/* ============ Design tokens ============ */
:root {
  --color-bg: #ffffff;
  --color-bg-alt: #f6f7fb;
  --color-surface: #ffffff;
  --color-border: #e5e7eb;
  --color-text: #14161c;
  --color-text-muted: #5b6070;
  --color-accent: #4f46e5;
  --color-accent-hover: #4338ca;
  --color-accent-soft: #eef0fe;
  --shadow-sm: 0 1px 2px rgba(16, 18, 27, 0.06);
  --shadow-md: 0 8px 24px rgba(16, 18, 27, 0.08);
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 22px;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', Consolas, monospace;
  --max-width: 1160px;
  --transition: 200ms ease;
}

[data-theme='dark'] {
  --color-bg: #0d0f14;
  --color-bg-alt: #12151c;
  --color-surface: #161922;
  --color-border: #262b38;
  --color-text: #eef0f6;
  --color-text-muted: #9aa0b4;
  --color-accent: #818cf8;
  --color-accent-hover: #a5b0fb;
  --color-accent-soft: #1b1e3a;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.4);
  --shadow-md: 0 12px 32px rgba(0, 0, 0, 0.45);
}

/* ============ Reset ============ */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font-sans);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
  transition: background var(--transition), color var(--transition);
  overflow-x: hidden;
}
img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
ul { margin: 0; padding: 0; list-style: none; }
h1, h2, h3, h4 { margin: 0; line-height: 1.2; }
p { margin: 0; }
button { font-family: inherit; cursor: pointer; }

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

section { padding: 96px 0; }
.section-title {
  font-size: clamp(1.75rem, 3vw, 2.25rem);
  font-weight: 700;
  margin-bottom: 8px;
  text-align: center;
}
.section-subtitle {
  text-align: center;
  color: var(--color-text-muted);
  margin-bottom: 48px;
}
.bg-alt { background: var(--color-bg-alt); }

/* ============ Buttons ============ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 12px 24px;
  border-radius: var(--radius-sm);
  font-weight: 600;
  font-size: 0.95rem;
  border: 1px solid transparent;
  transition: transform var(--transition), background var(--transition), border-color var(--transition);
}
.btn:hover { transform: translateY(-2px); }
.btn-primary { background: var(--color-accent); color: #fff; }
.btn-primary:hover { background: var(--color-accent-hover); }
.btn-outline { border-color: var(--color-border); color: var(--color-text); background: transparent; }
.btn-outline:hover { border-color: var(--color-accent); color: var(--color-accent); }
.btn-sm { padding: 8px 14px; font-size: 0.85rem; }

/* ============ Navbar ============ */
.navbar {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 1000;
  background: color-mix(in srgb, var(--color-bg) 85%, transparent);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--color-border);
}
.nav-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 14px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.nav-brand { font-weight: 800; font-size: 1.1rem; letter-spacing: -0.02em; }
.nav-menu { display: flex; align-items: center; gap: 28px; }
.nav-link {
  font-weight: 500;
  color: var(--color-text-muted);
  padding: 6px 2px;
  border-bottom: 2px solid transparent;
  transition: color var(--transition), border-color var(--transition);
}
.nav-link:hover, .nav-link.active { color: var(--color-text); border-color: var(--color-accent); }
.nav-actions { display: flex; align-items: center; gap: 12px; }
.icon-btn {
  background: transparent;
  border: 1px solid var(--color-border);
  border-radius: 50%;
  width: 40px; height: 40px;
  display: flex; align-items: center; justify-content: center;
  font-size: 1.05rem;
  transition: border-color var(--transition), transform var(--transition);
}
.icon-btn:hover { border-color: var(--color-accent); transform: translateY(-1px); }
.nav-toggle {
  display: none;
  background: none; border: none;
  flex-direction: column; gap: 5px;
}
.nav-toggle span { width: 22px; height: 2px; background: var(--color-text); transition: transform var(--transition), opacity var(--transition); }

