/* ============================================================
   Z.R.A.K. Education — Static Site Stylesheet
   ============================================================ */

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

/* --- Skip Link (a11y) --- */
.skip-link {
  position: absolute; top: -100%; left: 1rem;
  background: var(--accent); color: var(--bg);
  padding: .5rem 1rem; border-radius: 0 0 6px 6px;
  font-weight: 600; font-size: .9rem; z-index: 200;
  transition: top .2s;
}
.skip-link:focus { top: 0; }

/* --- Breadcrumb --- */
.breadcrumb {
  list-style: none; display: flex; gap: .4rem;
  font-size: .82rem; padding: .8rem 0 0;
  color: var(--text-dim);
}
.breadcrumb li + li::before { content: '/'; margin-right: .4rem; color: var(--border); }
.breadcrumb a { color: var(--text-dim); }
.breadcrumb a:hover { color: var(--accent); }
.breadcrumb [aria-current] { color: var(--text); }

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

:root {
  --bg:        #0b0e14;
  --bg-card:   #131720;
  --bg-nav:    #0f1219;
  --accent:    #00e0a0;
  --accent2:   #00b8ff;
  --accent-dim:#0a3d2f;
  --red:       #ff4060;
  --orange:    #ffa040;
  --text:      #d4d8e0;
  --text-dim:  #7a8194;
  --text-bright:#f0f2f5;
  --border:    #1e2430;
  --radius:    10px;
  --max-w:     1140px;
  --font:      'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --mono:      'JetBrains Mono', 'Fira Code', 'Consolas', monospace;
}

html { scroll-behavior: smooth; }

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--accent); text-decoration: none; transition: color .2s; }
a:hover { color: var(--accent2); }

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

h1, h2, h3, h4 { color: var(--text-bright); line-height: 1.3; }
h1 { font-size: 2.6rem; font-weight: 800; letter-spacing: -0.02em; }
h2 { font-size: 1.8rem; font-weight: 700; margin-bottom: .6em; }
h3 { font-size: 1.25rem; font-weight: 600; margin-bottom: .4em; }

p { margin-bottom: 1em; }

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

/* --- Navigation --- */
.site-nav {
  position: sticky; top: 0; z-index: 100;
  background: var(--bg-nav);
  border-bottom: 1px solid var(--border);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}
.site-nav .container {
  display: flex; align-items: center; justify-content: space-between;
  height: 64px;
}
.nav-logo {
  font-family: var(--mono);
  font-size: 1.25rem; font-weight: 800;
  color: var(--accent);
  letter-spacing: .06em;
}
.nav-logo span { color: var(--text-dim); font-weight: 400; }
.nav-logo-full { font-size: .75rem; font-weight: 400; letter-spacing: .02em; }
.nav-links { display: flex; gap: 1.8rem; list-style: none; }
.nav-links a {
  color: var(--text-dim); font-size: .92rem; font-weight: 500;
  transition: color .2s;
}
.nav-links a:hover,
.nav-links a.active { color: var(--accent); }

/* Hamburger */
.nav-toggle { display: none; background: none; border: none; cursor: pointer; padding: 6px; }
.nav-toggle span {
  display: block; width: 24px; height: 2px;
  background: var(--text); margin: 5px 0; transition: .3s;
  border-radius: 2px;
}
.nav-toggle.open span:nth-child(1) { transform: rotate(45deg) translate(5px,5px); }
.nav-toggle.open span:nth-child(2) { opacity: 0; }
.nav-toggle.open span:nth-child(3) { transform: rotate(-45deg) translate(5px,-5px); }

/* --- Hero --- */
.hero {
  padding: 5rem 0 4rem;
  text-align: center;
  background: radial-gradient(ellipse at 50% 0%, rgba(0,224,160,.08) 0%, transparent 60%);
}
.hero h1 { margin-bottom: .5em; }
.hero h1 .accent { color: var(--accent); }
.hero .subtitle {
  font-size: 1.15rem; color: var(--text-dim);
  max-width: 640px; margin: 0 auto 2rem;
}
.hero-buttons { display: flex; gap: 1rem; justify-content: center; flex-wrap: wrap; }

/* --- Buttons --- */
.btn {
  display: inline-flex; align-items: center; gap: .5rem;
  padding: .7rem 1.6rem; border-radius: var(--radius);
  font-size: .95rem; font-weight: 600;
  border: none; cursor: pointer; transition: all .2s;
}
.btn-primary {
  background: var(--accent); color: #0b0e14;
}
.btn-primary:hover { background: #00fbb4; color: #0b0e14; }
.btn-outline {
  background: transparent; color: var(--accent);
  border: 1.5px solid var(--accent);
}
.btn-outline:hover { background: var(--accent-dim); }
.btn-sm { padding: .45rem 1rem; font-size: .85rem; }

