/* =========================================================
   Northfold Research — style.css
   ========================================================= */

/* Google Fonts */
@import url('https://fonts.googleapis.com/css2?family=Source+Serif+4:ital,wght@0,300;0,400;0,600;0,700;1,400;1,600&family=Inter:wght@300;400;500;600&display=swap');

/* =========================================================
   CSS Custom Properties
   ========================================================= */
:root {
  --color-primary: #1a1a2e;
  --color-accent: #b8860b;
  --color-accent-dark: #8a6408;
  --color-bg-main: #fafaf7;
  --color-bg-section: #f0ede5;
  --color-text: #2a2a2a;
  --color-line: #d4cfc0;
  --color-muted: #6b6860;
  --color-card-shadow: rgba(26, 26, 46, 0.08);

  --font-serif: 'Source Serif 4', Georgia, 'Times New Roman', serif;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif;

  --max-width: 1100px;
  --padding-desktop: 40px;
  --padding-mobile: 24px;
  --section-padding-desktop: 80px;
  --section-padding-mobile: 48px;

  --radius-card: 6px;
  --radius-btn: 4px;
  --transition: 0.2s ease;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  font-size: 1rem;
  line-height: 1.6;
  color: var(--color-text);
  background-color: var(--color-bg-main);
  -webkit-font-smoothing: antialiased;
}

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

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

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

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

ul, ol {
  list-style: none;
}

/* =========================================================
   Typography
   ========================================================= */
h1, h2, h3, h4 {
  font-family: var(--font-serif);
  color: var(--color-primary);
  font-weight: 600;
}

h1 {
  font-size: clamp(2rem, 4vw, 3rem);
  line-height: 1.2;
  letter-spacing: -0.02em;
}

h2 {
  font-size: clamp(1.5rem, 3vw, 2rem);
  line-height: 1.25;
  letter-spacing: -0.01em;
}

h3 {
  font-size: clamp(1.1rem, 2vw, 1.3rem);
  line-height: 1.35;
}

h4 {
  font-size: 1rem;
  line-height: 1.4;
}

p {
  max-width: 70ch;
  margin-bottom: 1em;
}

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

.lead {
  font-size: 1.125rem;
  line-height: 1.55;
  color: #444;
}

small, .small {
  font-size: 0.875rem;
  color: var(--color-muted);
}

em {
  font-style: italic;
}

/* =========================================================
   Layout Utilities
   ========================================================= */
.container {
  max-width: var(--max-width);
  margin-left: auto;
  margin-right: auto;
  padding-left: var(--padding-desktop);
  padding-right: var(--padding-desktop);
}

.section {
  padding-top: var(--section-padding-desktop);
  padding-bottom: var(--section-padding-desktop);
}

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

.section__header {
  margin-bottom: 2.5rem;
}

.section__header h2 {
  margin-bottom: 0.75rem;
}

.section__intro {
  max-width: 65ch;
  font-size: 1.0625rem;
  color: #444;
}

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

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

/* =========================================================
   Header / Navigation
   ========================================================= */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: var(--color-bg-main);
  border-bottom: 1px solid var(--color-line);
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.site-header__logo {
  font-family: var(--font-serif);
  font-size: 1.2rem;
  font-weight: 600;
  color: var(--color-primary);
  letter-spacing: -0.01em;
  white-space: nowrap;
}

.site-header__logo:hover {
  color: var(--color-primary);
  opacity: 0.85;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 2rem;
}

.site-nav a {
  font-family: var(--font-sans);
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--color-primary);
  transition: color var(--transition);
}

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

/* Mobile menu toggle */
.menu-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
  color: var(--color-primary);
}

.menu-toggle:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
  border-radius: 2px;
}

.menu-toggle svg {
  display: block;
  width: 24px;
  height: 24px;
}

/* =========================================================
   Buttons
   ========================================================= */
.btn {
  display: inline-block;
  font-family: var(--font-sans);
  font-size: 0.9375rem;
  font-weight: 500;
  border-radius: var(--radius-btn);
  padding: 14px 28px;
  cursor: pointer;
  border: 1px solid transparent;
  transition: background-color var(--transition), color var(--transition), border-color var(--transition);
  text-align: center;
  line-height: 1;
}

