:root {
  --primary-color: #F8B400;
  --primary-hover: #DF9E00;
  --text-dark: #1F2937;
  --text-body: #4B5563;
  --text-light: #9CA3AF;
  --bg-color: #FFFFFF;
  --bg-light: #F9FAFB;
  --border-color: #E5E7EB;
  --font-family: 'Pretendard', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --max-width: 900px;
}

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

body {
  font-family: var(--font-family);
  background-color: var(--bg-color);
  color: var(--text-dark);
  line-height: 1.6;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  word-break: keep-all;
}

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

/* Header */
.header {
  position: fixed;
  top: 0;
  width: 100%;
  background-color: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(0, 0, 0, 0.05);
  z-index: 100;
}

.header-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 1rem 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  font-size: 1.25rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--primary-color);
}

.nav-links {
  display: flex;
  gap: 1.5rem;
}

.nav-links a {
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--text-body);
  transition: color 0.2s;
}

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

/* Common Section */
.section {
  padding: 6rem 2rem;
}

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

.section-container {
  max-width: var(--max-width);
  margin: 0 auto;
}

.section-title {
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 2.5rem;
  color: var(--text-dark);
  letter-spacing: -0.02em;
}

/* Hero Section */
.hero {
  padding: 10rem 2rem 6rem;
  background-color: var(--bg-color);
  text-align: left;
}

.hero-content {
  max-width: var(--max-width);
  margin: 0 auto;
}

.hero-title {
  font-size: 3rem;
  font-weight: 800;
  line-height: 1.3;
  margin-bottom: 1.5rem;
  letter-spacing: -0.03em;
}

.highlight {
  color: var(--primary-color);
}

.hero-subtitle {
  font-size: 1.25rem;
  color: var(--text-body);
  margin-bottom: 3rem;
}

.contact-info {
  display: flex;
  gap: 2rem;
  font-size: 1rem;
  color: var(--text-body);
  border-left: 3px solid var(--border-color);
  padding-left: 1rem;
  align-items: center;
  flex-wrap: wrap;
}

.contact-details {
  display: flex;
  gap: 2rem;
  flex-wrap: wrap;
}

.contact-info strong {
  margin-right: 0.5rem;
  color: var(--text-dark);
}

.btn-download {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.6rem 1.2rem;
  background-color: var(--text-dark);
  color: #fff;
  border-radius: 6px;
  font-weight: 600;
  font-size: 0.95rem;
  transition: all 0.2s;
}
.btn-download:hover {
  background-color: var(--primary-color);
}

/* Typography & Content */
.content-text p {
  margin-bottom: 1.25rem;
  font-size: 1.05rem;
  color: var(--text-body);
  line-height: 1.8;
}

/* Card Grid for Competency */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.5rem;
}

.card {
  background: white;
  padding: 2rem;
  border-radius: 12px;
  border: 1px solid var(--border-color);
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05);
  transition: transform 0.2s, box-shadow 0.2s;
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.05);
}

.card-emoji {
  font-size: 2.5rem;
  margin-bottom: 0.75rem;
  line-height: 1;
}

.card h4 {
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: 1rem;
  color: var(--primary-color);
}

.card ul {
  list-style: none;
}

.card ul li {
  position: relative;
  padding-left: 1.25rem;
  margin-bottom: 0.75rem;
  color: var(--text-body);
  font-size: 0.95rem;
}

.card ul li::before {
  content: "•";
  position: absolute;
  left: 0;
  color: var(--primary-color);
  font-weight: bold;
}

/* Timeline (Experience) */
.section-header-flex {
  display: flex;
  align-items: baseline;
  gap: 1rem;
  margin-bottom: 2.5rem;
}

.badge {
  background: var(--bg-light);
  color: var(--text-dark);
  padding: 0.25rem 0.75rem;
  border-radius: 999px;
  font-size: 0.875rem;
  font-weight: 600;
  border: 1px solid var(--border-color);
}

.timeline {
  display: flex;
  flex-direction: column;
  gap: 3rem;
}

.timeline-item {
  display: grid;
  grid-template-columns: 250px 1fr;
  gap: 2rem;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 3rem;
}

