/* ===== Reset & Base ===== */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  /* Light mode (default) */
  --bg-primary: #ffffff;
  --bg-secondary: #f8f8fa;
  --bg-card: #f4f4f6;
  --bg-card-hover: #eeeef0;
  --text-primary: #1a1a1f;
  --text-secondary: #52525b;
  --text-muted: #8b8b96;
  --accent: #52525b;
  --accent-hover: #1a1a1f;
  --border: #e4e4e7;
  --border-hover: #c8c8cd;
  --tag-bg: rgba(0, 0, 0, 0.03);
  --tag-border: rgba(0, 0, 0, 0.07);
  --tag-text: #6b6b76;
  --nav-bg: rgba(255, 255, 255, 0.9);
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --max-width: 960px;
  --radius: 6px;
}

[data-theme="dark"] {
  --bg-primary: #101014;
  --bg-secondary: #18181c;
  --bg-card: #1c1c21;
  --bg-card-hover: #222228;
  --text-primary: #ececef;
  --text-secondary: #a0a0ab;
  --text-muted: #6b6b76;
  --accent: #a0a0ab;
  --accent-hover: #ececef;
  --border: #27272d;
  --border-hover: #3a3a42;
  --tag-bg: rgba(255, 255, 255, 0.04);
  --tag-border: rgba(255, 255, 255, 0.08);
  --tag-text: #8a8a95;
  --nav-bg: rgba(16, 16, 20, 0.9);
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font-sans);
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.7;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a {
  color: var(--text-primary);
  text-decoration: none;
  transition: color 0.15s;
}

a:hover {
  color: var(--text-secondary);
}

img {
  max-width: 100%;
  height: auto;
}

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

section {
  padding: 5rem 0;
}

section + section {
  border-top: 1px solid var(--border);
}

/* ===== Navigation ===== */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: var(--nav-bg);
  backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border);
}

.nav .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 56px;
}

.nav-logo {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-primary);
  letter-spacing: -0.01em;
}

.nav-links {
  display: flex;
  gap: 2rem;
  list-style: none;
}

.nav-links a {
  color: var(--text-muted);
  font-size: 0.85rem;
  font-weight: 450;
  transition: color 0.15s;
}

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

.nav-right {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.theme-toggle {
  background: none;
  border: 1px solid var(--border);
  color: var(--text-muted);
  width: 32px;
  height: 32px;
  border-radius: 6px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: color 0.15s, border-color 0.15s;
}

.theme-toggle:hover {
  color: var(--text-primary);
  border-color: var(--border-hover);
}

.theme-toggle svg {
  width: 16px;
  height: 16px;
}

.theme-toggle .icon-moon { display: block; }
.theme-toggle .icon-sun { display: none; }
[data-theme="dark"] .theme-toggle .icon-moon { display: none; }
[data-theme="dark"] .theme-toggle .icon-sun { display: block; }

.nav-toggle {
  display: none;
  background: none;
  border: none;
  color: var(--text-primary);
  font-size: 1.25rem;
  cursor: pointer;
}

/* ===== Hero ===== */
.hero {
  padding: 9rem 0 5rem;
}

.hero-content {
  max-width: 620px;
}

.hero-label {
  font-size: 0.85rem;
  font-weight: 450;
  color: var(--text-muted);
  margin-bottom: 1rem;
  letter-spacing: 0.02em;
  text-transform: uppercase;
}

.hero h1 {
  font-size: 2.75rem;
  font-weight: 700;
  line-height: 1.15;
  margin-bottom: 1.25rem;
  letter-spacing: -0.03em;
  color: var(--text-primary);
}

.hero-description {
  font-size: 1.05rem;
  color: var(--text-secondary);
  line-height: 1.75;
  max-width: 560px;
  margin-bottom: 2.5rem;
}

.hero-cta {
  display: flex;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.6rem 1.25rem;
  border-radius: var(--radius);
  font-size: 0.85rem;
  font-weight: 500;
  transition: all 0.15s;
  border: none;
  cursor: pointer;
}

