/* =========================================
   Custom CSS — Dzianis Kuziomkin Personal Site
   ========================================= */

/* --- Variables --- */
:root {
  --bg:         #F7F5F0;
  --text:       #1A1A18;
  --text-sec:   #6B6860;
  --accent:     #2563A8;
  --accent-hv:  #1A4A80;
  --divider:    #E2DFD8;
  --surface:    #EFEDE8;
  --nav-h:      64px;
}

/* --- Reset / Base --- */
*, *::before, *::after { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
}

body {
  background-color: var(--bg);
  color: var(--text);
  font-family: 'DM Sans', sans-serif;
  font-size: 16px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  margin: 0;
}

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

img { display: block; max-width: 100%; }

/* --- Typography --- */
.font-display {
  font-family: 'Playfair Display', serif;
}

/* --- Layout wrapper --- */
.container {
  max-width: 720px;
  margin: 0 auto;
  padding: 0 24px;
}

.container--wide {
  max-width: 960px;
}

/* --- Section label (small uppercase heading) --- */
.section-label {
  display: block;
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 32px;
}

/* --- Horizontal divider --- */
.divider {
  border: none;
  border-top: 1px solid var(--divider);
  margin: 0 0 64px 0;
}

/* =========================================
   Navigation
   ========================================= */
.site-nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  height: var(--nav-h);
  display: flex;
  align-items: center;
  transition: background 0.3s ease, box-shadow 0.3s ease;
}

.site-nav.scrolled {
  background: rgba(247, 245, 240, 0.95);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  box-shadow: 0 1px 0 var(--divider);
}

.nav-inner {
  max-width: 960px;
  margin: 0 auto;
  padding: 0 24px;
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  font-family: 'Playfair Display', serif;
  font-size: 16px;
  font-weight: 700;
  color: var(--text);
  white-space: nowrap;
}

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

.nav-links {
  display: flex;
  align-items: center;
  gap: 28px;
  list-style: none;
  margin: 0;
  padding: 0;
}

.nav-links a {
  font-size: 13.5px;
  font-weight: 500;
  color: var(--text-sec);
  transition: color 0.2s;
}

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

/* Hamburger */
.nav-hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  background: none;
  border: none;
  padding: 4px;
}

.nav-hamburger span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text);
  border-radius: 2px;
  transition: transform 0.3s, opacity 0.3s;
}

.nav-hamburger.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-hamburger.open span:nth-child(2) { opacity: 0; }
.nav-hamburger.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* Mobile nav overlay */
.nav-mobile {
  display: none;
  position: fixed;
  top: var(--nav-h);
  left: 0;
  right: 0;
  background: rgba(247, 245, 240, 0.98);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  padding: 24px;
  z-index: 99;
  border-bottom: 1px solid var(--divider);
}

.nav-mobile.open { display: block; }

.nav-mobile ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.nav-mobile ul a {
  font-size: 15px;
  font-weight: 500;
  color: var(--text);
}

/* =========================================
   Page offset for fixed nav
   ========================================= */
#top { scroll-margin-top: 0; }
#about, #expertise, #products, #publications, #contact {
  scroll-margin-top: calc(var(--nav-h) + 16px);
}

/* =========================================
   Fade-in on scroll
   ========================================= */
.fade-in {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* =========================================
   Hero Section
   ========================================= */
.hero {
  padding-top: calc(var(--nav-h) + 56px);
  padding-bottom: 64px;
}

.hero-inner {
  max-width: 960px;
  margin: 0 auto;
  padding: 0 24px;
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 64px;
  align-items: center;
}

.hero-text { order: 1; }
.hero-photo { order: 2; }

.hero-eyebrow {
  display: block;
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-sec);
  margin-bottom: 20px;
  line-height: 1.8;
}

.hero-name {
  font-family: 'Playfair Display', serif;
  font-size: clamp(56px, 8.5vw, 88px);
  line-height: 1.05;
  color: var(--text);
  margin: 0 0 28px 0;
}

.hero-subtitle {
  font-size: 16px;
  color: var(--text);
  line-height: 1.75;
  margin: 0 0 16px 0;
  max-width: 480px;
}

.hero-subtitle-2 {
  font-size: 15px;
  color: var(--text-sec);
  line-height: 1.75;
  margin: 0 0 36px 0;
  max-width: 480px;
}

.hero-ctas {
  display: flex;
  flex-wrap: wrap;
  gap: 20px;
}

.hero-ctas a {
  font-size: 14px;
  font-weight: 500;
  color: var(--accent);
  border-bottom: 1px solid var(--accent);
  padding-bottom: 1px;
  transition: color 0.2s, border-color 0.2s;
}

