/* ============================================
   KerfOS — Landing Page Styles
   ============================================ */

/* ----- Design Tokens ----- */
:root {
  /* Brand Colors */
  --color-walnut: #2C1810;
  --color-oak: #8B5E3C;
  --color-maple: #D4A574;
  --color-parchment: #FAF6F1;
  --color-cta: #C45D2C;
  --color-cta-hover: #A84E25;
  --color-success: #4A7C59;

  /* Neutral */
  --color-white: #FFFFFF;
  --color-black: #1A1A1A;
  --color-gray-600: #6B7280;

  /* Typography */
  --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto,
    Oxygen, Ubuntu, Cantarell, 'Helvetica Neue', sans-serif;
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;
  --font-size-3xl: 1.875rem;
  --font-size-4xl: 2.25rem;
  --font-size-5xl: 3rem;

  /* Spacing Scale */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;

  /* Layout */
  --container-max-width: 1140px;
  --border-radius: 0.5rem;
  --border-radius-lg: 1rem;

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;
}

/* ----- CSS Reset / Normalize ----- */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

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

body {
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  line-height: 1.6;
  color: var(--color-walnut);
  background-color: var(--color-parchment);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

img,
picture,
video,
canvas,
svg {
  display: block;
  max-width: 100%;
}

input,
button,
textarea,
select {
  font: inherit;
  color: inherit;
}

button {
  cursor: pointer;
  border: none;
  background: none;
}

ul,
ol {
  list-style: none;
}

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

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

h1 {
  font-size: var(--font-size-5xl);
}

h2 {
  font-size: var(--font-size-4xl);
}

h3 {
  font-size: var(--font-size-2xl);
}

h4 {
  font-size: var(--font-size-xl);
}

p {
  margin-bottom: var(--space-4);
}

a:hover,
a:focus-visible {
  color: var(--color-cta);
}

a:focus-visible {
  outline: 2px solid var(--color-cta);
  outline-offset: 2px;
}

/* ----- Global Layout Utilities ----- */
.container {
  width: 100%;
  max-width: var(--container-max-width);
  margin-inline: auto;
  padding-inline: var(--space-6);
}

.section {
  padding-block: var(--space-20);
}

.section--sm {
  padding-block: var(--space-12);
}

.section--lg {
  padding-block: var(--space-24);
}

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

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* ----- Site Header ----- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: var(--color-parchment);
  border-bottom: 1px solid var(--color-maple);
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-block: var(--space-4);
}

.nav__logo {
  font-size: var(--font-size-xl);
  font-weight: 700;
  color: var(--color-walnut);
  letter-spacing: -0.02em;
}

.nav__logo:hover,
.nav__logo:focus-visible {
  color: var(--color-oak);
}

.nav__menu {
  display: flex;
  align-items: center;
  gap: var(--space-8);
  /* Mobile-first: overridden by responsive section below */
}

.nav__link {
  font-size: var(--font-size-sm);
  font-weight: 500;
  color: var(--color-walnut);
  transition: color var(--transition-fast);
}

.nav__link:hover,
.nav__link:focus-visible {
  color: var(--color-cta);
}

.nav__link--cta {
  color: var(--color-white);
  background-color: var(--color-cta);
  padding: var(--space-2) var(--space-5);
  border-radius: var(--border-radius);
  transition: background-color var(--transition-fast), color var(--transition-fast);
}

.nav__link--cta:hover,
.nav__link--cta:focus-visible {
  color: var(--color-white);
  background-color: var(--color-cta-hover);
}

/* nav__toggle base styles are in responsive section below */

.nav__hamburger,
.nav__hamburger::before,
.nav__hamburger::after {
  display: block;
  width: 1.25rem;
  height: 2px;
  background-color: var(--color-walnut);
  border-radius: 1px;
  transition: transform var(--transition-fast), opacity var(--transition-fast);
}

.nav__hamburger {
  position: relative;
}

.nav__hamburger::before,
.nav__hamburger::after {
  content: '';
  position: absolute;
  left: 0;
}

.nav__hamburger::before {
  top: -6px;
}

.nav__hamburger::after {
  top: 6px;
}

/* ----- Hero Section ----- */
#hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  background: linear-gradient(
    135deg,
    var(--color-parchment) 0%,
    #F5EDE4 40%,
    #EDE0D4 100%
  );
}

.hero__inner {
  text-align: center;
  max-width: 48rem;
  margin-inline: auto;
  padding-block: var(--space-24);
}

