/* ================================================================
   Azabell1993.GITHUB.IO  ·  main.css
   ================================================================

   Table of Contents
     1.  Design tokens (CSS custom properties)
     2.  Reset & base elements
     3.  Accessibility helpers
     4.  Layout shell
     5.  Site header & navigation
     6.  Site footer
     7.  Page intro block
     8.  Prose regions
     9.  Component — entry  (CV items, notes list rows)
    10.  Component — card   (project cards)
    11.  Component — tag / label
    12.  Component — skills table
    13.  Component — inline link row
    14.  Home page sections
    15.  CV page
    16.  Research page
    17.  Contact page
    18.  Utilities
    19.  Responsive (≤ 640 px)
    20.  Print (CV)

   ================================================================ */


/* ------------------------------------------------------------------
   1. Design tokens
   ------------------------------------------------------------------ */

:root {
  /* Palette */
  --c-bg:           #ffffff;
  --c-bg-subtle:    #f8fafc;
  --c-bg-muted:     #f1f5f9;
  --c-text:         #0f172a;
  --c-text-muted:   #475569;
  --c-text-faint:   #94a3b8;
  --c-accent:       #1d4ed8;
  --c-accent-dark:  #1e3a8a;
  --c-border:       #e2e8f0;
  --c-border-dark:  #cbd5e1;

  /* Typography */
  --f-sans: system-ui, -apple-system, 'Segoe UI', Roboto,
            'Helvetica Neue', Arial, sans-serif;
  --f-mono: 'JetBrains Mono', 'Cascadia Code', 'Fira Code',
            Consolas, 'Courier New', monospace;

  /* Spacing (4-point scale) */
  --sp-1:  0.25rem;
  --sp-2:  0.5rem;
  --sp-3:  0.75rem;
  --sp-4:  1rem;
  --sp-5:  1.25rem;
  --sp-6:  1.5rem;
  --sp-8:  2rem;
  --sp-10: 2.5rem;
  --sp-12: 3rem;
  --sp-16: 4rem;

  /* Layout */
  --max-w:  1000px;
  --nav-h:  56px;
  --radius: 4px;
}


/* ------------------------------------------------------------------
   2. Reset & base elements
   ------------------------------------------------------------------ */

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--f-sans);
  font-size: 1rem;
  line-height: 1.65;
  color: var(--c-text);
  background-color: var(--c-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

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

a {
  color: var(--c-accent);
  text-decoration: underline;
  text-underline-offset: 3px;
  text-decoration-thickness: 1px;
}

a:hover {
  color: var(--c-accent-dark);
}

ul, ol {
  padding-left: 1.35rem;
}

li {
  margin-bottom: var(--sp-1);
}

h1, h2, h3, h4, h5 {
  line-height: 1.25;
  font-weight: 600;
  letter-spacing: -0.01em;
}

h1 { font-size: 1.875rem; }
h2 { font-size: 1.375rem; }
h3 { font-size: 1.125rem; }
h4 { font-size: 1rem; }

p {
}

strong {
  font-weight: 600;
}

code {
  font-family: var(--f-mono);
  font-size: 0.875em;
  background: var(--c-bg-muted);
  border: 1px solid var(--c-border);
  padding: 0.1em 0.35em;
  border-radius: 3px;
}

pre {
  font-family: var(--f-mono);
  font-size: 0.875rem;
  background: var(--c-bg-muted);
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  padding: var(--sp-4) var(--sp-6);
  overflow-x: auto;
  line-height: 1.55;
}

pre code {
  background: none;
  border: none;
  padding: 0;
  font-size: inherit;
}

blockquote {
  border-left: 3px solid var(--c-accent);
  padding-left: var(--sp-4);
  color: var(--c-text-muted);
  font-style: italic;
  margin: var(--sp-4) 0;
}

hr {
  border: none;
  border-top: 1px solid var(--c-border);
  margin: var(--sp-8) 0;
}


/* ------------------------------------------------------------------
   3. Accessibility helpers
   ------------------------------------------------------------------ */

