/* ============================================
   BMore Cardiology — Shared Stylesheet
   ============================================ */

/* Custom Properties */
:root {
  --navy:        #1a2b4a;
  --white:       #ffffff;
  --light-blue:  #e8f4fd;
  --accent:      #2e86de;
  --accent-dark: #1a6fc4;
  --text:        #2d3748;
  --text-light:  #64748b;
  --border:      #c8dff5;
  --shadow-sm:   0 1px 4px rgba(26, 43, 74, 0.08);
  --shadow:      0 4px 16px rgba(26, 43, 74, 0.12);
  --shadow-lg:   0 8px 32px rgba(26, 43, 74, 0.16);
  --radius-sm:   4px;
  --radius:      10px;
  --radius-lg:   16px;
  --transition:  0.2s ease;
  --max-width:   1140px;
  --nav-height:  68px;
}

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

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto,
               'Helvetica Neue', Arial, sans-serif;
  font-size: 1rem;
  line-height: 1.7;
  color: var(--text);
  background: var(--white);
  padding-top: var(--nav-height);
}

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

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

a:hover {
  color: var(--accent-dark);
  text-decoration: underline;
}

ul {
  list-style: none;
}

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

h1 { font-size: clamp(1.875rem, 4.5vw, 3.25rem); }
h2 { font-size: clamp(1.5rem, 3vw, 2.125rem); }
h3 { font-size: clamp(1.125rem, 2.5vw, 1.5rem); }
h4 { font-size: 1.125rem; }

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

/* ============================================
   Layout
   ============================================ */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.25rem;
}

.section {
  padding: 5rem 0;
}

.section--alt {
  background: var(--light-blue);
}

.section-header {
  text-align: center;
  margin-bottom: 3rem;
}

.section-header h2 {
  margin-bottom: 0.75rem;
}

.section-header p {
  color: var(--text-light);
  font-size: 1.1rem;
  max-width: 560px;
  margin: 0 auto;
}

/* ============================================
   Navigation
   ============================================ */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  background: var(--navy);
  z-index: 1000;
  box-shadow: 0 2px 12px rgba(0, 0, 0, 0.2);
}

.nav__inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.25rem;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav__logo {
  display: flex;
  align-items: center;
  gap: 0.625rem;
  color: var(--white);
  font-size: 1.2rem;
  font-weight: 700;
  letter-spacing: -0.01em;
  text-decoration: none;
  transition: opacity var(--transition);
}

.nav__logo:hover {
  opacity: 0.88;
  color: var(--white);
  text-decoration: none;
}

.nav__logo-icon {
  color: #e74c8b;
  flex-shrink: 0;
}

.nav__links {
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

.nav__links a {
  color: rgba(255, 255, 255, 0.85);
  padding: 0.5rem 0.875rem;
  border-radius: var(--radius-sm);
  font-size: 0.9375rem;
  font-weight: 500;
  transition: color var(--transition), background var(--transition);
  text-decoration: none;
}

.nav__links a:hover,
.nav__links a.active {
  color: var(--white);
  background: rgba(255, 255, 255, 0.12);
}

/* Hamburger */
.nav__hamburger {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  width: 40px;
  height: 40px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
  border-radius: var(--radius-sm);
  transition: background var(--transition);
}

.nav__hamburger:hover {
  background: rgba(255, 255, 255, 0.12);
}

.nav__hamburger span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--white);
  border-radius: 2px;
  transition: transform var(--transition), opacity var(--transition);
}

.nav__hamburger.open span:nth-child(1) {
  transform: translateY(7px) rotate(45deg);
}
.nav__hamburger.open span:nth-child(2) {
  opacity: 0;
}
.nav__hamburger.open span:nth-child(3) {
  transform: translateY(-7px) rotate(-45deg);
}

/* ============================================
   Buttons
   ============================================ */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1.625rem;
  border-radius: var(--radius);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  text-decoration: none;
  transition: transform var(--transition), box-shadow var(--transition),
              background var(--transition), color var(--transition);
  border: 2px solid transparent;
}

.btn:hover {
  text-decoration: none;
  transform: translateY(-1px);
}

.btn-primary {
  background: var(--accent);
  color: var(--white);
  box-shadow: 0 4px 14px rgba(46, 134, 222, 0.35);
}