.hero__headline {
  font-size: var(--font-size-5xl);
  margin-bottom: var(--space-6);
}

.hero__subheadline {
  font-size: var(--font-size-lg);
  color: var(--color-oak);
  margin-bottom: var(--space-8);
  max-width: 36rem;
  margin-inline: auto;
}

.hero__kerf-callout {
  display: inline-block;
  font-size: var(--font-size-sm);
  color: var(--color-oak);
  background-color: var(--color-white);
  border: 1px solid var(--color-maple);
  border-radius: var(--border-radius);
  padding: var(--space-3) var(--space-5);
  margin-bottom: var(--space-10);
}

.hero__kerf-phonetic {
  font-weight: 600;
  color: var(--color-walnut);
}

/* ----- Buttons ----- */
.btn {
  display: inline-block;
  font-weight: 600;
  text-align: center;
  border-radius: var(--border-radius);
  padding: var(--space-4) var(--space-8);
  transition: background-color var(--transition-fast), transform var(--transition-fast);
}

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

.btn--cta {
  font-size: var(--font-size-lg);
  color: var(--color-white);
  background-color: var(--color-cta);
}

.btn--cta:hover {
  color: var(--color-white);
  background-color: var(--color-cta-hover);
  transform: translateY(-1px);
}

.btn--cta:focus-visible {
  color: var(--color-white);
  background-color: var(--color-cta-hover);
}

/* ----- Features Section ----- */
.features {
  padding-block: var(--space-24);
  background-color: var(--color-white);
}

.features__heading {
  margin-bottom: var(--space-16);
}

.features__grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: var(--space-8);
}

.feature-card {
  background-color: var(--color-parchment);
  border-radius: var(--border-radius-lg);
  padding: var(--space-8);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.06);
  transition: transform var(--transition-base), box-shadow var(--transition-base);
}

.feature-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 24px rgba(44, 24, 16, 0.1);
}

.feature-card__icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 3rem;
  height: 3rem;
  background-color: var(--color-white);
  border-radius: var(--border-radius);
  color: var(--color-cta);
  margin-bottom: var(--space-5);
}

.feature-card__title {
  font-size: var(--font-size-xl);
  margin-bottom: var(--space-3);
}

.feature-card__description {
  font-size: var(--font-size-sm);
  color: var(--color-gray-600);
  line-height: 1.7;
  margin-bottom: 0;
}

/* ----- How It Works Section ----- */
.how-it-works {
  padding-block: var(--space-24);
  background-color: var(--color-parchment);
}

.how-it-works__heading {
  margin-bottom: var(--space-16);
}

.how-it-works__steps {
  display: flex;
  justify-content: center;
  gap: var(--space-12);
  position: relative;
}

.step {
  flex: 1;
  max-width: 280px;
  text-align: center;
  position: relative;
}

/* Connector lines between steps */
.step:not(:last-child)::after {
  content: '';
  position: absolute;
  top: 1.75rem;
  left: calc(50% + 2rem);
  width: calc(100% - 2rem);
  height: 2px;
  background-color: var(--color-maple);
}

.step__badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 3.5rem;
  height: 3.5rem;
  border-radius: 50%;
  background-color: var(--color-cta);
  color: var(--color-white);
  font-size: var(--font-size-xl);
  font-weight: 700;
  margin-bottom: var(--space-5);
  position: relative;
  z-index: 1;
}

.step__icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 3rem;
  height: 3rem;
  margin-inline: auto;
  margin-bottom: var(--space-5);
  color: var(--color-oak);
}

.step__title {
  font-size: var(--font-size-xl);
  margin-bottom: var(--space-3);
}

.step__description {
  font-size: var(--font-size-sm);
  color: var(--color-gray-600);
  line-height: 1.7;
  margin-bottom: 0;
}

/* ----- Signup Section ----- */
.signup {
  padding-block: var(--space-24);
  background-color: var(--color-walnut);
  color: var(--color-parchment);
}

.signup__inner {
  max-width: 36rem;
  margin-inline: auto;
  text-align: center;
}

.signup__heading {
  color: var(--color-parchment);
  margin-bottom: var(--space-4);
}

.signup__description {
  color: var(--color-maple);
  font-size: var(--font-size-lg);
  margin-bottom: var(--space-8);
}

.signup__label {
  display: block;
  font-size: var(--font-size-sm);
  font-weight: 500;
  margin-bottom: var(--space-2);
  text-align: left;
}