.skip-link {
  position: absolute;
  top: -100%;
  left: var(--sp-4);
  z-index: 9999;
  background: var(--c-text);
  color: var(--c-bg);
  padding: var(--sp-2) var(--sp-4);
  border-radius: var(--radius);
  font-size: 0.875rem;
  font-weight: 600;
  text-decoration: none;
  transition: top 0.1s;
}

.skip-link:focus {
  top: var(--sp-2);
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border-width: 0;
}


/* ------------------------------------------------------------------
   4. Layout shell
   ------------------------------------------------------------------ */

.container {
  width: 100%;
  max-width: var(--max-w);
  margin-inline: auto;
  padding-inline: var(--sp-6);
}

main {
  flex: 1 1 auto;
  padding-top: var(--sp-10);
  padding-bottom: var(--sp-16);
}


/* ------------------------------------------------------------------
   5. Site header & navigation
   ------------------------------------------------------------------ */

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--nav-h);
  background: var(--c-bg);
  border-bottom: 1px solid var(--c-border);
}

.site-header .container {
  height: 100%;
  display: flex;
  align-items: center;
  gap: var(--sp-8);
}

.site-name {
  font-size: 1rem;
  font-weight: 700;
  color: var(--c-text);
  text-decoration: none;
  letter-spacing: -0.02em;
  white-space: nowrap;
  margin-right: auto;
}

.site-name:hover {
  color: var(--c-accent);
}

.site-nav {
  display: flex;
  align-items: center;
  gap: var(--sp-1);
}

.site-nav a {
  font-size: 0.9rem;
  color: var(--c-text-muted);
  text-decoration: none;
  padding: var(--sp-1) var(--sp-3);
  border-radius: var(--radius);
  transition: color 0.12s, background-color 0.12s;
}

.site-nav a:hover {
  color: var(--c-text);
  background-color: var(--c-bg-muted);
}

.site-nav a[aria-current="page"],
.site-nav a.active {
  color: var(--c-accent);
  font-weight: 600;
}

/* Hamburger button — hidden on desktop */
.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 36px;
  height: 36px;
  padding: 7px 6px;
  background: none;
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  cursor: pointer;
  flex-shrink: 0;
}

.nav-toggle span {
  display: block;
  height: 2px;
  background: var(--c-text);
  border-radius: 2px;
}


/* ------------------------------------------------------------------
   6. Site footer
   ------------------------------------------------------------------ */

.site-footer {
  border-top: 1px solid var(--c-border);
  background: var(--c-bg-subtle);
  padding: var(--sp-6) 0;
  font-size: 0.875rem;
  color: var(--c-text-muted);
}

.site-footer .container {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--sp-4);
}

.site-footer a {
  color: var(--c-text-muted);
  text-decoration: none;
}

.site-footer a:hover {
  color: var(--c-accent);
}


/* ------------------------------------------------------------------
   7. Page intro block
   ------------------------------------------------------------------ */

.page-intro {
  padding-bottom: var(--sp-8);
  border-bottom: 1px solid var(--c-border);
  margin-bottom: var(--sp-8);
}

.page-intro h1 {
  margin-bottom: var(--sp-3);
}

.page-intro p {
  color: var(--c-text-muted);
  font-size: 1.05rem;
}

.page-intro .meta-line {
  font-size: 0.875rem;
  color: var(--c-text-faint);
  margin-top: var(--sp-3);
}


/* ------------------------------------------------------------------
   8. Prose regions
   ------------------------------------------------------------------ */

.prose > * + * {
  margin-top: var(--sp-4);
}

.prose h2 {
  margin-top: var(--sp-10);
}

.prose h3 {
  margin-top: var(--sp-6);
}

.prose ul,
.prose ol {
}


/* ------------------------------------------------------------------
   9. Component — entry  (CV items, notes list)
   ------------------------------------------------------------------ */

.entry-list {
  list-style: none;
  padding: 0;
  border-top: 1px solid var(--c-border);
}

.entry {
  display: grid;
  grid-template-columns: 1fr auto;
  grid-template-rows: auto auto auto;
  column-gap: var(--sp-6);
  row-gap: var(--sp-1);
  padding: var(--sp-5) 0;
  border-bottom: 1px solid var(--c-border);
}

