/* ============================================================
   SIGNAL & SOCIETY — DESIGN SYSTEM & STYLESHEET
   Innovation Law, Precision Health & Public Evidence
   ============================================================ */

/* CSS Variables */
:root {
  --aubergine: #2A1838;
  --aubergine-dark: #1C0F26;
  --aubergine-light: #3F2454;
  --aubergine-soft: rgba(42, 24, 56, 0.06);
  --aubergine-glass: rgba(42, 24, 56, 0.85);

  --berry: #A83E6C;
  --berry-light: #C24F81;
  --berry-soft: rgba(168, 62, 108, 0.1);
  --berry-glow: rgba(168, 62, 108, 0.25);

  --apricot: #F2A65A;
  --apricot-light: #F6BC82;
  --apricot-soft: rgba(242, 166, 90, 0.15);
  --apricot-glow: rgba(242, 166, 90, 0.3);

  --mint: #D8F3E6;
  --mint-dark: #1D6B4E;
  --mint-soft: rgba(216, 243, 230, 0.5);

  --pearl: #FBF8F4;
  --pearl-pure: #FFFFFF;
  --pearl-warm: #F4EFEA;
  --pearl-card: #FAF6F0;

  --slate: #3B3A44;
  --slate-dark: #27262D;
  --slate-light: #52505C;

  --muted: #74717C;
  --muted-light: #9B98A3;

  --border: #DDD5DF;
  --border-light: #ECE6ED;
  --border-dark: rgba(42, 24, 56, 0.15);

  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 18px;
  --radius-xl: 26px;
  --radius-full: 9999px;

  --shadow-sm: 0 2px 8px rgba(42, 24, 56, 0.05);
  --shadow-md: 0 8px 24px rgba(42, 24, 56, 0.08);
  --shadow-lg: 0 16px 40px rgba(42, 24, 56, 0.12);
  --shadow-hover: 0 20px 48px rgba(42, 24, 56, 0.16);

  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --font-serif: "Newsreader", "Charter", "Georgia", "Cambria", serif;

  --transition-fast: 0.2s cubic-bezier(0.16, 1, 0.3, 1);
  --transition-normal: 0.35s cubic-bezier(0.16, 1, 0.3, 1);
  --transition-slow: 0.6s cubic-bezier(0.16, 1, 0.3, 1);

  --container-max: 1200px;
  --header-height: 80px;
}

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

html {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.6;
  color: var(--slate);
  background-color: var(--pearl);
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  color: var(--slate);
  background-color: var(--pearl);
  position: relative;
  overflow-x: hidden;
}

/* Accessibility: Skip to Content */
.skip-link {
  position: absolute;
  top: -60px;
  left: 20px;
  background: var(--aubergine);
  color: var(--pearl);
  padding: 12px 20px;
  border-radius: var(--radius-sm);
  font-weight: 600;
  z-index: 1000;
  text-decoration: none;
  transition: top var(--transition-fast);
}

.skip-link:focus {
  top: 20px;
  outline: 3px solid var(--apricot);
}

:focus-visible {
  outline: 3px solid var(--berry);
  outline-offset: 3px;
}

/* Typography Helpers */
h1, h2, h3, h4, h5, h6 {
  color: var(--aubergine);
  font-weight: 700;
  line-height: 1.25;
}

a {
  color: var(--berry);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--aubergine);
}

p {
  color: var(--slate);
  font-size: 1.05rem;
  line-height: 1.7;
}

/* Layout Container */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin-left: auto;
  margin-right: auto;
  padding-left: 24px;
  padding-right: 24px;
}

/* Section Common Styling */
.section {
  padding: 96px 0;
  position: relative;
}

.section-header {
  margin-bottom: 48px;
  max-width: 760px;
}

.section-header.center {
  margin-left: auto;
  margin-right: auto;
  text-align: center;
}

