/* ============================================================
   Infotech Tutorials — Premium Dark Redesign
   ============================================================ */

:root {
  /* Core palette */
  --bg-deep: #070b14;
  --bg-base: #0f172a;
  --bg-elevated: #151d2e;
  --bg-card: #1a2336;
  --bg-card-hover: #1f2840;

  /* Iridescent spectrum */
  --iris-indigo: #6366f1;
  --iris-violet: #a78bfa;
  --iris-cyan: #22d3ee;
  --iris-magenta: #e879f9;
  --iris-emerald: #34d399;

  --gradient-iris: linear-gradient(135deg, var(--iris-indigo) 0%, var(--iris-cyan) 45%, var(--iris-magenta) 100%);
  --gradient-iris-soft: linear-gradient(135deg, rgba(99, 102, 241, 0.15) 0%, rgba(34, 211, 238, 0.1) 50%, rgba(232, 121, 249, 0.12) 100%);

  /* Text */
  --text-primary: #f1f5f9;
  --text-secondary: #94a3b8;
  --text-dim: #64748b;

  /* Borders & glow */
  --border-subtle: rgba(255, 255, 255, 0.06);
  --border-medium: rgba(255, 255, 255, 0.1);
  --glow-cyan: rgba(34, 211, 238, 0.35);
  --glow-violet: rgba(167, 139, 250, 0.35);
  --glow-magenta: rgba(232, 121, 249, 0.25);

  /* Typography */
  --font-display: 'Syne', system-ui, sans-serif;
  --font-body: 'Inter', system-ui, -apple-system, sans-serif;

  --fs-xs: clamp(0.6875rem, 0.65rem + 0.15vw, 0.75rem);
  --fs-sm: clamp(0.8125rem, 0.78rem + 0.2vw, 0.875rem);
  --fs-base: clamp(0.9375rem, 0.88rem + 0.25vw, 1rem);
  --fs-md: clamp(1.0625rem, 1rem + 0.3vw, 1.125rem);
  --fs-lg: clamp(1.2rem, 1.05rem + 0.55vw, 1.375rem);
  --fs-xl: clamp(1.625rem, 1.3rem + 1vw, 2rem);
  --fs-hero: clamp(2rem, 1.4rem + 2.5vw, 3.25rem);

  /* Spacing */
  --space-xs: 0.375rem;
  --space-sm: 0.625rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  --space-3xl: 4.5rem;

  /* Layout */
  --radius-sm: 0.5rem;
  --radius-md: 0.875rem;
  --radius-lg: 1.125rem;
  --radius-xl: 1.375rem;
  --radius-2xl: 1.75rem;
  --radius-full: 9999px;
  --max-width: 68rem;
  --header-h: 4.25rem;

  --transition: 0.28s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ============================================================
   Reset & Base
   ============================================================ */

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

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

body {
  font-family: var(--font-body);
  font-size: var(--fs-base);
  font-weight: 400;
  line-height: 1.65;
  color: var(--text-primary);
  background: var(--bg-deep);
  min-height: 100dvh;
  overflow-x: hidden;
  position: relative;
}

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

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

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

button {
  font: inherit;
  cursor: pointer;
  border: none;
  background: none;
  color: inherit;
}

ul[role="list"] {
  list-style: none;
}

/* ============================================================
   Utilities
   ============================================================ */

.visually-hidden {
  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 {
  position: absolute;
  top: -100%;
  left: var(--space-md);
  z-index: 1000;
  padding: var(--space-sm) var(--space-md);
  background: var(--gradient-iris);
  color: var(--text-primary);
  border-radius: var(--radius-sm);
  font-weight: 600;
}

.skip-link:focus {
  top: var(--space-md);
}

.text-gradient {
  background: var(--gradient-iris);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

/* ============================================================
   Ambient Background Layer
   ============================================================ */

.ambient-layer {
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 0;
  overflow: hidden;
}

.ambient-orb {
  position: absolute;
  border-radius: 50%;
  filter: blur(100px);
  opacity: 0.35;
  animation: float-orb 20s ease-in-out infinite;
}

