/* ============================================
   Hien Nguyen Cybersecurity — Consulting Landing
   Dark + light theme via data-theme
   ============================================ */

:root,
[data-theme="dark"] {
  --bg-primary: #0a0c10;
  --bg-secondary: #111318;
  --bg-card: #161a22;
  --bg-card-hover: #1a1f28;
  --header-bg: rgba(10, 12, 16, 0.92);
  --border: #252a35;
  --border-light: #2d3340;
  --text-primary: #e6eaf0;
  --text-secondary: #9ca3b4;
  --text-muted: #6b7280;
  --accent: #3b82f6;
  --accent-hover: #2563eb;
  --accent-muted: #1e3a5f;
  --shadow-accent: rgba(59, 130, 246, 0.25);
  --shadow-card: rgba(0, 0, 0, 0.25);
  --btn-primary-text: #fff;
}

[data-theme="light"] {
  --bg-primary: #f8fafc;
  --bg-secondary: #f1f5f9;
  --bg-card: #ffffff;
  --bg-card-hover: #f1f5f9;
  --header-bg: rgba(248, 250, 252, 0.92);
  --border: #e2e8f0;
  --border-light: #cbd5e1;
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #64748b;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --accent-muted: #dbeafe;
  --shadow-accent: rgba(37, 99, 235, 0.2);
  --shadow-card: rgba(0, 0, 0, 0.08);
  --btn-primary-text: #fff;
}

:root {
  --font-sans: "DM Sans", system-ui, -apple-system, sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, monospace;
  --radius: 10px;
  --radius-lg: 14px;
  --space: 1.25rem;
  --container: min(100% - 2rem, 900px);
}

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font-sans);
  font-size: 1rem;
  line-height: 1.6;
  color: var(--text-primary);
  background: var(--bg-primary);
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--accent);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

a:focus-visible,
button:focus-visible,
input:focus-visible,
select:focus-visible,
textarea:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.container {
  width: var(--container);
  margin-inline: auto;
  padding-inline: var(--space);
}

/* ----- Header ----- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  background: var(--header-bg);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-block: 0.875rem 0.75rem;
  gap: 1rem;
}

.logo {
  font-weight: 600;
  font-size: 1rem;
  color: var(--text-primary);
  letter-spacing: -0.01em;
}

.logo:hover {
  text-decoration: none;
  color: var(--accent);
}

.nav {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  flex-wrap: wrap;
}

.nav a {
  color: var(--text-secondary);
  font-size: 0.9375rem;
}

.nav a:hover {
  color: var(--text-primary);
}

.btn-nav {
  padding: 0.5rem 1rem;
  font-size: 0.875rem;
}

.nav-toggle {
  display: none;
  width: 2rem;
  height: 2rem;
  padding: 0;
  border: 0;
  background: transparent;
  cursor: pointer;
  position: relative;
  flex-shrink: 0;
}

.nav-toggle::before,
.nav-toggle::after {
  content: "";
  position: absolute;
  left: 0.25rem;
  right: 0.25rem;
  height: 2px;
  background: var(--text-primary);
  transition: transform 0.2s;
}

.nav-toggle::before {
  top: 0.5rem;
}

.nav-toggle::after {
  bottom: 0.5rem;
}

.nav-toggle span {
  position: absolute;
  left: 0.25rem;
  right: 0.25rem;
  top: 50%;
  margin-top: -1px;
  height: 2px;
  background: var(--text-primary);
}

.nav-toggle[aria-expanded="true"]::before {
  transform: translateY(5px) rotate(45deg);
}

.nav-toggle[aria-expanded="true"]::after {
  transform: translateY(-5px) rotate(-45deg);
}

.nav-toggle[aria-expanded="true"] span {
  opacity: 0;
}

@media (max-width: 768px) {
  .nav-toggle {
    display: block;
  }

  .nav {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--bg-secondary);
    border-bottom: 1px solid var(--border);
    padding: 1rem var(--space);
    flex-direction: column;
    align-items: stretch;
    gap: 0.5rem;
    display: none;
  }

