/* CSS Variables for Dark Theme Design System */
:root {
  /* Colors */
  --bg-dark: #0f1115;
  --bg-card: rgba(30, 33, 40, 0.6);
  --bg-card-hover: rgba(45, 49, 58, 0.8);
  --text-primary: #f8f9fa;
  --text-secondary: #a0aab2;
  --accent-color: #6366f1; /* Trendy Indigo */
  --accent-gradient: linear-gradient(135deg, #6366f1 0%, #a855f7 100%);
  --border-color: rgba(255, 255, 255, 0.1);
  --glass-border: 1px solid rgba(255, 255, 255, 0.05);

  /* Typography */
  --font-main: 'Pretendard', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  
  /* Layout */
  --container-max: 1100px;
  --section-padding: 100px 0;

  /* Animation */
  --transition-fast: 0.2s ease;
  --transition-normal: 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
  scroll-behavior: smooth;
}

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

/* Typography Utilities */
h1, h2, h3, h4, h5 {
  font-weight: 700;
  line-height: 1.3;
}

a {
  text-decoration: none;
  color: inherit;
}

ul {
  list-style: none;
}

/* Layout Utilities */
.container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 24px;
}

.section-padding {
  padding: var(--section-padding);
}

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

.glass-panel {
  background: var(--bg-card);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: var(--glass-border);
  border-radius: 16px;
  padding: 32px;
  transition: transform var(--transition-normal), background var(--transition-normal), box-shadow var(--transition-normal);
}

.glass-panel:hover {
  transform: translateY(-5px);
  background: var(--bg-card-hover);
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.5);
  border: 1px solid rgba(255, 255, 255, 0.15);
}

.highlight {
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* Navigation Header */
.header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 1000;
  background: rgba(15, 17, 21, 0.85);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid rgba(255, 255, 255, 0.05);
  transition: all var(--transition-normal);
}

.nav-container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 20px 24px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  font-size: 1.25rem;
  font-weight: 800;
  letter-spacing: -0.5px;
}

.nav-links {
  display: flex;
  gap: 32px;
}

.nav-links a {
  font-size: 0.95rem;
  color: var(--text-secondary);
  font-weight: 500;
  transition: color var(--transition-fast);
}

.nav-links a:hover {
  color: var(--text-primary);
}

/* Hero Section */
.hero-section {
  min-height: 100vh;
  display: flex;
  align-items: center;
  position: relative;
  padding-top: 80px;
}

.badge {
  display: inline-block;
  padding: 6px 16px;
  background: rgba(99, 102, 241, 0.15);
  color: var(--accent-color);
  border-radius: 100px;
  font-size: 0.875rem;
  font-weight: 600;
  margin-bottom: 24px;
  border: 1px solid rgba(99, 102, 241, 0.3);
}

.hero-title {
  font-size: clamp(2.5rem, 5vw, 4.5rem);
  letter-spacing: -0.02em;
  margin-bottom: 16px;
}

.hero-subtitle {
  font-size: 1.5rem;
  color: var(--text-secondary);
  font-weight: 500;
  margin-bottom: 32px;
}

.hero-subtitle .divider {
  margin: 0 12px;
  color: var(--border-color);
  font-weight: 300;
}

.hero-description {
  max-width: 600px;
  font-size: 1.125rem;
  color: var(--text-secondary);
}

.hero-description p {
  margin-bottom: 0;
}

/* Scroll Indicator */
.scroll-indicator {
  position: absolute;
  bottom: 40px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  opacity: 0.6;
}

.scroll-indicator p {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 2px;
}

.mouse {
  width: 26px;
  height: 40px;
  border: 2px solid var(--text-secondary);
  border-radius: 20px;
  display: flex;
  justify-content: center;
  padding-top: 6px;
}

.wheel {
  width: 4px;
  height: 8px;
  background: var(--text-secondary);
  border-radius: 2px;
  animation: scroll 2s infinite;
}

@keyframes scroll {
  0% { transform: translateY(0); opacity: 1; }
  100% { transform: translateY(15px); opacity: 0; }
}

/* Common Section Styles */
.section-header {
  margin-bottom: 64px;
}

.section-title {
  font-size: 2.5rem;
  margin-bottom: 8px;
}

.section-subtitle {
  color: var(--text-secondary);
  font-size: 1.125rem;
}

/* About / Summary Section */
.summary-content {
  display: flex;
  flex-direction: column;
  gap: 48px;
}

