/* ==========================================================================
   N2O.biz — Industrial Design System
   Fonts: Rajdhani 600/700 (headings), DM Sans 400/500 (body)
   Accent: #00FFB2 (single mint-green accent)
   ========================================================================== */

/* 1. Custom Properties
   ========================================================================== */
:root {
  --bg:       #07080C;
  --surface:  #0D1018;
  --surface2: #121620;
  --border:   #1C2133;
  --accent:   #00FFB2;
  --accent-dim: rgba(0, 255, 178, 0.12);
  --muted:    #565D78;
  --text:     #E8ECF4;
  --text-sub: #8892A8;

  --font-head: 'Rajdhani', sans-serif;
  --font-body: 'DM Sans', sans-serif;

  --max-w: 1200px;
  --radius: 6px;

  --z-header: 100;
  --z-nav:    200;
}

/* 2. Reset
   ========================================================================== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }

body {
  font-family: var(--font-body);
  background: var(--bg);
  color: var(--text);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  position: relative;
}

/* Film grain overlay */
body::after {
  content: '';
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 9999;
  opacity: 0.035;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='200' height='200'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.75' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='200' height='200' filter='url(%23n)'/%3E%3C/svg%3E");
  background-repeat: repeat;
}

img, svg { display: block; max-width: 100%; height: auto; }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
/* Inline links in body text must have underline for WCAG 1.4.1 */
p a, li a { text-decoration: underline; text-underline-offset: 3px; }
p a:hover, li a:hover { text-decoration: underline; }
ul, ol { list-style: none; }

/* 3. Typography
   ========================================================================== */
h1, h2, h3, h4 {
  font-family: var(--font-head);
  font-weight: 700;
  letter-spacing: 0.02em;
  text-transform: uppercase;
  line-height: 1.15;
  color: var(--text);
}
h1 { font-size: clamp(2rem, 5.5vw, 3.5rem); }
h2 { font-size: clamp(1.5rem, 3.5vw, 2.25rem); margin-bottom: 1rem; }
h3 { font-size: clamp(1.1rem, 2.5vw, 1.5rem); margin-bottom: 0.75rem; }
p  { color: var(--text-sub); margin-bottom: 1rem; }

/* 4. Layout
   ========================================================================== */
.container  { max-width: var(--max-w); margin: 0 auto; padding: 0 1.5rem; }
.section    { padding: 5rem 0; }
.grid-2     { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 2rem; }
.grid-4     { display: grid; grid-template-columns: repeat(auto-fit, minmax(230px, 1fr)); gap: 1.25rem; }
.text-center { text-align: center; }

/* 5. Header & Logo
   ========================================================================== */
.header {
  position: sticky;
  top: 0;
  z-index: var(--z-header);
  background: rgba(7, 8, 12, 0.96);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  padding: 0.9rem 0;
}
.header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

/* Text logo — N₂O.biz */
.logo {
  font-family: var(--font-head);
  font-weight: 700;
  font-size: 1.7rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--text);
  line-height: 1;
  text-decoration: none;
}
.logo:hover { text-decoration: none; color: var(--text); }
.logo sub {
  font-size: 0.75em;
  vertical-align: sub;
  color: var(--text-sub);
  letter-spacing: 0;
}
.logo__tld {
  color: var(--accent);
  font-size: 0.85em;
}

/* Navigation */
.nav { display: flex; align-items: center; gap: 2.5rem; }
.nav__link {
  font-family: var(--font-head);
  font-weight: 600;
  font-size: 0.95rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--text-sub);
  transition: color 0.2s;
}
.nav__link:hover,
.nav__link--active {
  color: var(--accent);
  text-decoration: none;
}

/* Hamburger — CSS-only */
.nav__toggle   { display: none; }
.nav__hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  padding: 4px;
}
.nav__hamburger span {
  display: block;
  width: 26px;
  height: 2px;
  background: var(--text);
  transition: transform 0.3s, opacity 0.3s;
}

