/* ============================================================
   NEURAL BLOG — style.css
   Design: modern editorial, dark navy + electric blue accent
   ============================================================ */

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

:root {
  --color-bg:         #0d1117;
  --color-bg-alt:     #111820;
  --color-surface:    #161d27;
  --color-border:     #1e2d3d;
  --color-accent:     #3b82f6;
  --color-accent-dim: #1d4ed8;
  --color-accent2:    #8b5cf6;
  --color-text:       #c9d1d9;
  --color-text-muted: #6b7f94;
  --color-heading:    #e6edf3;
  --color-white:      #ffffff;

  --font-sans:  system-ui, -apple-system, "Segoe UI", Helvetica, Arial, sans-serif;
  --font-mono:  "SF Mono", "Fira Code", "Fira Mono", Menlo, Consolas, monospace;

  --radius-sm:  6px;
  --radius-md:  12px;
  --radius-lg:  20px;

  --transition: 0.2s ease;
  --max-width:  860px;
  --nav-h:      64px;
}

html {
  scroll-behavior: smooth;
}

body {
  background-color: var(--color-bg);
  color: var(--color-text);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
}

/* ---------- Typography ---------- */
h1, h2, h3, h4 {
  color: var(--color-heading);
  line-height: 1.3;
}

h2 { font-size: clamp(1.5rem, 3vw, 2rem); margin-bottom: 1.25rem; }
h3 { font-size: 1.15rem; margin: 2rem 0 0.6rem; }
h4 { font-size: 1rem; }

p { margin-bottom: 1rem; }
p:last-child { margin-bottom: 0; }

a {
  color: var(--color-accent);
  text-decoration: none;
  transition: color var(--transition);
}
a:hover { color: #93c5fd; }

strong { color: var(--color-heading); font-weight: 600; }

code {
  font-family: var(--font-mono);
  font-size: 0.88em;
  background: rgba(59, 130, 246, 0.1);
  color: #7dd3fc;
  padding: 0.15em 0.45em;
  border-radius: var(--radius-sm);
}

/* ---------- Nav ---------- */
.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--nav-h);
  background: rgba(13, 17, 23, 0.85);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
}

.nav__inner {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 2rem;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 2rem;
}

.nav__logo {
  font-size: 1.1rem;
  font-weight: 700;
  background: linear-gradient(90deg, var(--color-accent), var(--color-accent2));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  letter-spacing: -0.02em;
  white-space: nowrap;
}

.nav__links {
  display: flex;
  gap: 2rem;
  list-style: none;
}

.nav__links a {
  color: var(--color-text-muted);
  font-size: 0.9rem;
  font-weight: 500;
  transition: color var(--transition);
}
.nav__links a:hover { color: var(--color-heading); }

/* ---------- Hero ---------- */
.hero {
  min-height: calc(100vh - var(--nav-h));
  display: grid;
  grid-template-columns: 1fr 380px;
  align-items: center;
  gap: 3rem;
  max-width: 1100px;
  margin: 0 auto;
  padding: 5rem 2rem 4rem;
}

.hero__tag {
  display: inline-block;
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--color-accent);
  background: rgba(59, 130, 246, 0.1);
  border: 1px solid rgba(59, 130, 246, 0.25);
  padding: 0.3em 0.9em;
  border-radius: 100px;
  margin-bottom: 1.5rem;
}

.hero__title {
  font-size: clamp(2.2rem, 5vw, 3.6rem);
  font-weight: 800;
  letter-spacing: -0.03em;
  color: var(--color-heading);
  margin-bottom: 1.25rem;
  line-height: 1.15;
}

.hero__title--accent {
  background: linear-gradient(120deg, var(--color-accent) 0%, var(--color-accent2) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero__desc {
  font-size: 1.15rem;
  color: var(--color-text-muted);
  max-width: 480px;
  margin-bottom: 2rem;
  line-height: 1.65;
}

.hero__meta {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  font-size: 0.85rem;
  color: var(--color-text-muted);
  flex-wrap: wrap;
}

.dot {
  display: inline-block;
  width: 3px;
  height: 3px;
  border-radius: 50%;
  background: var(--color-text-muted);
}

/* Neural net SVG diagram */
.hero__diagram {
  display: flex;
  align-items: center;
  justify-content: center;
}

.nn-svg {
  width: 100%;
  max-width: 320px;
  filter: drop-shadow(0 0 24px rgba(59, 130, 246, 0.25));
}