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

.btn--primary {
  background-color: var(--color-accent);
  color: #fff;
  border-color: var(--color-accent);
}

.btn--primary:hover {
  background-color: var(--color-accent-dark);
  border-color: var(--color-accent-dark);
  color: #fff;
}

.btn--secondary {
  background-color: transparent;
  color: var(--color-accent);
  border-color: var(--color-accent);
}

.btn--secondary:hover {
  background-color: var(--color-accent);
  color: #fff;
}

.btn-group {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  align-items: center;
  margin-top: 1.75rem;
}

/* =========================================================
   Hero
   ========================================================= */
.hero {
  padding-top: 88px;
  padding-bottom: 88px;
  background-color: var(--color-bg-main);
}

.hero--compact {
  padding-top: 60px;
  padding-bottom: 60px;
}

.hero__label {
  display: inline-block;
  font-family: var(--font-sans);
  font-size: 0.8125rem;
  font-weight: 500;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: 1rem;
}

.hero__title {
  max-width: 18ch;
  margin-bottom: 1.25rem;
}

.hero__subtitle {
  font-size: 1.125rem;
  line-height: 1.6;
  color: #444;
  max-width: 56ch;
  margin-bottom: 0;
}

/* =========================================================
   Cards
   ========================================================= */
.card {
  background-color: var(--color-bg-main);
  border: 1px solid var(--color-line);
  border-radius: var(--radius-card);
  padding: 1.75rem;
  box-shadow: 0 2px 8px var(--color-card-shadow);
  display: flex;
  flex-direction: column;
}

.card__label {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.07em;
  text-transform: uppercase;
  margin-bottom: 0.75rem;
}

.card__label--available {
  color: #2a7a2a;
}

.card__label--preparation {
  color: var(--color-muted);
}

.card__code {
  font-family: 'Courier New', monospace;
  font-size: 0.75rem;
  color: var(--color-muted);
  margin-bottom: 0.5rem;
}

.card__title {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--color-primary);
  margin-bottom: 0.5rem;
  line-height: 1.35;
}

.card__subtitle {
  font-style: italic;
  color: #555;
  font-size: 0.9375rem;
  margin-bottom: 1rem;
  line-height: 1.5;
}

.card__body {
  font-size: 0.9375rem;
  color: var(--color-text);
  margin-bottom: 1rem;
  flex: 1;
}

.card__meta {
  font-size: 0.8125rem;
  color: var(--color-muted);
  margin-bottom: 0.4rem;
}

.card__footer {
  margin-top: auto;
  padding-top: 1.25rem;
}

.card--dimmed {
  opacity: 0.6;
}

.card--large {
  padding: 2rem 2.25rem;
  margin-bottom: 1.5rem;
}

/* =========================================================
   Process Steps
   ========================================================= */
.steps {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1.5rem;
}

.step {
  position: relative;
}

.step__number {
  font-family: var(--font-serif);
  font-size: 2rem;
  font-weight: 300;
  color: var(--color-accent);
  line-height: 1;
  margin-bottom: 0.75rem;
}

.step__title {
  font-family: var(--font-serif);
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--color-primary);
  margin-bottom: 0.5rem;
}

.step__text {
  font-size: 0.9375rem;
  color: var(--color-text);
  line-height: 1.6;
}

/* =========================================================
   Briefs Grid on Homepage
   ========================================================= */
.briefs-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
}

/* =========================================================
   Pricing Columns
   ========================================================= */
.pricing-cols {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
  margin-bottom: 1.5rem;
}

.pricing-col {
  background-color: var(--color-bg-main);
  border: 1px solid var(--color-line);
  border-radius: var(--radius-card);
  padding: 1.75rem;
  box-shadow: 0 2px 8px var(--color-card-shadow);
}

.section--alt .pricing-col {
  background-color: var(--color-bg-section);
}

.pricing-col h3 {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  color: var(--color-primary);
  margin-bottom: 0.5rem;
}

.pricing-col__price {
  font-family: var(--font-serif);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--color-accent);
  margin: 0.5rem 0 0.75rem;
}

.pricing-col p {
  font-size: 0.9375rem;
  color: var(--color-text);
}

.pricing-note {
  font-size: 0.9375rem;
  color: var(--color-text);
  padding-top: 1rem;
  border-top: 1px solid var(--color-line);
  max-width: 80ch;
}