/* ============ Hero ============ */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding-top: 96px;
}
.hero-content { max-width: 640px; margin: 0 auto; }
.hero-photo {
  width: 132px; height: 132px;
  border-radius: 50%;
  object-fit: cover;
  margin: 0 auto 24px;
  border: 3px solid var(--color-accent-soft);
  box-shadow: var(--shadow-md);
}
.hero-photo--placeholder {
  display: flex; align-items: center; justify-content: center;
  background: var(--color-accent-soft);
  color: var(--color-accent);
  font-weight: 700; font-size: 2rem;
}
.hero-greeting { color: var(--color-text-muted); font-weight: 600; margin-bottom: 6px; }
.hero-name { font-size: clamp(2.2rem, 5vw, 3.4rem); font-weight: 800; letter-spacing: -0.03em; margin-bottom: 8px; }
.hero-title {
  color: var(--color-accent);
  font-weight: 600;
  font-size: 1.15rem;
  margin-bottom: 20px;
}
.hero-intro { color: var(--color-text-muted); margin-bottom: 32px; font-size: 1.05rem; }
.hero-actions { display: flex; gap: 16px; justify-content: center; flex-wrap: wrap; margin-bottom: 28px; }
.social-links { display: flex; gap: 12px; justify-content: center; }
.social-link {
  width: 42px; height: 42px;
  border-radius: 50%;
  border: 1px solid var(--color-border);
  display: flex; align-items: center; justify-content: center;
  transition: border-color var(--transition), transform var(--transition);
}
.social-link:hover { border-color: var(--color-accent); transform: translateY(-2px); }

/* ============ About ============ */
.about-grid { max-width: 760px; margin: 0 auto; text-align: center; }
.about-bio { font-size: 1.05rem; color: var(--color-text-muted); margin-bottom: 28px; }
.about-meta {
  display: inline-flex;
  flex-direction: column;
  gap: 10px;
  text-align: left;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 24px 28px;
}

/* ============ Skills ============ */
.skills-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 20px; }
.skill-category {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 24px;
  box-shadow: var(--shadow-sm);
}
.skill-category-title { font-size: 1rem; margin-bottom: 14px; color: var(--color-accent); }
.skill-tags { display: flex; flex-wrap: wrap; gap: 8px; }
.skill-tag {
  background: var(--color-accent-soft);
  color: var(--color-accent);
  padding: 6px 12px;
  border-radius: 999px;
  font-size: 0.82rem;
  font-weight: 600;
}
.skill-tag--sm { padding: 4px 10px; font-size: 0.75rem; }

/* ============ Projects ============ */
.featured-section.hidden { display: none; }
.projects-grid, .featured-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 24px;
}
.featured-grid { margin-bottom: 64px; }
.project-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition), box-shadow var(--transition);
  display: flex;
  flex-direction: column;
}
.project-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-md); }
.project-card-image { aspect-ratio: 16 / 10; background: var(--color-bg-alt); overflow: hidden; }
.project-card-image img { width: 100%; height: 100%; object-fit: cover; }
.project-card-placeholder {
  width: 100%; height: 100%;
  display: flex; align-items: center; justify-content: center;
  font-size: 2.5rem; font-weight: 800;
  color: var(--color-accent);
  background: var(--color-accent-soft);
}
.project-card-body { padding: 20px; display: flex; flex-direction: column; gap: 12px; flex: 1; }
.project-card-desc { color: var(--color-text-muted); font-size: 0.92rem; }
.project-card-actions { display: flex; flex-wrap: wrap; gap: 8px; margin-top: auto; padding-top: 8px; }

/* Pagination */
.pagination { display: flex; justify-content: center; align-items: center; gap: 8px; margin-top: 40px; flex-wrap: wrap; }
.page-btn {
  border: 1px solid var(--color-border);
  background: var(--color-surface);
  color: var(--color-text);
  padding: 8px 14px;
  border-radius: var(--radius-sm);
  font-weight: 600;
  transition: border-color var(--transition), background var(--transition);
}
.page-btn:hover:not(:disabled) { border-color: var(--color-accent); }
.page-btn.active { background: var(--color-accent); color: #fff; border-color: var(--color-accent); }
.page-btn:disabled { opacity: 0.4; cursor: not-allowed; }

/* Skeleton loaders */
.skeleton { background: linear-gradient(90deg, var(--color-border) 25%, var(--color-bg-alt) 37%, var(--color-border) 63%); background-size: 400% 100%; animation: skeleton-pulse 1.4s ease infinite; border-radius: 6px; }
.skeleton-image { aspect-ratio: 16/10; }
.skeleton-line { height: 12px; margin: 16px 20px 0; }
@keyframes skeleton-pulse { 0% { background-position: 100% 50%; } 100% { background-position: 0 50%; } }

