/* ==========================================================================
   Design System & CSS Variables
   Inspired by: GitHub, Stripe, HashiCorp
   ========================================================================== */

:root {
  /* Brand Colors */
  --bg-primary: #ffffff;
  --bg-secondary: #f8fafc;
  --text-primary: #0f172a;
  --text-muted: #475569;
  
  /* Accent Colors */
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --accent-light: #eff6ff;
  
  /* Borders & UI Lines */
  --border-color: #e2e8f0;
  --border-hover: #cbd5e1;
  
  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', Consolas, monospace;
  
  /* Layout Constraints */
  --max-width: 1120px;
  --radius-sm: 6px;
  --radius-md: 10px;
  --transition: all 0.2s ease-in-out;
}

/* ==========================================================================
   Modern CSS Reset
   ========================================================================== */

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

html {
  scroll-behavior: smooth;
}

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

/* ==========================================================================
   Layout Components & Utilities
   ========================================================================== */

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
}

.section {
  padding: 5rem 0;
  border-bottom: 1px solid var(--border-color);
}

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

/* Button Components */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1.25rem;
  font-size: 0.95rem;
  font-weight: 500;
  border-radius: var(--radius-sm);
  text-decoration: none;
  transition: var(--transition);
  cursor: pointer;
  border: 1px solid transparent;
}

.btn-primary {
  background-color: var(--accent);
  color: #ffffff;
  border-color: var(--accent);
}

.btn-primary:hover {
  background-color: var(--accent-hover);
  border-color: var(--accent-hover);
}

.btn-secondary {
  background-color: #ffffff;
  color: var(--text-primary);
  border-color: var(--border-color);
}

.btn-secondary:hover {
  background-color: var(--bg-secondary);
  border-color: var(--border-hover);
}

/* ==========================================================================
   Header & Navigation
   ========================================================================== */

.site-header {
  position: sticky;
  top: 0;
  background-color: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border-color);
  z-index: 100;
}

.nav-wrapper {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 4.5rem;
}

.brand-logo {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 0.6rem;
}

.brand-tag {
  font-size: 0.75rem;
  font-family: var(--font-mono);
  background: var(--bg-secondary);
  padding: 0.2rem 0.5rem;
  border-radius: 4px;
  border: 1px solid var(--border-color);
  color: var(--text-muted);
}

.nav-links {
  display: flex;
  list-style: none;
  gap: 1.75rem;
  align-items: center;
}

.nav-links a {
  text-decoration: none;
  color: var(--text-muted);
  font-weight: 500;
  font-size: 0.95rem;
  transition: var(--transition);
}

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

.mobile-menu-btn {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.5rem;
  color: var(--text-primary);
}

/* ==========================================================================
   Hero Section
   ========================================================================== */

.hero-section {
  padding: 6.5rem 0 5rem 0;
  background-color: var(--bg-primary);
  border-bottom: 1px solid var(--border-color);
}

.hero-content {
  max-width: 820px;
}

.hero-title {
  font-size: 3.5rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.1;
  margin-bottom: 1.25rem;
  color: var(--text-primary);
}

.hero-roles {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin-bottom: 1.5rem;
}

.role-badge {
  font-size: 0.85rem;
  font-family: var(--font-mono);
  background-color: var(--accent-light);
  color: var(--accent);
  padding: 0.3rem 0.75rem;
  border-radius: 9999px;
  border: 1px solid rgba(37, 99, 235, 0.2);
  font-weight: 500;
}

.hero-description {
  font-size: 1.2rem;
  color: var(--text-muted);
  line-height: 1.7;
  margin-bottom: 2.25rem;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.85rem;
}

/* ==========================================================================
   About Section
   ========================================================================== */

.about-content {
  max-width: 800px;
  font-size: 1.1rem;
  color: var(--text-muted);
}

.about-content p {
  margin-bottom: 1.25rem;
}

.about-list {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 0.75rem;
  list-style: none;
  margin: 1.5rem 0;
}

.about-list li {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 500;
  color: var(--text-primary);
}

.about-list li::before {
  content: "→";
  color: var(--accent);
  font-weight: bold;
}

/* ==========================================================================
   Skills Section
   ========================================================================== */

.skills-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.5rem;
}

.skill-card {
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  transition: var(--transition);
}