.ambient-orb--1 {
  width: 40vw;
  height: 40vw;
  max-width: 28rem;
  max-height: 28rem;
  top: -10%;
  left: -5%;
  background: radial-gradient(circle, var(--iris-indigo) 0%, transparent 70%);
}

.ambient-orb--2 {
  width: 35vw;
  height: 35vw;
  max-width: 24rem;
  max-height: 24rem;
  top: 30%;
  right: -8%;
  background: radial-gradient(circle, var(--iris-magenta) 0%, transparent 70%);
  animation-delay: -7s;
}

.ambient-orb--3 {
  width: 30vw;
  height: 30vw;
  max-width: 20rem;
  max-height: 20rem;
  bottom: 10%;
  left: 20%;
  background: radial-gradient(circle, var(--iris-cyan) 0%, transparent 70%);
  animation-delay: -14s;
}

@keyframes float-orb {
  0%, 100% { transform: translate(0, 0) scale(1); }
  33% { transform: translate(3%, 5%) scale(1.05); }
  66% { transform: translate(-2%, -3%) scale(0.95); }
}

/* ============================================================
   Header
   ============================================================ */

.site-header {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  z-index: 50;
}

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

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

.brand-logo {
  width: 2.25rem;
  height: 2.25rem;
  border-radius: var(--radius-sm);
  object-fit: cover;
  filter: drop-shadow(0 0 12px var(--glow-cyan));
}

.brand-text {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: var(--fs-md);
  letter-spacing: -0.02em;
}

.menu-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 2.75rem;
  height: 2.75rem;
  border-radius: var(--radius-full);
  border: 1px solid var(--border-medium);
  background: rgba(15, 23, 42, 0.5);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  transition: border-color var(--transition), box-shadow var(--transition);
}

.menu-toggle:hover,
.menu-toggle:focus-visible {
  border-color: rgba(34, 211, 238, 0.4);
  box-shadow: 0 0 24px var(--glow-cyan);
  outline: none;
}

.menu-icon {
  width: 1.375rem;
  height: 1.375rem;
  object-fit: contain;
  opacity: 0.9;
}

/* Mobile Menu */
.mobile-menu {
  position: fixed;
  inset: 0;
  z-index: 40;
  background: rgba(7, 11, 20, 0.92);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  display: flex;
  align-items: center;
  justify-content: center;
}

.mobile-menu[hidden] {
  display: none;
}

.mobile-nav-list {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-xl);
}

.mobile-nav-list a {
  font-family: var(--font-display);
  font-size: var(--fs-xl);
  font-weight: 700;
  transition: color var(--transition);
}

.mobile-nav-list a:hover,
.mobile-nav-list a:focus-visible {
  background: var(--gradient-iris);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  outline: none;
}

/* ============================================================
   Hero
   ============================================================ */

.hero {
  position: relative;
  z-index: 1;
  text-align: center;
  padding: calc(var(--header-h) + var(--space-3xl)) var(--space-xl) calc(var(--space-3xl) + 6rem);
  overflow: hidden;
  min-height: 32rem;
  display: flex;
  align-items: center;
  justify-content: center;
}

.hero-bg {
  position: absolute;
  inset: 0;
  z-index: -2;
}

.hero-bg picture,
.hero-bg img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center 40%;
}

.hero-overlay {
  position: absolute;
  inset: 0;
  z-index: -1;
  background:
    linear-gradient(to bottom, rgba(7, 11, 20, 0.3) 0%, rgba(7, 11, 20, 0.75) 70%, var(--bg-deep) 100%),
    radial-gradient(ellipse 80% 60% at 50% 30%, rgba(99, 102, 241, 0.12) 0%, transparent 60%);
}

.hero-content {
  position: relative;
  max-width: 40rem;
}

.hero h1 {
  font-family: var(--font-display);
  font-size: var(--fs-hero);
  font-weight: 800;
  line-height: 1.1;
  letter-spacing: -0.035em;
  margin-bottom: var(--space-lg);
}

.hero-subtitle {
  font-size: var(--fs-md);
  font-weight: 400;
  color: var(--text-secondary);
  max-width: 36ch;
  margin: 0 auto;
  line-height: 1.7;
}

/* ============================================================
   Highlight Cards
   ============================================================ */