.entry-title {
  grid-column: 1;
  grid-row: 1;
  font-size: 1rem;
  font-weight: 600;
  color: var(--c-text);
  text-decoration: none;
}

a.entry-title:hover {
  color: var(--c-accent);
}

.entry-meta {
  grid-column: 2;
  grid-row: 1;
  font-size: 0.8125rem;
  color: var(--c-text-faint);
  white-space: nowrap;
  text-align: right;
  line-height: 1.5;
  padding-top: 0.175rem;
}

.entry-sub {
  grid-column: 1 / -1;
  grid-row: 2;
  font-size: 0.9rem;
  color: var(--c-text-muted);
}

.entry-body {
  grid-column: 1 / -1;
  grid-row: 3;
  font-size: 0.9rem;
  color: var(--c-text-muted);
  margin-top: var(--sp-2);
}

.entry-body ul {
  margin: var(--sp-2) 0 0;
}

/* Section divider used in CV */
.section-heading {
  font-size: 0.6875rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--c-text-faint);
  margin-top: var(--sp-10);
  margin-bottom: var(--sp-4);
}


/* ------------------------------------------------------------------
   10. Component — card  (project cards)
   ------------------------------------------------------------------ */

.card-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--sp-4);
}

.card {
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  padding: var(--sp-6);
  display: flex;
  flex-direction: column;
  gap: var(--sp-3);
  background: var(--c-bg);
}

.card:hover {
  border-color: var(--c-border-dark);
}

.card-name {
  font-size: 1rem;
  font-weight: 700;
  color: var(--c-text);
  text-decoration: none;
  letter-spacing: -0.01em;
}

a.card-name:hover {
  color: var(--c-accent);
}

.card-status {
  font-size: 0.75rem;
  font-family: var(--f-mono);
  color: var(--c-text-faint);
  margin-left: var(--sp-2);
  font-weight: 400;
}

.card-description {
  font-size: 0.9rem;
  color: var(--c-text-muted);
  line-height: 1.6;
  flex: 1;
}

.card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--sp-3);
  flex-wrap: wrap;
  margin-top: auto;
  padding-top: var(--sp-4);
  border-top: 1px solid var(--c-border);
}

.card-links {
  display: flex;
  gap: var(--sp-4);
  font-size: 0.8125rem;
}

.card-links a {
  color: var(--c-text-muted);
  text-decoration: none;
}

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


/* ------------------------------------------------------------------
   11. Component — tag / label
   ------------------------------------------------------------------ */

.tag {
  display: inline-block;
  font-family: var(--f-mono);
  font-size: 0.75rem;
  color: var(--c-text-muted);
  background: var(--c-bg-muted);
  border: 1px solid var(--c-border);
  padding: 0.1em 0.5em;
  border-radius: 3px;
  white-space: nowrap;
}

.tag-list {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-1);
  list-style: none;
  padding: 0;
}


/* ------------------------------------------------------------------
   12. Component — skills table
   ------------------------------------------------------------------ */

.skills-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
}

.skills-table th {
  text-align: left;
  font-weight: 600;
  font-size: 0.8125rem;
  color: var(--c-text);
  padding: var(--sp-3) var(--sp-5) var(--sp-3) 0;
  border-bottom: 1px solid var(--c-border);
  white-space: nowrap;
  vertical-align: top;
  width: 10rem;
}

.skills-table td {
  padding: var(--sp-3) var(--sp-4) var(--sp-3) 0;
  border-bottom: 1px solid var(--c-border);
  color: var(--c-text-muted);
  vertical-align: top;
  line-height: 1.6;
}

.skills-table thead th {
  border-bottom: 2px solid var(--c-border-dark);
  font-size: 0.75rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--c-text-faint);
}

.skills-table tr:last-child th,
.skills-table tr:last-child td {
  border-bottom: none;
}


/* ------------------------------------------------------------------
   13. Component — inline link row
   ------------------------------------------------------------------ */

.link-row {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-2) var(--sp-5);
  list-style: none;
  padding: 0;
  font-size: 0.9rem;
}

.link-row a {
  text-decoration: none;
  color: var(--c-text-muted);
}

.link-row a:hover {
  color: var(--c-accent);
  text-decoration: underline;
  text-underline-offset: 3px;
}