@media (max-width: 768px) {
  .nav__hamburger { display: flex; }
  .nav {
    position: fixed;
    top: 0; right: -100%;
    width: 72%;
    height: 100vh;
    flex-direction: column;
    background: var(--surface);
    padding: 5rem 2rem 2rem;
    gap: 1.5rem;
    transition: right 0.3s ease;
    border-left: 1px solid var(--border);
    z-index: var(--z-nav);
  }
  .nav__toggle:checked ~ .nav { right: 0; }
  .nav__toggle:checked ~ .nav__hamburger span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
  }
  .nav__toggle:checked ~ .nav__hamburger span:nth-child(2) { opacity: 0; }
  .nav__toggle:checked ~ .nav__hamburger span:nth-child(3) {
    transform: rotate(-45deg) translate(5px, -5px);
  }
}

/* 6. Buttons
   ========================================================================== */
.btn {
  display: inline-block;
  padding: 0.75rem 2rem;
  font-family: var(--font-head);
  font-weight: 600;
  font-size: 1rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  border: none;
  border-radius: var(--radius);
  cursor: pointer;
  transition: transform 0.2s, opacity 0.2s;
  text-align: center;
  line-height: 1.3;
}
.btn:hover { transform: translateY(-2px); text-decoration: none; opacity: 0.9; }
.btn:focus-visible { outline: 2px solid var(--accent); outline-offset: 3px; }

.btn--call {
  background: var(--accent);
  color: #07080C;
}
.btn--call:hover { opacity: 1; box-shadow: 0 0 24px rgba(0, 255, 178, 0.35); }

.btn--ghost {
  background: transparent;
  color: var(--accent);
  border: 1px solid var(--accent);
}
.btn--ghost:hover { background: var(--accent-dim); }

.btn--outline {
  background: transparent;
  color: var(--text-sub);
  border: 1px solid var(--border);
}
.btn--outline:hover { border-color: var(--accent); color: var(--accent); }

/* 7. Hero
   ========================================================================== */
.hero {
  position: relative;
  overflow: hidden;
  padding: 7rem 0 5rem;
  text-align: center;
}

/* Scan lines */
.hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background: repeating-linear-gradient(
    0deg,
    transparent,
    transparent 3px,
    rgba(0, 255, 178, 0.018) 3px,
    rgba(0, 255, 178, 0.018) 4px
  );
  pointer-events: none;
}

/* Large watermark text */
.hero__bg {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  font-family: var(--font-head);
  font-weight: 700;
  font-size: clamp(6rem, 18vw, 16rem);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: rgba(255, 255, 255, 0.025);
  white-space: nowrap;
  pointer-events: none;
  user-select: none;
  line-height: 1;
}

.hero__content { position: relative; z-index: 1; }

.hero h1 { margin-bottom: 1rem; }
.hero h1 em {
  font-style: normal;
  color: var(--accent);
}

.hero__subtitle {
  font-size: clamp(1rem, 2.5vw, 1.2rem);
  color: var(--text-sub);
  max-width: 560px;
  margin: 0 auto 2.5rem;
  font-weight: 400;
}
.hero__buttons { display: flex; gap: 1rem; justify-content: center; flex-wrap: wrap; }

/* 8. Products Grid & Price Rows
   ========================================================================== */
.product-card {
  background: var(--surface);
  border-radius: var(--radius);
  padding: 1.75rem;
  border: 1px solid var(--border);
  transition: border-color 0.25s;
  display: flex;
  flex-direction: column;
}
.product-card:hover { border-color: rgba(0, 255, 178, 0.35); }

.product-card__volume {
  font-family: var(--font-head);
  font-weight: 700;
  font-size: 1.6rem;
  letter-spacing: 0.03em;
  color: var(--text);
  margin-bottom: 0.4rem;
}
.product-card__desc {
  color: var(--text-sub);
  font-size: 0.875rem;
  flex: 1;
  margin-bottom: 1.25rem;
  line-height: 1.5;
}

/* Price rows */
.price-rows { margin-bottom: 1.5rem; }
.price-row {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  padding: 0.45rem 0;
  border-bottom: 1px solid var(--border);
}
.price-row:last-child { border-bottom: none; }
.price-row__label {
  font-family: var(--font-head);
  font-weight: 600;
  font-size: 0.8rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-sub);
}
.price-row__val {
  font-family: var(--font-head);
  font-weight: 700;
  font-size: 1.15rem;
  letter-spacing: 0.02em;
}
.price-row__val--sale     { color: var(--accent); }
.price-row__val--exchange { color: var(--text); }

