/* ==========================================================================
   DongThue.com — Landing Page Design System
   Brand: Blue, friendly, trustworthy
   Font: Inter
   Grid: 8px spacing system
   Mobile-first responsive
   ========================================================================== */

/* ---------- CSS RESET & VARIABLES ---------- */
:root {
  /* Brand Colors */
  --brand-50: #eff6ff;
  --brand-100: #dbeafe;
  --brand-200: #bfdbfe;
  --brand-300: #93c5fd;
  --brand-400: #60a5fa;
  --brand-500: #2563eb;
  --brand-600: #1d4ed8;
  --brand-700: #1e40af;
  --brand-800: #1e3a8a;
  --brand-900: #172554;

  /* Accent (Amber — urgency, warmth) */
  --accent-50: #fffbeb;
  --accent-100: #fef3c7;
  --accent-400: #fbbf24;
  --accent-500: #f59e0b;
  --accent-600: #d97706;

  /* Semantic */
  --success: #16a34a;
  --success-bg: #dcfce7;
  --danger: #dc2626;
  --danger-bg: #fef2f2;

  /* Neutrals */
  --slate-50: #f8fafc;
  --slate-100: #f1f5f9;
  --slate-200: #e2e8f0;
  --slate-300: #cbd5e1;
  --slate-400: #94a3b8;
  --slate-500: #64748b;
  --slate-600: #475569;
  --slate-700: #334155;
  --slate-800: #1e293b;
  --slate-900: #0f172a;

  /* Surfaces */
  --surface: #ffffff;
  --surface-elevated: #ffffff;
  --surface-muted: var(--slate-50);
  --surface-overlay: rgba(0, 0, 0, 0.5);

  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --text-xs: 0.75rem;
  --text-sm: 0.875rem;
  --text-base: 1rem;
  --text-lg: 1.125rem;
  --text-xl: 1.25rem;
  --text-2xl: 1.5rem;
  --text-3xl: 1.875rem;
  --text-4xl: 2.25rem;
  --text-5xl: 3rem;

  /* Spacing (8px grid) */
  --sp-1: 4px;
  --sp-2: 8px;
  --sp-3: 12px;
  --sp-4: 16px;
  --sp-5: 20px;
  --sp-6: 24px;
  --sp-8: 32px;
  --sp-10: 40px;
  --sp-12: 48px;
  --sp-16: 64px;
  --sp-20: 80px;
  --sp-24: 96px;

  /* Radius */
  --radius-sm: 6px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  --radius-2xl: 20px;
  --radius-full: 9999px;

  /* Shadows */
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.07), 0 2px 4px -2px rgba(0, 0, 0, 0.05);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -4px rgba(0, 0, 0, 0.04);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.08), 0 8px 10px -6px rgba(0, 0, 0, 0.04);
  --shadow-header: 0 1px 3px rgba(0, 0, 0, 0.08);

  /* Transitions */
  --ease-default: cubic-bezier(0.4, 0, 0.2, 1);
  --ease-spring: cubic-bezier(0.32, 0.72, 0, 1);
  --duration-fast: 150ms;
  --duration-normal: 250ms;
  --duration-slow: 400ms;

  /* Layout */
  --max-width: 1120px;
  --header-height: 64px;
}

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

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

body {
  font-family: var(--font-sans);
  font-size: var(--text-base);
  line-height: 1.6;
  color: var(--slate-800);
  background: var(--surface);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

a { color: var(--brand-500); text-decoration: none; }
a:hover { color: var(--brand-600); }

/* ---------- LAYOUT ---------- */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--sp-5);
}

.section {
  padding: var(--sp-16) 0;
}

.section--muted {
  background: var(--surface-muted);
}

.section--brand {
  background: linear-gradient(135deg, var(--brand-600), var(--brand-800));
  color: white;
}

/* ---------- TYPOGRAPHY ---------- */
h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: 1.2;
  color: var(--slate-900);
}

.section--brand h1,
.section--brand h2,
.section--brand h3 { color: white; }

.section-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: var(--sp-2);
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--brand-500);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: var(--sp-3);
}

.section-title {
  font-size: var(--text-3xl);
  margin-bottom: var(--sp-4);
}

.section-subtitle {
  font-size: var(--text-lg);
  color: var(--slate-500);
  max-width: 600px;
  line-height: 1.6;
}

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

/* ---------- HEADER ---------- */
.lp-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid transparent;
  transition: border-color var(--duration-normal) var(--ease-default),
              box-shadow var(--duration-normal) var(--ease-default);
  height: var(--header-height);
}