/* ------------------------------------------------------------------
   14. Home page sections
   ------------------------------------------------------------------ */

.home-intro {
  padding: var(--sp-10) 0 var(--sp-8);
  border-bottom: 1px solid var(--c-border);
  margin-bottom: var(--sp-8);
}

.home-name {
  font-size: 2rem;
  font-weight: 700;
  letter-spacing: -0.025em;
  margin-bottom: var(--sp-2);
}

.home-tagline {
  font-size: 0.9375rem;
  color: var(--c-text-muted);
  margin-bottom: var(--sp-5);
}

.home-bio {
  line-height: 1.7;
  margin-bottom: var(--sp-4);
}

.home-section {
  margin-bottom: var(--sp-10);
}

.home-section-heading {
  font-size: 0.6875rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--c-text-faint);
  margin-bottom: var(--sp-4);
}

.interest-list {
  list-style: none;
  padding: 0;
  column-count: 2;
  column-gap: var(--sp-6);
}

.interest-list li {
  font-size: 0.9rem;
  color: var(--c-text-muted);
  padding: var(--sp-1) 0;
  break-inside: avoid;
  margin-bottom: 0;
}

.interest-list li::before {
  content: '\2014'; /* em dash */
  color: var(--c-text-faint);
  margin-right: var(--sp-2);
}

.highlights-list {
  list-style: none;
  padding: 0;
  border-top: 1px solid var(--c-border);
}

.highlights-list li {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: var(--sp-6);
  padding: var(--sp-4) 0;
  border-bottom: 1px solid var(--c-border);
  font-size: 0.9rem;
  margin-bottom: 0;
}

.hl-label {
  color: var(--c-text);
}

.hl-label a {
  color: var(--c-text);
}

.hl-label a:hover {
  color: var(--c-accent);
}

.hl-date {
  font-size: 0.8125rem;
  color: var(--c-text-faint);
  white-space: nowrap;
  flex-shrink: 0;
}


/* ------------------------------------------------------------------
   15. CV page
   ------------------------------------------------------------------ */

.cv-pub {
  padding: var(--sp-4) 0;
  border-bottom: 1px solid var(--c-border);
}

.cv-pub:first-of-type {
  border-top: 1px solid var(--c-border);
}

.cv-pub-title {
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--c-text);
  margin-bottom: var(--sp-1);
}

.cv-pub-meta {
  font-size: 0.875rem;
  color: var(--c-text-muted);
  line-height: 1.6;
}

.cv-pub-meta a {
  color: var(--c-text-muted);
}

.cv-pub-meta a:hover {
  color: var(--c-accent);
}

.cv-download-bar {
  display: flex;
  align-items: center;
  gap: var(--sp-4);
  font-size: 0.875rem;
  color: var(--c-text-faint);
  margin-bottom: var(--sp-8);
}

.cv-download-bar a {
  color: var(--c-text-muted);
}


/* ------------------------------------------------------------------
   16. Research page
   ------------------------------------------------------------------ */

.research-area {
  padding: var(--sp-6) 0;
  border-bottom: 1px solid var(--c-border);
}

.research-area:first-of-type {
  border-top: 1px solid var(--c-border);
}

.research-area h3 {
  margin-bottom: var(--sp-3);
}

.research-area p {
  font-size: 0.9rem;
  color: var(--c-text-muted);
  margin-bottom: var(--sp-3);
}

.research-area .tag-list {
  margin-top: var(--sp-3);
}


/* ------------------------------------------------------------------
   17. Contact page
   ------------------------------------------------------------------ */

.contact-item {
  padding: var(--sp-5) 0;
  border-bottom: 1px solid var(--c-border);
  display: grid;
  grid-template-columns: 9rem 1fr;
  gap: var(--sp-4);
  align-items: baseline;
}

.contact-item:first-of-type {
  border-top: 1px solid var(--c-border);
}

.contact-label {
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--c-text-faint);
}

.contact-value {
  font-size: 0.9375rem;
  color: var(--c-text);
}

.contact-note {
  font-size: 0.875rem;
  color: var(--c-text-muted);
  margin-top: var(--sp-1);
}