.btn-primary {
  background: var(--text-primary);
  color: var(--bg-primary);
}

.btn-primary:hover {
  background: #fff;
  color: var(--bg-primary);
}

.btn-outline {
  background: transparent;
  color: var(--text-secondary);
  border: 1px solid var(--border-hover);
}

.btn-outline:hover {
  border-color: var(--text-muted);
  color: var(--text-primary);
}

/* ===== Section Headers ===== */
.section-header {
  margin-bottom: 3rem;
}

.section-label {
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 0.5rem;
}

.section-title {
  font-size: 1.75rem;
  font-weight: 650;
  letter-spacing: -0.02em;
}

/* ===== Skills ===== */
.skills-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1px;
  background: var(--border);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
}

.skill-card {
  background: var(--bg-secondary);
  padding: 1.5rem;
}

.skill-card:hover {
  background: var(--bg-card-hover);
}

.skill-card h3 {
  font-size: 0.95rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
}

.skill-card p {
  font-size: 0.85rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: 1rem;
}

.skill-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
}

.skill-tag {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  padding: 0.2rem 0.5rem;
  background: var(--tag-bg);
  color: var(--tag-text);
  border-radius: 3px;
  border: 1px solid var(--tag-border);
}

/* ===== Resume / Experience ===== */
.resume-grid {
  display: grid;
  grid-template-columns: 5fr 3fr;
  gap: 4rem;
  align-items: start;
}

.timeline {
  position: relative;
  padding-left: 0;
}

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

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

.timeline-item + .timeline-item {
  border-top: 1px solid var(--border);
  padding-top: 2.5rem;
}

.timeline-date {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-bottom: 0.35rem;
}

.timeline-title {
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: 0.1rem;
}

.timeline-company {
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin-bottom: 0.75rem;
}

.timeline-description {
  font-size: 0.85rem;
  color: var(--text-secondary);
  line-height: 1.65;
}

.timeline-description li {
  margin-bottom: 0.25rem;
  list-style: none;
  position: relative;
  padding-left: 0.9rem;
}

.timeline-description li::before {
  content: '\2013';
  position: absolute;
  left: 0;
  color: var(--text-muted);
}

/* Resume sidebar */
.resume-sidebar {
  position: sticky;
  top: 80px;
}

.resume-sidebar h3 {
  font-size: 0.75rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  margin-bottom: 0.75rem;
}

.resume-sidebar h3 + h3 {
  margin-top: 2rem;
}

.cert-list, .edu-list {
  list-style: none;
}

.cert-list li, .edu-list li {
  padding: 0.5rem 0;
  border-bottom: 1px solid var(--border);
  font-size: 0.85rem;
  color: var(--text-secondary);
}

.cert-list li:last-child, .edu-list li:last-child {
  border-bottom: none;
}

.cert-list .cert-name, .edu-list .edu-name {
  color: var(--text-primary);
  font-weight: 500;
  display: block;
}

.cert-list .cert-issuer, .edu-list .edu-details {
  font-size: 0.78rem;
  color: var(--text-muted);
}

.resume-download {
  margin-top: 2rem;
}

/* ===== Blog ===== */
.blog-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0;
}

.blog-card {
  padding: 1.5rem 0;
  display: flex;
  flex-direction: column;
  border-bottom: 1px solid var(--border);
}

.blog-card:first-child {
  padding-top: 0;
}

.blog-card:last-child {
  border-bottom: none;
}

.blog-card-meta {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--text-muted);
  margin-bottom: 0.35rem;
  display: flex;
  align-items: center;
  gap: 1rem;
}

.blog-card h3 {
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: 0.35rem;
}

.blog-card h3 a {
  color: var(--text-primary);
}

.blog-card h3 a:hover {
  color: var(--text-secondary);
}

.blog-card p {
  font-size: 0.85rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

.blog-card-tags {
  display: flex;
  gap: 0.35rem;
  margin-top: 0.75rem;
  flex-wrap: wrap;
}

.blog-tag {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  padding: 0.15rem 0.45rem;
  background: var(--tag-bg);
  color: var(--tag-text);
  border-radius: 3px;
  border: 1px solid var(--tag-border);
}