.btn-primary:hover {
  background: var(--accent-dark);
  color: var(--white);
  box-shadow: 0 6px 20px rgba(46, 134, 222, 0.45);
}

.btn-outline {
  background: transparent;
  color: var(--navy);
  border-color: var(--navy);
}

.btn-outline:hover {
  background: var(--navy);
  color: var(--white);
}

.btn-outline-white {
  background: transparent;
  color: var(--white);
  border-color: rgba(255, 255, 255, 0.7);
}

.btn-outline-white:hover {
  background: rgba(255, 255, 255, 0.15);
  color: var(--white);
  border-color: var(--white);
}

.btn-sm {
  padding: 0.5rem 1.125rem;
  font-size: 0.9rem;
}

/* ============================================
   Cards
   ============================================ */
.card {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.75rem;
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition), box-shadow var(--transition);
}

.card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow);
}

.card__icon {
  width: 52px;
  height: 52px;
  background: var(--light-blue);
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 1.125rem;
  color: var(--accent);
}

.card__title {
  margin-bottom: 0.5rem;
  font-size: 1.2rem;
}

.card__desc {
  color: var(--text-light);
  font-size: 0.95rem;
  margin-bottom: 1.25rem;
  line-height: 1.6;
}

/* Grid layouts */
.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
}

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

.grid-4 {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1.25rem;
}

/* ============================================
   Hero
   ============================================ */
.hero {
  background: linear-gradient(135deg, var(--navy) 0%, #243a5e 60%, #1e4d8c 100%);
  color: var(--white);
  padding: 5.5rem 0 5rem;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -80px;
  right: -80px;
  width: 400px;
  height: 400px;
  background: radial-gradient(circle, rgba(46, 134, 222, 0.18) 0%, transparent 70%);
  pointer-events: none;
}

.hero::after {
  content: '';
  position: absolute;
  bottom: -60px;
  left: -60px;
  width: 320px;
  height: 320px;
  background: radial-gradient(circle, rgba(231, 76, 139, 0.1) 0%, transparent 70%);
  pointer-events: none;
}

.hero__inner {
  position: relative;
  z-index: 1;
  max-width: 720px;
}

.hero__badge {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  background: rgba(46, 134, 222, 0.2);
  border: 1px solid rgba(46, 134, 222, 0.4);
  color: #7ec8f8;
  font-size: 0.85rem;
  font-weight: 600;
  padding: 0.35rem 0.875rem;
  border-radius: 100px;
  margin-bottom: 1.5rem;
  letter-spacing: 0.03em;
  text-transform: uppercase;
}

.hero h1 {
  color: var(--white);
  margin-bottom: 1.125rem;
}

.hero p {
  font-size: clamp(1.05rem, 2.5vw, 1.25rem);
  color: rgba(255, 255, 255, 0.8);
  margin-bottom: 2.25rem;
  max-width: 560px;
}

.hero__buttons {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}

/* ============================================
   Feature Strip
   ============================================ */
.features {
  padding: 3rem 0;
  border-bottom: 1px solid var(--border);
}

.features__grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2rem;
}

.feature-item {
  display: flex;
  align-items: flex-start;
  gap: 1rem;
}

.feature-item__icon {
  width: 44px;
  height: 44px;
  background: var(--light-blue);
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--accent);
  flex-shrink: 0;
}

.feature-item__title {
  font-size: 1rem;
  font-weight: 700;
  color: var(--navy);
  margin-bottom: 0.25rem;
}

.feature-item__desc {
  font-size: 0.9rem;
  color: var(--text-light);
  margin: 0;
}

/* ============================================
   Topic Cards
   ============================================ */
.topic-card {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.75rem;
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition), box-shadow var(--transition),
              border-color var(--transition);
  display: flex;
  flex-direction: column;
}

.topic-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow);
  border-color: var(--accent);
}

.topic-card__icon {
  width: 56px;
  height: 56px;
  border-radius: 14px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 1.25rem;
  font-size: 1.5rem;
}

.topic-card__tag {
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 0.5rem;
}

.topic-card h3 {
  font-size: 1.25rem;
  margin-bottom: 0.625rem;
}

.topic-card p {
  color: var(--text-light);
  font-size: 0.9375rem;
  flex: 1;
  margin-bottom: 1.5rem;
}