.hero-ctas a:hover {
  color: var(--accent-hv);
  border-color: var(--accent-hv);
}

.hero-portrait {
  width: 280px;
  height: 280px;
  border-radius: 50%;
  border: 2px solid #E2DFD8;
  object-fit: cover;
  object-position: center top;
}

/* =========================================
   Currently Section
   ========================================= */
.currently-wrap {
  max-width: 960px;
  margin: 0 auto;
  padding: 0 24px;
}

.currently-block {
  border-top: 1px solid var(--divider);
  border-bottom: 1px solid var(--divider);
  padding: 36px 0;
  display: grid;
  grid-template-columns: 120px 1fr;
  gap: 40px;
  align-items: start;
}

.currently-label {
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-sec);
  padding-top: 3px;
}

.currently-row {
  display: grid;
  grid-template-columns: 90px 1fr;
  gap: 24px;
  padding: 12px 0;
  border-top: 1px solid var(--divider);
  align-items: baseline;
}

.currently-row:first-child {
  padding-top: 0;
  border-top: none;
}

.currently-row-key {
  font-size: 10px;
  font-weight: 500;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-sec);
}

.currently-row-val {
  font-size: 15px;
  color: var(--text);
  line-height: 1.5;
}

/* =========================================
   Stats Section
   ========================================= */
.stats-wrap {
  padding: 64px 0;
  border-bottom: 1px solid var(--divider);
}

.stats-inner {
  max-width: 960px;
  margin: 0 auto;
  padding: 0 24px;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}

.stat-head {
  display: flex;
  align-items: baseline;
  gap: 8px;
  margin-bottom: 4px;
}

.stat-num {
  font-family: 'Playfair Display', serif;
  font-size: 64px;
  line-height: 1;
  color: var(--text);
}

.stat-unit {
  font-size: 14px;
  color: var(--text-sec);
}

.stat-sub {
  font-size: 12px;
  color: var(--text-sec);
  line-height: 1.5;
}

/* =========================================
   Generic section spacing
   ========================================= */
.section {
  padding: 80px 0;
}

/* =========================================
   About Section
   ========================================= */
.about-body {
  font-size: 17px;
  color: var(--text);
  line-height: 1.8;
}

.about-body p { margin: 0 0 20px 0; }
.about-body p:last-child { margin-bottom: 0; }

/* =========================================
   Expertise Section
   ========================================= */
.expertise-intro {
  font-size: 16px;
  color: var(--text-sec);
  margin: 0 0 40px 0;
}

.expertise-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0;
}

.expertise-item {
  padding: 20px 0;
  border-top: 1px solid var(--divider);
}

.expertise-item:nth-child(odd) { padding-right: 32px; }
.expertise-item:nth-child(even) { padding-left: 32px; border-left: 1px solid var(--divider); }

.expertise-title {
  font-size: 15px;
  font-weight: 500;
  color: var(--text);
  margin: 0 0 4px 0;
}

.expertise-sub {
  font-size: 13px;
  color: var(--text-sec);
  margin: 0;
  line-height: 1.5;
}

.cert-list {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: 6px;
}

.cert-badge {
  font-size: 11px;
  font-weight: 500;
  color: var(--text-sec);
  background: var(--bg);
  border: 1px solid var(--divider);
  border-radius: 4px;
  padding: 2px 8px;
  white-space: nowrap;
}

/* =========================================
   Products Section
   ========================================= */
.products-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
}

@media (max-width: 680px) {
  .products-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 440px) {
  .products-grid {
    grid-template-columns: 1fr;
  }
}

.product-card {
  background: var(--surface);
  border: 1px solid var(--divider);
  border-radius: 12px;
  padding: 24px;
  display: flex;
  flex-direction: column;
  transition: box-shadow 0.2s, border-color 0.2s;
}

.product-card:hover {
  box-shadow: 0 4px 20px rgba(0,0,0,0.07);
  border-color: #ccc9c0;
}

.product-logo-wrap {
  width: 52px;
  height: 52px;
  border-radius: 12px;
  overflow: hidden;
  margin-bottom: 16px;
  flex-shrink: 0;
  background: var(--bg);
  display: flex;
  align-items: center;
  justify-content: center;
}

.product-logo-wrap img {
  width: 52px;
  height: 52px;
  object-fit: cover;
}

.product-logo-placeholder {
  width: 52px;
  height: 52px;
  border-radius: 12px;
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: 'Playfair Display', serif;
  font-size: 20px;
  font-weight: 700;
  color: #fff;
  flex-shrink: 0;
}

.product-name {
  font-family: 'Playfair Display', serif;
  font-size: 20px;
  color: var(--text);
  margin: 0 0 8px 0;
}