.eyebrow {
  display: inline-block;
  font-size: 0.85rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 2px;
  color: var(--berry);
  margin-bottom: 12px;
  padding: 4px 12px;
  background-color: var(--berry-soft);
  border-radius: var(--radius-full);
}

.section-title {
  font-size: 2.35rem;
  font-weight: 800;
  letter-spacing: -0.5px;
  margin-bottom: 16px;
  color: var(--aubergine);
}

.section-intro {
  font-size: 1.15rem;
  color: var(--muted);
  line-height: 1.7;
}

/* Buttons */
.btn-group {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  align-items: center;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 14px 28px;
  font-size: 1rem;
  font-weight: 600;
  border-radius: var(--radius-full);
  cursor: pointer;
  transition: all var(--transition-normal);
  text-decoration: none;
  border: 1px solid transparent;
}

.btn-primary {
  background-color: var(--aubergine);
  color: var(--pearl);
  box-shadow: 0 4px 14px rgba(42, 24, 56, 0.2);
}

.btn-primary:hover {
  background-color: var(--berry);
  color: var(--pearl);
  transform: translateY(-2px);
  box-shadow: 0 8px 20px rgba(168, 62, 108, 0.3);
}

.btn-secondary {
  background-color: var(--pearl-pure);
  color: var(--aubergine);
  border-color: var(--border);
}

.btn-secondary:hover {
  background-color: var(--pearl-warm);
  border-color: var(--berry);
  color: var(--berry);
  transform: translateY(-2px);
}

/* ============================================================
   HEADER & NAVIGATION
   ============================================================ */
.site-header {
  position: sticky;
  top: 0;
  width: 100%;
  height: var(--header-height);
  background-color: rgba(251, 248, 244, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  z-index: 900;
  display: flex;
  align-items: center;
  transition: all var(--transition-normal);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.brand-link {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
}

.brand-logo {
  height: 44px;
  width: auto;
  display: block;
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: 32px;
  list-style: none;
}

.nav-link {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--slate);
  text-decoration: none;
  padding: 8px 4px;
  position: relative;
  transition: color var(--transition-fast);
}

.nav-link::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0%;
  height: 2px;
  background-color: var(--berry);
  transition: width var(--transition-normal);
  border-radius: var(--radius-full);
}

.nav-link:hover,
.nav-link.active {
  color: var(--berry);
}

.nav-link:hover::after,
.nav-link.active::after {
  width: 100%;
}

.nav-toggle {
  display: none;
  background: none;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 8px 14px;
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--aubergine);
  cursor: pointer;
  align-items: center;
  gap: 8px;
  transition: all var(--transition-fast);
}

.nav-toggle:hover {
  background-color: var(--pearl-warm);
  border-color: var(--berry);
}

.nav-toggle-icon {
  display: inline-block;
  width: 18px;
  height: 12px;
  position: relative;
}

.nav-toggle-icon span,
.nav-toggle-icon span::before,
.nav-toggle-icon span::after {
  position: absolute;
  width: 100%;
  height: 2px;
  background-color: var(--aubergine);
  border-radius: 2px;
  transition: transform var(--transition-fast);
}

.nav-toggle-icon span {
  top: 5px;
}

.nav-toggle-icon span::before {
  content: "";
  top: -5px;
}

.nav-toggle-icon span::after {
  content: "";
  top: 5px;
}

/* ============================================================
   HERO SECTION
   ============================================================ */
.hero-section {
  padding: 80px 0 90px;
  background: radial-gradient(circle at top right, rgba(242, 166, 90, 0.12), transparent 45%),
              radial-gradient(circle at bottom left, rgba(216, 243, 230, 0.4), transparent 40%),
              var(--pearl);
  position: relative;
  overflow: hidden;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.15fr 0.85fr;
  gap: 60px;
  align-items: center;
}