.topic-card__link {
  display: inline-flex;
  align-items: center;
  gap: 0.375rem;
  color: var(--accent);
  font-weight: 600;
  font-size: 0.9375rem;
  transition: gap var(--transition), color var(--transition);
}

.topic-card__link:hover {
  color: var(--accent-dark);
  gap: 0.625rem;
  text-decoration: none;
}

.topic-card__link svg {
  transition: transform var(--transition);
}

.topic-card__link:hover svg {
  transform: translateX(2px);
}

/* Icon colors per topic */
.icon-afib    { background: #fef0f6; color: #e74c8b; }
.icon-htn     { background: #fff3e0; color: #f57c00; }
.icon-hf      { background: #e8f5e9; color: #2e7d32; }
.icon-cad     { background: #e3f2fd; color: #1565c0; }

/* ============================================
   CTA Banner
   ============================================ */
.cta-banner {
  background: linear-gradient(135deg, var(--navy) 0%, #1e4d8c 100%);
  color: var(--white);
  padding: 4rem 0;
  text-align: center;
}

.cta-banner h2 {
  color: var(--white);
  margin-bottom: 0.875rem;
}

.cta-banner p {
  color: rgba(255, 255, 255, 0.78);
  font-size: 1.1rem;
  margin-bottom: 2rem;
  max-width: 520px;
  margin-left: auto;
  margin-right: auto;
}

/* ============================================
   About Page
   ============================================ */
.about-hero {
  background: linear-gradient(135deg, var(--navy) 0%, #243a5e 100%);
  color: var(--white);
  padding: 4rem 0;
}

.about-hero h1 {
  color: var(--white);
  margin-bottom: 0.625rem;
}

.about-hero .subtitle {
  color: rgba(255, 255, 255, 0.75);
  font-size: 1.1rem;
}

.about-content {
  display: grid;
  grid-template-columns: 1fr 2fr;
  gap: 3.5rem;
  align-items: start;
}

.about-avatar {
  background: var(--light-blue);
  border-radius: var(--radius-lg);
  aspect-ratio: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--accent);
  border: 3px solid var(--border);
}

.about-avatar svg {
  width: 40%;
  height: 40%;
  opacity: 0.5;
}

.about-bio h2 {
  margin-bottom: 1.25rem;
}

.about-bio p {
  color: var(--text-light);
  line-height: 1.8;
  margin-bottom: 1.25rem;
}

.mission-box {
  background: var(--light-blue);
  border-left: 4px solid var(--accent);
  border-radius: 0 var(--radius) var(--radius) 0;
  padding: 1.5rem 1.75rem;
  margin-top: 2rem;
}

.mission-box h3 {
  margin-bottom: 0.625rem;
}

.mission-box p {
  margin: 0;
  color: var(--text);
}

.credentials-list {
  margin-top: 1.75rem;
}

.credentials-list h3 {
  margin-bottom: 1rem;
}

.credential-item {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.625rem 0;
  border-bottom: 1px solid var(--border);
  color: var(--text);
  font-size: 0.9375rem;
}

.credential-item:last-child {
  border-bottom: none;
}

.credential-item svg {
  color: var(--accent);
  flex-shrink: 0;
}

/* ============================================
   Article Pages
   ============================================ */
.article-hero {
  background: linear-gradient(135deg, var(--navy) 0%, #243a5e 100%);
  color: var(--white);
  padding: 3.5rem 0;
}

.article-hero__back {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  color: rgba(255, 255, 255, 0.7);
  font-size: 0.9rem;
  margin-bottom: 1.25rem;
  transition: color var(--transition);
}

.article-hero__back:hover {
  color: var(--white);
  text-decoration: none;
}

.article-hero__tag {
  display: inline-block;
  background: rgba(46, 134, 222, 0.25);
  color: #7ec8f8;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 0.3rem 0.75rem;
  border-radius: 100px;
  margin-bottom: 0.875rem;
}

.article-hero h1 {
  color: var(--white);
  margin-bottom: 0.75rem;
}

.article-hero__subtitle {
  color: rgba(255, 255, 255, 0.75);
  font-size: 1.1rem;
}

.article-layout {
  display: grid;
  grid-template-columns: 1fr 280px;
  gap: 3rem;
  align-items: start;
  padding: 3.5rem 0 4rem;
}

/* Table of contents sidebar */
.article-sidebar {
  position: sticky;
  top: calc(var(--nav-height) + 1.5rem);
}