.lp-header.scrolled {
  border-bottom-color: var(--slate-200);
  box-shadow: var(--shadow-header);
}

.lp-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--sp-5);
}

.lp-header__logo {
  display: flex;
  align-items: center;
  gap: var(--sp-3);
}

.lp-header__logo-icon {
  width: 36px;
  height: 36px;
  border-radius: var(--radius-lg);
  background: linear-gradient(135deg, var(--brand-500), var(--brand-700));
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-size: 16px;
}

.lp-header__logo-text {
  font-weight: 700;
  font-size: var(--text-lg);
  color: var(--slate-900);
}

.lp-header__nav {
  display: none;
  align-items: center;
  gap: var(--sp-8);
  list-style: none;
}

.lp-header__nav a {
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--slate-600);
  transition: color var(--duration-fast);
}

.lp-header__nav a:hover {
  color: var(--brand-500);
}

.lp-header__cta {
  display: flex;
  align-items: center;
  gap: var(--sp-3);
}

/* ---------- BUTTONS ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--sp-2);
  font-family: var(--font-sans);
  font-weight: 600;
  border: none;
  cursor: pointer;
  transition: all var(--duration-fast) var(--ease-default);
  text-decoration: none;
  line-height: 1.4;
  white-space: nowrap;
  min-height: 44px; /* UX: Fitts's Law — Touch target ≥ 44px */
}

.btn:focus-visible {
  outline: 2px solid var(--brand-400);
  outline-offset: 2px;
}

.btn--primary {
  background: var(--brand-500);
  color: white;
  padding: var(--sp-3) var(--sp-6);
  border-radius: var(--radius-md);
  font-size: var(--text-sm);
}

.btn--primary:hover {
  background: var(--brand-600);
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(37, 99, 235, 0.3);
}

.btn--primary:active { transform: translateY(0); }

.btn--primary-lg {
  background: var(--brand-500);
  color: white;
  padding: var(--sp-4) var(--sp-8);
  border-radius: var(--radius-lg);
  font-size: var(--text-base);
}

.btn--primary-lg:hover {
  background: var(--brand-600);
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(37, 99, 235, 0.3);
}

.btn--primary-lg:active { transform: translateY(0); }

.btn--outline {
  background: transparent;
  color: var(--brand-500);
  border: 1.5px solid var(--brand-200);
  padding: var(--sp-3) var(--sp-6);
  border-radius: var(--radius-md);
  font-size: var(--text-sm);
}

.btn--outline:hover {
  background: var(--brand-50);
  border-color: var(--brand-300);
}

.btn--white {
  background: white;
  color: var(--brand-600);
  padding: var(--sp-4) var(--sp-8);
  border-radius: var(--radius-lg);
  font-size: var(--text-base);
}

.btn--white:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.15);
}

.btn--ghost {
  background: transparent;
  color: var(--slate-600);
  padding: var(--sp-2) var(--sp-4);
  border-radius: var(--radius-md);
  font-size: var(--text-sm);
}

.btn--ghost:hover { background: var(--slate-100); color: var(--slate-800); }

.btn--sm { min-height: 36px; font-size: var(--text-xs); padding: var(--sp-2) var(--sp-4); }

/* ---------- CARDS ---------- */
.card {
  background: var(--surface);
  border: 1px solid var(--slate-200);
  border-radius: var(--radius-xl);
  padding: var(--sp-6);
  transition: all var(--duration-normal) var(--ease-default);
}

.card:hover {
  box-shadow: var(--shadow-lg);
  border-color: var(--slate-300);
}

.card--highlight {
  border-color: var(--brand-200);
  background: var(--brand-50);
}

.card--highlight:hover {
  border-color: var(--brand-300);
}

.card__icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 20px;
  margin-bottom: var(--sp-4);
}

.card__icon--blue { background: var(--brand-100); color: var(--brand-600); }
.card__icon--amber { background: var(--accent-100); color: var(--accent-600); }
.card__icon--green { background: var(--success-bg); color: var(--success); }
.card__icon--red { background: var(--danger-bg); color: var(--danger); }

.card__title {
  font-size: var(--text-lg);
  font-weight: 600;
  color: var(--slate-900);
  margin-bottom: var(--sp-2);
}

.card__desc {
  font-size: var(--text-sm);
  color: var(--slate-500);
  line-height: 1.6;
}

