/* ==========================================================================
   Eric Klavins — Site Stylesheet
   Aesthetic: Swiss typography × LaTeX × engineering blueprint
   ========================================================================== */

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

:root {
  --color-bg: #fcfcfc;
  --color-surface: #ffffff;
  --color-text: #1a1a1a;
  --color-text-secondary: #555;
  --color-text-tertiary: #888;
  --color-accent: #2d5a8e;
  --color-accent-light: #e8eff7;
  --color-rule: #d8d8d8;
  --color-rule-light: #ebebeb;
  --color-highlight: #c9553a;
  --color-grid: rgba(45, 90, 142, 0.04);

  --font-body: 'Inter', -apple-system, 'Helvetica Neue', sans-serif;
  --font-heading: 'Menlo', 'Monaco', 'Courier New', monospace;
  --font-mono: 'Menlo', 'Monaco', 'Courier New', monospace;

  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 2rem;
  --space-xl: 3rem;
  --space-2xl: 5rem;

  --max-width: 860px;
  --header-height: 64px;
}

html {
  font-size: 17px;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-body);
  color: var(--color-text);
  background-color: var(--color-bg);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  min-height: 100vh;
  min-height: 100dvh;
  display: flex;
  flex-direction: column;

}

/* --- Header --- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--header-height);
  background: rgba(252, 252, 252, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-rule);
}

.header-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-lg);
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.site-logo {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  text-decoration: none;
  color: var(--color-text);
}

.logo-icon {
  height: 24px;
  width: auto;
}

.logo-text {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 500;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.site-nav {
  display: flex;
  gap: var(--space-lg);
}

.nav-link {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 400;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  text-decoration: none;
  color: var(--color-text-secondary);
  padding: var(--space-xs) 0;
  position: relative;
  transition: color 0.2s ease;
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 0;
  height: 1.5px;
  background: var(--color-accent);
  transition: width 0.25s ease;
}

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

.nav-link.active::after,
.nav-link:hover::after {
  width: 100%;
}

/* Mobile nav toggle */
.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--space-sm);
  flex-direction: column;
  gap: 5px;
}

.nav-toggle-bar {
  display: block;
  width: 22px;
  height: 1.5px;
  background: var(--color-text);
  transition: transform 0.3s ease, opacity 0.3s ease;
}

/* --- Main Content --- */
.site-main {
  flex: 1;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: var(--space-2xl) var(--space-lg) var(--space-xl);
  width: 100%;
}

/* --- Typography --- */
h1, h2, h3, h4 {
  font-family: var(--font-heading);
  font-weight: 700;
  line-height: 1.2;
  color: var(--color-text);
}

h1 {
  font-size: 2.4rem;
  letter-spacing: -0.03em;
  margin-bottom: var(--space-lg);
}

h2 {
  font-size: 1.4rem;
  letter-spacing: -0.01em;
  margin-top: var(--space-xl);
  margin-bottom: var(--space-md);
  padding-bottom: var(--space-sm);
  border-bottom: 1px solid var(--color-rule-light);
}

h3 {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 500;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-accent);
  margin-top: var(--space-xl);
  margin-bottom: var(--space-md);
}

p {
  margin-bottom: var(--space-md);
}

a {
  color: var(--color-accent);
  text-decoration-thickness: 1px;
  text-underline-offset: 2px;
  transition: color 0.2s ease;
}

a:hover {
  color: var(--color-highlight);
}

/* --- Home Page --- */
.home-hero {
  display: grid;
  grid-template-columns: 200px 1fr;
  gap: var(--space-xl);
  align-items: start;
  margin-bottom: var(--space-2xl);
}

.hero-portrait {
  width: 200px;
  height: 200px;
  border-radius: 4px;
  object-fit: cover;
  filter: grayscale(30%);
  border: 1px solid var(--color-rule);
}

.hero-content h1 {
  margin-bottom: var(--space-sm);
}

.hero-subtitle {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--color-text-tertiary);
  letter-spacing: 0.04em;
  margin-bottom: var(--space-lg);
}

.hero-bio {
  font-size: 1.05rem;
  line-height: 1.75;
  color: var(--color-text-secondary);
}

.home-section {
  margin-top: var(--space-2xl);
}

.home-section h2 {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.section-symbol {
  font-family: var(--font-mono);
  font-size: 0.9rem;
  color: var(--color-accent);
  opacity: 0.6;
}

.quick-links {
  list-style: none;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: var(--space-md);
  margin-top: var(--space-md);
}

.quick-link-card {
  display: block;
  padding: var(--space-lg);
  background: var(--color-surface);
  border: 1px solid var(--color-rule-light);
  border-radius: 4px;
  text-decoration: none;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.quick-link-card:hover {
  border-color: var(--color-accent);
  box-shadow: 0 2px 12px rgba(45, 90, 142, 0.08);
}

.quick-link-card .card-label {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--color-text-tertiary);
  display: block;
  margin-bottom: var(--space-xs);
}

.quick-link-card .card-title {
  font-family: var(--font-heading);
  font-weight: 600;
  font-size: 1rem;
  color: var(--color-text);
  display: block;
}

/* --- Publications --- */
.page-header {
  margin-bottom: var(--space-xl);
}

.page-header h1 {
  margin-bottom: var(--space-xs);
}

.page-header .page-desc {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--color-text-tertiary);
  letter-spacing: 0.03em;
}