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

  .nav a.btn-nav {
    justify-content: center;
  }

  .theme-toggle {
    justify-content: center;
  }
}

/* Theme toggle button */
.theme-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2.25rem;
  height: 2.25rem;
  padding: 0;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg-card);
  color: var(--text-primary);
  cursor: pointer;
  transition: background 0.2s, border-color 0.2s, color 0.2s;
}

.theme-toggle:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-light);
}

.theme-toggle:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.theme-toggle[aria-pressed="true"] {
  background: var(--accent-muted);
  border-color: var(--accent);
  color: var(--accent);
}

.theme-toggle-icon {
  display: none;
  width: 1.125rem;
  height: 1.125rem;
  line-height: 0;
}

.theme-toggle-icon svg {
  width: 100%;
  height: 100%;
  vertical-align: middle;
}

[data-theme="dark"] .theme-toggle-moon {
  display: block;
}

[data-theme="light"] .theme-toggle-sun {
  display: block;
}

/* ----- Buttons ----- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.75rem 1.25rem;
  font-family: var(--font-sans);
  font-size: 0.9375rem;
  font-weight: 500;
  border-radius: var(--radius);
  border: 1px solid transparent;
  cursor: pointer;
  transition: background 0.2s, border-color 0.2s, color 0.2s, transform 0.2s, box-shadow 0.2s;
}

.btn:hover {
  text-decoration: none;
}

.btn:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.btn-primary {
  background: var(--accent);
  color: var(--btn-primary-text);
  border-color: var(--accent);
}

.btn-primary:hover {
  background: var(--accent-hover);
  border-color: var(--accent-hover);
  transform: translateY(-1px);
  box-shadow: 0 4px 12px var(--shadow-accent);
}

.btn-secondary {
  background: var(--bg-card);
  color: var(--text-primary);
  border-color: var(--border);
}

.btn-secondary:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-light);
  transform: translateY(-1px);
  box-shadow: 0 4px 12px var(--shadow-card);
}

.btn-ghost {
  background: transparent;
  color: var(--text-secondary);
  border-color: var(--border);
}

.btn-ghost:hover {
  background: var(--bg-card);
  color: var(--text-primary);
}

.btn-block {
  width: 100%;
}

/* ----- Hero ----- */
.hero {
  padding: 4rem 0 3.5rem;
  border-bottom: 1px solid var(--border);
}

.hero-inner {
  text-align: center;
}

.hero-byline {
  margin: 0 0 0.5rem;
  font-size: 1rem;
  color: var(--text-muted);
  font-family: var(--font-sans);
}

.hero-headline {
  margin: 0 0 1rem;
  font-size: clamp(1.75rem, 4vw, 2.25rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1.2;
  max-width: 32ch;
  margin-inline: auto;
}

.hero-subheadline {
  margin: 0 0 0.75rem;
  font-size: 1.0625rem;
  color: var(--text-secondary);
  max-width: 48ch;
  margin-inline: auto;
  line-height: 1.55;
}

.hero-bridge {
  margin: 0 0 1rem;
  font-size: 0.9375rem;
  color: var(--text-muted);
  line-height: 1.5;
}

.hero-bridge a {
  font-weight: 500;
  color: var(--accent);
}

.hero-bridge a:hover {
  color: var(--accent-hover);
}

.hero-credibility {
  margin: 0 0 1.5rem;
  font-size: 0.8125rem;
  color: var(--text-muted);
  font-family: var(--font-mono);
}

.hero-cta {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  justify-content: center;
  align-items: center;
}

.hero-link-tertiary {
  font-size: 0.9375rem;
  color: var(--text-muted);
}

.hero-link-tertiary:hover {
  color: var(--accent);
}

.hero-reassurance {
  margin: 1.25rem 0 0;
  font-size: 0.8125rem;
  color: var(--text-muted);
  text-align: center;
}

/* ----- Trust strip ----- */
.trust-strip {
  padding: 1rem 0;
  background: var(--bg-secondary);
  border-bottom: 1px solid var(--border);
}

.trust-inner {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 1rem 1.5rem;
  font-size: 0.875rem;
  color: var(--text-secondary);
}

.trust-item {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
}

.trust-icon {
  display: inline-block;
  width: 0.5rem;
  height: 0.5rem;
  border-radius: 50%;
  background: var(--accent);
  flex-shrink: 0;
}