/* ---------- BADGES ---------- */
.badge {
  display: inline-flex;
  align-items: center;
  gap: var(--sp-2);
  font-size: var(--text-xs);
  font-weight: 600;
  padding: var(--sp-1) var(--sp-3);
  border-radius: var(--radius-full);
}

.badge--blue { background: var(--brand-100); color: var(--brand-700); }
.badge--amber { background: var(--accent-100); color: var(--accent-600); }
.badge--green { background: var(--success-bg); color: var(--success); }

/* ---------- HERO ---------- */
.hero {
  padding-top: calc(var(--header-height) + var(--sp-16));
  padding-bottom: var(--sp-16);
  background: linear-gradient(180deg, var(--brand-50) 0%, var(--surface) 100%);
  overflow: hidden;
}

.hero__inner {
  text-align: center;
  max-width: 720px;
  margin: 0 auto;
}

.hero__badge {
  margin-bottom: var(--sp-6);
}

.hero__title {
  font-size: var(--text-4xl);
  font-weight: 800;
  line-height: 1.15;
  margin-bottom: var(--sp-5);
  color: var(--slate-900);
}

.hero__title em {
  font-style: normal;
  color: var(--brand-500);
  position: relative;
}

.hero__title em::after {
  content: '';
  position: absolute;
  bottom: 2px;
  left: 0;
  right: 0;
  height: 6px;
  background: var(--accent-400);
  opacity: 0.4;
  border-radius: 3px;
  z-index: -1;
}

.hero__subtitle {
  font-size: var(--text-lg);
  color: var(--slate-500);
  margin-bottom: var(--sp-8);
  line-height: 1.7;
}

.hero__cta-group {
  display: flex;
  flex-direction: column;
  gap: var(--sp-3);
  align-items: center;
  margin-bottom: var(--sp-10);
}

.hero__trust {
  display: flex;
  flex-wrap: wrap;
  gap: var(--sp-6);
  justify-content: center;
  padding-top: var(--sp-8);
  border-top: 1px solid var(--slate-200);
}

.hero__trust-item {
  display: flex;
  align-items: center;
  gap: var(--sp-2);
  font-size: var(--text-sm);
  color: var(--slate-500);
}

.hero__trust-item i {
  color: var(--brand-400);
}

/* ---------- PAIN POINTS ---------- */
.pain-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--sp-5);
  margin-top: var(--sp-10);
}

.pain-card {
  display: flex;
  gap: var(--sp-4);
  padding: var(--sp-5);
  background: var(--surface);
  border: 1px solid var(--slate-200);
  border-radius: var(--radius-xl);
  transition: all var(--duration-normal) var(--ease-default);
}

.pain-card:hover {
  border-color: var(--danger);
  background: var(--danger-bg);
}

.pain-card__icon {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-lg);
  background: var(--danger-bg);
  color: var(--danger);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 18px;
  flex-shrink: 0;
}

.pain-card:hover .pain-card__icon {
  background: white;
}

.pain-card__title {
  font-weight: 600;
  font-size: var(--text-base);
  color: var(--slate-900);
  margin-bottom: var(--sp-1);
}

.pain-card__desc {
  font-size: var(--text-sm);
  color: var(--slate-500);
  line-height: 1.5;
}

/* ---------- SERVICES ---------- */
.services-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--sp-6);
  margin-top: var(--sp-10);
}

.service-card {
  background: var(--surface);
  border: 1px solid var(--slate-200);
  border-radius: var(--radius-2xl);
  padding: var(--sp-8);
  position: relative;
  overflow: hidden;
  transition: all var(--duration-normal) var(--ease-default);
}

.service-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--brand-400), var(--brand-600));
  opacity: 0;
  transition: opacity var(--duration-normal);
}

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

.service-card:hover {
  box-shadow: var(--shadow-xl);
  border-color: var(--brand-200);
  transform: translateY(-2px);
}

.service-card__badge {
  margin-bottom: var(--sp-4);
}

.service-card__title {
  font-size: var(--text-2xl);
  font-weight: 700;
  margin-bottom: var(--sp-3);
}

.service-card__desc {
  font-size: var(--text-base);
  color: var(--slate-500);
  margin-bottom: var(--sp-6);
  line-height: 1.6;
}

.service-card__features {
  list-style: none;
  margin-bottom: var(--sp-6);
}

.service-card__features li {
  display: flex;
  align-items: flex-start;
  gap: var(--sp-3);
  padding: var(--sp-2) 0;
  font-size: var(--text-sm);
  color: var(--slate-700);
}