.timeline-item:last-child {
  border-bottom: none;
  padding-bottom: 0;
}

.timeline-meta h4 {
  font-size: 1.35rem;
  font-weight: 800;
  margin-bottom: 0.25rem;
}

.timeline-meta .role {
  font-weight: 600;
  color: var(--primary-color);
  margin-bottom: 0.5rem;
}

.timeline-meta .date {
  font-size: 0.875rem;
  color: var(--text-light);
}

.content-block {
  margin-bottom: 1.5rem;
}

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

.content-block h5 {
  font-size: 1.05rem;
  margin-bottom: 0.75rem;
  color: var(--text-dark);
  font-weight: 700;
}

.content-block ul {
  list-style: none;
}

.content-block ul li {
  position: relative;
  padding-left: 1.25rem;
  margin-bottom: 0.5rem;
  color: var(--text-body);
  font-size: 0.95rem;
  line-height: 1.6;
}

.content-block ul li::before {
  content: "-";
  position: absolute;
  left: 0;
  color: var(--text-light);
}

.tech-stack {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 1rem;
}

.tech-stack span {
  background: #FFF9E6;
  color: #B28200;
  padding: 0.25rem 0.6rem;
  border-radius: 4px;
  font-size: 0.8rem;
  font-weight: 600;
}

/* Projects Section */
.project-grid {
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

.project-card {
  border: 1px solid var(--border-color);
  border-radius: 12px;
  overflow: hidden;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  background: #fff;
}
.project-card:hover {
  transform: translateY(-6px);
  box-shadow: 0 12px 24px -5px rgba(0, 0, 0, 0.08);
}

.project-header {
  background: var(--bg-light);
  padding: 1.5rem 2rem;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.project-header h4 {
  font-size: 1.25rem;
  font-weight: 700;
}

.project-date {
  font-size: 0.875rem;
  color: var(--text-light);
}

.project-body {
  padding: 2rem;
  background: white;
}

.prob-sol {
  margin-bottom: 1.5rem;
}

.prob-sol:last-child {
  margin-bottom: 0;
}

.prob-sol strong {
  display: block;
  margin-bottom: 0.5rem;
  color: var(--text-dark);
  font-size: 1rem;
}

.prob-sol p {
  color: var(--text-body);
  font-size: 0.95rem;
}

.highlight-box {
  background: var(--bg-light);
  padding: 1.25rem;
  border-radius: 8px;
}

.highlight-box ul {
  list-style: none;
}

.highlight-box ul li {
  position: relative;
  padding-left: 1.25rem;
  margin-bottom: 0.5rem;
  color: var(--text-dark);
  font-weight: 500;
  font-size: 0.95rem;
}

.highlight-box ul li::before {
  content: "→";
  position: absolute;
  left: 0;
  color: var(--primary-color);
}

/* Education Section */
.edu-item {
  margin-bottom: 2.5rem;
}

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

.edu-item h4 {
  font-size: 1.25rem;
  margin-bottom: 1rem;
  color: var(--primary-color);
}

.edu-row {
  display: flex;
  justify-content: space-between;
  padding: 1rem;
  background: white;
  border: 1px solid var(--border-color);
  border-radius: 8px;
}

.edu-row-multi {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.edu-block {
  padding: 1.5rem;
  background: white;
  border: 1px solid var(--border-color);
  border-radius: 8px;
}

.edu-block strong {
  display: block;
  font-size: 1.1rem;
  margin-bottom: 0.25rem;
}

.edu-block span {
  display: block;
  font-size: 0.9rem;
  color: var(--text-light);
  margin-bottom: 1rem;
}

.edu-block ul {
  list-style: none;
}

.edu-block ul li {
  position: relative;
  padding-left: 1rem;
  margin-bottom: 0.25rem;
  font-size: 0.95rem;
  color: var(--text-body);
}

.edu-block ul li::before {
  content: "-";
  position: absolute;
  left: 0;
  color: var(--text-light);
}

/* UI Enhancements */
.chip-container {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-bottom: 1rem;
}

.chip {
  background-color: rgba(248, 180, 0, 0.1);
  color: var(--primary-color);
  padding: 0.25rem 0.8rem;
  border-radius: 9999px;
  font-size: 0.8rem;
  font-weight: 700;
}