.product-card__actions { display: flex; flex-direction: column; gap: 0.5rem; margin-top: auto; }
.product-card__actions .btn { width: 100%; }

/* 9. Benefits Strip
   ========================================================================== */
.benefits {
  background: var(--surface);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  padding: 3rem 0;
}
.benefits__grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 2rem;
  text-align: center;
}
.benefit__icon {
  font-size: 2rem;
  margin-bottom: 0.75rem;
  display: block;
}
.benefit__title {
  font-family: var(--font-head);
  font-weight: 700;
  font-size: 1rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--text);
  margin-bottom: 0.35rem;
}
.benefit__text {
  font-size: 0.875rem;
  color: var(--text-sub);
  margin: 0;
}

/* 10. Phone CTA Section
   ========================================================================== */
.cta-phone {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 4rem 2rem;
  text-align: center;
  margin: 2rem 0;
}
.cta-phone h2 { margin-bottom: 0.75rem; }
.cta-phone p  { margin-bottom: 2rem; max-width: 480px; margin-left: auto; margin-right: auto; }
.cta-phone__number {
  display: block;
  font-family: var(--font-head);
  font-weight: 700;
  font-size: clamp(1.5rem, 4vw, 2.5rem);
  letter-spacing: 0.06em;
  color: var(--accent);
  margin-bottom: 1.5rem;
  text-decoration: none;
}
.cta-phone__number:hover { text-decoration: none; opacity: 0.85; }

/* 11. Blog Cards
   ========================================================================== */
.blog-card {
  background: var(--surface);
  border-radius: var(--radius);
  padding: 1.5rem;
  border: 1px solid var(--border);
  transition: border-color 0.25s;
}
.blog-card:hover { border-color: rgba(0, 255, 178, 0.3); }

.blog-card__date {
  font-family: var(--font-head);
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--text-sub);
  margin-bottom: 0.5rem;
}
.blog-card h3 a { color: var(--text); }
.blog-card h3 a:hover { color: var(--accent); text-decoration: none; }
.blog-card__excerpt {
  color: var(--text-sub);
  font-size: 0.9rem;
  margin-bottom: 1rem;
}
.blog-card__link {
  font-family: var(--font-head);
  font-weight: 600;
  font-size: 0.875rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

/* 12. FAQ Accordion
   ========================================================================== */
.faq { max-width: 800px; margin: 0 auto; }
.faq details {
  background: var(--surface);
  border-radius: var(--radius);
  margin-bottom: 0.6rem;
  border: 1px solid var(--border);
}
.faq summary {
  padding: 1rem 1.25rem;
  cursor: pointer;
  font-family: var(--font-head);
  font-weight: 600;
  font-size: 1rem;
  letter-spacing: 0.02em;
  color: var(--text);
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.faq summary:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after {
  content: '+';
  font-size: 1.25rem;
  color: var(--accent);
  transition: transform 0.2s;
  flex-shrink: 0;
  margin-left: 1rem;
}
.faq details[open] summary::after { content: '−'; }
.faq details p { padding: 0 1.25rem 1rem; font-size: 0.95rem; }

/* 13. Breadcrumbs
   ========================================================================== */
.breadcrumbs {
  padding: 1rem 0 0;
  font-size: 0.82rem;
  letter-spacing: 0.03em;
}
.breadcrumbs a { color: var(--text-sub); text-decoration: underline; text-underline-offset: 3px; }
.breadcrumbs a:hover { color: var(--accent); text-decoration: underline; }
.breadcrumbs span { color: var(--border); margin: 0 0.4rem; }
.breadcrumbs__current { color: var(--text); }

/* 14. Footer
   ========================================================================== */
.footer {
  border-top: 1px solid var(--border);
  padding: 3.5rem 0 1.5rem;
  margin-top: 4rem;
}
.footer__grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(190px, 1fr));
  gap: 2rem;
  margin-bottom: 2rem;
}
.footer__title {
  font-family: var(--font-head);
  font-weight: 700;
  font-size: 0.85rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-sub);
  margin-bottom: 1rem;
}
.footer__links li { margin-bottom: 0.5rem; }
.footer__links a { color: var(--text-sub); font-size: 0.9rem; transition: color 0.2s; text-decoration: underline; text-underline-offset: 3px; }
.footer__links a:hover { color: var(--accent); text-decoration: underline; }
.footer__phone {
  font-family: var(--font-head);
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--accent);
}
.footer__copy {
  text-align: center;
  color: var(--text-sub);
  font-size: 0.78rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
}

