:root {
    --primary-color: #1a365d;
    --primary-light: #2d3748;
    --secondary-color: #4a5568;
    --secondary-light: #718096;
    --accent-color: #3182ce;
    --accent-hover: #2b77cb;
    --text-primary: #2d3748;
    --text-secondary: #4a5568;
    --text-muted: #718096;
    --bg-primary: #ffffff;
    --bg-secondary: #f7fafc;
    --bg-tertiary: #edf2f7;
    --border-color: #e2e8f0;
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.1);
    --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.1);
    --font-primary: 'Pretendard', 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
}


* { margin: 0; padding: 0; box-sizing: border-box; }
body { font-family: var(--font-primary); line-height: 1.6; }
p { margin-bottom: 1rem; }
html{ font-size: 80%;}

/* Hero tags */
.research-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-top: 1.5rem;
}
.research-tag {
    background: var(--bg-secondary);
    color: var(--primary-color);
    font-size: 0.85rem;
    font-weight: 500;
    padding: 0.35rem 0.75rem;
    border-radius: 999px;
    border: 1px solid var(--border-color);
    transition: background 0.2s, color 0.2s;
}
.research-tag:hover {
    background: var(--bg-tertiary);
    color: var(--accent-color);
}


/* Hero academic links */
.academic-links {
    display: flex;
    gap: 1rem;
    margin-top: 1.5rem;
}
.academic-link {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    padding: 0.5rem 1rem;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    color: var(--primary-color);
    font-weight: 500;
    text-decoration: none;
    transition: background 0.2s, color 0.2s;
}
.academic-link:hover {
    background: var(--bg-tertiary);
    color: var(--accent-color);
}

/* About grid */
.about-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
}
.about-col h3 { margin-bottom: 1rem; }
@media (max-width: 768px) {
    .about-grid { grid-template-columns: 1fr; }
}

/* Career list */
.career-list { list-style: none; padding-left: 0; }
.career-list li { margin-bottom: 1rem; }
.career-period { font-weight: 600; color: var(--primary-color); }
.career-role { color: var(--text-secondary); margin-left: 0.5rem; }
    
/* =========================
   Research Section Styling
   ========================= */
#research {
    position: relative;
    background-color: var(--bg-secondary);
    overflow: hidden;
    isolation: isolate;
}

  
/* Research cards */
.research-card {
    position: relative;
    background: #fff;
    border: 1px solid var(--border-color);
    border-radius: .75rem;
    padding: 2rem;
    text-align: center;
    box-shadow: 0 4px 12px rgba(49,130,206,0.1), 0 2px 6px rgba(0,0,0,0.06);
    transition: transform 0.3s, box-shadow 0.3s;
}
#research .research-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 20px rgba(49,130,206,0.18), 0 6px 12px rgba(0,0,0,0.1);
}
/* 상단 그라디언트 라인 */
#research .research-card::before {
    content:"";
    position:absolute; left:0; right:0; top:0; height:6px;
    border-top-left-radius:.75rem; border-top-right-radius:.75rem;
    background: linear-gradient(90deg, #2152ff 0%, #22d3ee 100%);
}
  
/* Course tabs */
.course-tabs {
    display: inline-flex;
    gap: .5rem;
    padding: .5rem;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: .5rem;
    margin-top: 1rem;
}
  
.course-tab {
    appearance: none;
    background: transparent;
    border: 1px solid transparent;
    color: var(--text-secondary);
    font-weight: 500;
    padding: .5rem 1rem;
    border-radius: .375rem;
    cursor: pointer;
    transition: background .2s, color .2s, border-color .2s, transform .05s;
}
  
.course-tab:hover {
    background: var(--bg-tertiary);
    color: var(--primary-color);
}
  
.course-tab.active {
    background: #fff;
    color: var(--accent-color);
    border-color: var(--border-color);
    box-shadow: var(--shadow-sm);
}

/* 학년 배지 */
.course-year {
    background: var(--bg-tertiary);
    color: var(--text-secondary);
    padding: .25rem .5rem;
    border-radius: .25rem;
    font-size: .8rem;
    margin-right: .5rem;
    white-space: nowrap;
}

.course-year {
    background: #eaf3ff;
    color: #1a57b8;
    border: 1px solid #d7e7ff;
}
  
.badge {
    display: inline-block;
    background: var(--bg-tertiary);
    color: var(--text-secondary);
    padding: .25rem .6rem;
    margin-right: .4rem;
    border-radius: .375rem;
    font-size: .8rem;
    font-weight: 500;
  }
  
  /* 학부/대학원 강조 색상 */
  .badge.level {
    background: var(--accent-color);
    color: #fff;
  }
  
  

  


    