.pricing-disclaimer {
  font-size: 0.8125rem;
  color: var(--color-muted);
  margin-top: 1rem;
}

/* =========================================================
   Who reads / Bullet lists (styled)
   ========================================================= */
.reader-list {
  list-style: none;
  padding: 0;
  margin: 1rem 0;
}

.reader-list li {
  padding: 0.75rem 0 0.75rem 1.5rem;
  border-bottom: 1px solid var(--color-line);
  position: relative;
  font-size: 0.9375rem;
  line-height: 1.55;
}

.reader-list li:first-child {
  border-top: 1px solid var(--color-line);
}

.reader-list li::before {
  content: '—';
  position: absolute;
  left: 0;
  color: var(--color-accent);
  font-weight: 600;
}

/* =========================================================
   Two-column editorial
   ========================================================= */
.editorial-cols {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
}

.editorial-col h3 {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  color: var(--color-primary);
  margin-bottom: 1rem;
  padding-bottom: 0.5rem;
  border-bottom: 2px solid var(--color-accent);
}

/* =========================================================
   Brief Detail Pages
   ========================================================= */
.brief-hero {
  padding-top: 72px;
  padding-bottom: 72px;
  background-color: var(--color-bg-main);
  border-bottom: 1px solid var(--color-line);
}

.brief-hero__label {
  font-family: var(--font-sans);
  font-size: 0.8125rem;
  font-weight: 500;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: 1rem;
}

.brief-hero__title {
  max-width: 22ch;
  margin-bottom: 1rem;
}

.brief-hero__subtitle {
  font-style: italic;
  font-size: 1.2rem;
  color: #444;
  max-width: 55ch;
  margin-bottom: 1rem;
  line-height: 1.5;
  font-family: var(--font-serif);
}

.brief-hero__desc {
  max-width: 60ch;
  font-size: 1rem;
  color: #555;
  line-height: 1.6;
}

/* Preview block */
.preview-note {
  font-style: italic;
  font-size: 0.875rem;
  color: var(--color-muted);
  margin-bottom: 1.5rem;
}

.preview-text {
  max-width: 72ch;
}

.preview-text p {
  margin-bottom: 1.25em;
}

.preview-text p:last-child {
  margin-bottom: 0;
}

/* Parts grid */
.parts-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
  margin-bottom: 1.5rem;
}

.part-item h3 {
  font-family: var(--font-serif);
  font-size: 1rem;
  font-weight: 600;
  color: var(--color-primary);
  margin-bottom: 0.5rem;
  padding-bottom: 0.4rem;
  border-bottom: 1px solid var(--color-accent);
}

.part-item p {
  font-size: 0.9375rem;
  color: var(--color-text);
}

.appendix-note {
  font-size: 0.875rem;
  color: var(--color-muted);
  padding-top: 1rem;
  border-top: 1px solid var(--color-line);
}

/* =========================================================
   Brief card large (briefs.html)
   ========================================================= */
.brief-card-large {
  background-color: var(--color-bg-main);
  border: 1px solid var(--color-line);
  border-radius: var(--radius-card);
  padding: 2.25rem;
  box-shadow: 0 2px 10px var(--color-card-shadow);
  margin-bottom: 2rem;
}

.brief-card-large__label {
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.07em;
  text-transform: uppercase;
  color: #2a7a2a;
  margin-bottom: 0.75rem;
  display: block;
}

.brief-card-large__label--prep {
  color: var(--color-muted);
}

.brief-card-large__title {
  font-family: var(--font-serif);
  font-size: 1.4rem;
  font-weight: 600;
  color: var(--color-primary);
  margin-bottom: 0.5rem;
}

.brief-card-large__subtitle {
  font-style: italic;
  color: #555;
  font-size: 1rem;
  margin-bottom: 1rem;
  line-height: 1.5;
}

.brief-card-large__body {
  font-size: 0.9375rem;
  color: var(--color-text);
  margin-bottom: 0.75rem;
  max-width: 72ch;
}

.brief-card-large__meta {
  font-size: 0.8125rem;
  color: var(--color-muted);
  margin-bottom: 0.3rem;
}