.service-card__features li i {
  color: var(--success);
  margin-top: 3px;
  flex-shrink: 0;
}

/* ---------- STEPS ---------- */
.steps {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--sp-6);
  margin-top: var(--sp-10);
  counter-reset: step;
}

.step {
  display: flex;
  gap: var(--sp-5);
  align-items: flex-start;
}

.step__number {
  counter-increment: step;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: var(--brand-500);
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: var(--text-xl);
  font-weight: 700;
  flex-shrink: 0;
}

.step__content {
  padding-top: var(--sp-2);
}

.step__title {
  font-size: var(--text-lg);
  font-weight: 600;
  color: var(--slate-900);
  margin-bottom: var(--sp-1);
}

.step__desc {
  font-size: var(--text-sm);
  color: var(--slate-500);
  line-height: 1.6;
}

/* ---------- TOOLS SHOWCASE ---------- */
.tools-preview {
  margin-top: var(--sp-10);
  background: var(--surface);
  border: 1px solid var(--slate-200);
  border-radius: var(--radius-2xl);
  overflow: hidden;
  box-shadow: var(--shadow-lg);
}

.tools-preview__header {
  background: var(--slate-900);
  padding: var(--sp-3) var(--sp-4);
  display: flex;
  align-items: center;
  gap: var(--sp-2);
}

.tools-preview__dots {
  display: flex;
  gap: 6px;
}

.tools-preview__dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
}

.tools-preview__dot--red { background: #ef4444; }
.tools-preview__dot--yellow { background: #eab308; }
.tools-preview__dot--green { background: #22c55e; }

.tools-preview__url {
  flex: 1;
  background: var(--slate-800);
  border-radius: var(--radius-sm);
  padding: var(--sp-1) var(--sp-3);
  font-size: var(--text-xs);
  color: var(--slate-400);
  text-align: center;
}

.tools-preview__body {
  padding: var(--sp-8);
  text-align: center;
}

.tools-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--sp-5);
  margin-top: var(--sp-6);
}

.tool-item {
  padding: var(--sp-5);
  border: 1px solid var(--slate-200);
  border-radius: var(--radius-lg);
  text-align: left;
  transition: all var(--duration-normal);
}

.tool-item:hover {
  border-color: var(--brand-300);
  background: var(--brand-50);
}

.tool-item__icon {
  font-size: 24px;
  margin-bottom: var(--sp-3);
}

.tool-item__title {
  font-weight: 600;
  font-size: var(--text-base);
  color: var(--slate-900);
  margin-bottom: var(--sp-1);
}

.tool-item__desc {
  font-size: var(--text-sm);
  color: var(--slate-500);
}

.tool-item__badge {
  margin-top: var(--sp-2);
}

/* ---------- SOCIAL PROOF ---------- */
.proof-stats {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--sp-5);
  margin-top: var(--sp-10);
}

.proof-stat {
  text-align: center;
  padding: var(--sp-6);
}

.proof-stat__number {
  font-size: var(--text-4xl);
  font-weight: 800;
  color: white;
  line-height: 1;
  margin-bottom: var(--sp-2);
}

.proof-stat__label {
  font-size: var(--text-sm);
  color: rgba(255, 255, 255, 0.8);
}

.proof-team {
  margin-top: var(--sp-10);
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--sp-6);
}

.proof-point {
  display: flex;
  gap: var(--sp-4);
  align-items: flex-start;
}

.proof-point__icon {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.15);
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 16px;
  flex-shrink: 0;
}

.proof-point__text {
  font-size: var(--text-base);
  color: rgba(255, 255, 255, 0.9);
  line-height: 1.6;
}

.proof-point__text strong {
  color: white;
}

/* ---------- FAQ ---------- */
.faq-list {
  max-width: 720px;
  margin: var(--sp-10) auto 0;
}

.faq-item {
  border-bottom: 1px solid var(--slate-200);
}

.faq-item:first-child {
  border-top: 1px solid var(--slate-200);
}

.faq-question {
  width: 100%;
  background: none;
  border: none;
  padding: var(--sp-5) 0;
  font-family: var(--font-sans);
  font-size: var(--text-base);
  font-weight: 600;
  color: var(--slate-800);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--sp-4);
  text-align: left;
  min-height: 44px; /* UX: Fitts's Law */
}

.faq-question:hover {
  color: var(--brand-500);
}

.faq-question i {
  transition: transform var(--duration-normal) var(--ease-default);
  color: var(--slate-400);
  flex-shrink: 0;
}