/* ===== Blog Post Page ===== */
.post {
  padding: 7rem 0 4rem;
}

.post-header {
  margin-bottom: 2.5rem;
  padding-bottom: 2rem;
  border-bottom: 1px solid var(--border);
}

.post-back {
  font-size: 0.85rem;
  color: var(--text-muted);
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  margin-bottom: 1.5rem;
}

.post-back:hover {
  color: var(--text-primary);
}

.post-title {
  font-size: 2rem;
  font-weight: 700;
  line-height: 1.25;
  margin-bottom: 1rem;
  letter-spacing: -0.02em;
}

.post-meta {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--text-muted);
  display: flex;
  gap: 1.5rem;
  flex-wrap: wrap;
}

.post-content {
  max-width: 680px;
}

.post-content h2 {
  font-size: 1.35rem;
  font-weight: 650;
  margin: 2.5rem 0 0.75rem;
  letter-spacing: -0.01em;
}

.post-content h3 {
  font-size: 1.1rem;
  font-weight: 600;
  margin: 2rem 0 0.5rem;
}

.post-content p {
  margin-bottom: 1.25rem;
  color: var(--text-secondary);
  line-height: 1.75;
}

.post-content ul, .post-content ol {
  margin-bottom: 1.25rem;
  padding-left: 1.25rem;
  color: var(--text-secondary);
}

.post-content li {
  margin-bottom: 0.35rem;
}

.post-content code {
  font-family: var(--font-mono);
  font-size: 0.83em;
  background: var(--bg-card);
  padding: 0.15em 0.4em;
  border-radius: 3px;
  color: var(--text-primary);
}

.post-content pre {
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem;
  overflow-x: auto;
  margin-bottom: 1.5rem;
}

.post-content pre code {
  background: none;
  padding: 0;
  font-size: 0.82rem;
  color: var(--text-primary);
}

.post-content blockquote {
  border-left: 2px solid var(--border-hover);
  padding-left: 1rem;
  margin: 1.5rem 0;
  color: var(--text-muted);
}

.post-content img {
  border-radius: var(--radius);
  border: 1px solid var(--border);
  margin: 1.5rem 0;
}

.post-content a {
  text-decoration: underline;
  text-decoration-color: var(--border-hover);
  text-underline-offset: 3px;
}

.post-content a:hover {
  text-decoration-color: var(--text-muted);
}

/* ===== Contact ===== */
.contact-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 1px;
  background: var(--border);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
}

.contact-card {
  background: var(--bg-secondary);
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 0.1rem;
  transition: background 0.15s;
}

.contact-card:hover {
  background: var(--bg-card-hover);
}

.contact-info .label {
  font-size: 0.72rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
}

.contact-info .value {
  font-size: 0.9rem;
  color: var(--text-primary);
  font-weight: 500;
}

/* ===== Footer ===== */
.footer {
  border-top: 1px solid var(--border);
  padding: 2rem 0;
  text-align: center;
}

.footer p {
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* ===== Mobile ===== */
@media (max-width: 768px) {
  .nav-links {
    display: none;
    position: absolute;
    top: 56px;
    left: 0;
    right: 0;
    background: var(--nav-bg);
    backdrop-filter: blur(16px);
    flex-direction: column;
    padding: 0.75rem 1.5rem;
    gap: 0;
    border-bottom: 1px solid var(--border);
  }

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

  .nav-links li {
    padding: 0.6rem 0;
    border-bottom: 1px solid var(--border);
  }

  .nav-links li:last-child {
    border-bottom: none;
  }

  .nav-toggle {
    display: block;
  }

  .hero h1 {
    font-size: 2rem;
  }

  .hero-description {
    font-size: 0.95rem;
  }

  .skills-grid {
    grid-template-columns: 1fr;
  }

  .resume-grid {
    grid-template-columns: 1fr;
    gap: 3rem;
  }

  .contact-grid {
    grid-template-columns: 1fr;
  }

  section {
    padding: 3.5rem 0;
  }

  .hero {
    padding: 7rem 0 3rem;
  }
}

@media (max-width: 480px) {
  .hero h1 {
    font-size: 1.6rem;
  }

  .hero-cta {
    flex-direction: column;
  }

  .btn {
    justify-content: center;
  }
}