.hero-content {
  max-width: 620px;
}

.hero-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 0.88rem;
  font-weight: 700;
  letter-spacing: 1.5px;
  text-transform: uppercase;
  color: var(--berry);
  margin-bottom: 20px;
  background: var(--berry-soft);
  padding: 6px 14px;
  border-radius: var(--radius-full);
}

.hero-title {
  font-size: 3rem;
  font-weight: 800;
  line-height: 1.16;
  letter-spacing: -0.8px;
  color: var(--aubergine);
  margin-bottom: 24px;
}

.hero-title .highlight {
  position: relative;
  color: var(--berry);
  display: inline-block;
}

.hero-title .highlight::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 2px;
  width: 100%;
  height: 6px;
  background: var(--apricot-soft);
  border-radius: var(--radius-full);
  z-index: -1;
}

.hero-description {
  font-size: 1.2rem;
  line-height: 1.7;
  color: var(--slate);
  margin-bottom: 36px;
}

.hero-visual {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 40px 20px;
}

.mark-wrapper {
  position: relative;
  width: 280px;
  height: 280px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.hero-mark-img {
  width: 100%;
  height: 100%;
  display: block;
  filter: drop-shadow(0 16px 32px rgba(42, 24, 56, 0.2));
  animation: pulseFloat 6s ease-in-out infinite alternate;
}

@keyframes pulseFloat {
  0% {
    transform: translateY(0px) scale(1);
  }
  100% {
    transform: translateY(-8px) scale(1.02);
  }
}

/* Floating Badges */
.floating-tag {
  position: absolute;
  padding: 8px 16px;
  border-radius: var(--radius-full);
  font-size: 0.85rem;
  font-weight: 700;
  letter-spacing: 0.8px;
  box-shadow: var(--shadow-md);
  backdrop-filter: blur(8px);
  border: 1px solid rgba(255, 255, 255, 0.6);
  animation: floatTag 4s ease-in-out infinite alternate;
  z-index: 2;
}

.tag-regulate {
  top: 10px;
  left: -20px;
  background: var(--aubergine);
  color: var(--pearl);
  animation-delay: 0s;
}

.tag-measure {
  top: 15px;
  right: -25px;
  background: var(--berry);
  color: var(--pearl);
  animation-delay: 1s;
}

.tag-interpret {
  bottom: 15px;
  left: -25px;
  background: var(--apricot);
  color: var(--aubergine);
  animation-delay: 2s;
}

.tag-apply {
  bottom: 10px;
  right: -20px;
  background: var(--mint);
  color: var(--aubergine);
  border-color: var(--border);
  animation-delay: 3s;
}

@keyframes floatTag {
  0% {
    transform: translateY(0px);
  }
  100% {
    transform: translateY(-6px);
  }
}

/* ============================================================
   PRINCIPLES STRIP
   ============================================================ */
.principles-strip {
  background-color: var(--aubergine);
  color: var(--pearl);
  padding: 24px 0;
  border-top: 1px solid rgba(242, 166, 90, 0.25);
  border-bottom: 1px solid rgba(242, 166, 90, 0.25);
  overflow: hidden;
}

.principles-content {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  gap: 18px 24px;
  text-align: center;
  font-size: 1.05rem;
  font-weight: 600;
  letter-spacing: 0.3px;
}

.principle-item {
  display: inline-flex;
  align-items: center;
  color: var(--pearl);
}

.principle-separator {
  color: var(--apricot);
  font-size: 0.95rem;
  display: inline-block;
}

/* ============================================================
   FOUR LEARNING FIELDS
   ============================================================ */
.fields-section {
  background-color: var(--pearl);
}

.fields-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}

.field-card {
  background: var(--pearl-pure);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 32px 24px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: all var(--transition-normal);
  position: relative;
  overflow: hidden;
}

.field-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 4px;
  background: linear-gradient(90deg, var(--berry), var(--apricot));
  opacity: 0;
  transition: opacity var(--transition-fast);
}

.field-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-hover);
  border-color: var(--border-dark);
}

