html {
  scroll-behavior: smooth;
  scroll-padding-top: 90px; /* Offset for sticky header (70px header + 20px padding) */
}

:root {
  --bg-main: #f8fafc;
  --bg-card: #ffffff;
  --text-main: #0f172a;
  --text-muted: #475569;
  --primary: #2563eb; /* Royal Blue */
  --primary-light: #eff6ff;
  --border: #e2e8f0;
  --border-hover: #cbd5e1;
  --radius: 12px;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

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

body {
  font-family: var(--font-sans);
  background-color: var(--bg-main);
  color: var(--text-main);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a {
  color: inherit;
  text-decoration: none;
  transition: all 0.2s ease;
}

/* Container */
.container {
  max-width: 900px;
  margin: 0 auto;
  padding: 0 24px;
}

/* Header & Nav */
header {
  border-bottom: 1px solid var(--border);
  background-color: rgba(255, 255, 255, 0.8);
  backdrop-filter: blur(8px);
  position: sticky;
  top: 0;
  z-index: 100;
}

.nav-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 70px;
}

.logo {
  font-size: 1.1rem;
  font-weight: 700;
  letter-spacing: -0.5px;
}

.logo span {
  color: var(--primary);
}

.nav-links {
  display: flex;
  gap: 24px;
  list-style: none;
}

.nav-link {
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text-muted);
}

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

/* Hero Section */
.hero {
  padding: 90px 0 60px 0;
}

.hero h1 {
  font-size: 2.8rem;
  font-weight: 800;
  letter-spacing: -1.5px;
  line-height: 1.15;
  margin-bottom: 16px;
}

.hero h2 {
  font-size: 1.35rem;
  font-weight: 500;
  color: var(--text-muted);
  margin-bottom: 24px;
}

.hero h2 span {
  color: var(--primary);
  font-weight: 600;
}

.hero p {
  font-size: 1.1rem;
  color: var(--text-muted);
  max-width: 680px;
  margin-bottom: 32px;
}

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

.social-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  border: 1px solid var(--border);
  background: var(--bg-card);
  color: var(--text-muted);
  font-size: 1.1rem;
}

.social-btn:hover {
  border-color: var(--primary);
  color: var(--primary);
  background: var(--primary-light);
  transform: translateY(-2px);
}

/* Section General */
section {
  padding: 60px 0;
}

.section-title {
  font-size: 1.5rem;
  font-weight: 700;
  letter-spacing: -0.5px;
  margin-bottom: 32px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.section-title::after {
  content: "";
  flex-grow: 1;
  height: 1px;
  background-color: var(--border);
}

/* About / Expertise Grid */
.expertise-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 20px;
  margin-top: 24px;
}

.expertise-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  transition: all 0.2s ease;
}

.expertise-card:hover {
  border-color: var(--border-hover);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.03);
}

.expertise-card i {
  font-size: 1.5rem;
  color: var(--primary);
  margin-bottom: 16px;
  display: inline-block;
}

.expertise-card h3 {
  font-size: 1.1rem;
  font-weight: 650;
  margin-bottom: 8px;
}

.expertise-card p {
  font-size: 0.9rem;
  color: var(--text-muted);
}

/* Experience / Timeline */
.timeline {
  display: flex;
  flex-direction: column;
  gap: 32px;
  position: relative;
}

.timeline::before {
  content: "";
  position: absolute;
  left: 16px;
  top: 8px;
  bottom: 8px;
  width: 1px;
  background-color: var(--border);
}

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

.timeline-marker {
  position: absolute;
  left: 10px;
  top: 6px;
  width: 13px;
  height: 13px;
  border-radius: 50%;
  background-color: var(--bg-main);
  border: 3px solid var(--primary);
  z-index: 2;
}

.timeline-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 12px;
}

.timeline-title h3 {
  font-size: 1.15rem;
  font-weight: 700;
}

.timeline-title p {
  font-size: 0.95rem;
  color: var(--text-muted);
  font-weight: 500;
}

.timeline-date {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--primary);
  background-color: var(--primary-light);
  padding: 4px 12px;
  border-radius: 100px;
}

.timeline-content ul {
  list-style-type: none;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.timeline-content li {
  font-size: 0.95rem;
  color: var(--text-muted);
  position: relative;
  padding-left: 18px;
}

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

/* Portfolio Grid */
.portfolio-filters {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 24px;
}

.filter-btn {
  background: var(--bg-card);
  border: 1px solid var(--border);
  padding: 8px 16px;
  border-radius: 100px;
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--text-muted);
  cursor: pointer;
  transition: all 0.2s ease;
}

.filter-btn:hover, .filter-btn.active {
  background-color: var(--primary);
  color: #ffffff;
  border-color: var(--primary);
}

.portfolio-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 20px;
}

.portfolio-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  display: flex;
  flex-direction: column;
  height: 100%;
  transition: all 0.2s ease;
}

.portfolio-card:hover {
  border-color: var(--border-hover);
  box-shadow: 0 6px 16px rgba(0, 0, 0, 0.04);
  transform: translateY(-2px);
}

.portfolio-card h3 {
  font-size: 1.15rem;
  font-weight: 700;
  margin-bottom: 8px;
}

.portfolio-card p {
  font-size: 0.9rem;
  color: var(--text-muted);
  flex-grow: 1;
  margin-bottom: 20px;
}

.portfolio-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.portfolio-tag {
  font-size: 0.75rem;
  font-weight: 600;
  background-color: var(--bg-main);
  border: 1px solid var(--border);
  color: var(--text-muted);
  padding: 4px 10px;
  border-radius: 4px;
  text-transform: uppercase;
}

/* Contact Section */
.contact-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 20px;
}

.contact-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  text-align: center;
  transition: all 0.2s ease;
}

.contact-card:hover {
  border-color: var(--border-hover);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.03);
}

.contact-card i {
  font-size: 1.5rem;
  color: var(--primary);
  margin-bottom: 12px;
  display: inline-block;
}

.contact-card h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 4px;
}

.contact-card p {
  font-size: 0.9rem;
  color: var(--text-muted);
}

/* Footer */
footer {
  border-top: 1px solid var(--border);
  padding: 40px 0;
  background: var(--bg-card);
  text-align: center;
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* Responsive */
@media (max-width: 768px) {
  .hero h1 {
    font-size: 2.2rem;
  }
  .timeline::before {
    left: 12px;
  }
  .timeline-item {
    padding-left: 36px;
  }
  .timeline-marker {
    left: 6px;
  }
  .timeline-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 4px;
  }
  .timeline-date {
    align-self: flex-start;
  }
}