/* ============ Modal ============ */
.modal-overlay {
  position: fixed; inset: 0;
  background: rgba(10, 12, 18, 0.6);
  display: flex; align-items: center; justify-content: center;
  padding: 24px;
  opacity: 0; pointer-events: none;
  transition: opacity var(--transition);
  z-index: 2000;
}
.modal-overlay.open { opacity: 1; pointer-events: auto; }
.modal {
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  max-width: 640px;
  width: 100%;
  max-height: 85vh;
  overflow-y: auto;
  padding: 32px;
  position: relative;
  transform: translateY(16px);
  transition: transform var(--transition);
}
.modal-overlay.open .modal { transform: translateY(0); }
.modal-close {
  position: absolute; top: 16px; right: 16px;
  background: var(--color-bg-alt);
  border: none; border-radius: 50%;
  width: 36px; height: 36px;
  font-size: 1.1rem;
}
.modal-image { border-radius: var(--radius-md); margin-bottom: 20px; aspect-ratio: 16/9; object-fit: cover; }
.modal-description { color: var(--color-text-muted); margin: 12px 0 20px; }
body.modal-open { overflow: hidden; }

/* ============ Experience / Education timeline ============ */
.timeline { position: relative; max-width: 720px; margin: 0 auto; padding-left: 28px; border-left: 2px solid var(--color-border); }
.timeline-item { position: relative; padding-bottom: 40px; }
.timeline-item:last-child { padding-bottom: 0; }
.timeline-dot { position: absolute; left: -34px; top: 4px; width: 12px; height: 12px; border-radius: 50%; background: var(--color-accent); box-shadow: 0 0 0 4px var(--color-accent-soft); }
.timeline-content h3 { font-size: 1.1rem; margin-bottom: 4px; }
.timeline-subtitle { color: var(--color-text-muted); font-size: 0.9rem; margin-bottom: 12px; }
.timeline-bullets { display: flex; flex-direction: column; gap: 6px; margin-bottom: 12px; }
.timeline-bullets li { position: relative; padding-left: 16px; color: var(--color-text-muted); font-size: 0.92rem; }
.timeline-bullets li::before { content: ''; position: absolute; left: 0; top: 8px; width: 5px; height: 5px; border-radius: 50%; background: var(--color-accent); }

.education-grid { display: grid; gap: 20px; max-width: 720px; margin: 0 auto; }
.education-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 24px;
}
.education-years { color: var(--color-accent); font-weight: 600; font-size: 0.85rem; margin: 6px 0 10px; }

/* ============ Contact ============ */
.contact-grid { display: grid; grid-template-columns: 1fr 1.3fr; gap: 48px; align-items: start; }
.contact-info-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 28px;
}
.contact-info-card h3 { margin-bottom: 16px; }
.contact-info-list { display: flex; flex-direction: column; gap: 12px; margin-bottom: 20px; color: var(--color-text-muted); }
.contact-form { display: flex; flex-direction: column; gap: 18px; }
.form-group { display: flex; flex-direction: column; gap: 6px; }
.form-group label { font-weight: 600; font-size: 0.9rem; }
.form-group input, .form-group textarea {
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  padding: 12px 14px;
  color: var(--color-text);
  font-family: inherit;
  font-size: 0.95rem;
  transition: border-color var(--transition);
}
.form-group input:focus, .form-group textarea:focus { outline: none; border-color: var(--color-accent); }
.form-status { min-height: 20px; font-size: 0.9rem; font-weight: 600; }
.form-status.success { color: #16a34a; }
.form-status.error { color: #dc2626; }

/* ============ States ============ */
.loading-state, .error-state, .empty-state { text-align: center; color: var(--color-text-muted); padding: 24px; grid-column: 1 / -1; }
.error-state { color: #dc2626; }

/* ============ Footer ============ */
.footer { padding: 32px 0; text-align: center; color: var(--color-text-muted); border-top: 1px solid var(--color-border); font-size: 0.9rem; }

/* ============ Back to top ============ */
.back-to-top {
  position: fixed;
  right: 24px; bottom: 24px;
  width: 46px; height: 46px;
  border-radius: 50%;
  background: var(--color-accent);
  color: #fff;
  border: none;
  font-size: 1.1rem;
  box-shadow: var(--shadow-md);
  opacity: 0; pointer-events: none;
  transform: translateY(12px);
  transition: opacity var(--transition), transform var(--transition);
  z-index: 900;
}
.back-to-top.visible { opacity: 1; pointer-events: auto; transform: translateY(0); }

/* ============ Scroll-in animation ============ */
.fade-in-up { opacity: 0; transform: translateY(20px); transition: opacity 0.5s ease, transform 0.5s ease; }
.fade-in-up.visible { opacity: 1; transform: translateY(0); }