.summary-text.main-focus {
  font-size: 1.5rem;
  font-weight: 500;
  line-height: 1.5;
  color: var(--text-primary);
  max-width: 800px;
  border-left: 4px solid var(--accent-color);
  padding-left: 24px;
}

.summary-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 24px;
}

.summary-card {
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid rgba(255, 255, 255, 0.05);
  border-radius: 16px;
  padding: 32px;
  transition: background var(--transition-fast);
}

.summary-card:hover {
  background: rgba(255, 255, 255, 0.05);
}

.icon-wrapper {
  font-size: 2.5rem;
  margin-bottom: 20px;
}

.summary-card h3 {
  font-size: 1.25rem;
  margin-bottom: 12px;
}

.summary-card p {
  color: var(--text-secondary);
  font-size: 0.95rem;
}

/* Experience Timeline Section */
.timeline {
  display: flex;
  flex-direction: column;
  gap: 40px;
  position: relative;
  min-height: 100vh; /* 스크롤 시 사라지는 현상 방지 */
}

/* Timeline vertical line */
.timeline::before {
  content: '';
  position: absolute;
  top: 0;
  left: 12px; /* Center of the 24px dot */
  height: 100%;
  width: 2px;
  background: linear-gradient(to bottom, var(--accent-color), rgba(99, 102, 241, 0.1));
}

.timeline-item {
  position: relative;
  padding-left: 48px;
}

.timeline-dot {
  position: absolute;
  left: 0;
  top: 32px;
  width: 24px;
  height: 24px;
  background: var(--bg-dark);
  border: 4px solid var(--accent-color);
  border-radius: 50%;
  box-shadow: 0 0 10px rgba(99, 102, 241, 0.5);
  z-index: 10;
}

.company-header {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 8px;
}

.company-logo {
  height: 24px;
  width: auto;
  object-fit: contain;
  background: rgba(255, 255, 255, 0.05);
  padding: 4px 8px;
  border-radius: 6px;
  border: 1px solid var(--glass-border);
}

.logo-hotels {
  padding: 8px 10px; /* 위아래 여백 추가 */
  height: 28px;
}

.logo-wot {
  margin-top: -10px;
  height: 42px; /* 눈에 띄게 키움 */
  padding: 0px 4px; /* 여백 최소화하여 크롭 효과 */
  transform: scale(1.1); /* 약간 확대하여 여백 더 제거 */
}

.logo-expressvpn {
  height: 30px; /* 추가 확대 */
  padding: 4px 10px;
}

.company {
  font-size: 1.75rem;
  color: var(--text-primary);
  margin-bottom: 0px;
}

.role {
  font-size: 1.125rem;
  color: var(--accent-color);
  font-weight: 500;
  margin-bottom: 16px;
}

.project-desc {
  font-size: 1rem;
  color: var(--text-secondary);
  margin-bottom: 24px;
}

.achievements-list, .role-details {
  margin-top: 24px;
}

.achievements-list h5, .role-details h5 {
  font-size: 1.05rem;
  margin-bottom: 12px;
  color: var(--text-primary);
}

.timeline-content ul {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.timeline-content li {
  position: relative;
  padding-left: 20px;
  color: var(--text-secondary);
  font-size: 0.95rem;
}

.timeline-content li::before {
  content: "•";
  position: absolute;
  left: 0;
  color: var(--accent-color);
  font-size: 1.2rem;
  line-height: 1;
}

.timeline-content strong {
  color: var(--text-primary);
}

.tags {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 32px;
}

.tags span {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.1);
  padding: 6px 14px;
  border-radius: 6px;
  font-size: 0.85rem;
  color: var(--text-secondary);
}

/* Skills & Leadership Section */
.skills-leadership-container {
  display: flex;
  flex-direction: column;
  gap: 64px;
}

.skills-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
}

.skill-tag {
  background: linear-gradient(135deg, rgba(99, 102, 241, 0.1) 0%, rgba(168, 85, 247, 0.1) 100%);
  border: 1px solid rgba(99, 102, 241, 0.3);
  color: #fff;
  padding: 16px 24px;
  border-radius: 12px;
  font-size: 1.125rem;
  font-weight: 500;
  transition: all var(--transition-fast);
  cursor: default;
}

.skill-tag:hover {
  background: rgba(99, 102, 241, 0.2);
  transform: translateY(-2px);
  border-color: rgba(99, 102, 241, 0.5);
}

.leadership-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(340px, 1fr));
  gap: 32px;
}

.leader-card h4 {
  font-size: 1.25rem;
  margin: 16px 0 8px;
}

.leader-card p {
  color: var(--text-secondary);
  font-size: 0.95rem;
  margin-bottom: 24px;
}