.toc {
  background: var(--light-blue);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  border: 1px solid var(--border);
}

.toc__title {
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-light);
  margin-bottom: 0.875rem;
}

.toc__list {
  display: flex;
  flex-direction: column;
  gap: 0.125rem;
}

.toc__list a {
  display: block;
  padding: 0.4rem 0.625rem;
  color: var(--text);
  font-size: 0.9rem;
  border-radius: var(--radius-sm);
  transition: background var(--transition), color var(--transition);
}

.toc__list a:hover {
  background: rgba(46, 134, 222, 0.12);
  color: var(--accent);
  text-decoration: none;
}

.article-disclaimer {
  margin-top: 1.5rem;
  background: #fff8e1;
  border: 1px solid #ffe082;
  border-radius: var(--radius);
  padding: 1rem 1.125rem;
  font-size: 0.84rem;
  color: #6d5005;
  line-height: 1.55;
}

.article-disclaimer strong {
  display: block;
  margin-bottom: 0.25rem;
  color: #b7800a;
}

/* Article body */
.article-body {
  min-width: 0;
}

.article-section {
  margin-bottom: 3rem;
  scroll-margin-top: calc(var(--nav-height) + 1.5rem);
}

.article-section h2 {
  font-size: 1.5rem;
  margin-bottom: 1rem;
  padding-bottom: 0.625rem;
  border-bottom: 2px solid var(--light-blue);
  display: flex;
  align-items: center;
  gap: 0.625rem;
}

.article-section h2 .section-icon {
  width: 32px;
  height: 32px;
  background: var(--light-blue);
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--accent);
  flex-shrink: 0;
}

.article-section p {
  color: var(--text);
  line-height: 1.8;
  font-size: 1.0125rem;
}

.article-section ul, .article-section ol {
  padding-left: 1.5rem;
  margin-bottom: 1rem;
}

.article-section li {
  color: var(--text);
  margin-bottom: 0.5rem;
  line-height: 1.7;
  font-size: 1.0125rem;
}

.article-section ul li {
  list-style: disc;
}

.article-section ol li {
  list-style: decimal;
}

.info-box {
  background: var(--light-blue);
  border-radius: var(--radius);
  padding: 1.25rem 1.5rem;
  margin: 1.25rem 0;
  border-left: 4px solid var(--accent);
}

.info-box p {
  margin: 0;
  color: var(--navy);
  font-size: 0.96rem;
}

.warning-box {
  background: #fff3e0;
  border-radius: var(--radius);
  padding: 1.25rem 1.5rem;
  margin: 1.25rem 0;
  border-left: 4px solid #f57c00;
}

.warning-box__title {
  font-weight: 700;
  color: #e65100;
  margin-bottom: 0.5rem;
  display: flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.95rem;
}

.warning-box p {
  margin: 0;
  color: #5d3800;
  font-size: 0.95rem;
}

.emergency-box {
  background: #ffebee;
  border-radius: var(--radius);
  padding: 1.25rem 1.5rem;
  margin: 1.25rem 0;
  border-left: 4px solid #d32f2f;
}

.emergency-box__title {
  font-weight: 700;
  color: #b71c1c;
  margin-bottom: 0.5rem;
  font-size: 1rem;
}

.emergency-box p, .emergency-box li {
  color: #5c0000 !important;
  font-size: 0.96rem;
}

.emergency-box ul {
  padding-left: 1.25rem;
  margin-top: 0.5rem;
  margin-bottom: 0;
}

.emergency-box ul li {
  list-style: disc;
  margin-bottom: 0.375rem;
}

.article-back-bottom {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  color: var(--accent);
  font-weight: 600;
  font-size: 0.9375rem;
  margin-top: 1rem;
  padding: 0.625rem 1.125rem;
  border: 2px solid var(--accent);
  border-radius: var(--radius);
  transition: background var(--transition), color var(--transition);
}

.article-back-bottom:hover {
  background: var(--accent);
  color: var(--white);
  text-decoration: none;
}

/* ============================================
   Contact Page
   ============================================ */
.contact-hero {
  background: linear-gradient(135deg, var(--navy) 0%, #243a5e 100%);
  padding: 4rem 0;
}