/* --- Section --- */
.section { padding: 4rem 0; }
.section-alt { background: var(--bg-card); }
.section-title {
  text-align: center; margin-bottom: 2.5rem;
}
.section-title h2 { margin-bottom: .3em; }
.section-title p { color: var(--text-dim); max-width: 600px; margin: 0 auto; }

/* --- Cards Grid --- */
.cards { display: grid; gap: 1.5rem; }
.cards-2 { grid-template-columns: repeat(auto-fit, minmax(320px, 1fr)); }
.cards-3 { grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); }
.cards-4 { grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); }

.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.8rem;
  transition: border-color .25s, transform .25s;
}
.card:hover {
  border-color: var(--accent);
  transform: translateY(-3px);
}
.card-icon {
  width: 48px; height: 48px;
  display: flex; align-items: center; justify-content: center;
  border-radius: 10px;
  background: var(--accent-dim);
  color: var(--accent);
  font-size: 1.4rem;
  margin-bottom: 1rem;
}
.card h3 { margin-bottom: .5rem; }
.card p { color: var(--text-dim); font-size: .92rem; margin-bottom: 0; }

/* --- Book Cards --- */
.book-card {
  display: flex; gap: 2rem; align-items: flex-start;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 2rem;
  margin-bottom: 1.5rem;
  transition: border-color .25s;
}
.book-card:hover { border-color: var(--accent); }
.book-cover {
  flex-shrink: 0; width: 140px;
  border-radius: 6px; overflow: hidden;
  box-shadow: 0 8px 24px rgba(0,0,0,.4);
}
.book-cover img { width: 100%; }
.book-cover-placeholder {
  width: 140px; height: 200px;
  background: linear-gradient(135deg, var(--accent-dim), var(--bg));
  border-radius: 6px;
  display: flex; align-items: center; justify-content: center;
  color: var(--accent); font-family: var(--mono);
  font-size: .8rem; text-align: center; padding: 1rem;
}
.book-info h3 { font-size: 1.2rem; margin-bottom: .25rem; }
.book-info .book-num { color: var(--accent); font-size: .8rem; font-weight: 600; text-transform: uppercase; letter-spacing: .08em; margin-bottom: .4rem; }
.book-info p { font-size: .92rem; }
.book-teaching { margin-top: .8rem; padding: .8rem 1rem; background: rgba(0,224,160,.06); border-left: 3px solid var(--accent); border-radius: 0 6px 6px 0; }
.book-teaching strong { color: var(--accent); font-size: .82rem; text-transform: uppercase; letter-spacing: .05em; }
.book-teaching p { font-size: .85rem; color: var(--text-dim); margin-bottom: 0; margin-top: .3rem; }

/* --- Feature List --- */
.feature-list { list-style: none; }
.feature-list li {
  padding: .8rem 0; border-bottom: 1px solid var(--border);
  display: flex; align-items: baseline; gap: .8rem;
  font-size: .95rem;
}
.feature-list li::before {
  content: '›';
  color: var(--accent); font-weight: 700; font-size: 1.2rem;
  flex-shrink: 0;
}

/* --- Lab Cards --- */
.lab-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  transition: border-color .25s, transform .25s;
}
.lab-card:hover { border-color: var(--accent); transform: translateY(-3px); }
.lab-header {
  padding: 1.2rem 1.5rem;
  background: linear-gradient(135deg, rgba(0,224,160,.1), rgba(0,184,255,.05));
  border-bottom: 1px solid var(--border);
  display: flex; align-items: center; justify-content: space-between;
}
.lab-header h3 { margin-bottom: 0; }
.lab-diff {
  font-size: .75rem; font-weight: 700; text-transform: uppercase;
  letter-spacing: .06em; padding: .2rem .6rem; border-radius: 4px;
}
.lab-diff.beginner { background: rgba(0,224,160,.15); color: var(--accent); }
.lab-diff.intermediate { background: rgba(0,184,255,.15); color: var(--accent2); }
.lab-diff.advanced { background: rgba(255,64,96,.15); color: var(--red); }
.lab-body { padding: 1.5rem; }
.lab-body p { font-size: .92rem; color: var(--text-dim); }
.lab-meta {
  display: flex; gap: 1.5rem; margin-top: 1rem; font-size: .82rem; color: var(--text-dim);
}
.lab-meta span { display: flex; align-items: center; gap: .3rem; }