.pub-tabs {
  display: flex;
  gap: var(--space-md);
  margin-bottom: var(--space-xl);
  border-bottom: 1px solid var(--color-rule-light);
  padding-bottom: 0;
}

.pub-tab {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  background: none;
  border: none;
  border-bottom: 2px solid transparent;
  padding: var(--space-sm) var(--space-sm) calc(var(--space-sm) + 1px);
  color: var(--color-text-secondary);
  cursor: pointer;
  transition: color 0.2s ease, border-color 0.2s ease;
  margin-bottom: -1px;
}

.pub-tab:hover {
  color: var(--color-text);
}

.pub-tab.active {
  color: var(--color-accent);
  border-bottom-color: var(--color-accent);
}

ul.pubs {
  list-style: none;
  padding: 0;
}

ul.pubs li {
  padding: var(--space-md) 0;
  border-bottom: 1px solid var(--color-rule-light);
  line-height: 1.6;
  font-size: 0.95rem;
}

ul.pubs li:last-child {
  border-bottom: none;
}

a.pub-link {
  text-decoration: none;
}

ul.pubs .num {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--color-accent);
  margin-right: var(--space-xs);
}

.paper-figure {
  float: right;
  margin: 0 0 var(--space-md) var(--space-lg);
  max-width: 180px;
}

.paper-figure img {
  width: 100%;
  border: 1px solid var(--color-rule-light);
  border-radius: 2px;
}

.paper-figure p {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  color: var(--color-text-tertiary);
  margin-top: var(--space-xs);
  line-height: 1.4;
}

.year-heading {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 500;
  letter-spacing: 0.08em;
  color: var(--color-accent);
  margin-top: var(--space-xl);
  margin-bottom: var(--space-sm);
  padding-bottom: var(--space-xs);
  border-bottom: 1px solid var(--color-accent-light);
}

/* --- Courses & Artifacts (card grids) --- */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: var(--space-lg);
  margin-top: var(--space-lg);
}

.card {
  display: block;
  background: var(--color-surface);
  border: 1px solid var(--color-rule-light);
  border-radius: 4px;
  padding: var(--space-lg);
  text-decoration: none;
  color: inherit;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.card:hover {
  border-color: var(--color-accent);
  box-shadow: 0 2px 16px rgba(45, 90, 142, 0.06);
}

.card-number {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--color-text-tertiary);
  letter-spacing: 0.1em;
  margin-bottom: var(--space-xs);
}

.card-title {
  font-family: var(--font-heading);
  font-weight: 600;
  font-size: 1.05rem;
  color: var(--color-text);
  margin-bottom: var(--space-sm);
  line-height: 1.3;
}

.card-desc {
  font-size: 0.9rem;
  color: var(--color-text-secondary);
  line-height: 1.6;
}

.card-tags {
  margin-top: var(--space-md);
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-xs);
}

.tag {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--color-accent);
  background: var(--color-accent-light);
  padding: 2px 8px;
  border-radius: 2px;
}

/* --- Mobile Tab Bar --- */
.mobile-tab-bar {
  display: none;
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: rgba(252, 252, 252, 0.95);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-top: 1px solid var(--color-rule);
  height: calc(56px + env(safe-area-inset-bottom, 0px));
  justify-content: space-around;
  align-items: center;
  padding: 0 var(--space-sm) env(safe-area-inset-bottom, 0px);
}

.tab-link {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
  text-decoration: none;
  color: var(--color-text-tertiary);
  font-family: var(--font-mono);
  font-size: 0.6rem;
  letter-spacing: 0.04em;
  padding: var(--space-xs) var(--space-sm);
  transition: color 0.2s ease;
}

.tab-link.active {
  color: var(--color-accent);
}

.tab-icon {
  font-size: 1.5rem;
  line-height: 1;
  font-weight: 700;
}

/* --- Footer --- */
.site-footer {
  border-top: 1px solid var(--color-rule);
  margin-top: auto;
  background: rgba(252, 252, 252, 0.8);
}

.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: var(--space-lg);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.footer-left {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-family: var(--font-mono);
  font-size: 0.72rem;
  color: var(--color-text-tertiary);
  letter-spacing: 0.03em;
}

.footer-symbol {
  font-size: 1.2rem;
  color: var(--color-accent);
  opacity: 0.4;
}

.footer-right {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  color: var(--color-text-tertiary);
  letter-spacing: 0.03em;
}

/* --- Responsive --- */
@media (max-width: 680px) {
  html {
    font-size: 16px;
  }

  .header-inner {
    padding: 0 var(--space-md);
  }

  .nav-toggle {
    display: none;
  }

  .site-nav {
    display: none;
  }

  .mobile-tab-bar {
    display: flex;
  }

  .site-main {
    padding: var(--space-xl) var(--space-md) var(--space-lg);
    padding-bottom: calc(var(--space-lg) + 60px);
  }

  h1 {
    font-size: 1.8rem;
  }

  .home-hero {
    grid-template-columns: 1fr;
    gap: var(--space-lg);
    text-align: center;
  }

  .hero-portrait {
    margin: 0 auto;
    width: 160px;
    height: 160px;
  }

  .quick-links {
    grid-template-columns: 1fr;
  }

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

  .footer-inner {
    flex-direction: column;
    gap: var(--space-sm);
    text-align: center;
  }

  .paper-figure {
    float: none;
    margin: 0 0 var(--space-md) 0;
    max-width: 100%;
  }

  .pub-tabs {
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
  }
}