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

.field-card-top {
  margin-bottom: 24px;
}

.field-number {
  font-size: 0.95rem;
  font-weight: 800;
  letter-spacing: 1.5px;
  color: var(--berry);
  margin-bottom: 14px;
  display: inline-block;
  background: var(--berry-soft);
  padding: 4px 10px;
  border-radius: var(--radius-sm);
}

.field-title {
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--aubergine);
  margin-bottom: 14px;
  line-height: 1.3;
}

.field-desc {
  font-size: 0.95rem;
  color: var(--slate);
  line-height: 1.65;
}

.field-concepts {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 20px;
  padding-top: 18px;
  border-top: 1px solid var(--border-light);
}

.concept-badge {
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--slate);
  background-color: var(--pearl-warm);
  border: 1px solid var(--border);
  padding: 4px 10px;
  border-radius: var(--radius-full);
}

/* ============================================================
   FRAMEWORK SECTION (DARK)
   ============================================================ */
.framework-section {
  background-color: var(--aubergine);
  color: var(--pearl);
  position: relative;
  overflow: hidden;
}

.framework-section::after {
  content: "";
  position: absolute;
  bottom: -20%;
  right: -10%;
  width: 500px;
  height: 500px;
  background: radial-gradient(circle, rgba(168, 62, 108, 0.18), transparent 70%);
  pointer-events: none;
}

.framework-section .eyebrow {
  background-color: rgba(242, 166, 90, 0.15);
  color: var(--apricot);
}

.framework-section .section-title {
  color: var(--pearl);
}

.framework-section .section-intro {
  color: var(--mint);
  opacity: 0.9;
}

.framework-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
  position: relative;
  z-index: 1;
}

.framework-col {
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: var(--radius-lg);
  padding: 32px 24px;
  transition: all var(--transition-normal);
  backdrop-filter: blur(4px);
}

.framework-col:hover {
  background: rgba(255, 255, 255, 0.08);
  border-color: var(--apricot);
  transform: translateY(-4px);
}

.framework-step-num {
  font-size: 1.6rem;
  font-weight: 800;
  color: var(--apricot);
  margin-bottom: 12px;
  opacity: 0.9;
}

.framework-col-title {
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--pearl);
  margin-bottom: 14px;
}

.framework-col-text {
  font-size: 0.96rem;
  color: #D3CCD6;
  line-height: 1.65;
}

/* ============================================================
   ACADEMIC PERSPECTIVES
   ============================================================ */
.perspectives-section {
  background-color: var(--pearl-warm);
}

.perspectives-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
  margin-bottom: 48px;
}

.academic-card {
  background: var(--pearl-pure);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 32px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-normal);
}

.academic-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-hover);
  border-color: var(--berry);
}

.academic-header {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: 20px;
}

.avatar-initials {
  width: 52px;
  height: 52px;
  border-radius: var(--radius-md);
  background: linear-gradient(135deg, var(--aubergine), var(--berry));
  color: var(--pearl);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.15rem;
  font-weight: 800;
  letter-spacing: 1px;
  flex-shrink: 0;
  box-shadow: 0 4px 10px rgba(42, 24, 56, 0.15);
}

.academic-meta {
  flex-grow: 1;
}

.academic-name {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--aubergine);
  margin-bottom: 2px;
}

.academic-institution {
  font-size: 0.85rem;
  color: var(--muted);
  font-weight: 500;
  line-height: 1.4;
}

.academic-area-badge {
  display: inline-block;
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--berry);
  background: var(--berry-soft);
  padding: 4px 10px;
  border-radius: var(--radius-sm);
  margin-bottom: 16px;
}

.academic-desc {
  font-size: 0.94rem;
  color: var(--slate);
  line-height: 1.65;
  margin-bottom: 24px;
}

.academic-footer {
  padding-top: 18px;
  border-top: 1px solid var(--border-light);
  display: flex;
  flex-direction: column;
  gap: 10px;
  font-size: 0.85rem;
}