/* ----- Sections ----- */
.section {
  padding: 3.5rem 0 4rem;
  border-bottom: 1px solid var(--border);
}

.section:last-of-type {
  border-bottom: none;
}

.section-title {
  margin: 0 0 1.5rem;
  font-size: 1.375rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  color: var(--text-primary);
}

/* ----- Who this is for ----- */
.who-list {
  margin: 0;
  padding-left: 1.25rem;
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.7;
  max-width: 55ch;
}

.who-list li {
  margin-bottom: 0.5rem;
}

.who-list li:last-child {
  margin-bottom: 0;
}

/* ----- Services ----- */
.services-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 1.25rem;
  margin-bottom: 1.5rem;
}

.service-card {
  padding: 1.5rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  transition: border-color 0.2s, transform 0.2s, box-shadow 0.2s;
}

.service-card:hover {
  border-color: var(--border-light);
  transform: translateY(-2px);
  box-shadow: 0 8px 24px var(--shadow-card);
}

.service-name {
  margin: 0;
  font-size: 1.0625rem;
  font-weight: 600;
  color: var(--text-primary);
}

.service-outcome {
  margin: 0;
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.45;
}

.service-meta {
  margin: 0.25rem 0 0;
  font-size: 0.8125rem;
  color: var(--text-muted);
}

.service-meta strong {
  color: var(--text-primary);
}

.services-note {
  margin: 0;
  font-size: 0.9375rem;
  color: var(--text-muted);
  font-style: italic;
}

.consulting-intro {
  margin: 0 0 1.5rem;
  font-size: 0.9375rem;
  color: var(--text-secondary);
  max-width: 55ch;
  line-height: 1.6;
}

.consulting-cta-wrap {
  margin: 0;
  margin-top: 1rem;
}

.explore-details {
  margin-top: 1.25rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem 1rem;
  font-size: 0.9375rem;
}

.explore-details-label {
  color: var(--text-muted);
  margin-right: 0.25rem;
}

.explore-details a {
  color: var(--text-secondary);
}

.explore-details a:hover {
  color: var(--accent);
}

/* ----- Research & Writing ----- */
.research-intro {
  margin: 0 0 1rem;
  font-size: 0.9375rem;
  color: var(--text-secondary);
  max-width: 55ch;
  line-height: 1.6;
}

.research-links {
  margin: 0;
  padding: 0;
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 1rem 1.5rem;
}

.research-links a {
  font-size: 1rem;
  font-weight: 500;
}

.research-links a:hover {
  color: var(--text-primary);
}

/* ----- Proof ----- */
.proof-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 1.25rem;
  margin-bottom: 2rem;
}

.proof-card {
  padding: 1.5rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  transition: border-color 0.2s, transform 0.2s, box-shadow 0.2s;
}

.proof-card:hover {
  border-color: var(--border-light);
  transform: translateY(-2px);
  box-shadow: 0 8px 24px var(--shadow-card);
}

.proof-headline {
  margin: 0 0 0.75rem;
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-primary);
  line-height: 1.35;
}

.proof-card p {
  margin: 0 0 0.5rem;
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

.proof-card p:last-of-type {
  margin-bottom: 0.75rem;
}

.proof-link {
  font-size: 0.875rem;
  font-weight: 500;
}

/* Proof compact (1-line outcome cards) */
.proof-grid-compact {
  margin-bottom: 1rem;
}

.proof-card-compact {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.proof-outcome {
  margin: 0;
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.45;
}

.proof-cta-wrap {
  margin: 0;
}

/* ----- Blog preview ----- */
.blog-preview-list {
  margin: 0 0 1rem;
  padding: 0;
  list-style: none;
}

.blog-preview-list li {
  margin-bottom: 0.5rem;
}

.blog-preview-list a {
  font-size: 0.9375rem;
  color: var(--text-secondary);
}

.blog-preview-list a:hover {
  color: var(--accent);
}

.blog-cta-wrap {
  margin: 0;
}

/* ----- Quick Security Advice ----- */
.quick-advice-intro {
  margin: 0 0 1.5rem;
  font-size: 0.9375rem;
  color: var(--text-secondary);
  max-width: 48ch;
  line-height: 1.6;
}