.signup__field {
  display: flex;
  gap: var(--space-3);
}

.signup__input {
  flex: 1;
  padding: var(--space-4);
  font-size: var(--font-size-base);
  border: 2px solid transparent;
  border-radius: var(--border-radius);
  background-color: var(--color-white);
  color: var(--color-walnut);
  transition: border-color var(--transition-fast);
}

.signup__input::placeholder {
  color: var(--color-gray-600);
}

.signup__input:focus {
  outline: none;
  border-color: var(--color-cta);
}

.signup__submit {
  white-space: nowrap;
}

.signup__success {
  margin-top: var(--space-4);
  padding: var(--space-3) var(--space-4);
  background-color: var(--color-success);
  color: var(--color-white);
  border-radius: var(--border-radius);
  font-size: var(--font-size-sm);
}

.signup__error {
  margin-top: var(--space-4);
  padding: var(--space-3) var(--space-4);
  background-color: #C44D4D;
  color: var(--color-white);
  border-radius: var(--border-radius);
  font-size: var(--font-size-sm);
}

.signup__error a {
  color: var(--color-white);
  text-decoration: underline;
}

.signup__noscript {
  margin-top: var(--space-3);
  font-size: var(--font-size-xs);
  color: var(--color-maple);
}

/* ----- Site Footer ----- */
.site-footer {
  padding-block: var(--space-8);
  background-color: var(--color-black);
  color: var(--color-gray-600);
}

.site-footer__inner {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-6);
  flex-wrap: wrap;
  font-size: var(--font-size-sm);
}

.site-footer__copyright {
  margin-bottom: 0;
}

.site-footer__tagline {
  margin-bottom: 0;
  font-style: italic;
}

.site-footer__link {
  color: var(--color-maple);
  transition: color var(--transition-fast);
}

.site-footer__link:hover,
.site-footer__link:focus-visible {
  color: var(--color-parchment);
}

/* ============================================
   Responsive Design — Mobile-First
   ============================================ */

/* ----- Mobile Navigation (off-canvas slide-in) ----- */
.nav__toggle {
  display: flex;
  width: 2.75rem;
  height: 2.75rem;
  min-height: 44px;
  min-width: 44px;
  align-items: center;
  justify-content: center;
}

.nav__menu {
  position: fixed;
  top: 0;
  right: 0;
  bottom: 0;
  width: min(80vw, 20rem);
  flex-direction: column;
  background-color: var(--color-parchment);
  border-left: 1px solid var(--color-maple);
  padding: var(--space-16) var(--space-6) var(--space-6);
  gap: var(--space-4);
  transform: translateX(100%);
  transition: transform var(--transition-base);
  z-index: 200;
  overflow-y: auto;
}

.nav__menu.is-open {
  transform: translateX(0);
}

/* Overlay behind mobile menu */
.nav__overlay {
  display: none;
  position: fixed;
  inset: 0;
  background-color: rgba(0, 0, 0, 0.4);
  z-index: 150;
}

.nav__overlay.is-visible {
  display: block;
}

/* Hamburger-to-X animation */
.nav__toggle[aria-expanded="true"] .nav__hamburger {
  background-color: transparent;
}

.nav__toggle[aria-expanded="true"] .nav__hamburger::before {
  top: 0;
  transform: rotate(45deg);
}

.nav__toggle[aria-expanded="true"] .nav__hamburger::after {
  top: 0;
  transform: rotate(-45deg);
}

/* Mobile nav links — ensure touch targets */
.nav__link {
  min-height: 44px;
  display: inline-flex;
  align-items: center;
}

/* ----- Mobile Base (< 768px) ----- */
.site-header {
  position: relative;
}

.hero__headline {
  font-size: var(--font-size-3xl);
}

.hero__subheadline {
  font-size: var(--font-size-base);
}

.how-it-works__steps {
  flex-direction: column;
  align-items: center;
  gap: var(--space-8);
}

.step:not(:last-child)::after {
  display: none;
}

.signup__field {
  flex-direction: column;
}

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

/* Prevent horizontal scroll */
html {
  overflow-x: hidden;
}

/* ----- Tablet (min-width: 768px) ----- */
@media (min-width: 768px) {
  .nav__toggle {
    display: none;
  }

  .nav__menu {
    position: static;
    width: auto;
    flex-direction: row;
    background-color: transparent;
    border-left: none;
    padding: 0;
    gap: var(--space-8);
    transform: none;
    transition: none;
    z-index: auto;
    overflow-y: visible;
  }