.orcid-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  color: var(--slate);
  font-weight: 500;
  transition: color var(--transition-fast);
}

.orcid-link svg {
  width: 16px;
  height: 16px;
  fill: #A6CE39;
  flex-shrink: 0;
}

.orcid-link:hover {
  color: var(--berry);
}

.platform-contact {
  display: flex;
  flex-direction: column;
  gap: 2px;
  background: var(--pearl);
  padding: 10px 12px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
}

.contact-label {
  font-size: 0.74rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.6px;
  color: var(--muted);
}

.contact-email {
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--berry);
  word-break: break-all;
}

.contact-email:hover {
  color: var(--aubergine);
  text-decoration: underline;
}

/* Independence Note Box */
.independence-box {
  background-color: var(--pearl-pure);
  border: 1px solid var(--border);
  border-left: 4px solid var(--apricot);
  border-radius: var(--radius-md);
  padding: 24px 28px;
  box-shadow: var(--shadow-sm);
}

.independence-title {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--aubergine);
  margin-bottom: 8px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.independence-text {
  font-size: 0.94rem;
  color: var(--slate);
  line-height: 1.65;
  margin-bottom: 8px;
}

.independence-text:last-child {
  margin-bottom: 0;
}

/* ============================================================
   LEARNING LIBRARY & SEARCH
   ============================================================ */
.library-section {
  background-color: var(--pearl);
}

.library-search-container {
  max-width: 600px;
  margin: 0 auto 40px;
  position: relative;
}

.search-input-wrapper {
  position: relative;
  display: flex;
  align-items: center;
}

.search-icon {
  position: absolute;
  left: 18px;
  width: 20px;
  height: 20px;
  color: var(--muted);
  pointer-events: none;
}

.library-search-input {
  width: 100%;
  padding: 16px 20px 16px 50px;
  font-size: 1.05rem;
  font-family: inherit;
  color: var(--aubergine);
  background-color: var(--pearl-pure);
  border: 2px solid var(--border);
  border-radius: var(--radius-full);
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-fast);
}

.library-search-input:focus {
  outline: none;
  border-color: var(--berry);
  box-shadow: 0 0 0 4px var(--berry-soft);
}

.search-clear-btn {
  position: absolute;
  right: 16px;
  background: none;
  border: none;
  color: var(--muted);
  cursor: pointer;
  padding: 4px 8px;
  font-size: 1.1rem;
  display: none;
}

.search-clear-btn:hover {
  color: var(--aubergine);
}

.resources-list {
  max-width: 860px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.resource-item {
  background: var(--pearl-pure);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
  overflow: hidden;
  transition: all var(--transition-normal);
}

.resource-item:hover {
  border-color: var(--border-dark);
  box-shadow: var(--shadow-md);
}

.resource-item details {
  width: 100%;
}

.resource-item summary {
  padding: 22px 28px;
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--aubergine);
  cursor: pointer;
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  user-select: none;
  transition: background-color var(--transition-fast);
}

.resource-item summary::-webkit-details-marker {
  display: none;
}

.resource-item summary:hover {
  background-color: var(--pearl-warm);
}

.summary-title-wrapper {
  display: flex;
  align-items: center;
  gap: 14px;
}

.resource-tag {
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--berry);
  background: var(--berry-soft);
  padding: 3px 8px;
  border-radius: var(--radius-sm);
  text-transform: uppercase;
}

.summary-icon {
  width: 20px;
  height: 20px;
  flex-shrink: 0;
  transition: transform var(--transition-normal);
  color: var(--muted);
}

.resource-item details[open] .summary-icon {
  transform: rotate(180deg);
  color: var(--berry);
}

.resource-content {
  padding: 0 28px 24px;
  border-top: 1px solid var(--border-light);
  margin-top: 4px;
  padding-top: 18px;
}