.contact-hero h1 {
  color: var(--white);
}

.contact-hero .subtitle {
  color: rgba(255, 255, 255, 0.75);
  font-size: 1.1rem;
  margin-top: 0.5rem;
}

.contact-layout {
  display: grid;
  grid-template-columns: 1fr 1.6fr;
  gap: 3.5rem;
  padding: 4rem 0;
  align-items: start;
}

.contact-info h2 {
  margin-bottom: 1rem;
}

.contact-info p {
  color: var(--text-light);
  line-height: 1.8;
}

.contact-disclaimer {
  background: #fff8e1;
  border: 1px solid #ffe082;
  border-radius: var(--radius);
  padding: 1.25rem 1.5rem;
  margin: 1.75rem 0;
}

.contact-disclaimer__title {
  font-weight: 700;
  color: #b7800a;
  margin-bottom: 0.5rem;
  font-size: 0.95rem;
}

.contact-disclaimer p {
  color: #6d5005;
  font-size: 0.9rem;
  line-height: 1.6;
  margin: 0;
}

.contact-emergency {
  background: #ffebee;
  border: 1px solid #ffcdd2;
  border-radius: var(--radius);
  padding: 1.125rem 1.375rem;
}

.contact-emergency p {
  color: #b71c1c;
  font-size: 0.9rem;
  font-weight: 600;
  margin: 0;
}

/* Form */
.contact-form {
  background: var(--white);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 2rem 2.25rem;
  box-shadow: var(--shadow);
}

.contact-form h2 {
  margin-bottom: 1.75rem;
  font-size: 1.5rem;
}

.form-group {
  margin-bottom: 1.25rem;
}

.form-group label {
  display: block;
  font-weight: 600;
  font-size: 0.9rem;
  color: var(--navy);
  margin-bottom: 0.4rem;
}

.form-group input,
.form-group select,
.form-group textarea {
  width: 100%;
  padding: 0.75rem 1rem;
  border: 2px solid var(--border);
  border-radius: var(--radius);
  font-size: 1rem;
  font-family: inherit;
  color: var(--text);
  background: var(--white);
  transition: border-color var(--transition), box-shadow var(--transition);
  outline: none;
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(46, 134, 222, 0.15);
}

.form-group textarea {
  min-height: 140px;
  resize: vertical;
  line-height: 1.6;
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}

.form-note {
  font-size: 0.82rem;
  color: var(--text-light);
  margin-top: 0.25rem;
}

.form-submit {
  width: 100%;
  padding: 0.875rem;
  font-size: 1.05rem;
  margin-top: 0.5rem;
  justify-content: center;
}

/* ============================================
   Footer
   ============================================ */
.footer {
  background: var(--navy);
  color: rgba(255, 255, 255, 0.7);
  padding: 2.5rem 0;
}

.footer__inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: 0.75rem;
}

.footer__logo {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--white);
  font-weight: 700;
  font-size: 1.05rem;
  text-decoration: none;
  margin-bottom: 0.25rem;
}

.footer__logo:hover {
  color: var(--white);
  text-decoration: none;
  opacity: 0.88;
}

.footer__logo svg {
  color: #e74c8b;
}

.footer__links {
  display: flex;
  gap: 1.5rem;
  flex-wrap: wrap;
  justify-content: center;
}

.footer__links a {
  color: rgba(255, 255, 255, 0.65);
  font-size: 0.875rem;
  transition: color var(--transition);
}

.footer__links a:hover {
  color: var(--white);
  text-decoration: none;
}

.footer__divider {
  width: 40px;
  height: 1px;
  background: rgba(255, 255, 255, 0.2);
  margin: 0.25rem 0;
}

.footer__copy {
  font-size: 0.875rem;
}

.footer__disclaimer {
  font-size: 0.8rem;
  color: rgba(255, 255, 255, 0.45);
  max-width: 560px;
  line-height: 1.5;
}

/* ============================================
   Responsive
   ============================================ */
@media (max-width: 900px) {
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
  .about-content { grid-template-columns: 1fr; }
  .about-avatar { max-width: 200px; }
  .article-layout { grid-template-columns: 1fr; }
  .article-sidebar { position: static; }
  .contact-layout { grid-template-columns: 1fr; }
  .features__grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 640px) {
  :root { --nav-height: 62px; }
  body { padding-top: var(--nav-height); }