.product-desc {
  font-size: 14px;
  color: var(--text-sec);
  line-height: 1.65;
  margin: 0 0 16px 0;
  flex: 1;
}

.product-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-bottom: 20px;
}

.product-tag {
  font-size: 11px;
  font-weight: 500;
  color: var(--text-sec);
  background: var(--bg);
  border: 1px solid var(--divider);
  border-radius: 4px;
  padding: 2px 8px;
}

.product-link {
  font-size: 13px;
  font-weight: 500;
  color: var(--accent);
  border-bottom: 1px solid var(--accent);
  padding-bottom: 1px;
  transition: color 0.2s, border-color 0.2s;
  align-self: flex-start;
  margin-top: auto;
}

.product-link:hover {
  color: var(--accent-hv);
  border-color: var(--accent-hv);
}

.product-store-links {
  display: flex;
  gap: 20px;
  flex-wrap: wrap;
  margin-top: auto;
}

/* =========================================
   Publications Section
   ========================================= */
.pub-intro {
  font-size: 16px;
  color: var(--text-sec);
  margin: 0 0 40px 0;
}

.pub-list { list-style: none; margin: 0; padding: 0; }

.pub-item {
  display: grid;
  grid-template-columns: 72px 1fr auto;
  align-items: baseline;
  gap: 16px;
  padding: 20px 0;
  border-top: 1px solid var(--divider);
}

.pub-item:last-child { border-bottom: 1px solid var(--divider); }

.pub-source {
  font-size: 10px;
  font-weight: 500;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent);
  white-space: nowrap;
}

.pub-body { min-width: 0; }

.pub-title {
  font-size: 15px;
  font-weight: 500;
  color: var(--text);
  margin: 0 0 2px 0;
}

.pub-sub {
  font-size: 13px;
  color: var(--text-sec);
  margin: 0;
}

.pub-link {
  font-size: 13px;
  font-weight: 500;
  color: var(--accent);
  white-space: nowrap;
  transition: color 0.2s;
}

.pub-link:hover { color: var(--accent-hv); }

.pub-item.muted .pub-source,
.pub-item.muted .pub-title,
.pub-item.muted .pub-sub {
  opacity: 0.45;
}

/* =========================================
   Contact Section
   ========================================= */
.contact-body {
  font-size: 17px;
  color: var(--text-sec);
  line-height: 1.8;
  margin: 0 0 28px 0;
}

.contact-links {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.contact-links a {
  font-size: 15px;
  font-weight: 500;
  color: var(--accent);
  transition: color 0.2s;
}

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

/* =========================================
   Footer
   ========================================= */
.site-footer {
  border-top: 1px solid var(--divider);
  padding: 32px 0;
}

.footer-inner {
  max-width: 960px;
  margin: 0 auto;
  padding: 0 24px;
  text-align: center;
  font-size: 13px;
  color: var(--text-sec);
}

/* =========================================
   Scrollbar
   ========================================= */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--divider); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: #c8c4bc; }

/* =========================================
   Responsive
   ========================================= */
@media (max-width: 1024px) {
  .hero-portrait { width: 220px; height: 220px; border-radius: 50%; }
  .hero-inner { gap: 40px; }
}

@media (max-width: 640px) {
  /* Nav */
  .nav-links { display: none; }
  .nav-hamburger { display: flex; }

  /* Hero — photo on top, text below */
  .hero {
    padding-top: calc(var(--nav-h) + 40px);
    padding-bottom: 64px;
  }

  .hero-inner {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .hero-text { order: 2; }
  .hero-photo {
    order: 1;
    display: flex;
    justify-content: center;
  }

  .hero-portrait {
    width: 180px;
    height: 180px;
    border-radius: 50%;
  }

  .hero-subtitle { font-size: 15px; }
  .hero-subtitle-2 { font-size: 14px; }

  /* Currently — stack on mobile */
  .currently-block {
    grid-template-columns: 1fr;
    gap: 20px;
  }

  .currently-row {
    grid-template-columns: 80px 1fr;
    gap: 16px;
  }

  /* Stats — 2 cols on mobile */
  .stats-inner {
    grid-template-columns: repeat(2, 1fr);
    gap: 32px 24px;
  }

  /* Expertise — single column */
  .expertise-grid { grid-template-columns: 1fr; }
  .expertise-item:nth-child(odd) { padding-right: 0; }
  .expertise-item:nth-child(even) { padding-left: 0; border-left: none; }

  /* Publications — stack on mobile */
  .pub-item {
    grid-template-columns: 1fr;
    gap: 6px;
  }

  .pub-link { align-self: start; }

  /* Section spacing */
  .section { padding: 56px 0; }
  .divider { margin-bottom: 48px; }
}