.highlights {
  position: relative;
  z-index: 10;
  max-width: var(--max-width);
  margin: -6rem auto 0;
  padding: 0 var(--space-xl) var(--space-3xl);
}

.highlights-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-xl);
}

.highlight-card {
  position: relative;
  background: var(--bg-card);
  border: 1px solid var(--border-medium);
  border-radius: var(--radius-2xl);
  overflow: visible;
  transition: transform var(--transition), border-color var(--transition), box-shadow var(--transition);
}

.highlight-card::before {
  content: '';
  position: absolute;
  inset: -1px;
  border-radius: inherit;
  padding: 1px;
  background: var(--gradient-iris);
  -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
  -webkit-mask-composite: xor;
  mask-composite: exclude;
  opacity: 0;
  transition: opacity var(--transition);
  pointer-events: none;
}

.highlight-card:hover {
  transform: translateY(-8px);
  border-color: transparent;
  box-shadow:
    0 24px 64px rgba(0, 0, 0, 0.5),
    0 0 48px var(--glow-violet);
}

.highlight-card:hover::before {
  opacity: 1;
}

.highlight-card[data-accent="violet"]:hover {
  box-shadow: 0 24px 64px rgba(0, 0, 0, 0.5), 0 0 48px var(--glow-violet);
}

.highlight-card[data-accent="emerald"]:hover {
  box-shadow: 0 24px 64px rgba(0, 0, 0, 0.5), 0 0 48px rgba(52, 211, 153, 0.3);
}

.highlight-card[data-accent="cyan"]:hover {
  box-shadow: 0 24px 64px rgba(0, 0, 0, 0.5), 0 0 48px var(--glow-cyan);
}

.highlight-visual {
  position: relative;
  aspect-ratio: 16 / 10;
  overflow: visible;
  border-radius: var(--radius-2xl) var(--radius-2xl) 0 0;
}

.highlight-visual picture,
.highlight-visual img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  border-radius: var(--radius-2xl) var(--radius-2xl) 0 0;
  transition: transform 0.5s ease;
}

.highlight-card:hover .highlight-visual img,
.highlight-card:hover .highlight-visual picture img {
  transform: scale(1.04);
}

.highlight-visual::after {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: var(--radius-2xl) var(--radius-2xl) 0 0;
  background: linear-gradient(to bottom, transparent 40%, var(--bg-card) 100%);
  pointer-events: none;
}

.highlight-icon-wrap {
  position: absolute;
  left: 50%;
  bottom: 0;
  transform: translate(-50%, 50%);
  z-index: 5;
  width: 3.5rem;
  height: 3.5rem;
  border-radius: var(--radius-md);
  overflow: hidden;
  border: 3px solid var(--bg-card);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.45);
}

.highlight-icon-img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.highlight-body {
  padding: calc(var(--space-xl) + 0.75rem) var(--space-lg) var(--space-xl);
  text-align: center;
}

.highlight-body h3 {
  font-family: var(--font-display);
  font-size: var(--fs-lg);
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: var(--space-sm);
}

.highlight-body p {
  font-size: var(--fs-sm);
  color: var(--text-secondary);
  line-height: 1.65;
  margin-bottom: var(--space-md);
  max-width: 30ch;
  margin-left: auto;
  margin-right: auto;
}

.highlight-link {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-size: var(--fs-sm);
  font-weight: 600;
  color: var(--iris-cyan);
  transition: gap var(--transition), color var(--transition);
}

.highlight-link .link-label {
  color: var(--iris-cyan);
}

.highlight-link:hover .link-label,
.highlight-link:hover .link-arrow {
  color: var(--iris-violet);
}

.highlight-link:hover {
  gap: 8px;
}

.link-arrow {
  color: var(--iris-cyan);
  font-size: 1.1em;
  transition: color var(--transition);
}

/* ============================================================
   Latest Articles
   ============================================================ */

.articles {
  position: relative;
  z-index: 1;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: var(--space-2xl) var(--space-xl) var(--space-3xl);
}

.articles::before {
  content: '';
  position: absolute;
  inset: 0;
  background: var(--gradient-iris-soft);
  border-radius: var(--radius-2xl);
  opacity: 0.5;
  pointer-events: none;
}