  .nav__links {
    display: none;
    position: absolute;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background: var(--navy);
    flex-direction: column;
    padding: 0.75rem 1rem 1.25rem;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    box-shadow: 0 8px 24px rgba(0,0,0,0.3);
    gap: 0;
  }

  .nav__links.open {
    display: flex;
  }

  .nav__links a {
    padding: 0.75rem 1rem;
    font-size: 1rem;
    border-radius: var(--radius);
  }

  .nav__hamburger {
    display: flex;
  }

  .hero { padding: 3.5rem 0 3rem; }
  .hero__buttons { flex-direction: column; }
  .hero__buttons .btn { width: 100%; justify-content: center; }

  .grid-3, .grid-4 { grid-template-columns: 1fr; }
  .grid-2 { grid-template-columns: 1fr; }
  .features__grid { grid-template-columns: 1fr; }
  .form-row { grid-template-columns: 1fr; }

  .section { padding: 3.5rem 0; }
  .toc { display: none; }
  .contact-layout { gap: 2rem; }
  .contact-form { padding: 1.5rem; }
}

/* ============================================
   Interactive Elements
   ============================================ */

/* Expandable/Collapsible Toggle */
.toggle-section {
  margin: 1.5rem 0;
  border-radius: 8px;
  overflow: hidden;
  border: 1px solid #e0e0e0;
  background: white;
}

.toggle-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem 1.25rem;
  background: #f5f5f5;
  cursor: pointer;
  user-select: none;
  transition: background-color 0.2s ease;
  font-weight: 600;
  color: #1a3a52;
}

.toggle-header:hover {
  background: #eeeeee;
}

.toggle-header.active {
  background: #e3f2fd;
  color: #2e86de;
}

.toggle-icon {
  display: inline-block;
  transition: transform 0.3s ease;
  font-size: 1.2em;
}

.toggle-icon.active {
  transform: rotate(180deg);
}

.toggle-content {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease;
  padding: 0 1.25rem;
}

.toggle-content.active {
  max-height: 2000px;
  padding: 1.25rem;
}

/* Tabs */
.tabs {
  margin: 2rem 0;
}

.tabs-nav {
  display: flex;
  gap: 0;
  border-bottom: 2px solid #e0e0e0;
  margin-bottom: 1.5rem;
  flex-wrap: wrap;
}

.tab-button {
  padding: 0.75rem 1.5rem;
  background: none;
  border: none;
  font-size: 1rem;
  font-weight: 500;
  color: #666;
  cursor: pointer;
  transition: all 0.2s ease;
  border-bottom: 3px solid transparent;
  margin-bottom: -2px;
}

.tab-button:hover {
  color: #2e86de;
  background: #f5f5f5;
}

.tab-button.active {
  color: #2e86de;
  border-bottom-color: #2e86de;
}

.tab-content {
  display: none;
  animation: fadeIn 0.3s ease;
}

.tab-content.active {
  display: block;
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Info Cards with Hover Effect */
.info-card {
  background: white;
  padding: 1.5rem;
  border-radius: 8px;
  border-left: 4px solid #2e86de;
  box-shadow: 0 2px 8px rgba(0,0,0,0.08);
  transition: all 0.3s ease;
  cursor: default;
}

.info-card:hover {
  box-shadow: 0 4px 16px rgba(0,0,0,0.12);
  transform: translateY(-2px);
}

/* Gradient Accents */
.gradient-text {
  background: linear-gradient(135deg, #1a3a52 0%, #2e86de 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  font-weight: 600;
}

/* Smooth animations for diagrams */
.diagram-svg {
  animation: slideUp 0.6s ease-out;
}

@keyframes slideUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Comparison boxes */
.comparison-container {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2rem;
  margin: 2rem 0;
}

.comparison-card {
  padding: 2rem;
  border-radius: 8px;
  background: #f9f9f9;
  border: 2px solid #e0e0e0;
  transition: all 0.3s ease;
}

.comparison-card:hover {
  border-color: #2e86de;
  box-shadow: 0 4px 16px rgba(46, 134, 222, 0.15);
}

.comparison-card.success {
  background: #e8f5e9;
  border-color: #4CAF50;
}

.comparison-card.warning {
  background: #fff3e0;
  border-color: #ff9800;
}

@media (max-width: 768px) {
  .comparison-container {
    grid-template-columns: 1fr;
  }
  
  .tabs-nav {
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
  }
}