.faq-item.open .faq-question i {
  transform: rotate(180deg);
  color: var(--brand-500);
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height var(--duration-slow) var(--ease-default);
}

.faq-answer__inner {
  padding: 0 0 var(--sp-5);
  font-size: var(--text-sm);
  color: var(--slate-600);
  line-height: 1.7;
}

.faq-item.open .faq-answer {
  max-height: 300px;
}

/* ---------- CTA BANNER ---------- */
.cta-banner {
  background: linear-gradient(135deg, var(--brand-500), var(--brand-700));
  border-radius: var(--radius-2xl);
  padding: var(--sp-12) var(--sp-8);
  text-align: center;
  margin: var(--sp-16) auto;
  max-width: var(--max-width);
  position: relative;
  overflow: hidden;
}

.cta-banner::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -20%;
  width: 400px;
  height: 400px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.06);
}

.cta-banner__title {
  font-size: var(--text-3xl);
  font-weight: 800;
  color: white;
  margin-bottom: var(--sp-4);
  position: relative;
}

.cta-banner__subtitle {
  font-size: var(--text-lg);
  color: rgba(255, 255, 255, 0.85);
  margin-bottom: var(--sp-8);
  position: relative;
}

/* ---------- FOOTER ---------- */
.lp-footer {
  background: var(--slate-900);
  color: var(--slate-400);
  padding: var(--sp-12) 0 var(--sp-8);
}

.lp-footer__inner {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--sp-8);
}

.lp-footer__brand {
  display: flex;
  align-items: center;
  gap: var(--sp-3);
  margin-bottom: var(--sp-4);
}

.lp-footer__brand-icon {
  width: 32px;
  height: 32px;
  border-radius: var(--radius-md);
  background: var(--brand-500);
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-size: 14px;
}

.lp-footer__brand-text {
  font-weight: 700;
  font-size: var(--text-base);
  color: white;
}

.lp-footer__desc {
  font-size: var(--text-sm);
  line-height: 1.6;
  max-width: 320px;
}

.lp-footer__heading {
  font-size: var(--text-sm);
  font-weight: 600;
  color: white;
  margin-bottom: var(--sp-4);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.lp-footer__links {
  list-style: none;
}

.lp-footer__links li { margin-bottom: var(--sp-3); }

.lp-footer__links a {
  font-size: var(--text-sm);
  color: var(--slate-400);
  transition: color var(--duration-fast);
}

.lp-footer__links a:hover { color: white; }

.lp-footer__bottom {
  border-top: 1px solid var(--slate-800);
  margin-top: var(--sp-8);
  padding-top: var(--sp-6);
  font-size: var(--text-xs);
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: var(--sp-4);
}

/* ---------- SCROLL ANIMATIONS ---------- */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s var(--ease-default), transform 0.6s var(--ease-default);
}

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

.reveal-delay-1 { transition-delay: 100ms; }
.reveal-delay-2 { transition-delay: 200ms; }
.reveal-delay-3 { transition-delay: 300ms; }
.reveal-delay-4 { transition-delay: 400ms; }

/* ---------- MOBILE NAV ---------- */
.mobile-menu-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  border: none;
  background: none;
  color: var(--slate-700);
  font-size: 20px;
  cursor: pointer;
  border-radius: var(--radius-md);
}

.mobile-menu-btn:hover { background: var(--slate-100); }

.mobile-nav {
  display: none;
  position: fixed;
  top: var(--header-height);
  left: 0;
  right: 0;
  bottom: 0;
  background: var(--surface);
  z-index: 99;
  padding: var(--sp-6);
  overflow-y: auto;
}

.mobile-nav.open { display: block; }

.mobile-nav__list {
  list-style: none;
}

.mobile-nav__list li { border-bottom: 1px solid var(--slate-100); }

.mobile-nav__list a {
  display: block;
  padding: var(--sp-4) 0;
  font-size: var(--text-base);
  font-weight: 500;
  color: var(--slate-700);
  min-height: 44px;
}

.mobile-nav__list a:hover { color: var(--brand-500); }

/* ---------- STICKY CTA (Mobile) ---------- */
.sticky-cta {
  display: flex;
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  z-index: 90;
  background: rgba(255, 255, 255, 0.96);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-top: 1px solid var(--slate-200);
  padding: var(--sp-3) var(--sp-5);
  padding-bottom: calc(var(--sp-3) + env(safe-area-inset-bottom, 0));
  gap: var(--sp-3);
}