/* --- Collapsible / Accordion --- */
.accordion { border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden; margin-bottom: 1rem; }
.accordion-header {
  width: 100%; background: var(--bg-card); border: none; color: var(--text-bright);
  padding: 1rem 1.5rem; font-size: 1rem; font-weight: 600;
  text-align: left; cursor: pointer;
  display: flex; align-items: center; justify-content: space-between;
  transition: background .2s;
  font-family: var(--font);
}
.accordion-header:hover { background: rgba(0,224,160,.05); }
.accordion-arrow {
  transition: transform .3s; font-size: .8rem; color: var(--accent);
}
.accordion.open .accordion-arrow { transform: rotate(180deg); }
.accordion-body {
  max-height: 0; overflow: hidden;
  transition: max-height .4s ease, padding .3s;
  background: var(--bg);
}
.accordion.open .accordion-body {
  max-height: 3000px; padding: 1.2rem 1.5rem;
}
.accordion-body p,
.accordion-body li { font-size: .92rem; }
.accordion-body ul { padding-left: 1.2rem; margin-bottom: .8rem; }
.accordion-body li { margin-bottom: .4rem; color: var(--text-dim); }
.accordion-body code {
  background: rgba(0,224,160,.08); color: var(--accent);
  padding: .15em .4em; border-radius: 4px;
  font-family: var(--mono); font-size: .85em;
}
.accordion-body pre {
  background: #0a0d12; border: 1px solid var(--border);
  border-radius: 6px; padding: 1rem 1.2rem;
  overflow-x: auto; margin: .8rem 0;
  font-family: var(--mono); font-size: .85rem;
  color: var(--text); line-height: 1.6;
}

/* --- Tables --- */
.table-wrap { overflow-x: auto; margin: 1rem 0; }
table {
  width: 100%; border-collapse: collapse;
  font-size: .9rem;
}
th, td { padding: .7rem 1rem; text-align: left; border-bottom: 1px solid var(--border); }
th { color: var(--accent); font-weight: 600; font-size: .82rem; text-transform: uppercase; letter-spacing: .05em; white-space: nowrap; }
td { color: var(--text-dim); }
tr:hover td { color: var(--text); }

/* --- Tags / Badges --- */
.tag {
  display: inline-block; font-size: .75rem; font-weight: 600;
  padding: .15rem .55rem; border-radius: 4px;
  text-transform: uppercase; letter-spacing: .04em;
}
.tag-green { background: rgba(0,224,160,.12); color: var(--accent); }
.tag-blue  { background: rgba(0,184,255,.12); color: var(--accent2); }
.tag-red   { background: rgba(255,64,96,.12); color: var(--red); }
.tag-orange{ background: rgba(255,160,64,.12); color: var(--orange); }

/* --- Stat Counters --- */
.stats { display: flex; gap: 2rem; justify-content: center; flex-wrap: wrap; padding: 2rem 0; }
.stat { text-align: center; }
.stat-num { font-size: 2.4rem; font-weight: 800; color: var(--accent); font-family: var(--mono); }
.stat-label { font-size: .85rem; color: var(--text-dim); margin-top: .2rem; }

/* --- Download Items --- */
.download-item {
  display: flex; align-items: center; justify-content: space-between;
  padding: 1rem 1.5rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  margin-bottom: .8rem;
  transition: border-color .2s;
}
.download-item:hover { border-color: var(--accent); }
.download-info { display: flex; align-items: center; gap: 1rem; }
.download-icon { color: var(--accent); font-size: 1.3rem; }
.download-info h4 { font-size: .95rem; margin-bottom: .1rem; }
.download-info p { font-size: .8rem; color: var(--text-dim); margin-bottom: 0; }

/* --- Callout --- */
.callout {
  padding: 1.2rem 1.5rem;
  border-radius: var(--radius);
  border-left: 4px solid var(--accent);
  background: rgba(0,224,160,.04);
  margin: 1.5rem 0;
}
.callout.warning { border-left-color: var(--orange); background: rgba(255,160,64,.04); }
.callout p { margin-bottom: 0; font-size: .92rem; }
.callout strong { color: var(--text-bright); }

/* --- Footer --- */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 3rem 0 2rem;
  color: var(--text-dim);
  font-size: .85rem;
}
.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 2rem;
  margin-bottom: 2rem;
}
.footer-brand p { margin-top: .5rem; max-width: 280px; }
.footer-col h4 {
  color: var(--text-bright); font-size: .82rem;
  text-transform: uppercase; letter-spacing: .08em;
  margin-bottom: .8rem;
}
.footer-col ul { list-style: none; }
.footer-col li { margin-bottom: .4rem; }
.footer-col a { color: var(--text-dim); font-size: .85rem; }
.footer-col a:hover { color: var(--accent); }
.footer-bottom {
  border-top: 1px solid var(--border);
  padding-top: 1.5rem;
  display: flex; justify-content: space-between; align-items: center;
  flex-wrap: wrap; gap: 1rem;
}

/* --- Ethical Banner --- */
.ethics-banner {
  background: linear-gradient(135deg, rgba(0,224,160,.06), rgba(0,184,255,.04));
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 2rem;
  text-align: center;
  margin: 2rem 0;
}
.ethics-banner h3 { color: var(--accent); margin-bottom: .5rem; }
.ethics-banner p { color: var(--text-dim); max-width: 600px; margin: 0 auto; font-size: .92rem; }

