/* ==========================================================================
   CPS Learning App — Design System Stylesheet
   Project Specification Template

   Implements extracted Figma design tokens (frame figma_2:3):
   - Colors:  #FFFFFF (white surface), #FF5500 (accent)
   - Fonts:   Inter (12/14px, weights 400/600/700), Manrope (16/20px, weight 900)
   - Spacing: 2 / 4 / 6 / 8 / 12 / 24 px
   - Radius:  8 / 12 / 16 / 24 px

   Design patterns: minimalist_typography, scroll_triggered_reveals,
   skeleton_loading. No build step required — deployable to GitHub Pages as-is.
   ========================================================================== */

/* --------------------------------------------------------------------------
   1. Design Tokens (CSS Custom Properties)
   -------------------------------------------------------------------------- */
:root {
  /* Core brand colors (from Figma) */
  --color-white: #ffffff;
  --color-accent: #ff5500;

  /* Derived accent states (kept close to brand, AA-compliant on white) */
  --color-accent-hover: #e64d00;
  --color-accent-active: #cc4400;
  --color-accent-soft: #fff1ea;

  /* Neutral scale — near-black text for softer contrast than pure #000 */
  --color-text: #1a1a1f;
  --color-text-muted: #5a5a63;
  --color-surface: var(--color-white);
  --color-surface-alt: #f7f7f8;
  --color-border: #e4e4e7;
  --color-skeleton: #e5e7eb;
  --color-skeleton-sheen: rgba(255, 255, 255, 0.6);

  /* Font families (Google Fonts loaded in index.html) */
  --font-inter: "Inter", system-ui, -apple-system, "Segoe UI", Roboto,
    "Helvetica Neue", Arial, sans-serif;
  --font-manrope: "Manrope", var(--font-inter);

  /* Spacing scale (2 / 4 / 6 / 8 / 12 / 24 px) */
  --spacing-2: 0.125rem; /* 2px */
  --spacing-4: 0.25rem; /* 4px */
  --spacing-6: 0.375rem; /* 6px */
  --spacing-8: 0.5rem; /* 8px */
  --spacing-12: 0.75rem; /* 12px */
  --spacing-24: 1.5rem; /* 24px */

  /* Larger layout rhythm derived from the base scale */
  --spacing-section: clamp(4rem, 2rem + 8vw, 7.5rem); /* 120px+ at desktop */

  /* Border radius scale (8 / 12 / 16 / 24 px) */
  --radius-8: 0.5rem;
  --radius-12: 0.75rem;
  --radius-16: 1rem;
  --radius-24: 1.5rem;
  --radius-pill: 9999px;

  /* Fluid typography — minimalist scale using clamp() */
  --font-size-xs: clamp(0.75rem, 0.72rem + 0.15vw, 0.8125rem); /* ~12-13px */
  --font-size-sm: clamp(0.875rem, 0.84rem + 0.18vw, 0.9375rem); /* ~14-15px */
  --font-size-base: clamp(1rem, 0.95rem + 0.3vw, 1.125rem); /* 16-18px */
  --font-size-lg: clamp(1.125rem, 1rem + 0.6vw, 1.375rem); /* 18-22px */
  --font-size-xl: clamp(1.5rem, 1.2rem + 1.4vw, 2rem); /* 24-32px */
  --font-size-2xl: clamp(2rem, 1.4rem + 2.8vw, 3rem); /* 32-48px */
  --font-size-hero: clamp(2.5rem, 1.5rem + 5vw, 4.5rem); /* 40-72px */

  /* Elevation */
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08), 0 4px 12px rgba(0, 0, 0, 0.04);
  --shadow-md: 0 6px 16px rgba(0, 0, 0, 0.08), 0 12px 32px rgba(0, 0, 0, 0.06);

  /* Motion */
  --transition-fast: 0.2s ease;
  --transition-reveal: 0.6s cubic-bezier(0.25, 0.1, 0.25, 1);

  /* Layout */
  --container-max: 72rem;
  --prose-max: 65ch;
}

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

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

body {
  min-height: 100vh;
  font-family: var(--font-inter);
  font-size: var(--font-size-base);
  font-weight: 400;
  line-height: 1.6;
  color: var(--color-text);
  background-color: var(--color-surface);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