/* 15. Product Detail
   ========================================================================== */
.product-detail {
  display: grid;
  grid-template-columns: 1fr;
  gap: 2rem;
  align-items: start;
}
@media (min-width: 769px) {
  .product-detail {
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
  }
}
.product-detail__image {
  background: var(--surface);
  border-radius: var(--radius);
  padding: 2rem;
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 300px;
  border: 1px solid var(--border);
}
.product-detail__info h1 { margin-bottom: 1rem; }
.product-detail__price {
  font-family: var(--font-head);
  font-size: 2.25rem;
  font-weight: 700;
  color: var(--accent);
  margin-bottom: 0.5rem;
}
.product-detail__features { margin: 1.5rem 0; }
.product-detail__features li {
  padding: 0.5rem 0;
  border-bottom: 1px solid var(--border);
  color: var(--text-sub);
  font-size: 0.95rem;
}
.product-detail__features li::before {
  content: '— ';
  color: var(--accent);
  font-weight: 700;
}

/* 16. Article / Blog
   ========================================================================== */
.article { max-width: 800px; margin: 0 auto; }
.article h1 { margin-bottom: 0.5rem; }
.article__meta {
  font-family: var(--font-head);
  font-size: 0.8rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
  margin-bottom: 2.5rem;
}
.article h2 { margin-top: 2rem; }
.article p  { font-size: 1.025rem; line-height: 1.85; }
.article ul, .article ol {
  margin: 1rem 0 1rem 1.5rem;
  list-style: disc;
}
.article li {
  color: var(--text-sub);
  margin-bottom: 0.5rem;
  font-size: 1.025rem;
}
.article__related {
  margin-top: 3rem;
  padding-top: 2rem;
  border-top: 1px solid var(--border);
}

/* 17. Delivery & Contacts
   ========================================================================== */
.delivery-options {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1.25rem;
}
.delivery-card {
  background: var(--surface);
  border-radius: var(--radius);
  padding: 2rem;
  border: 1px solid var(--border);
  text-align: center;
}
.delivery-card__icon  { font-size: 2.25rem; margin-bottom: 1rem; display: block; }
.delivery-card__title {
  font-family: var(--font-head);
  font-weight: 700;
  font-size: 1.05rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  margin-bottom: 0.75rem;
}

.contacts-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 2rem;
  align-items: start;
}
@media (min-width: 769px) {
  .contacts-grid { grid-template-columns: 1fr 1fr; gap: 3rem; }
}
.contact-item       { margin-bottom: 1.5rem; }
.contact-item__label {
  font-family: var(--font-head);
  font-size: 0.78rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--muted);
  margin-bottom: 0.25rem;
}
.contact-item__value { font-size: 1.05rem; color: var(--text); }

/* 18. 404
   ========================================================================== */
.not-found { text-align: center; padding: 8rem 0; }
.not-found__code {
  font-family: var(--font-head);
  font-weight: 700;
  font-size: clamp(5rem, 15vw, 10rem);
  color: var(--accent);
  line-height: 1;
  margin-bottom: 1rem;
  opacity: 0.6;
}

/* 19. Section Headings with Accent Line
   ========================================================================== */
.section-title {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 2.5rem;
}
.section-title::after {
  content: '';
  flex: 1;
  height: 1px;
  background: var(--border);
}
.section-title--center {
  justify-content: center;
  text-align: center;
}
.section-title--center::before,
.section-title--center::after {
  content: '';
  flex: 1;
  height: 1px;
  background: var(--border);
}

/* 20. Utilities
   ========================================================================== */
.accent  { color: var(--accent); }
.muted   { color: var(--muted); }
.surface { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); }

/* 21. Reduced Motion
   ========================================================================== */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { transition-duration: 0.01ms !important; animation-duration: 0.01ms !important; }
}