%;
    }
    
    .btn {
        width: 100%;
        justify-content: center;
    }
    
    .pub-filter {
        gap: 0.5rem;
    }
    
    .filter-btn {
        padding: 0.5rem 1rem;
        font-size: 0.9rem;
    }
}

/* ============================================
   PRINT STYLES
============================================ */
@media print {
    .navbar,
    .hero-buttons,
    .scroll-top,
    .contact-form-wrapper {
        display: none;
    }
    
    .section {
        page-break-inside: avoid;
    }
}