.resource-content p {
  margin-bottom: 14px;
  font-size: 0.98rem;
  color: var(--slate);
  line-height: 1.7;
}

.resource-content p:last-child {
  margin-bottom: 0;
}

.resource-keywords {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: 14px;
}

.keyword-pill {
  font-size: 0.74rem;
  font-weight: 600;
  color: var(--muted);
  background: var(--pearl);
  border: 1px solid var(--border);
  padding: 2px 8px;
  border-radius: var(--radius-full);
}

.no-results-msg {
  display: none;
  text-align: center;
  padding: 48px 20px;
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--muted);
  background: var(--pearl-pure);
  border: 1px dashed var(--border);
  border-radius: var(--radius-md);
  max-width: 860px;
  margin: 0 auto;
}

/* ============================================================
   ABOUT SECTION
   ============================================================ */
.about-section {
  background-color: var(--pearl-warm);
  border-top: 1px solid var(--border);
}

.about-grid {
  display: grid;
  grid-template-columns: 0.9fr 1.1fr;
  gap: 56px;
  align-items: center;
}

.about-visual {
  display: flex;
  justify-content: center;
  align-items: center;
}

.about-mark-wrapper {
  width: 220px;
  height: 220px;
  padding: 16px;
  background: var(--pearl-pure);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-md);
  display: flex;
  align-items: center;
  justify-content: center;
}

.about-mark-img {
  width: 100%;
  height: 100%;
  display: block;
}

.about-content {
  max-width: 600px;
}

.about-title {
  font-size: 2.15rem;
  font-weight: 800;
  color: var(--aubergine);
  margin-bottom: 18px;
}

.about-lead {
  font-size: 1.1rem;
  line-height: 1.75;
  color: var(--slate);
  margin-bottom: 24px;
}

.about-disclaimer-box {
  background: var(--pearl-pure);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 24px;
  box-shadow: var(--shadow-sm);
}

.disclaimer-lead {
  font-weight: 700;
  color: var(--aubergine);
  margin-bottom: 12px;
  font-size: 1rem;
}

.disclaimer-intro {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--muted);
  margin-bottom: 8px;
}

.disclaimer-list {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 8px 16px;
  list-style: none;
}

.disclaimer-list li {
  font-size: 0.9rem;
  color: var(--slate);
  display: flex;
  align-items: center;
  gap: 8px;
}

.disclaimer-list li::before {
  content: "✕";
  color: var(--berry);
  font-weight: 800;
  font-size: 0.8rem;
}

/* ============================================================
   FOOTER
   ============================================================ */
.site-footer {
  background-color: var(--aubergine);
  color: var(--pearl);
  padding: 64px 0 36px;
  border-top: 1px solid rgba(255, 255, 255, 0.08);
}

.footer-top {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  flex-wrap: wrap;
  gap: 40px;
  margin-bottom: 48px;
  padding-bottom: 40px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.footer-brand {
  max-width: 400px;
}

.footer-logo-link {
  display: inline-block;
  margin-bottom: 18px;
}

.footer-logo {
  height: 48px;
  width: auto;
  display: block;
  filter: brightness(0) invert(1);
}

.footer-tagline {
  font-size: 0.96rem;
  color: #D3CCD6;
  line-height: 1.6;
}

.footer-nav {
  display: flex;
  gap: 48px;
  flex-wrap: wrap;
}

.footer-nav-col h4 {
  font-size: 0.88rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1.2px;
  color: var(--apricot);
  margin-bottom: 16px;
}

.footer-links {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.footer-links a {
  color: #D3CCD6;
  font-size: 0.92rem;
  transition: color var(--transition-fast);
}

.footer-links a:hover {
  color: var(--pearl);
}

.footer-bottom {
  text-align: center;
  font-size: 0.88rem;
  color: var(--muted-light);
}