.articles-header {
  position: relative;
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: var(--space-md);
  margin-bottom: var(--space-xl);
  flex-wrap: wrap;
}

.articles-header-left {
  display: flex;
  align-items: flex-start;
  gap: var(--space-md);
}

.section-icon-img {
  width: 2.75rem;
  height: 2.75rem;
  border-radius: var(--radius-md);
  object-fit: cover;
  flex-shrink: 0;
  filter: drop-shadow(0 0 16px var(--glow-violet));
}

.articles-header h2 {
  font-family: var(--font-display);
  font-size: var(--fs-xl);
  font-weight: 700;
  letter-spacing: -0.025em;
  line-height: 1.15;
}

.articles-subtitle {
  font-size: var(--fs-sm);
  color: var(--text-secondary);
  margin-top: 4px;
}

.view-all-link {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-size: var(--fs-sm);
  font-weight: 600;
  color: var(--iris-violet);
  white-space: nowrap;
  padding-top: 0.4rem;
  transition: gap var(--transition), color var(--transition);
}

.view-all-link:hover {
  gap: 8px;
  color: var(--iris-cyan);
}

.articles-list {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
}

.article-card {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
  padding: var(--space-md);
  background: rgba(26, 35, 54, 0.7);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-xl);
  transition: border-color var(--transition), background var(--transition), transform var(--transition);
}

.article-card:hover {
  border-color: var(--border-medium);
  background: var(--bg-card-hover);
  transform: translateX(4px);
}

.article-thumb-link {
  flex-shrink: 0;
  border-radius: var(--radius-lg);
  overflow: hidden;
  position: relative;
}

.article-thumb-link picture,
.article-thumb {
  display: block;
  width: 100%;
  height: 100%;
}

.article-thumb-link::after {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: inherit;
  box-shadow: inset 0 0 0 1px rgba(255, 255, 255, 0.08);
  pointer-events: none;
}

.article-thumb {
  width: 100%;
  aspect-ratio: 4 / 3;
  object-fit: cover;
  border-radius: var(--radius-lg);
  transition: transform 0.4s ease;
}

.article-card:hover .article-thumb {
  transform: scale(1.03);
}

.article-content {
  display: flex;
  flex-direction: column;
  flex: 1;
  min-width: 0;
}

.article-content h3 {
  font-family: var(--font-display);
  font-size: var(--fs-md);
  font-weight: 700;
  line-height: 1.35;
  letter-spacing: -0.015em;
  margin-bottom: var(--space-xs);
}

.article-content h3 a {
  transition: color var(--transition);
}

.article-content h3 a:hover {
  color: var(--iris-cyan);
}

.article-excerpt {
  font-size: var(--fs-sm);
  color: var(--text-secondary);
  line-height: 1.65;
  margin-bottom: var(--space-md);
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.article-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-md);
  margin-top: auto;
  flex-wrap: wrap;
}

.article-meta {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  flex-wrap: wrap;
}

.meta-item {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  font-size: var(--fs-xs);
  color: var(--text-dim);
}

.meta-item svg {
  opacity: 0.7;
}

.meta-divider {
  color: var(--text-dim);
  opacity: 0.5;
}

.read-more-link {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-size: var(--fs-sm);
  font-weight: 600;
  color: var(--iris-violet);
  white-space: nowrap;
  margin-left: auto;
  transition: gap var(--transition), color var(--transition);
}

.read-more-link:hover {
  gap: 8px;
  color: var(--iris-cyan);
}

/* ============================================================
   CTA Banner
   ============================================================ */

.cta-banner {
  position: relative;
  z-index: 1;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-xl) var(--space-3xl);
}

.cta-banner-inner {
  position: relative;
  border-radius: var(--radius-2xl);
  overflow: hidden;
}

.cta-glow-ring {
  position: absolute;
  inset: -2px;
  border-radius: inherit;
  background: var(--gradient-iris);
  opacity: 0.6;
  animation: shimmer-ring 4s linear infinite;
  background-size: 200% 200%;
}

@keyframes shimmer-ring {
  0% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
  100% { background-position: 0% 50%; }
}

.cta-content {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: var(--space-lg);
  padding: var(--space-xl) var(--space-xl);
  background: var(--bg-elevated);
  border-radius: calc(var(--radius-2xl) - 2px);
  margin: 2px;
}