.quick-advice-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.25rem;
  margin-bottom: 1.5rem;
}

.offer-card {
  padding: 1.5rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  transition: border-color 0.2s, transform 0.2s, box-shadow 0.2s;
}

.offer-card:hover {
  border-color: var(--border-light);
  transform: translateY(-2px);
  box-shadow: 0 8px 24px var(--shadow-card);
}

.offer-title {
  margin: 0;
  font-size: 1.0625rem;
  font-weight: 600;
  color: var(--text-primary);
}

.offer-price {
  margin: 0;
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--text-primary);
}

.offer-best-for {
  margin: 0;
  font-size: 0.8125rem;
  color: var(--text-muted);
  line-height: 1.4;
}

.offer-includes {
  margin: 0;
  padding-left: 1.25rem;
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

.offer-includes li {
  margin-bottom: 0.35rem;
}

.offer-includes li:last-child {
  margin-bottom: 0;
}

.quick-advice-reassurance {
  margin: 0;
  font-size: 0.8125rem;
  color: var(--text-muted);
  text-align: center;
  line-height: 1.5;
}

/* ----- Tools strip ----- */
.tools-strip {
  padding: 1.25rem 0;
  background: var(--bg-secondary);
  border-bottom: 1px solid var(--border);
}

.tool-badges {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  align-items: center;
  gap: 0.5rem 0.75rem;
}

.tool-badge {
  display: inline-block;
  padding: 0.35rem 0.75rem;
  font-size: 0.8125rem;
  font-family: var(--font-mono);
  font-weight: 500;
  color: var(--text-secondary);
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 6px;
  white-space: nowrap;
}

/* Tools categories (inside cards) */
.tool-stack .tool-badges {
  justify-content: flex-start;
}

/* ----- Philosophy ----- */
.philosophy-list {
  margin: 0;
  padding-left: 1.25rem;
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.7;
  max-width: 70ch;
}

.philosophy-list li {
  margin-bottom: 0.6rem;
}

.philosophy-list li:last-child {
  margin-bottom: 0;
}

.philosophy-list strong {
  color: var(--text-primary);
}

/* ----- Explore details ----- */
.explore-links {
  margin: 0;
  padding: 0;
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 1rem 1.5rem;
}

.explore-links a {
  font-size: 0.9375rem;
  color: var(--text-secondary);
}

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

/* ----- Process ----- */
.process-intro {
  margin: 0 0 1.5rem;
  font-size: 0.9375rem;
  color: var(--text-secondary);
  max-width: 55ch;
  line-height: 1.6;
}

.process-timeline {
  margin: 0;
  padding: 0;
  list-style: none;
  counter-reset: step;
}

.process-step {
  display: flex;
  align-items: flex-start;
  gap: 1rem;
  padding: 0.75rem 0;
  border-bottom: 1px solid var(--border);
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

.process-step:last-child {
  border-bottom: none;
}

.process-num {
  flex-shrink: 0;
  width: 1.75rem;
  height: 1.75rem;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: var(--accent-muted);
  color: var(--accent);
  border-radius: 50%;
  font-size: 0.8125rem;
  font-weight: 600;
  font-family: var(--font-mono);
}

.process-step strong {
  color: var(--text-primary);
}

/* ----- Pricing ----- */
.pricing-intro {
  margin: 0 0 1.5rem;
  font-size: 0.9375rem;
  color: var(--text-secondary);
  max-width: 55ch;
  line-height: 1.6;
}

.pricing-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
  margin-bottom: 1.5rem;
}

.pricing-tier {
  padding: 1.5rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  transition: border-color 0.2s, transform 0.2s, box-shadow 0.2s;
}

.pricing-tier:hover {
  border-color: var(--border-light);
  transform: translateY(-2px);
  box-shadow: 0 8px 24px var(--shadow-card);
}

.pricing-tier-featured {
  border-color: var(--accent-muted);
  background: var(--bg-secondary);
}

.pricing-tier-name {
  margin: 0 0 0.5rem;
  font-size: 1.0625rem;
  font-weight: 600;
  color: var(--text-primary);
}