/* ------------------------------------------------------------------
   18. Utilities
   ------------------------------------------------------------------ */

.text-muted  { color: var(--c-text-muted); }
.text-faint  { color: var(--c-text-faint); }
.text-sm     { font-size: 0.875rem; }
.text-xs     { font-size: 0.75rem; }
.font-mono   { font-family: var(--f-mono); }

.mt-2  { margin-top: var(--sp-2); }
.mt-4  { margin-top: var(--sp-4); }
.mt-6  { margin-top: var(--sp-6); }
.mt-8  { margin-top: var(--sp-8); }
.mb-4  { margin-bottom: var(--sp-4); }
.mb-8  { margin-bottom: var(--sp-8); }


/* ------------------------------------------------------------------
   19. Responsive  (≤ 900 px — tablet)
   ------------------------------------------------------------------ */

@media (max-width: 900px) {
  .card-grid {
    grid-template-columns: 1fr 1fr;
    gap: var(--sp-3);
  }

  .interest-list {
    column-gap: var(--sp-4);
  }

  .contact-item {
    grid-template-columns: 7.5rem 1fr;
  }

  .skills-table {
    display: block;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
  }

  .entry {
    column-gap: var(--sp-3);
  }
}


/* ------------------------------------------------------------------
   19b. Responsive  (≤ 640 px — mobile)
   ------------------------------------------------------------------ */

@media (max-width: 640px) {
  /* Header collapses to multi-line */
  .site-header {
    height: auto;
    min-height: 52px;
    position: sticky;
  }

  .site-header .container {
    flex-wrap: wrap;
    height: auto;
    padding-block: var(--sp-3);
    gap: var(--sp-3);
  }

  .site-name {
    margin-right: auto;
  }

  .nav-toggle {
    display: flex;
  }

  .site-nav {
    display: none;
    flex-direction: column;
    align-items: flex-start;
    width: 100%;
    gap: 0;
    border-top: 1px solid var(--c-border);
    padding-top: var(--sp-2);
    padding-bottom: var(--sp-2);
  }

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

  .site-nav a {
    font-size: 0.9375rem;
    width: 100%;
    padding: var(--sp-2) var(--sp-2);
  }

  /* Main content */
  main {
    padding-top: var(--sp-6);
    padding-bottom: var(--sp-12);
  }

  h1 { font-size: 1.5rem; }
  h2 { font-size: 1.25rem; }

  .home-name {
    font-size: 1.625rem;
  }

  /* Cards: 1 column */
  .card-grid {
    grid-template-columns: 1fr;
  }

  /* Interest list: single column */
  .interest-list {
    column-count: 1;
  }

  /* Entry: flatten grid to single column */
  .entry {
    grid-template-columns: 1fr;
  }

  .entry-meta {
    grid-column: 1;
    grid-row: 2;
    text-align: left;
  }

  .entry-sub  { grid-row: 3; }
  .entry-body { grid-row: 4; }

  /* Contact: single column */
  .contact-item {
    grid-template-columns: 1fr;
    gap: var(--sp-1);
  }

  /* Skills table: fixed first column narrower */
  .skills-table th {
    width: auto;
    padding-right: var(--sp-3);
  }
}


/* ------------------------------------------------------------------
   20. Print  (CV page — use browser print for PDF)
   ------------------------------------------------------------------ */

@media print {
  .site-header,
  .site-footer,
  .skip-link,
  .nav-toggle,
  .cv-download-bar {
    display: none !important;
  }

  body {
    font-size: 11pt;
    line-height: 1.5;
    color: #000;
    background: #fff;
  }

  main {
    padding: 0;
  }

  a {
    color: #000;
    text-decoration: none;
  }

  a[href]::after {
    content: ' (' attr(href) ')';
    font-size: 0.8em;
    color: #555;
  }

  /* Suppress href display for internal links */
  a[href^="/"]::after,
  a[href^="#"]::after {
    content: '';
  }

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

  .entry,
  .cv-pub {
    break-inside: avoid;
  }

  .section-heading {
    break-before: auto;
    page-break-before: auto;
  }
}