.highlight-text {
  background: linear-gradient(120deg, rgba(248, 180, 0, 0.4) 0%, rgba(248, 180, 0, 0.4) 100%);
  background-repeat: no-repeat;
  background-size: 100% 40%;
  background-position: 0 85%;
  font-weight: 800;
  color: var(--text-dark);
}

/* Footer */
.footer {
  text-align: center;
  padding: 3rem 0;
  border-top: 1px solid var(--border-color);
  color: var(--text-light);
  font-size: 0.875rem;
}

/* Animations */
.reveal {
  opacity: 0;
  transform: translateY(30px);
  transition: all 0.8s cubic-bezier(0.5, 0, 0, 1);
}

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

/* Media Queries */
@media (max-width: 768px) {
  .hero-title { font-size: 2.25rem; }
  .contact-info { flex-direction: column; gap: 0.5rem; }
  .timeline-item { grid-template-columns: 1fr; gap: 1rem; }
  .project-header { flex-direction: column; align-items: flex-start; gap: 0.5rem; }
  .nav-links { display: none; } /* Could add mobile menu if needed */
  .edu-row { flex-direction: column; gap: 0.5rem; }
}

/* Modal */
.modal-overlay {
  position: fixed;
  top: 0; left: 0; width: 100%; height: 100%;
  background: rgba(0,0,0,0.5);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  opacity: 0;
  visibility: hidden;
  transition: all 0.3s ease;
  backdrop-filter: blur(2px);
}
.modal-overlay.active {
  opacity: 1;
  visibility: visible;
}
.modal-content {
  background: #fff;
  width: 90%;
  max-width: 800px;
  max-height: 85vh;
  border-radius: 12px;
  overflow-y: auto;
  position: relative;
  transform: translateY(20px);
  transition: all 0.3s ease;
  box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
}
.modal-overlay.active .modal-content {
  transform: translateY(0);
}
.modal-header {
  padding: 1.5rem 2rem;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  justify-content: space-between;
  align-items: center;
  position: sticky;
  top: 0;
  background: #fff;
  z-index: 10;
}
.modal-header h4 {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--text-dark);
}
.modal-close {
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  color: var(--text-light);
  padding: 0;
  line-height: 1;
}
.modal-close:hover {
  color: var(--text-dark);
}
.modal-body {
  padding: 2rem;
}
.modal-section {
  margin-bottom: 2rem;
}
.modal-section:last-child {
  margin-bottom: 0;
}
.modal-section h5 {
  font-size: 1.1rem;
  color: var(--primary-color);
  margin-bottom: 0.75rem;
  font-weight: 700;
}
.modal-body p {
  color: var(--text-body);
  margin-bottom: 1rem;
  line-height: 1.7;
}
.modal-body p:last-child {
  margin-bottom: 0;
}
.modal-body ul {
  list-style-type: none;
  margin-bottom: 1.5rem;
}
.modal-body ul li {
  position: relative;
  padding-left: 1.5rem;
  margin-bottom: 0.75rem;
  color: var(--text-body);
  line-height: 1.7;
}
.modal-body ul li::before {
  content: "•";
  position: absolute;
  left: 0.5rem;
  color: var(--primary-color);
}
.modal-body ul li strong {
  color: var(--text-dark);
}

/* Button */
.btn-more {
  display: inline-block;
  margin-top: 1.5rem;
  padding: 0.6rem 1.25rem;
  background: var(--bg-light);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  color: var(--text-dark);
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
  font-size: 0.95rem;
}
.btn-more:hover {
  background: var(--primary-color);
  color: #fff;
  border-color: var(--primary-color);
}

/* Scroll to Top Button */
.btn-top {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  width: 55px;
  height: 55px;
  background-color: #D1D5DB; /* Light gray to match the image */
  color: #FFFFFF;
  border: none;
  border-radius: 50%;
  display: flex;
  justify-content: center;
  align-items: center;
  cursor: pointer;
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  opacity: 0;
  visibility: hidden;
  transform: translateY(20px);
  transition: all 0.3s ease;
  z-index: 999;
}
.btn-top.show {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}
.btn-top:hover {
  background-color: #9CA3AF; /* Darker gray on hover */
  transform: translateY(-2px);
}