.pricing-tier-desc {
  margin: 0 0 0.75rem;
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

.pricing-tier-range {
  margin: 0;
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--text-primary);
}

.pricing-disclaimer {
  margin: 0 0 1rem;
  font-size: 0.875rem;
  color: var(--text-muted);
  font-style: italic;
}

.pricing-cta-wrap {
  margin: 0;
}

@media (max-width: 640px) {
  .pricing-grid {
    grid-template-columns: 1fr;
  }
}

/* ----- FAQ ----- */
.faq-list {
  margin: 0;
  padding: 0;
}

.faq-item {
  border-bottom: 1px solid var(--border);
  padding: 1rem 0;
}

.faq-item:first-child {
  padding-top: 0;
}

.faq-q {
  margin: 0 0 0.5rem;
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-primary);
}

.faq-a {
  margin: 0;
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.55;
}

/* ----- Contact ----- */
.contact-availability,
.contact-response {
  margin: 0 0 0.25rem;
  font-size: 0.9375rem;
  color: var(--text-secondary);
}

.contact-cards {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.25rem;
  margin-top: 1.5rem;
}

.contact-card {
  padding: 1.5rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  transition: border-color 0.2s, transform 0.2s, box-shadow 0.2s;
}

.contact-card:hover {
  border-color: var(--border-light);
  transform: translateY(-2px);
  box-shadow: 0 8px 24px var(--shadow-card);
}

.contact-card-title {
  margin: 0;
  font-size: 1.0625rem;
  font-weight: 600;
  color: var(--text-primary);
}

.contact-card-desc {
  margin: 0;
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.5;
  flex-grow: 1;
}

.contact-checklist {
  margin: 0;
  padding-left: 1.25rem;
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

.contact-checklist li {
  margin-bottom: 0.35rem;
}

.contact-checklist li:last-child {
  margin-bottom: 0;
}

.contact-card-secondary {
  margin-top: 0.25rem;
}

@media (max-width: 640px) {
  .contact-cards {
    grid-template-columns: 1fr;
  }
}

/* ----- Footer ----- */
.site-footer {
  padding: 2rem 0;
  border-top: 1px solid var(--border);
  background: var(--bg-secondary);
}

.footer-inner {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2rem 1.5rem;
  margin-bottom: 1.5rem;
}

.footer-col-title {
  margin: 0 0 0.5rem;
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-primary);
  letter-spacing: 0.02em;
  text-transform: uppercase;
}

.footer-brand-desc {
  margin: 0 0 0.75rem;
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

.footer-nav {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.footer-nav a {
  color: var(--text-secondary);
  font-size: 0.9375rem;
}

.footer-nav a:hover {
  color: var(--text-primary);
}

.footer-copy {
  margin: 0;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
  font-size: 0.8125rem;
  color: var(--text-muted);
  grid-column: 1 / -1;
}

@media (max-width: 540px) {
  .footer-inner {
    grid-template-columns: 1fr;
  }
}

/* ----- Responsive ----- */
/* ----- Series Card (research portfolio) ----- */
.series-card {
  padding: 1.5rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  transition: border-color 0.2s, transform 0.2s, box-shadow 0.2s;
}

.series-card:hover {
  border-color: var(--border-light);
  transform: translateY(-2px);
  box-shadow: 0 8px 24px var(--shadow-card);
}

.series-card-title {
  margin: 0;
  font-size: 1.0625rem;
  font-weight: 600;
  color: var(--text-primary);
  line-height: 1.3;
}

.series-card-desc {
  margin: 0;
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.45;
  flex-grow: 1;
}

.series-card-meta {
  margin: 0;
  font-size: 0.8125rem;
  color: var(--text-muted);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem 1rem;
}

.series-card-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem 0.5rem;
}

.series-card-tag {
  display: inline-block;
  padding: 0.2rem 0.5rem;
  font-size: 0.75rem;
  font-family: var(--font-mono);
  color: var(--text-secondary);
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: 4px;
}

/* ----- Post Card (blog / write-up listing) ----- */
.post-card {
  padding: 1.25rem 1.5rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  transition: border-color 0.2s, transform 0.2s, box-shadow 0.2s;
}