.nn-edges line {
  stroke: var(--color-accent);
  stroke-width: 1.2;
}

.nn-nodes circle {
  transition: r 0.3s;
}

.nn-nodes--input circle {
  fill: #1d4ed8;
  stroke: #3b82f6;
  stroke-width: 2;
}

.nn-nodes--hidden circle {
  fill: #5b21b6;
  stroke: #8b5cf6;
  stroke-width: 2;
  animation: pulse 2.4s ease-in-out infinite;
}

.nn-nodes--hidden circle:nth-child(2) { animation-delay: 0.3s; }
.nn-nodes--hidden circle:nth-child(3) { animation-delay: 0.6s; }
.nn-nodes--hidden circle:nth-child(4) { animation-delay: 0.9s; }

.nn-nodes--output circle {
  fill: #0e7490;
  stroke: #22d3ee;
  stroke-width: 2;
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50%       { opacity: 0.5; }
}

.nn-label {
  fill: var(--color-text-muted);
  font-size: 11px;
  font-family: var(--font-sans);
}

/* ---------- Main Sections ---------- */
.section {
  padding: 5rem 0;
}

.section--alt {
  background-color: var(--color-bg-alt);
}

.section__inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 2rem;
}

.section__title {
  position: relative;
  padding-bottom: 1rem;
  margin-bottom: 2rem;
}

.section__title::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  width: 48px;
  height: 3px;
  border-radius: 2px;
  background: linear-gradient(90deg, var(--color-accent), var(--color-accent2));
}

/* ---------- Lists ---------- */
.list {
  padding-left: 1.4rem;
  margin-bottom: 1rem;
}

.list li {
  margin-bottom: 0.45rem;
}

.list--ordered {
  list-style: decimal;
}

/* ---------- Callout ---------- */
.callout {
  display: flex;
  gap: 1rem;
  align-items: flex-start;
  background: rgba(59, 130, 246, 0.07);
  border: 1px solid rgba(59, 130, 246, 0.25);
  border-left: 4px solid var(--color-accent);
  border-radius: var(--radius-md);
  padding: 1.1rem 1.3rem;
  margin: 1.5rem 0;
}

.callout--info {
  background: rgba(139, 92, 246, 0.07);
  border-color: rgba(139, 92, 246, 0.25);
  border-left-color: var(--color-accent2);
}

.callout__icon {
  font-size: 1.3rem;
  flex-shrink: 0;
  line-height: 1.5;
}

/* ---------- Formula Block ---------- */
.formula-block {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 1.2rem 1.5rem;
  margin: 1.5rem 0;
}

.formula-title {
  font-size: 0.82rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--color-text-muted);
  margin-bottom: 0.6rem;
}

.formula-block code {
  display: block;
  background: transparent;
  padding: 0;
  font-size: 1rem;
  color: #a5f3fc;
}

/* ---------- Activation Cards ---------- */
.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1.2rem;
  margin: 1.5rem 0;
}

.card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 1.4rem;
  transition: border-color var(--transition), transform var(--transition);
}

.card:hover {
  border-color: var(--color-accent);
  transform: translateY(-2px);
}

.card__name {
  font-size: 1rem;
  font-weight: 700;
  color: var(--color-accent);
  margin-bottom: 0.5rem;
}

.card__formula {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.82rem;
  color: #7dd3fc;
  background: rgba(59, 130, 246, 0.08);
  padding: 0.4em 0.7em;
  border-radius: var(--radius-sm);
  margin-bottom: 0.75rem;
}

.card__desc {
  font-size: 0.9rem;
  color: var(--color-text-muted);
  line-height: 1.6;
}

/* ---------- Timeline ---------- */
.timeline {
  position: relative;
  padding-left: 2rem;
  margin: 2rem 0;
}

.timeline::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 2px;
  background: linear-gradient(180deg, var(--color-accent), var(--color-accent2), transparent);
  border-radius: 2px;
}

.timeline__item {
  position: relative;
  margin-bottom: 1.5rem;
}

.timeline__item::before {
  content: "";
  position: absolute;
  left: -2.45rem;
  top: 0.45rem;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--color-accent);
  border: 2px solid var(--color-bg);
  box-shadow: 0 0 0 2px var(--color-accent);
}

.timeline__year {
  display: inline-block;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--color-accent);
  background: rgba(59, 130, 246, 0.1);
  padding: 0.15em 0.6em;
  border-radius: 100px;
  margin-bottom: 0.25rem;
}