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

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

ul[class],
ol[class] {
  list-style: none;
}

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

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

/* --------------------------------------------------------------------------
   3. Typography System (minimalist_typography pattern)
   -------------------------------------------------------------------------- */
h1,
h2,
h3,
h4 {
  font-family: var(--font-manrope);
  font-weight: 900;
  line-height: 1.1;
  letter-spacing: -0.02em;
  color: var(--color-text);
  text-wrap: balance;
}

h1 {
  font-size: var(--font-size-hero);
}

h2 {
  font-size: var(--font-size-2xl);
}

h3 {
  font-size: var(--font-size-xl);
  line-height: 1.2;
}

h4 {
  font-size: var(--font-size-lg);
  line-height: 1.3;
}

p {
  max-width: var(--prose-max);
}

.eyebrow {
  display: inline-block;
  font-size: var(--font-size-xs);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.2em;
  color: var(--color-accent);
}

.lead {
  font-size: var(--font-size-lg);
  color: var(--color-text-muted);
  line-height: 1.6;
}

.text-muted {
  color: var(--color-text-muted);
}

/* --------------------------------------------------------------------------
   4. Layout Utilities
   -------------------------------------------------------------------------- */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin-inline: auto;
  padding-inline: var(--spacing-24);
}

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

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

.stack > * + * {
  margin-top: var(--spacing-24);
}

.flow > * + * {
  margin-top: var(--spacing-12);
}

.grid {
  display: grid;
  gap: var(--spacing-24);
}

.cluster {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-12);
  align-items: center;
}

/* Spacing utility classes mapped to the token scale */
.mt-8 {
  margin-top: var(--spacing-8);
}
.mt-12 {
  margin-top: var(--spacing-12);
}
.mt-24 {
  margin-top: var(--spacing-24);
}
.gap-8 {
  gap: var(--spacing-8);
}
.gap-12 {
  gap: var(--spacing-12);
}
.gap-24 {
  gap: var(--spacing-24);
}

/* Color utility classes */
.bg-white {
  background-color: var(--color-white);
}
.bg-accent {
  background-color: var(--color-accent);
}
.text-accent {
  color: var(--color-accent);
}

/* Accessibility helpers */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.skip-link {
  position: absolute;
  top: -100%;
  left: var(--spacing-8);
  z-index: 100;
  padding: var(--spacing-8) var(--spacing-24);
  background-color: var(--color-accent);
  color: var(--color-white);
  font-weight: 600;
  border-radius: var(--radius-8);
}

.skip-link:focus {
  top: var(--spacing-8);
}

/* --------------------------------------------------------------------------
   5. Header & Navigation
   -------------------------------------------------------------------------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 40;
  background-color: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--color-border);
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--spacing-24);
  padding-block: var(--spacing-12);
}

.site-header__brand {
  font-family: var(--font-manrope);
  font-weight: 900;
  font-size: var(--font-size-lg);
  letter-spacing: -0.02em;
}

.site-header__brand .text-accent {
  color: var(--color-accent);
}

.main-nav__list {
  display: flex;
  align-items: center;
  gap: var(--spacing-24);
}

.main-nav__link {
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: var(--color-text-muted);
  transition: color var(--transition-fast);
}

.main-nav__link:hover,
.main-nav__link[aria-current="page"] {
  color: var(--color-text);
}

.nav-toggle {
  display: none;
  width: 44px;
  height: 44px;
  padding: var(--spacing-8);
  background: transparent;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-8);
  cursor: pointer;
}

.nav-toggle__bar,
.nav-toggle__bar::before,
.nav-toggle__bar::after {
  display: block;
  width: 20px;
  height: 2px;
  background-color: var(--color-text);
  transition: transform var(--transition-fast), opacity var(--transition-fast);
}

.nav-toggle__bar {
  position: relative;
  margin-inline: auto;
}

.nav-toggle__bar::before,
.nav-toggle__bar::after {
  content: "";
  position: absolute;
  left: 0;
}

.nav-toggle__bar::before {
  top: -6px;
}

.nav-toggle__bar::after {
  top: 6px;
}

.nav-toggle[aria-expanded="true"] .nav-toggle__bar {
  background-color: transparent;
}

.nav-toggle[aria-expanded="true"] .nav-toggle__bar::before {
  transform: translateY(6px) rotate(45deg);
}

.nav-toggle[aria-expanded="true"] .nav-toggle__bar::after {
  transform: translateY(-6px) rotate(-45deg);
}

/* --------------------------------------------------------------------------
   6. Buttons (morphing states via transitions)
   -------------------------------------------------------------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-8);
  min-height: 44px;
  padding: var(--spacing-12) var(--spacing-24);
  font-size: var(--font-size-sm);
  font-weight: 600;
  border: 1px solid transparent;
  border-radius: var(--radius-12);
  cursor: pointer;
  transition: background-color var(--transition-fast),
    color var(--transition-fast), transform var(--transition-fast),
    box-shadow var(--transition-fast);
}