.sticky-cta .btn { flex: 1; }

/* ---------- RESPONSIVE ---------- */
@media (min-width: 640px) {
  .hero__title { font-size: var(--text-5xl); }
  .hero__cta-group { flex-direction: row; }
  .pain-grid { grid-template-columns: repeat(2, 1fr); }
  .tools-grid { grid-template-columns: repeat(2, 1fr); }
  .proof-stats { grid-template-columns: repeat(4, 1fr); }
  .lp-footer__inner { grid-template-columns: 2fr 1fr 1fr; }
}

@media (min-width: 768px) {
  .section-title { font-size: var(--text-4xl); }
  .services-grid { grid-template-columns: repeat(2, 1fr); }
  .steps { grid-template-columns: repeat(3, 1fr); }
  .step { flex-direction: column; text-align: center; align-items: center; }
  .proof-team { grid-template-columns: repeat(2, 1fr); }
  .tools-grid { grid-template-columns: repeat(3, 1fr); }
}

@media (min-width: 1024px) {
  .lp-header__nav { display: flex; }
  .mobile-menu-btn { display: none; }
  .sticky-cta { display: none; }
  .lp-footer__inner { grid-template-columns: 2fr 1fr 1fr 1fr; }
}

/* ---------- REDUCED MOTION ---------- */
@media (prefers-reduced-motion: reduce) {
  .reveal { transition: none; opacity: 1; transform: none; }
  * { transition-duration: 0ms !important; animation-duration: 0ms !important; }
}

/* ---------- PRINT ---------- */
@media print {
  .lp-header, .sticky-cta, .cta-banner, .mobile-nav { display: none !important; }
  .section { padding: var(--sp-6) 0; }
  .hero { padding-top: var(--sp-6); }
}
/* ==========================================================================
   Engagement Engine — Bottom Sheet CSS
   Universal responsive bottom sheet component.
   3 sizes: compact | standard | full
   Zero dependencies. Mobile-first.
   ========================================================================== */

/* ---------- BACKDROP ---------- */
.eng-backdrop {
  position: fixed;
  inset: 0;
  z-index: 1099;
  background: rgba(0, 0, 0, 0.4);
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s ease;
}

.eng-backdrop.active {
  opacity: 1;
  pointer-events: auto;
}

/* ---------- SHEET CORE ---------- */
.eng-sheet {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  z-index: 1100;
  transform: translateY(100%);
  transition: transform 0.4s cubic-bezier(0.32, 0.72, 0, 1);
  pointer-events: none;
  /* Safe area for notched devices */
  padding-bottom: env(safe-area-inset-bottom, 0);
}

.eng-sheet.active {
  transform: translateY(0);
  pointer-events: auto;
}

.eng-sheet.dragging {
  transition: none; /* Disable transition during drag for instant feedback */
}

/* ---------- SHEET INNER ---------- */
.eng-sheet__inner {
  position: relative;
  max-width: 480px;
  margin: 0 auto;
  background: rgba(255, 255, 255, 0.96);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  border-radius: 20px 20px 0 0;
  box-shadow: 0 -8px 40px rgba(0, 0, 0, 0.12);
}

/* ---------- DRAG HANDLE ---------- */
.eng-sheet__handle {
  display: flex;
  justify-content: center;
  padding: 12px 0 4px;
  cursor: grab;
  touch-action: none;
}

.eng-sheet__handle:active {
  cursor: grabbing;
}

.eng-sheet__handle-bar {
  width: 36px;
  height: 4px;
  background: rgba(0, 0, 0, 0.15);
  border-radius: 2px;
}

/* ---------- CLOSE BUTTON ---------- */
.eng-sheet__close {
  position: absolute;
  top: 12px;
  right: 12px;
  width: 32px;
  height: 32px;
  border-radius: 50%;
  border: none;
  background: rgba(0, 0, 0, 0.06);
  color: rgba(0, 0, 0, 0.5);
  font-size: 14px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.15s ease;
  z-index: 1;
}

.eng-sheet__close:hover {
  background: rgba(0, 0, 0, 0.1);
}

/* ---------- CONTENT AREA ---------- */
.eng-sheet__content {
  padding: 8px 20px 24px;
  overflow-y: auto;
  overscroll-behavior: contain;
  -webkit-overflow-scrolling: touch;
}

/* ---------- SIZE VARIANTS ---------- */

/* Compact: ~120px — CTA buttons, simple message */
.eng-sheet--compact .eng-sheet__content {
  max-height: 120px;
  padding: 8px 20px 16px;
}

