/* ============================================
   ReviveFlow AI — Premium landing page styles
   Clean, modern, tech-forward, outcome-focused
   ============================================ */

:root {
  --color-bg: #0a0b0d;
  --color-bg-elevated: #111215;
  --color-bg-card: #16181c;
  --color-surface: #1c1e24;
  --color-border: rgba(255, 255, 255, 0.06);
  --color-text: #e8eaed;
  --color-text-muted: #9ca3af;
  --color-text-faint: #6b7280;
  --color-accent: #4f9cf9;
  --color-accent-soft: rgba(79, 156, 249, 0.15);
  --color-accent-gradient: linear-gradient(135deg, #4f9cf9 0%, #7c6cf7 100%);
  --color-success: #34d399;
  --font-sans: "DM Sans", system-ui, sans-serif;
  --font-display: "Outfit", "DM Sans", system-ui, sans-serif;
  --space-xs: 0.5rem;
  --space-sm: 1rem;
  --space-md: 1.5rem;
  --space-lg: 2rem;
  --space-xl: 3rem;
  --space-2xl: 4rem;
  --space-3xl: 6rem;
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --transition: 0.2s ease;
}

*,
*::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(--color-text);
  background: var(--color-bg);
  -webkit-font-smoothing: antialiased;
}

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

/* ----- Header ----- */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  padding: var(--space-md) var(--space-lg);
  background: rgba(10, 11, 13, 0.85);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
}

.header-inner {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-lg);
}

.logo {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.25rem;
  letter-spacing: -0.02em;
}

.logo-ai {
  color: var(--color-accent);
  font-weight: 600;
}

.nav {
  display: flex;
  gap: var(--space-lg);
}

.nav a {
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--color-text-muted);
  transition: color var(--transition);
}

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

.btn-header {
  padding: 0.5rem 1rem;
  font-size: 0.9375rem;
  font-weight: 600;
  color: var(--color-text);
  background: var(--color-accent-soft);
  border: 1px solid rgba(79, 156, 249, 0.3);
  border-radius: var(--radius-sm);
  transition: background var(--transition), border-color var(--transition);
}

.btn-header:hover {
  background: rgba(79, 156, 249, 0.25);
  border-color: var(--color-accent);
}

/* ----- Buttons ----- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.75rem 1.5rem;
  font-family: var(--font-sans);
  font-size: 0.9375rem;
  font-weight: 600;
  border-radius: var(--radius-md);
  border: none;
  cursor: pointer;
  transition: opacity var(--transition), transform var(--transition), box-shadow var(--transition);
}

.btn:hover {
  opacity: 0.95;
  transform: translateY(-1px);
}

.btn-primary {
  color: #fff;
  background: var(--color-accent-gradient);
  box-shadow: 0 4px 14px rgba(79, 156, 249, 0.35);
}

.btn-primary:hover {
  box-shadow: 0 6px 20px rgba(79, 156, 249, 0.45);
}

.btn-secondary {
  color: var(--color-text);
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
}

.btn-secondary:hover {
  border-color: rgba(255, 255, 255, 0.12);
  background: var(--color-surface);
}

.btn-large {
  padding: 1rem 2rem;
  font-size: 1rem;
}

/* ----- Container ----- */
.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

/* ----- Hero ----- */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding: calc(80px + var(--space-3xl)) var(--space-lg) var(--space-3xl);
  overflow: hidden;
}

.hero-bg {
  position: absolute;
  inset: 0;
  background:
    radial-gradient(ellipse 80% 50% at 50% -20%, rgba(79, 156, 249, 0.12) 0%, transparent 50%),
    radial-gradient(ellipse 60% 40% at 80% 60%, rgba(124, 108, 247, 0.08) 0%, transparent 45%),
    var(--color-bg);
  pointer-events: none;
}

.hero-inner {
  position: relative;
  z-index: 1;
}

.hero-label {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-accent);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: var(--space-md);
}

.hero-headline {
  font-family: var(--font-display);
  font-size: clamp(2.5rem, 5vw, 3.75rem);
  font-weight: 700;
  line-height: 1.12;
  letter-spacing: -0.03em;
  margin: 0 0 var(--space-lg);
  max-width: 720px;
}

.hero-subheadline {
  font-size: 1.25rem;
  color: var(--color-text-muted);
  max-width: 580px;
  margin: 0 0 var(--space-xl);
  line-height: 1.55;
}

.hero-ctas {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-md);
}

/* ----- Section defaults ----- */
.section {
  padding: var(--space-3xl) 0;
}

.section-label {
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--color-accent);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin: 0 0 var(--space-sm);
}

.section-headline {
  font-family: var(--font-display);
  font-size: clamp(2rem, 4vw, 2.75rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1.2;
  margin: 0 0 var(--space-md);
}

.section-lead {
  font-size: 1.125rem;
  color: var(--color-text-muted);
  max-width: 640px;
  margin: 0 0 var(--space-xl);
  line-height: 1.6;
}

/* ----- Problem section ----- */
.section-problem {
  background: var(--color-bg-elevated);
}

.problem-grid {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-md);
}

@media (max-width: 768px) {
  .problem-grid {
    grid-template-columns: 1fr;
  }
}

.problem-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
  transition: border-color var(--transition);
}

.problem-card:hover {
  border-color: rgba(255, 255, 255, 0.1);
}

.problem-card-wide {
  grid-column: 1 / -1;
}

.problem-icon {
  display: block;
  width: 40px;
  height: 4px;
  background: var(--color-accent-gradient);
  border-radius: 2px;
  margin-bottom: var(--space-md);
}

.problem-card h3 {
  font-family: var(--font-display);
  font-size: 1.125rem;
  font-weight: 600;
  margin: 0 0 var(--space-xs);
}