/* --- Page Header (inner pages) --- */
.page-header {
  padding: 3rem 0 2rem;
  text-align: center;
  background: radial-gradient(ellipse at 50% 0%, rgba(0,224,160,.06) 0%, transparent 60%);
  border-bottom: 1px solid var(--border);
}
.page-header p { color: var(--text-dim); max-width: 600px; margin: .5rem auto 0; }

/* --- Two Column Layout --- */
.two-col {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  align-items: start;
}

/* --- Sidebar nav (labs/resources) --- */
.sidebar-nav { position: sticky; top: 80px; }
.sidebar-nav a {
  display: block; padding: .5rem 1rem;
  color: var(--text-dim); font-size: .9rem;
  border-left: 2px solid var(--border);
  transition: all .2s;
}
.sidebar-nav a:hover,
.sidebar-nav a.active {
  color: var(--accent);
  border-left-color: var(--accent);
  background: rgba(0,224,160,.04);
}

/* --- Tool Grid --- */
.tool-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: .8rem;
}
.tool-chip {
  display: flex; align-items: center; gap: .5rem;
  padding: .6rem .8rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  font-size: .82rem; color: var(--text-dim);
  transition: border-color .2s;
}
.tool-chip:hover { border-color: var(--accent); color: var(--text); }
.tool-chip .dot {
  width: 6px; height: 6px; border-radius: 50%;
  background: var(--accent); flex-shrink: 0;
}

/* --- Construction Banner --- */
.construction-banner {
  background: repeating-linear-gradient(
    -45deg,
    rgba(255,160,64,.08),
    rgba(255,160,64,.08) 10px,
    transparent 10px,
    transparent 20px
  );
  border-bottom: 1px solid rgba(255,160,64,.25);
  padding: .7rem 0;
}
.construction-banner .container {
  display: flex; align-items: center; gap: .7rem;
  justify-content: center;
}
.construction-banner .construction-icon { font-size: 1.1rem; flex-shrink: 0; }
.construction-banner p {
  margin: 0; font-size: .85rem; color: var(--orange);
}
.construction-banner strong { color: var(--text-bright); }

/* --- Contact Page --- */
.contact-details { margin-top: 1.5rem; }
.contact-item {
  display: flex; align-items: flex-start; gap: 1rem;
  padding: 1rem 0;
  border-bottom: 1px solid var(--border);
}
.contact-item:last-child { border-bottom: none; }
.contact-icon {
  font-size: 1.3rem; flex-shrink: 0;
  width: 40px; height: 40px;
  display: flex; align-items: center; justify-content: center;
  background: var(--accent-dim); border-radius: 8px;
  color: var(--accent);
}
.contact-item h4 { font-size: .82rem; text-transform: uppercase; letter-spacing: .06em; color: var(--text-dim); margin-bottom: .15rem; }

.contact-form { margin-top: .5rem; }
.form-group { margin-bottom: 1.2rem; }
.form-group label {
  display: block; font-size: .82rem; font-weight: 600;
  color: var(--text-dim); text-transform: uppercase;
  letter-spacing: .06em; margin-bottom: .4rem;
}
.form-group input,
.form-group textarea {
  width: 100%; padding: .7rem 1rem;
  background: var(--bg); color: var(--text);
  border: 1px solid var(--border); border-radius: 6px;
  font-family: var(--font); font-size: .95rem;
  transition: border-color .2s;
}
.form-group input:focus,
.form-group textarea:focus {
  outline: none; border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(0,224,160,.1);
}
.form-group textarea { resize: vertical; min-height: 120px; }

/* --- Responsive --- */
@media (max-width: 768px) {
  h1 { font-size: 1.8rem; }
  h2 { font-size: 1.4rem; }
  .hero { padding: 3rem 0 2.5rem; }

  .nav-links {
    display: none; flex-direction: column;
    position: absolute; top: 64px; left: 0; right: 0;
    background: var(--bg-nav); border-bottom: 1px solid var(--border);
    padding: 1rem 1.5rem; gap: .8rem;
  }
  .nav-links.open { display: flex; }
  .nav-toggle { display: block; }

  .footer-grid { grid-template-columns: 1fr 1fr; }
  .two-col { grid-template-columns: 1fr; }
  .book-card { flex-direction: column; align-items: center; text-align: center; }
  .book-cover { width: 120px; }
  .book-teaching { text-align: left; }
  .stats { gap: 1.2rem; }
  .stat-num { font-size: 1.8rem; }
  .footer-bottom { flex-direction: column; text-align: center; }
}

@media (max-width: 480px) {
  .footer-grid { grid-template-columns: 1fr; }
  .hero-buttons { flex-direction: column; align-items: center; }
}