/* ============================================================
   BACK TO TOP BUTTON
   ============================================================ */
.back-to-top {
  position: fixed;
  bottom: 24px;
  right: 24px;
  width: 44px;
  height: 44px;
  border-radius: var(--radius-full);
  background-color: var(--aubergine);
  color: var(--pearl);
  border: 1px solid var(--apricot);
  box-shadow: var(--shadow-md);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  visibility: hidden;
  transform: translateY(12px);
  transition: all var(--transition-normal);
  z-index: 800;
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.back-to-top:hover {
  background-color: var(--berry);
  transform: translateY(-3px);
  box-shadow: var(--shadow-lg);
}

.back-to-top svg {
  width: 20px;
  height: 20px;
  stroke: currentColor;
  stroke-width: 2.5;
  fill: none;
}

/* ============================================================
   ANIMATIONS & REVEALS
   ============================================================ */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.7s cubic-bezier(0.16, 1, 0.3, 1), transform 0.7s cubic-bezier(0.16, 1, 0.3, 1);
}

.reveal.active {
  opacity: 1;
  transform: translateY(0);
}

/* ============================================================
   RESPONSIVE MEDIA QUERIES
   ============================================================ */
/* Tablet & Medium Screens (< 950px) */
@media (max-width: 950px) {
  .section {
    padding: 72px 0;
  }

  .hero-grid {
    grid-template-columns: 1fr;
    gap: 40px;
    text-align: center;
  }

  .hero-content {
    max-width: 100%;
  }

  .hero-title {
    font-size: 2.4rem;
  }

  .btn-group {
    justify-content: center;
  }

  .hero-visual {
    margin-top: 10px;
  }

  /* 2 fields per row */
  .fields-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  /* 2 framework columns per row */
  .framework-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  /* 2 academic perspectives per row */
  .perspectives-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .about-grid {
    grid-template-columns: 1fr;
    gap: 40px;
    text-align: center;
  }

  .about-content {
    max-width: 100%;
  }

  .about-disclaimer-box {
    text-align: left;
  }
}

/* Mobile Screens (< 650px) */
@media (max-width: 650px) {
  :root {
    --header-height: 70px;
  }

  .section {
    padding: 56px 0;
  }

  .section-title {
    font-size: 1.85rem;
  }

  .hero-title {
    font-size: 2rem;
  }

  .hero-description {
    font-size: 1.05rem;
  }

  /* Navigation drawer */
  .nav-toggle {
    display: inline-flex;
  }

  .nav-menu {
    position: fixed;
    top: var(--header-height);
    left: 0;
    width: 100%;
    background-color: var(--pearl-pure);
    border-bottom: 2px solid var(--border);
    flex-direction: column;
    padding: 24px;
    gap: 16px;
    box-shadow: var(--shadow-lg);
    transform: translateY(-120%);
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-normal);
  }

  .nav-menu.open {
    transform: translateY(0);
    opacity: 1;
    visibility: visible;
  }

  .nav-link {
    width: 100%;
    font-size: 1.1rem;
    padding: 10px 0;
  }

  /* Floating tags adjustment */
  .floating-tag {
    font-size: 0.75rem;
    padding: 6px 12px;
  }
  .tag-regulate { left: -10px; top: 0; }
  .tag-measure { right: -10px; top: 5px; }
  .tag-interpret { left: -10px; bottom: 5px; }
  .tag-apply { right: -10px; bottom: 0; }

  /* 1 field per row */
  .fields-grid {
    grid-template-columns: 1fr;
  }

  /* 1 framework column per row */
  .framework-grid {
    grid-template-columns: 1fr;
  }

  /* 1 academic perspective per row */
  .perspectives-grid {
    grid-template-columns: 1fr;
  }

  .disclaimer-list {
    grid-template-columns: 1fr;
  }

  .footer-top {
    flex-direction: column;
    gap: 32px;
  }

  .footer-nav {
    flex-direction: column;
    gap: 24px;
  }

  .principles-content {
    font-size: 0.92rem;
    gap: 12px;
  }
}