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

.skill-card-title {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 1rem;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.tag-cloud {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}

.tag {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  background-color: var(--bg-secondary);
  color: var(--text-muted);
  padding: 0.25rem 0.6rem;
  border-radius: 4px;
  border: 1px solid var(--border-color);
}

/* ==========================================================================
   Projects Section
   ========================================================================== */

.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 1.5rem;
}

.project-card {
  background: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.75rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: var(--transition);
}

.project-card:hover {
  border-color: var(--accent);
  transform: translateY(-2px);
}

.project-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 1rem;
}

.project-title {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
}

.status-badge {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  padding: 0.2rem 0.5rem;
  border-radius: 4px;
  font-weight: 500;
}

.status-active {
  background-color: #dcfce7;
  color: #166534;
  border: 1px solid #bbf7d0;
}

.status-progress {
  background-color: #fef9c3;
  color: #854d0e;
  border: 1px solid #fef08a;
}

.project-description {
  color: var(--text-muted);
  font-size: 0.95rem;
  line-height: 1.6;
  margin-bottom: 1.5rem;
}

.project-tech {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-top: auto;
}

/* ==========================================================================
   Architecture Section (SVG Diagram)
   ========================================================================== */

.arch-container {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 2rem;
  overflow-x: auto;
  display: flex;
  justify-content: center;
}

.arch-svg {
  width: 100%;
  max-width: 800px;
  height: auto;
}

.arch-node {
  fill: #ffffff;
  stroke: var(--border-color);
  stroke-width: 1.5;
  transition: var(--transition);
}

.arch-node:hover {
  stroke: var(--accent);
  filter: drop-shadow(0 4px 6px rgba(0,0,0,0.05));
}

.arch-text-title {
  font-family: var(--font-sans);
  font-weight: 600;
  font-size: 14px;
  fill: var(--text-primary);
}

.arch-text-sub {
  font-family: var(--font-mono);
  font-size: 11px;
  fill: var(--text-muted);
}

/* ==========================================================================
   Timeline Section
   ========================================================================== */

.timeline {
  position: relative;
  max-width: 700px;
  margin: 0 auto;
  padding-left: 2rem;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 2px;
  background-color: var(--border-color);
}

.timeline-item {
  position: relative;
  margin-bottom: 2.5rem;
}

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

.timeline-dot {
  position: absolute;
  left: -2rem;
  top: 0.25rem;
  transform: translateX(-50%);
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background-color: var(--accent);
  border: 3px solid #ffffff;
  box-shadow: 0 0 0 1px var(--border-color);
}

.timeline-date {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--accent);
  font-weight: 600;
  margin-bottom: 0.25rem;
}

.timeline-content {
  font-size: 1rem;
  color: var(--text-primary);
}

.timeline-content ul {
  list-style: none;
  margin-top: 0.5rem;
}

.timeline-content li {
  color: var(--text-muted);
  position: relative;
  padding-left: 1.25rem;
  margin-bottom: 0.25rem;
  font-size: 0.95rem;
}

.timeline-content li::before {
  content: "•";
  position: absolute;
  left: 0;
  color: var(--border-hover);
}

/* ==========================================================================
   Contact & Footer
   ========================================================================== */

.contact-box {
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 3rem 2rem;
  text-align: center;
  max-width: 600px;
  margin: 0 auto;
}

.contact-links {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 1rem;
  margin-top: 1.5rem;
}

.site-footer {
  padding: 3rem 0;
  border-top: 1px solid var(--border-color);
  background-color: var(--bg-primary);
  color: var(--text-muted);
  font-size: 0.875rem;
}

.footer-content {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
}

.footer-meta {
  font-family: var(--font-mono);
  font-size: 0.8rem;
}

/* Mobile Responsiveness */
@media (max-width: 768px) {
  .mobile-menu-btn {
    display: block;
  }

  .nav-links {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background-color: var(--bg-primary);
    flex-direction: column;
    padding: 1.5rem;
    border-bottom: 1px solid var(--border-color);
    align-items: flex-start;
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.05);
  }

  .nav-links.is-open {
    display: flex;
  }

  .hero-title {
    font-size: 2.5rem;
  }

  .hero-description {
    font-size: 1.05rem;
  }

  .footer-content {
    flex-direction: column;
    text-align: center;
  }
}