.timeline__item p {
  font-size: 0.92rem;
  color: var(--color-text);
  margin: 0;
}

/* ---------- Type Cards Grid ---------- */
.type-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1.4rem;
  margin-top: 2rem;
}

.type-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 1.75rem;
  transition: border-color var(--transition), box-shadow var(--transition), transform var(--transition);
}

.type-card:hover {
  border-color: rgba(139, 92, 246, 0.5);
  box-shadow: 0 8px 32px rgba(59, 130, 246, 0.1);
  transform: translateY(-3px);
}

.type-card__icon {
  width: 44px;
  height: 44px;
  color: var(--color-accent2);
  margin-bottom: 1rem;
}

.type-card h3 {
  font-size: 1.05rem;
  margin: 0 0 0.7rem;
  color: var(--color-heading);
}

.type-card p {
  font-size: 0.9rem;
  color: var(--color-text-muted);
  line-height: 1.65;
  margin-bottom: 0.75rem;
}

.type-card__use {
  font-size: 0.8rem !important;
  color: var(--color-accent) !important;
  font-weight: 500;
  padding-top: 0.5rem;
  border-top: 1px solid var(--color-border);
}

/* ---------- App Grid ---------- */
.apps-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1.2rem;
  margin-top: 2rem;
}

.app-item {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  transition: border-color var(--transition), transform var(--transition);
}

.app-item:hover {
  border-color: var(--color-accent);
  transform: translateY(-2px);
}

.app-item__emoji {
  display: block;
  font-size: 2rem;
  margin-bottom: 0.75rem;
}

.app-item h4 {
  font-size: 1rem;
  font-weight: 700;
  color: var(--color-heading);
  margin-bottom: 0.45rem;
}

.app-item p {
  font-size: 0.85rem;
  color: var(--color-text-muted);
  line-height: 1.6;
}

/* ---------- Glossary Table ---------- */
.glossary {
  width: 100%;
  border-collapse: collapse;
  margin-top: 1.5rem;
  font-size: 0.92rem;
}

.glossary thead tr {
  background: rgba(59, 130, 246, 0.1);
  border-bottom: 2px solid var(--color-accent);
}

.glossary th {
  text-align: left;
  padding: 0.75rem 1rem;
  color: var(--color-accent);
  font-weight: 600;
  font-size: 0.85rem;
  letter-spacing: 0.04em;
}

.glossary td {
  padding: 0.8rem 1rem;
  border-bottom: 1px solid var(--color-border);
  vertical-align: top;
}

.glossary td:first-child {
  font-weight: 600;
  color: var(--color-heading);
  white-space: nowrap;
  width: 36%;
}

.glossary tr:last-child td {
  border-bottom: none;
}

.glossary tr:hover td {
  background: rgba(255, 255, 255, 0.02);
}

/* ---------- Footer ---------- */
.footer {
  background: var(--color-bg-alt);
  border-top: 1px solid var(--color-border);
  padding: 3rem 2rem;
  text-align: center;
}

.footer__inner {
  max-width: var(--max-width);
  margin: 0 auto;
}

.footer__brand {
  font-size: 1.2rem;
  font-weight: 800;
  background: linear-gradient(90deg, var(--color-accent), var(--color-accent2));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 0.5rem;
}

.footer__copy {
  font-size: 0.85rem;
  color: var(--color-text-muted);
  margin-bottom: 0.75rem;
}

.footer__links a {
  font-size: 0.85rem;
}

/* ---------- Responsive ---------- */
@media (max-width: 800px) {
  .hero {
    grid-template-columns: 1fr;
    padding: 3.5rem 1.5rem 3rem;
    text-align: center;
    min-height: auto;
    gap: 3rem;
  }

  .hero__desc { margin-left: auto; margin-right: auto; }
  .hero__meta { justify-content: center; }
  .hero__diagram { order: -1; }
  .nn-svg { max-width: 240px; }

  .section__title::after { left: 0; }

  .type-grid { grid-template-columns: 1fr; }
  .cards { grid-template-columns: 1fr; }
  .apps-grid { grid-template-columns: 1fr 1fr; }

  .glossary td:first-child { white-space: normal; width: auto; }
}

@media (max-width: 500px) {
  .nav__links { display: none; }
  .apps-grid { grid-template-columns: 1fr; }

  .glossary { font-size: 0.82rem; }
  .glossary th, .glossary td { padding: 0.65rem 0.6rem; }
}