.cta-text-block {
  display: flex;
  align-items: flex-start;
  gap: var(--space-md);
}

.cta-badge {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 2.5rem;
  height: 2.5rem;
  flex-shrink: 0;
  background: var(--gradient-iris-soft);
  border: 1px solid rgba(167, 139, 250, 0.3);
  border-radius: var(--radius-full);
  color: var(--iris-violet);
  filter: drop-shadow(0 0 12px var(--glow-violet));
}

.cta-text-block p {
  font-size: var(--fs-base);
  font-weight: 500;
  color: var(--text-secondary);
  line-height: 1.65;
  max-width: 44ch;
}

.heart {
  color: var(--iris-magenta);
}

/* Iridescent CTA Button */
.btn-iridescent {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 2px;
  border-radius: var(--radius-full);
  overflow: hidden;
  isolation: isolate;
  transition: transform var(--transition);
}

.btn-iridescent__bg {
  position: absolute;
  inset: 0;
  background: var(--gradient-iris);
  background-size: 200% 200%;
  animation: shimmer-ring 3s linear infinite;
  border-radius: inherit;
}

.btn-iridescent__label {
  position: relative;
  z-index: 1;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: var(--space-md) var(--space-xl);
  background: var(--bg-elevated);
  border-radius: calc(var(--radius-full) - 2px);
  font-family: var(--font-display);
  font-size: var(--fs-sm);
  font-weight: 700;
  letter-spacing: 0.01em;
  color: var(--text-primary);
  transition: background var(--transition), color var(--transition);
  white-space: nowrap;
}

.btn-iridescent:hover {
  transform: translateY(-3px);
}

.btn-iridescent:hover .btn-iridescent__label {
  background: transparent;
  color: var(--text-primary);
}

.btn-iridescent:active {
  transform: translateY(-1px) scale(0.98);
}

.btn-iridescent:focus-visible {
  outline: 2px solid var(--iris-cyan);
  outline-offset: 4px;
}

/* ============================================================
   Footer
   ============================================================ */

.site-footer {
  position: relative;
  z-index: 1;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: var(--space-xl) var(--space-xl) var(--space-2xl);
  text-align: center;
  border-top: 1px solid var(--border-subtle);
}

.site-footer p {
  font-size: var(--fs-sm);
  color: var(--text-dim);
  margin-bottom: var(--space-sm);
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: var(--space-lg);
  flex-wrap: wrap;
}

.footer-links a {
  font-size: var(--fs-sm);
  color: var(--text-secondary);
  transition: color var(--transition);
}

.footer-links a:hover,
.footer-links a:focus-visible {
  color: var(--iris-cyan);
  outline: none;
}

/* ============================================================
   Responsive
   ============================================================ */

@media (min-width: 480px) {
  .article-card {
    flex-direction: row;
    align-items: stretch;
    padding: var(--space-lg);
    gap: var(--space-lg);
  }

  .article-thumb-link {
    width: 9.5rem;
  }

  .article-thumb {
    width: 9.5rem;
    height: 100%;
    min-height: 6.75rem;
    aspect-ratio: auto;
  }
}

@media (min-width: 640px) {
  .highlights-grid {
    grid-template-columns: repeat(3, 1fr);
    gap: var(--space-lg);
  }

  .highlight-body p {
    max-width: none;
  }
}

@media (min-width: 768px) {
  .article-thumb-link {
    width: 11.5rem;
  }

  .article-thumb {
    width: 11.5rem;
    min-height: 7.5rem;
  }

  .cta-content {
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
    padding: var(--space-xl) var(--space-2xl);
  }
}

@media (min-width: 1024px) {
  .header-inner,
  .hero,
  .highlights,
  .articles,
  .cta-banner,
  .site-footer {
    padding-left: var(--space-2xl);
    padding-right: var(--space-2xl);
  }

  .article-thumb-link {
    width: 12.5rem;
  }

  .article-thumb {
    width: 12.5rem;
    min-height: 8rem;
  }
}

@media (min-width: 1440px) {
  :root {
    --max-width: 72rem;
  }
}

/* ============================================================
   Reduced Motion
   ============================================================ */

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}