.post-card:hover {
  border-color: var(--border-light);
  transform: translateY(-2px);
  box-shadow: 0 8px 24px var(--shadow-card);
}

.post-card-title {
  margin: 0;
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-primary);
  line-height: 1.35;
}

.post-card-title a {
  color: inherit;
}

.post-card-title a:hover {
  color: var(--accent);
}

.post-card-excerpt {
  margin: 0;
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.45;
}

.post-card-meta {
  margin: 0;
  font-size: 0.8125rem;
  color: var(--text-muted);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem 1rem;
}

.post-card-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem 0.5rem;
}

.post-card-tag {
  display: inline-block;
  padding: 0.2rem 0.5rem;
  font-size: 0.75rem;
  font-family: var(--font-mono);
  color: var(--text-secondary);
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: 4px;
}

/* ----- Research Index: domain groups & card grid ----- */
.research-domain {
  margin-bottom: 3rem;
}

.research-domain:last-of-type {
  margin-bottom: 0;
}

.research-domain-title {
  margin: 0 0 0.5rem;
  font-size: 1.375rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  color: var(--text-primary);
}

.research-domain-intro {
  margin: 0 0 1.25rem;
  font-size: 0.9375rem;
  color: var(--text-secondary);
  max-width: 60ch;
  line-height: 1.6;
}

.research-card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 1.25rem;
}

.research-post-card {
  padding: 1.25rem 1.5rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  transition: border-color 0.2s, transform 0.2s, box-shadow 0.2s;
}

.research-post-card:hover {
  border-color: var(--border-light);
  transform: translateY(-2px);
  box-shadow: 0 8px 24px var(--shadow-card);
}

.research-post-card > a:first-of-type {
  text-decoration: none;
  color: inherit;
}

.research-post-card > a:first-of-type:hover {
  color: var(--accent);
}

.research-post-card-title {
  margin: 0;
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-primary);
  line-height: 1.35;
}

.research-post-card-excerpt {
  margin: 0;
  font-size: 0.875rem;
  color: var(--text-secondary);
  line-height: 1.45;
  flex-grow: 1;
}

.research-post-card-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem 1rem;
  font-size: 0.8125rem;
  color: var(--text-muted);
}

.post-card-difficulty {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
}

.post-card-difficulty::before {
  content: "";
  width: 0.5rem;
  height: 0.5rem;
  border-radius: 50%;
  background: currentColor;
}

.post-card-difficulty[data-level="beginner"]::before { background: var(--accent); }
.post-card-difficulty[data-level="intermediate"]::before { background: #eab308; }
.post-card-difficulty[data-level="advanced"]::before { background: #ef4444; }

.post-card-read-time {
  font-family: var(--font-mono);
}

.research-post-card-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem 0.5rem;
}

.research-post-card-tag {
  display: inline-block;
  padding: 0.2rem 0.5rem;
  font-size: 0.7rem;
  font-family: var(--font-mono);
  color: var(--text-secondary);
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: 4px;
}

.research-post-card-related {
  margin: 0;
  padding-top: 0.5rem;
  border-top: 1px solid var(--border);
  font-size: 0.8125rem;
}

.research-post-card-related a {
  color: var(--text-muted);
}

.research-post-card-related a:hover {
  color: var(--accent);
}

@media (max-width: 640px) {
  .research-card-grid {
    grid-template-columns: 1fr;
  }
}

/* Research section on homepage */
.featured-research-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.25rem;
  margin-top: 1rem;
}

.audience-mini-section {
  padding: 1.25rem 1.5rem;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  margin-bottom: 1rem;
}

.audience-mini-section h3 {
  margin: 0 0 0.5rem;
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-primary);
}

.audience-mini-section p {
  margin: 0 0 0.75rem;
  font-size: 0.9375rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

.audience-mini-section .btn {
  margin-top: 0.25rem;
}

@media (max-width: 640px) {
  .hero {
    padding: 2.5rem 0 2rem;
  }

  .section {
    padding: 2.5rem 0 3rem;
  }

  .hero-cta {
    flex-direction: column;
  }

  .hero-cta .btn {
    width: 100%;
  }

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

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

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

  .featured-research-grid {
    grid-template-columns: 1fr;
  }
}