.nav-container { max-width: 1200px; margin: 0 auto; padding: 0 2rem; }
.nav { display:flex; align-items:center; justify-content: space-between; height: 70px; }
.logo { font-size: 1.0rem; font-weight: 700; color: var(--primary-color); text-decoration:none; }
.nav-menu { display:flex; list-style:none; gap:2rem; align-items:center; }
.nav-link { color: var(--text-secondary); text-decoration:none; font-weight:500; padding: .5rem 1rem; border-radius: .375rem; transition: .2s; }
.nav-link:hover,.nav-link.active { color: var(--accent-color); background: var(--bg-tertiary); }
.lang-toggle { background: var(--accent-color); color:#fff; border:none; padding: .5rem 1rem; border-radius:.375rem; cursor:pointer; font-weight:500; transition:.2s; }
.lang-toggle:hover { background: var(--accent-hover); }
.mobile-menu-toggle { display:none; background:none; border:none; font-size:1.5rem; color:var(--text-primary); cursor:pointer; }
.main-content { margin-top: 70px; }
.section { padding: 4rem 0; }
.container { max-width: 1200px; margin:0 auto; padding:0 2rem; }
.hero { background: linear-gradient(135deg, var(--bg-secondary), var(--bg-tertiary)); padding: 6rem 0; }
.hero-content { display:grid; grid-template-columns: 1fr auto; gap:4rem; align-items:center; }
.hero-text h1 { font-size:3rem; font-weight:700; color:var(--primary-color); margin-bottom:1rem; line-height:1.2; }
.hero-text h2 { font-size:1.5rem; color:var(--text-secondary); margin-bottom:2rem; font-weight:400; }
.hero-text p { font-size:1.1rem; color:var(--text-muted); margin-bottom:2rem; max-width:600px; }
.hero-stats { display:flex; justify-content: center; gap:2rem; margin-top:2rem; }
.stat-item { text-align:center; }
.stat-number { font-size:2rem; font-weight:700; color:var(--accent-color); display:block; }
.stat-label { font-size:.9rem; color:var(--text-muted); text-transform:uppercase; letter-spacing:.05em; }
.hero-image { position:relative; }
.profile-image { width:280px; height:350px; border-radius:1rem; object-fit:cover; box-shadow: var(--shadow-lg); border:4px solid var(--bg-primary); cursor:pointer; transition: .3s; }
.profile-image:hover { transform: translateY(-4px); box-shadow: 0 20px 25px -5px rgba(0,0,0,.1); }
.upload-overlay { position:absolute; inset:0; background: rgba(26,54,93,.8); display:flex; align-items:center; justify-content:center; opacity:0; transition: opacity .3s; border-radius:1rem; cursor:pointer; }
.profile-image:hover + .upload-overlay,
.upload-overlay:hover { opacity:1; }
.section-header { text-align:center; margin-bottom:3rem; }
.section-title { font-size:2.5rem; font-weight:700; color:var(--primary-color); margin-bottom:1rem; }
.section-subtitle { font-size:1.1rem; color:var(--text-muted); max-width:600px; margin:0 auto; }
.card { background:#fff; border-radius:.75rem; padding:2rem; box-shadow: var(--shadow-md); border:1px solid var(--border-color); transition:.3s; }
.card:hover { transform: translateY(-2px); box-shadow: var(--shadow-lg); }
.card-grid { display:grid; grid-template-columns: repeat(auto-fit, minmax(300px,1fr)); gap:2rem; }
.research-grid { display:grid; grid-template-columns: repeat(auto-fit, minmax(280px,1fr)); gap:2rem; }
.research-card { text-align:center; padding:2.5rem 2rem; }
.research-icon { font-size:3rem; color:var(--accent-color); margin-bottom:1.5rem; }
.research-card h3 { font-size:1.25rem; font-weight:600; color:var(--primary-color); margin-bottom:1rem; }
.research-card p { color:var(--text-muted); line-height:1.6; }
.publication-item { padding:1.5rem; border-left:4px solid var(--accent-color); background:var(--bg-secondary); margin-bottom:1.5rem; border-radius:0 .5rem .5rem 0; }
.publication-title { font-size:1.1rem; font-weight:600; color:var(--primary-color); margin-bottom:.5rem; }
.publication-authors { color:var(--text-secondary); margin-bottom:.5rem; }
.publication-journal { color:var(--accent-color); font-weight:500; margin-bottom:.5rem; }
.publication-meta { display:flex; gap:1rem; font-size:.9rem; color:var(--text-muted); }
.citation-count { background:var(--accent-color); color:#fff; padding:.25rem .5rem; border-radius:.25rem; font-size:.8rem; }
.conference-item, .course-item { padding:1.5rem 1.5rem 1.0rem; background:#fff; border:1px solid var(--border-color); border-radius:.5rem; margin-bottom:1rem; }
.conference-title, .course-title { font-size:1.1rem; font-weight:600; color:var(--primary-color); margin-bottom:.5rem; }
.conference-venue { color:var(--accent-color); font-weight:500; margin-bottom:.5rem; }
/* .course-code { background: var(--bg-tertiary); color: var(--text-secondary); padding:.25rem .5rem; border-radius:.25rem; font-size:.8rem; margin-right:.5rem; } */
.project-item {
    background: #fff;
    border: 1px solid var(--border-color);
    border-radius: .75rem;
    padding: 1rem 1.25rem;
    text-align: left;
    box-shadow: 0 4px 12px rgba(49,130,206,0.1), 
                0 2px 6px rgba(0,0,0,0.06); 
    transition: transform 0.3s, box-shadow 0.3s;
    min-height: 150px;
    display: flex;
    flex-direction: column;
    gap: .5rem;
}