.btn:active {
  transform: translateY(1px);
}

.btn--primary {
  background-color: var(--color-accent);
  color: var(--color-white);
}

.btn--primary:hover {
  background-color: var(--color-accent-hover);
  box-shadow: var(--shadow-sm);
}

.btn--primary:active {
  background-color: var(--color-accent-active);
}

.btn--ghost {
  background-color: transparent;
  color: var(--color-text);
  border-color: var(--color-border);
}

.btn--ghost:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

/* --------------------------------------------------------------------------
   7. Hero (minimalist_typography)
   -------------------------------------------------------------------------- */
.hero {
  padding-block: var(--spacing-section);
  text-align: center;
}

.hero__inner {
  max-width: 52rem;
  margin-inline: auto;
}

.hero__title {
  margin-top: var(--spacing-24);
}

.hero__title .text-accent {
  color: var(--color-accent);
}

.hero__lead {
  margin-inline: auto;
  margin-top: var(--spacing-24);
}

.hero__actions {
  justify-content: center;
  margin-top: var(--spacing-24);
}

/* --------------------------------------------------------------------------
   8. Feature Grid & Cards
   -------------------------------------------------------------------------- */
.section__header {
  max-width: 44rem;
  margin-inline: auto;
  margin-bottom: var(--spacing-section);
  margin-bottom: clamp(2rem, 1rem + 4vw, 4rem);
  text-align: center;
}

.section__header .lead {
  margin-inline: auto;
  margin-top: var(--spacing-12);
}

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

.card {
  padding: var(--spacing-24);
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-16);
  transition: transform var(--transition-fast),
    box-shadow var(--transition-fast);
}

.card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.card__index {
  font-family: var(--font-manrope);
  font-weight: 900;
  font-size: var(--font-size-2xl);
  color: var(--color-accent-soft);
  -webkit-text-stroke: 1px var(--color-accent);
}

.card__title {
  margin-top: var(--spacing-12);
}

.card__text {
  margin-top: var(--spacing-8);
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
}

/* --------------------------------------------------------------------------
   9. Testimonials (social proof)
   -------------------------------------------------------------------------- */
.testimonial-grid {
  grid-template-columns: 1fr;
}

.testimonial {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-24);
  height: 100%;
  padding: var(--spacing-24);
  background-color: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-16);
}

.testimonial__quote {
  font-size: var(--font-size-lg);
  line-height: 1.5;
}

.testimonial__quote::before {
  content: "\201C";
  color: var(--color-accent);
}

.testimonial__quote::after {
  content: "\201D";
  color: var(--color-accent);
}

.testimonial__author {
  display: flex;
  align-items: center;
  gap: var(--spacing-12);
  margin-top: auto;
}

.testimonial__avatar {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-pill);
  background-color: var(--color-accent-soft);
  object-fit: cover;
}

.testimonial__name {
  font-weight: 700;
  font-style: normal;
  font-size: var(--font-size-sm);
}

.testimonial__role {
  font-size: var(--font-size-xs);
  color: var(--color-text-muted);
}

/* --------------------------------------------------------------------------
   10. Call To Action
   -------------------------------------------------------------------------- */
.cta {
  text-align: center;
}

.cta__panel {
  max-width: 52rem;
  margin-inline: auto;
  padding: clamp(2.5rem, 1.5rem + 5vw, 5rem) var(--spacing-24);
  background-color: var(--color-text);
  color: var(--color-white);
  border-radius: var(--radius-24);
}

.cta__panel h2 {
  color: var(--color-white);
}

.cta__panel .lead {
  margin-inline: auto;
  margin-top: var(--spacing-12);
  color: rgba(255, 255, 255, 0.78);
}

.cta__actions {
  justify-content: center;
  margin-top: var(--spacing-24);
}

.cta__panel .btn--ghost {
  color: var(--color-white);
  border-color: rgba(255, 255, 255, 0.4);
}

.cta__panel .btn--ghost:hover {
  color: var(--color-accent);
  border-color: var(--color-white);
  background-color: var(--color-white);
}

/* --------------------------------------------------------------------------
   11. Footer
   -------------------------------------------------------------------------- */
.site-footer {
  padding-block: var(--spacing-section);
  background-color: var(--color-surface-alt);
  border-top: 1px solid var(--color-border);
}