.problem-card p {
  font-size: 0.9375rem;
  color: var(--color-text-muted);
  margin: 0;
  line-height: 1.55;
}

/* ----- Solution section ----- */
.solution-list {
  list-style: none;
  margin: 0;
  padding: 0;
  max-width: 700px;
}

.solution-list li {
  position: relative;
  padding-left: 1.75rem;
  margin-bottom: var(--space-md);
  font-size: 1.0625rem;
  color: var(--color-text-muted);
  line-height: 1.6;
}

.solution-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.5em;
  width: 8px;
  height: 8px;
  background: var(--color-accent);
  border-radius: 50%;
}

.solution-list strong {
  color: var(--color-text);
  font-weight: 600;
}

/* ----- How it works (steps) ----- */
.section-steps {
  background: var(--color-bg-elevated);
}

.steps-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-lg);
}

@media (max-width: 900px) {
  .steps-list {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 520px) {
  .steps-list {
    grid-template-columns: 1fr;
  }
}

.step {
  position: relative;
  padding-top: 2.5rem;
}

.step-num {
  position: absolute;
  top: 0;
  left: 0;
  font-family: var(--font-display);
  font-size: 2rem;
  font-weight: 700;
  color: var(--color-accent);
  opacity: 0.9;
  line-height: 1;
}

.step h3 {
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: 600;
  margin: 0 0 var(--space-sm);
}

.step p {
  font-size: 0.9375rem;
  color: var(--color-text-muted);
  margin: 0;
  line-height: 1.55;
}

/* ----- Results ----- */
.results-grid {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-md);
}

@media (max-width: 768px) {
  .results-grid {
    grid-template-columns: 1fr;
  }
}

.result-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
}

.result-value {
  display: block;
  font-family: var(--font-display);
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--color-accent);
  margin-bottom: var(--space-xs);
}

.result-card p {
  font-size: 0.9375rem;
  color: var(--color-text-muted);
  margin: 0;
  line-height: 1.55;
}

/* ----- Use cases ----- */
.section-usecases {
  background: var(--color-bg-elevated);
}

.usecases-grid {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-md);
}

@media (max-width: 768px) {
  .usecases-grid {
    grid-template-columns: 1fr;
  }
}

.usecase-card {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
}

.usecase-card h3 {
  font-family: var(--font-display);
  font-size: 1.0625rem;
  font-weight: 600;
  margin: 0 0 var(--space-sm);
}

.usecase-card p {
  font-size: 0.9375rem;
  color: var(--color-text-muted);
  margin: 0;
  line-height: 1.55;
}

/* ----- Trust ----- */
.trust-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-lg);
}

@media (max-width: 768px) {
  .trust-grid {
    grid-template-columns: 1fr;
  }
}

.trust-block {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
}

.trust-block-full {
  grid-column: 1 / -1;
}

.trust-block h3 {
  font-family: var(--font-display);
  font-size: 1.125rem;
  font-weight: 600;
  margin: 0 0 var(--space-md);
}

.trust-block p,
.testimonial footer {
  font-size: 0.9375rem;
  color: var(--color-text-muted);
  margin: 0 0 var(--space-md);
  line-height: 1.55;
}

.trust-block p:last-child,
.testimonial:last-of-type {
  margin-bottom: 0;
}

.testimonial {
  margin: 0 0 var(--space-lg);
  padding: 0;
  border: none;
}

.testimonial p {
  font-style: italic;
  color: var(--color-text);
  margin-bottom: var(--space-xs);
}

.testimonial footer {
  font-size: 0.875rem;
  color: var(--color-text-faint);
  font-style: normal;
}

/* ----- Final CTA ----- */
.section-cta {
  padding: var(--space-3xl) 0;
  background: linear-gradient(180deg, var(--color-bg-elevated) 0%, var(--color-bg) 100%);
}

.cta-inner {
  text-align: center;
  max-width: 640px;
  margin: 0 auto;
}

.cta-headline {
  font-family: var(--font-display);
  font-size: clamp(2rem, 4vw, 2.5rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  margin: 0 0 var(--space-md);
}

.cta-subheadline {
  font-size: 1.125rem;
  color: var(--color-text-muted);
  margin: 0 0 var(--space-xl);
  line-height: 1.6;
}

.cta-actions {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: var(--space-md);
  margin-bottom: var(--space-lg);
}

.cta-note {
  font-size: 0.875rem;
  color: var(--color-text-faint);
  margin: 0;
}

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

.footer-inner {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: var(--space-2xl);
  padding-bottom: var(--space-xl);
}

@media (max-width: 768px) {
  .footer-inner {
    grid-template-columns: 1fr;
  }
}

.footer-brand .logo {
  display: inline-block;
  margin-bottom: var(--space-sm);
}

.footer-brand p {
  font-size: 0.9375rem;
  color: var(--color-text-muted);
  max-width: 360px;
  margin: 0;
  line-height: 1.6;
}

.footer-links {
  display: flex;
  gap: var(--space-xl);
}

.footer-col h4 {
  font-family: var(--font-display);
  font-size: 0.8125rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-text-faint);
  margin: 0 0 var(--space-sm);
}

.footer-col a {
  display: block;
  font-size: 0.9375rem;
  color: var(--color-text-muted);
  margin-bottom: var(--space-xs);
  transition: color var(--transition);
}

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

.footer-bottom {
  padding: var(--space-md) 0;
  border-top: 1px solid var(--color-border);
}

.footer-bottom p {
  font-size: 0.8125rem;
  color: var(--color-text-faint);
  margin: 0;
}

/* Responsive nav: hide links on small screens, keep CTA */
@media (max-width: 640px) {
  .nav {
    display: none;
  }
}