/* =========================================================
   Terms Page
   ========================================================= */
.terms-content h2 {
  margin-top: 2.5rem;
  margin-bottom: 0.75rem;
  padding-top: 2rem;
  border-top: 1px solid var(--color-line);
}

.terms-content h2:first-child {
  border-top: none;
  padding-top: 0;
}

.terms-content h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-top: 1.25rem;
  margin-bottom: 0.4rem;
  color: var(--color-primary);
}

.terms-content p {
  margin-bottom: 0.75em;
}

/* =========================================================
   Legal pages (privacy, imprint)
   ========================================================= */
.legal-content h2 {
  margin-top: 2.5rem;
  margin-bottom: 0.75rem;
  font-size: 1.2rem;
}

.legal-content h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-top: 1.25rem;
  margin-bottom: 0.4rem;
}

.legal-content ul {
  list-style: disc;
  padding-left: 1.5rem;
  margin: 0.75rem 0;
}

.legal-content ul li {
  margin-bottom: 0.35rem;
  font-size: 0.9375rem;
}

.legal-content p {
  margin-bottom: 0.75em;
}

.legal-content a {
  word-break: break-all;
}

/* =========================================================
   Footer
   ========================================================= */
.site-footer {
  background-color: var(--color-primary);
  color: #c8c8d8;
  padding-top: 56px;
  padding-bottom: 32px;
}

.site-footer__grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2rem;
  margin-bottom: 2.5rem;
}

.site-footer__col h4 {
  font-family: var(--font-serif);
  font-size: 0.875rem;
  font-weight: 600;
  color: #fff;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 1rem;
}

.site-footer__col ul {
  list-style: none;
  padding: 0;
}

.site-footer__col ul li {
  margin-bottom: 0.5rem;
}

.site-footer__col a {
  color: #c8c8d8;
  font-size: 0.9375rem;
  transition: color var(--transition);
}

.site-footer__col a:hover {
  color: #fff;
}

.site-footer__col p {
  font-size: 0.9375rem;
  color: #c8c8d8;
  max-width: none;
}

.site-footer__bottom {
  border-top: 1px solid rgba(255,255,255,0.12);
  padding-top: 1.25rem;
  text-align: center;
  font-size: 0.8125rem;
  color: #a0a0b0;
}

/* =========================================================
   Responsive
   ========================================================= */
@media (max-width: 1024px) {
  .grid-3 {
    grid-template-columns: repeat(2, 1fr);
  }

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

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

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

@media (max-width: 768px) {
  :root {
    --padding-desktop: var(--padding-mobile);
    --section-padding-desktop: var(--section-padding-mobile);
  }

  .container {
    padding-left: var(--padding-mobile);
    padding-right: var(--padding-mobile);
  }

  .section {
    padding-top: var(--section-padding-mobile);
    padding-bottom: var(--section-padding-mobile);
  }

  /* Nav mobile */
  .menu-toggle {
    display: flex;
    align-items: center;
    justify-content: center;
  }

  .site-nav {
    display: none;
    flex-direction: column;
    gap: 0;
    position: absolute;
    top: 64px;
    left: 0;
    right: 0;
    background-color: var(--color-bg-main);
    border-bottom: 1px solid var(--color-line);
    padding: 1rem var(--padding-mobile);
    z-index: 99;
  }

  .site-nav.is-open {
    display: flex;
  }

  .site-nav a {
    padding: 0.75rem 0;
    border-bottom: 1px solid var(--color-line);
    width: 100%;
  }

  .site-nav a:last-child {
    border-bottom: none;
  }

  /* Grids */
  .grid-3,
  .grid-2,
  .briefs-grid,
  .pricing-cols,
  .parts-grid,
  .steps,
  .editorial-cols {
    grid-template-columns: 1fr;
  }

  /* Hero */
  .hero {
    padding-top: 56px;
    padding-bottom: 56px;
  }

  .hero__title {
    max-width: none;
  }

  .btn-group {
    flex-direction: column;
    align-items: flex-start;
  }

  .btn {
    width: 100%;
    text-align: center;
  }

  /* Footer */
  .site-footer__grid {
    grid-template-columns: 1fr;
    gap: 2rem;
  }
}