.sub-list li {
  color: var(--text-secondary);
  font-size: 0.9rem;
  margin-bottom: 8px;
  opacity: 0.8;
}

/* Animations & Transitions */
.hidden {
  opacity: 0;
  transform: translateY(30px);
  transition: all 0.8s cubic-bezier(0.4, 0, 0.2, 1);
}

.show {
  opacity: 1;
  transform: translateY(0);
}

.fade-in-up {
  animation: fadeInUp 1s cubic-bezier(0.4, 0, 0.2, 1) forwards;
}

@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(40px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Footer */
.footer {
  border-top: var(--glass-border);
  padding: 40px 0;
  color: var(--text-secondary);
  font-size: 0.9rem;
}

.copyright {
  margin-top: 8px;
  opacity: 0.5;
  font-size: 0.8rem;
}

/* Media Queries */
@media (max-width: 768px) {
  .section-padding {
    padding: 60px 0;
  }
  
  .nav-links {
    display: none; /* Hide links on mobile for simplicity, could add hamburger */
  }
  
  .hero-title {
    font-size: 2rem;
  }
  
  .hero-subtitle {
    font-size: 1.25rem;
  }
  
  .timeline::before {
    left: 8px;
  }
  
  .timeline-dot {
    width: 16px;
    height: 16px;
    border-width: 3px;
    top: 36px;
  }
  
  .timeline-item {
    padding-left: 32px;
  }
}
/* --- Reference Projects (Portfolio Links) --- */
.reference-section {
  margin-top: 32px;
  padding-top: 24px;
  border-top: 1px dashed rgba(255, 255, 255, 0.1);
}

.reference-title {
  font-size: 1rem;
  color: var(--accent-color);
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.reference-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 16px;
}

.ref-card {
  display: flex;
  flex-direction: column;
  background: rgba(15, 17, 21, 0.4);
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: 12px;
  padding: 20px;
  transition: all var(--transition-fast);
  position: relative;
  overflow: hidden;
  text-decoration: none;
}

.ref-card:hover {
  transform: translateY(-4px);
  background: rgba(99, 102, 241, 0.08);
  border-color: rgba(99, 102, 241, 0.4);
  box-shadow: 0 4px 20px rgba(99, 102, 241, 0.15);
}

.ref-card::before {
  content: '↗';
  position: absolute;
  top: 16px;
  right: 16px;
  color: var(--text-secondary);
  font-size: 1.2rem;
  transition: color var(--transition-fast), transform var(--transition-fast);
}

.ref-card:hover::before {
  color: var(--accent-color);
  transform: translate(2px, -2px);
}

.ref-badge {
  display: inline-block;
  align-self: flex-start;
  font-size: 0.75rem;
  font-weight: 600;
  padding: 4px 10px;
  border-radius: 20px;
  margin-bottom: 12px;
  background: rgba(255, 255, 255, 0.1);
  color: var(--text-primary);
}

.ref-badge.youtube {
  background: rgba(255, 0, 0, 0.15);
  color: #ff4e4e;
  border: 1px solid rgba(255, 0, 0, 0.3);
}

.ref-badge.blog {
  background: rgba(3, 199, 90, 0.15);
  color: #03c75a;
  border: 1px solid rgba(3, 199, 90, 0.3);
}

.ref-title {
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 8px;
  line-height: 1.4;
}

.ref-desc {
  font-size: 0.85rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

.stat-highlight {
  color: #ffb800; /* Gold for stats like views */
  font-weight: 700;
}
/* --- Profile Image in Hero Section --- */
.hero-content {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 64px;
  width: 100%;
}

.hero-text {
  flex: 1;
}

.hero-profile {
  flex-shrink: 0;
  width: 320px;
  height: 320px;
  border-radius: 50%;
  padding: 8px;
  background: linear-gradient(135deg, rgba(99, 102, 241, 0.4) 0%, rgba(168, 85, 247, 0.4) 100%);
  position: relative;
  animation: float 6s ease-in-out infinite;
}

.hero-profile img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  border-radius: 50%;
  border: 4px solid var(--bg-dark);
}

@keyframes float {
  0% { transform: translateY(0px); }
  50% { transform: translateY(-15px); }
  100% { transform: translateY(0px); }
}

@media (max-width: 992px) {
  .hero-content {
    flex-direction: column-reverse;
    text-align: center;
    gap: 40px;
  }
  
  .hero-profile {
    width: 240px;
    height: 240px;
  }
  
  .scroll-indicator {
    display: none; /* Hide on mobile to save space */
  }
}