  .nav__overlay {
    display: none !important;
  }

  .site-header {
    position: sticky;
  }

  .hero__headline {
    font-size: var(--font-size-4xl);
  }

  .hero__subheadline {
    font-size: var(--font-size-lg);
  }

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

  .how-it-works__steps {
    flex-direction: row;
    align-items: flex-start;
    gap: var(--space-12);
  }

  .step:not(:last-child)::after {
    display: block;
  }

  .signup__field {
    flex-direction: row;
  }
}

/* ----- Desktop (min-width: 1024px) ----- */
@media (min-width: 1024px) {
  .container {
    padding-inline: var(--space-8);
  }

  .section {
    padding-block: var(--space-24);
  }

  .section--lg {
    padding-block: calc(var(--space-24) + var(--space-8));
  }

  h1 {
    font-size: var(--font-size-5xl);
  }

  h2 {
    font-size: var(--font-size-4xl);
  }

  .hero__headline {
    font-size: var(--font-size-5xl);
  }

  .hero__subheadline {
    font-size: var(--font-size-xl);
  }

  .features {
    padding-block: calc(var(--space-24) + var(--space-8));
  }

  .features__grid {
    grid-template-columns: repeat(4, 1fr);
  }

  .how-it-works {
    padding-block: calc(var(--space-24) + var(--space-8));
  }

  .signup {
    padding-block: calc(var(--space-24) + var(--space-8));
  }
}

/* ============================================
   Dark Mode
   ============================================ */
@media (prefers-color-scheme: dark) {
  :root {
    --color-walnut: #FAF6F1;
    --color-oak: #D4A574;
    --color-maple: #8B5E3C;
    --color-parchment: #1A1A2E;
    --color-white: #242440;
    --color-black: #0F0F1E;
    --color-gray-600: #9CA3AF;
    --color-cta: #E07A4A;
    --color-cta-hover: #C45D2C;
    --color-success: #5DA06E;
  }

  body {
    -webkit-font-smoothing: antialiased;
  }

  /* Hero gradient for dark */
  #hero {
    background: linear-gradient(
      135deg,
      var(--color-parchment) 0%,
      #1E1E36 40%,
      #22223A 100%
    );
  }

  /* Feature cards */
  .feature-card {
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.3);
  }

  .feature-card:hover {
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.4);
  }

  .feature-card__icon {
    background-color: #2E2E4A;
  }

  /* Nav hamburger */
  .nav__hamburger,
  .nav__hamburger::before,
  .nav__hamburger::after {
    background-color: var(--color-walnut);
  }

  /* Signup section */
  .signup {
    background-color: #12122A;
  }

  .signup__input {
    background-color: #2A2A48;
    color: var(--color-walnut);
    border: 2px solid #3A3A58;
  }

  .signup__input::placeholder {
    color: var(--color-gray-600);
  }

  .signup__input:focus {
    border-color: var(--color-cta);
  }

  /* Success/error messages */
  .signup__success {
    background-color: var(--color-success);
    color: #FFFFFF;
  }

  .signup__error {
    background-color: #C44D4D;
    color: #FFFFFF;
  }

  .signup__error a {
    color: #FFFFFF;
  }

  /* Footer */
  .site-footer {
    background-color: #0A0A18;
  }

  .site-footer__link {
    color: var(--color-oak);
  }

  .site-footer__link:hover,
  .site-footer__link:focus-visible {
    color: var(--color-walnut);
  }

  /* Mobile menu overlay */
  .nav__overlay {
    background-color: rgba(0, 0, 0, 0.6);
  }

  /* Nav menu mobile panel */
  .nav__menu {
    background-color: var(--color-parchment);
    border-left-color: var(--color-maple);
  }

  /* Kerf callout */
  .hero__kerf-callout {
    background-color: #242440;
    border-color: var(--color-maple);
  }

  /* Step connector */
  .step:not(:last-child)::after {
    background-color: var(--color-maple);
  }

  /* Links and buttons maintain contrast */
  .nav__link--cta {
    color: #FFFFFF;
  }

  .nav__link--cta:hover,
  .nav__link--cta:focus-visible {
    color: #FFFFFF;
  }

  .btn--cta {
    color: #FFFFFF;
  }

  .btn--cta:hover,
  .btn--cta:focus-visible {
    color: #FFFFFF;
  }
}

/* ==========================================
   Scroll-triggered fade-in animations
   ========================================== */

.fade-in {
  opacity: 0;
  transform: translateY(1rem);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in--visible {
  opacity: 1;
  transform: translateY(0);
}