/* Standard: ~320px — forms, calendar CTA (default) */
.eng-sheet--standard .eng-sheet__content {
  max-height: 400px;
}

/* Full: ~80vh — surveys, multi-step forms */
.eng-sheet--full .eng-sheet__content {
  max-height: 80vh;
}

/* ---------- CONTENT PATTERNS ---------- */

/* Icon (emoji or image) */
.eng-content__icon {
  font-size: 40px;
  text-align: center;
  margin-bottom: 8px;
  line-height: 1;
}

/* Title */
.eng-content__title {
  font-size: 18px;
  font-weight: 600;
  text-align: center;
  margin: 0 0 8px;
  color: #1a1a1a;
}

/* Subtitle */
.eng-content__subtitle {
  font-size: 14px;
  color: #666;
  text-align: center;
  margin: 0 0 16px;
  line-height: 1.5;
}

/* Benefit text (post-CTA) */
.eng-content__benefit {
  font-size: 13px;
  color: #2d5016;
  text-align: center;
  margin: 12px 0 0;
  opacity: 0.8;
}

/* ---------- BUTTONS ---------- */
.eng-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 24px;
  border-radius: 12px;
  border: none;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.15s ease;
  text-decoration: none;
  line-height: 1.4;
  min-height: 48px; /* Touch target ≥ 48px */
}

.eng-btn--primary {
  background: #2d5016;
  color: #fff;
}

.eng-btn--primary:hover {
  background: #1e3a0f;
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(45, 80, 22, 0.3);
}

.eng-btn--primary:active {
  transform: translateY(0);
}

.eng-btn--outline {
  background: transparent;
  color: #2d5016;
  border: 1.5px solid #2d5016;
}

.eng-btn--outline:hover {
  background: rgba(45, 80, 22, 0.06);
}

.eng-btn--full {
  width: 100%;
}

/* Calendar buttons */
.eng-btn--gcal {
  background: #1a73e8;
  color: #fff;
}

.eng-btn--gcal:hover {
  background: #1557b0;
}

.eng-btn--ics {
  background: #f5f5f5;
  color: #333;
}

.eng-btn--ics:hover {
  background: #e8e8e8;
}

/* Chat channel buttons */
.eng-btn--zalo {
  background: #0068ff;
  color: #fff;
}

.eng-btn--phone {
  background: #34c759;
  color: #fff;
}

.eng-btn--messenger {
  background: #0084ff;
  color: #fff;
}

/* Button group */
.eng-calendar-buttons,
.eng-chat-buttons {
  display: flex;
  gap: 12px;
  justify-content: center;
  flex-wrap: wrap;
}

.eng-calendar-buttons .eng-btn,
.eng-chat-buttons .eng-btn {
  flex: 1;
  min-width: 140px;
  max-width: 200px;
}

/* ---------- FORM ELEMENTS ---------- */
.eng-sheet input[type="text"],
.eng-sheet input[type="tel"],
.eng-sheet input[type="email"],
.eng-sheet select,
.eng-sheet textarea {
  width: 100%;
  padding: 12px 16px;
  border: 1.5px solid rgba(0, 0, 0, 0.12);
  border-radius: 10px;
  font-size: 15px;
  margin-bottom: 12px;
  background: #fff;
  transition: border-color 0.2s ease;
  box-sizing: border-box;
}

.eng-sheet input:focus,
.eng-sheet select:focus,
.eng-sheet textarea:focus {
  outline: none;
  border-color: #2d5016;
  box-shadow: 0 0 0 3px rgba(45, 80, 22, 0.1);
}

.eng-sheet textarea {
  resize: vertical;
  min-height: 60px;
}

/* ---------- DATE & TIME CHIPS ---------- */
.eng-date-chips,
.eng-time-slots {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 8px;
  margin-bottom: 12px;
}

.eng-chip {
  padding: 10px 8px;
  border: 1.5px solid rgba(0, 0, 0, 0.1);
  border-radius: 10px;
  text-align: center;
  font-size: 13px;
  cursor: pointer;
  transition: all 0.15s ease;
  background: #fff;
  min-height: 44px; /* Touch target */
  display: flex;
  align-items: center;
  justify-content: center;
}

.eng-chip:hover {
  border-color: #2d5016;
  background: rgba(45, 80, 22, 0.04);
}

.eng-chip.active {
  background: #2d5016;
  color: #fff;
  border-color: #2d5016;
}

/* ---------- RATING STARS ---------- */
.eng-rating {
  display: flex;
  gap: 8px;
  justify-content: center;
  margin-bottom: 16px;
}