.site-footer__grid {
  grid-template-columns: 1fr;
}

.site-footer__brand {
  font-family: var(--font-manrope);
  font-weight: 900;
  font-size: var(--font-size-lg);
}

.site-footer__links {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-8);
}

.site-footer__link {
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
  transition: color var(--transition-fast);
}

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

.site-footer__bottom {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-12);
  justify-content: space-between;
  margin-top: var(--spacing-24);
  padding-top: var(--spacing-24);
  border-top: 1px solid var(--color-border);
  font-size: var(--font-size-xs);
  color: var(--color-text-muted);
}

/* --------------------------------------------------------------------------
   12. Scroll-Triggered Reveals (scroll_triggered_reveals pattern)
   Content is visible by default; JS adds `.is-hidden` on init so the page
   remains fully accessible if JavaScript fails to load.
   -------------------------------------------------------------------------- */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

[data-aos].is-hidden {
  opacity: 0;
  transform: translateY(30px);
  will-change: opacity, transform;
}

[data-aos].is-visible {
  animation: fadeInUp var(--transition-reveal) both;
}

/* --------------------------------------------------------------------------
   13. Skeleton Loading (skeleton_loading pattern)
   -------------------------------------------------------------------------- */
@keyframes shimmer {
  100% {
    transform: translateX(100%);
  }
}

.skeleton {
  position: relative;
  overflow: hidden;
  background-color: var(--color-skeleton);
  border-radius: var(--radius-8);
}

.skeleton::after {
  content: "";
  position: absolute;
  inset: 0;
  transform: translateX(-100%);
  background-image: linear-gradient(
    90deg,
    transparent 0,
    var(--color-skeleton-sheen) 50%,
    transparent 100%
  );
  animation: shimmer 1.5s infinite;
}

.skeleton--text {
  height: 0.875rem;
  margin-bottom: var(--spacing-8);
}

.skeleton--title {
  height: 1.5rem;
  width: 70%;
  margin-bottom: var(--spacing-12);
}

.skeleton--block {
  height: 200px;
  width: 100%;
}

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

/* Hide skeleton placeholders once content is ready */
[data-skeleton-group][hidden],
.skeleton[hidden] {
  display: none;
}

/* --------------------------------------------------------------------------
   14. Responsive Breakpoints (mobile-first)
   -------------------------------------------------------------------------- */
@media (min-width: 768px) {
  .feature-grid {
    grid-template-columns: repeat(2, 1fr);
  }

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

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

  .site-footer__grid {
    grid-template-columns: 2fr 1fr 1fr;
  }
}

@media (min-width: 1024px) {
  .feature-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .testimonial-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .skeleton-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

/* Mobile navigation — collapse the link list behind the toggle */
@media (max-width: 767px) {
  .nav-toggle {
    display: inline-flex;
    align-items: center;
    justify-content: center;
  }

  .main-nav {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background-color: var(--color-surface);
    border-bottom: 1px solid var(--color-border);
    box-shadow: var(--shadow-sm);
  }

  .main-nav[hidden] {
    display: none;
  }

  .main-nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: var(--spacing-8) var(--spacing-24) var(--spacing-24);
  }

  .main-nav__link {
    display: block;
    padding-block: var(--spacing-12);
    border-bottom: 1px solid var(--color-border);
  }
}

/* --------------------------------------------------------------------------
   15. Reduced Motion
   -------------------------------------------------------------------------- */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }

  [data-aos].is-hidden {
    opacity: 1;
    transform: none;
  }
}

/* --------------------------------------------------------------------------
   16. High Contrast
   -------------------------------------------------------------------------- */
@media (prefers-contrast: more) {
  :root {
    --color-text: #000000;
    --color-text-muted: #333333;
    --color-border: #666666;
  }

  .main-nav__link,
  .site-footer__link {
    text-decoration: underline;
  }
}

/* --------------------------------------------------------------------------
   17. Print Styles
   -------------------------------------------------------------------------- */
@media print {
  .site-header,
  .nav-toggle,
  .cta__actions,
  .hero__actions,
  .skeleton,
  .no-print {
    display: none !important;
  }

  *,
  *::before,
  *::after {
    background: transparent !important;
    color: #000000 !important;
    box-shadow: none !important;
  }

  body {
    font-size: 12pt;
    line-height: 1.4;
  }

  h1,
  h2,
  h3 {
    page-break-after: avoid;
  }

  a[href^="http"]::after {
    content: " (" attr(href) ")";
    font-size: 0.85em;
  }

  @page {
    margin: 2cm;
  }
}