.project-item:hover {
    transform: translateY(-3px);
    box-shadow: 0 6px 16px rgba(49,130,206,0.16),
                0 4px 8px rgba(0,0,0,0.08);
}

.projects-list {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 1.25rem;
}

.project-title { 
    font-size: 1.05rem;  
    font-weight: 600; 
    color: var(--primary-color); 
}

/* 상태 + 설명 배지 그룹 */
.project-meta {
    margin-top: auto;       /* 맨 아래쪽으로 밀기 */
    display: flex;
    gap: .5rem;
    justify-content: flex-start; /* 좌측 정렬 */
}


.project-status, .project-desc-badge { 
    display: inline-block;
    padding: .25rem .75rem;
    border-radius: 1rem;
    font-size: .75rem;
    font-weight: 500;
    white-space: nowrap;
}

.project-status { 
    background: var(--accent-color); 
    color: #fff;
}
.project-status.done { 
    background: var(--secondary-color); 
}

.project-desc-badge {
    background: var(--bg-tertiary);
    color: var(--text-secondary);
    border: 1px solid var(--border-color);
}



.contact-grid { display:grid; grid-template-columns: 1fr 1fr; gap:3rem; }
.contact-info { background: var(--bg-secondary); padding:2rem; border-radius:.75rem; }
.contact-item { display:flex; align-items:center; margin-bottom:1.5rem; }
.contact-icon { font-size:1.2rem; color:var(--accent-color); width:24px; margin-right:1rem; }
.contact-form { background:#fff; padding:2rem; border-radius:.75rem; border:1px solid var(--border-color); }
.form-group { margin-bottom:1.5rem; }
.form-label { display:block; font-weight:500; color:var(--text-primary); margin-bottom:.5rem; }
.form-input, .form-textarea { width:100%; padding:.75rem; border:1px solid var(--border-color); border-radius:.375rem; font-family:inherit; transition:border-color .2s; }
.form-input:focus, .form-textarea:focus { outline:none; border-color: var(--accent-color); box-shadow: 0 0 0 3px rgba(49,130,206,.1); }
.form-textarea { resize:vertical; min-height:120px; }
.btn { background: var(--accent-color); color:#fff; border:none; padding:.75rem 2rem; border-radius:.375rem; font-weight:500; cursor:pointer; transition:.2s; }
.btn:hover { background: var(--accent-hover); transform: translateY(-1px); }
.map-container { height: 300px; border-radius:.5rem; overflow:hidden; margin-top:2rem; }
.footer { background: var(--primary-color); color:#fff; padding:2rem 0; text-align:center; }
.footer-links { display:flex; justify-content:center; gap:2rem; margin-top:1rem; }
.footer-link { color:#fff; text-decoration:none; transition: opacity .2s; }
.footer-link:hover { opacity:.8; }
@media (max-width: 768px){
.nav-menu{ display:none; }
.mobile-menu-toggle{ display:block; }
.hero-content{ grid-template-columns:1fr; text-align:center; }
.hero-text h1{ font-size:2rem; }
.hero-stats{ justify-content:center; gap:1rem; }
.contact-grid{ grid-template-columns:1fr; gap:2rem; }
}
@media (max-width: 480px){
.container{ padding:0 1rem; }
.section{ padding:2rem 0; }
.hero{ padding:3rem 0; }
.card-grid, .research-grid{ grid-template-columns:1fr; }
}
/* Print Styles (원본 그대로) */
@media print{
.header, .mobile-menu-toggle, .upload-overlay{ display:none !important; }
.main-content{ margin-top:0; }
.section{ padding:1rem 0; page-break-inside: avoid; }
.card, .publication-item, .project-item{ break-inside: avoid; }
}