.eng-rating button {
  font-size: 32px;
  background: none;
  border: none;
  cursor: pointer;
  opacity: 0.3;
  transition: opacity 0.15s ease, transform 0.15s ease;
  padding: 4px;
}

.eng-rating button:hover,
.eng-rating button.active {
  opacity: 1;
  transform: scale(1.2);
}

/* ---------- COUNTDOWN ---------- */
.eng-countdown {
  display: flex;
  gap: 8px;
  justify-content: center;
  margin-bottom: 12px;
}

.eng-countdown__unit {
  background: #1a1a1a;
  color: #fff;
  padding: 8px 12px;
  border-radius: 8px;
  font-size: 20px;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  min-width: 56px;
  text-align: center;
}

/* ---------- TOAST NOTIFICATIONS ---------- */
.eng-toast {
  position: fixed;
  bottom: 20px;
  left: 50%;
  transform: translateX(-50%) translateY(120%);
  z-index: 1200;
  padding: 14px 20px;
  border-radius: 12px;
  font-size: 14px;
  font-weight: 500;
  max-width: 90%;
  text-align: center;
  transition: transform 0.3s cubic-bezier(0.32, 0.72, 0, 1);
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.15);
}

.eng-toast.active {
  transform: translateX(-50%) translateY(0);
}

.eng-toast--success {
  background: #dcfce7;
  color: #166534;
  border: 1px solid #bbf7d0;
}

.eng-toast--error {
  background: #fef2f2;
  color: #991b1b;
  border: 1px solid #fecaca;
}

.eng-toast--info {
  background: #eff6ff;
  color: #1e40af;
  border: 1px solid #bfdbfe;
}

/* ---------- DARK MODE ---------- */
@media (prefers-color-scheme: dark) {
  .eng-sheet__inner {
    background: rgba(30, 30, 30, 0.96);
    box-shadow: 0 -8px 40px rgba(0, 0, 0, 0.4);
  }

  .eng-sheet__handle-bar {
    background: rgba(255, 255, 255, 0.2);
  }

  .eng-sheet__close {
    background: rgba(255, 255, 255, 0.1);
    color: rgba(255, 255, 255, 0.6);
  }

  .eng-content__title { color: #f5f5f5; }
  .eng-content__subtitle { color: #aaa; }
  .eng-content__benefit { color: #86efac; }

  .eng-sheet input,
  .eng-sheet select,
  .eng-sheet textarea {
    background: #2a2a2a;
    border-color: rgba(255, 255, 255, 0.12);
    color: #f5f5f5;
  }

  .eng-chip {
    background: #2a2a2a;
    border-color: rgba(255, 255, 255, 0.1);
    color: #f5f5f5;
  }

  .eng-chip.active {
    background: #4ade80;
    color: #1a1a1a;
    border-color: #4ade80;
  }

  .eng-btn--ics {
    background: #333;
    color: #f5f5f5;
  }
}

/* ---------- RESPONSIVE ---------- */
@media (max-width: 768px) {
  .eng-sheet__inner {
    max-width: 100%;
    border-radius: 16px 16px 0 0;
  }

  .eng-sheet__content {
    padding: 8px 16px 20px;
  }

  .eng-content__title {
    font-size: 16px;
  }

  .eng-content__icon {
    font-size: 32px;
  }

  .eng-calendar-buttons,
  .eng-chat-buttons {
    flex-direction: column;
    align-items: stretch;
  }

  .eng-calendar-buttons .eng-btn,
  .eng-chat-buttons .eng-btn {
    max-width: none;
  }
}

@media (min-width: 1025px) {
  /* Desktop: optional right-aligned positioning */
  .eng-sheet--desktop-right {
    left: auto;
    right: 24px;
    bottom: 24px;
    max-width: 400px;
  }

  .eng-sheet--desktop-right .eng-sheet__inner {
    border-radius: 20px;
    box-shadow: 0 8px 40px rgba(0, 0, 0, 0.15);
  }

  .eng-sheet--desktop-right.active {
    transform: translateY(0);
  }
}

/* ---------- REDUCED MOTION ---------- */
@media (prefers-reduced-motion: reduce) {
  .eng-sheet,
  .eng-backdrop,
  .eng-toast,
  .eng-btn,
  .eng-chip {
    transition: none !important;
  }
}

/* ---------- PRINT ---------- */
@media print {
  .eng-sheet,
  .eng-backdrop,
  .eng-toast {
    display: none !important;
  }
}