/* ===== Переменные ===== */
:root {
  --ink: #10152B;
  --ink-soft: #4B5378;
  --paper: #F6F7FC;
  --white: #fff;
  --indigo: #141A4A;
  --indigo-2: #1E2670;
  --cobalt: #3B4BFF;
  --periwinkle: #8FA0FF;
  --amber: #FFB86B;
  --line: #DFE3F5;
  --font-sans: 'Manrope', system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;
  --font-serif: 'Newsreader', Georgia, 'Times New Roman', serif;
  --radius-lg: 28px;
  --radius-md: 16px;
  --ease: cubic-bezier(.22, .7, .2, 1);
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: 84px
}

body {
  font-family: var(--font-sans);
  color: var(--ink);
  background: var(--paper);
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden
}

h1,
h2,
h3,
h4 {
  letter-spacing: -.02em;
  font-weight: 800;
  text-wrap: balance
}

a {
  color: var(--cobalt)
}

:focus-visible {
  outline: 3px solid var(--amber);
  outline-offset: 3px;
  border-radius: 6px
}

.section {
  padding: clamp(4rem, 9vw, 7.5rem) 0
}

.section-title {
  font-size: clamp(1.9rem, 4vw, 3rem);
  line-height: 1.1;
  margin-bottom: 1rem
}

.lead-text {
  font-family: var(--font-serif);
  font-size: 1.3rem;
  line-height: 1.65;
  color: var(--ink-soft);
  max-width: 62ch
}

.prose {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  line-height: 1.75;
  max-width: 64ch
}

/* ===== Навигация ===== */
.site-nav {
  padding: 1rem 0;
  transition: background .3s, box-shadow .3s, padding .3s
}

.site-nav.scrolled {
  background: rgba(20, 26, 74, .92);
  backdrop-filter: blur(12px);
  box-shadow: 0 8px 30px rgba(10, 14, 40, .25);
  padding: .6rem 0
}

.brand {
  font-weight: 800;
  font-size: 1.2rem;
  color: #fff;
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: .6rem
}

.brand img {
  width: 30px;
  height: 30px
}

.site-nav .nav-link {
  color: #CBD2FF;
  font-weight: 600;
  padding: .5rem 1rem
}

.site-nav .nav-link:hover,
.site-nav .nav-link.active {
  color: #fff
}

.navbar-toggler {
  border-color: rgba(255, 255, 255, .35)
}

.navbar-toggler-icon {
  filter: invert(1)
}

@media(max-width:991.98px) {
  .site-nav .navbar-collapse {
    background: var(--indigo);
    margin-top: .8rem;
    padding: 1rem;
    border-radius: var(--radius-md)
  }
}

/* ===== Кнопки ===== */
.btn-amber {
  background: var(--amber);
  color: var(--ink);
  font-weight: 700;
  border: 0;
  border-radius: 999px;
  padding: .85rem 1.7rem;
  transition: transform .25s var(--ease), box-shadow .25s
}

.btn-amber:hover {
  background: #FFC888;
  color: var(--ink);
  transform: translateY(-2px);
  box-shadow: 0 12px 28px rgba(255, 184, 107, .35)
}

.btn-ghost {
  color: #fff;
  border: 1.5px solid rgba(255, 255, 255, .4);
  border-radius: 999px;
  padding: .85rem 1.7rem;
  font-weight: 700
}

.btn-ghost:hover {
  background: rgba(255, 255, 255, .1);
  color: #fff;
  border-color: #fff
}

/* ===== Hero ===== */
.hero {
  position: relative;
  color: #fff;
  padding: 9rem 0 6rem;
  background: radial-gradient(900px 500px at 85% 10%, #2A36B8 0, transparent 60%), var(--indigo);
  overflow: hidden
}

.hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background: url(../images/hero-grid.svg);
  -webkit-mask-image: linear-gradient(#000 40%, transparent);
  mask-image: linear-gradient(#000 40%, transparent)
}

.hero .container {
  position: relative
}

.hero h1 {
  font-size: clamp(2.5rem, 6.2vw, 4.9rem);
  line-height: 1.02;
  margin-bottom: 1.5rem
}

.hero p.lead-text {
  color: #C8CFF8
}

.hero-meta {
  color: #9AA5E8;
  font-size: .95rem;
  display: flex;
  flex-wrap: wrap;
  gap: .4rem 1.4rem;
  margin-top: 2rem
}

.hero-meta i {
  color: var(--amber);
  margin-right: .35rem
}

/* Демо: предсказание следующего токена */
.token-card {
  background: rgba(255, 255, 255, .07);
  border: 1px solid rgba(255, 255, 255, .16);
  border-radius: var(--radius-lg);
  padding: 1.6rem;
  backdrop-filter: blur(8px);
  box-shadow: 0 30px 60px rgba(5, 8, 30, .4)
}

.token-card .label {
  color: #AEB8FF;
  font-size: .9rem;
  font-weight: 600;
  margin-bottom: .8rem
}

.token-sentence {
  font-family: var(--font-serif);
  font-size: 1.55rem;
  line-height: 1.4;
  min-height: 5.4rem
}

.token-sentence .tok {
  display: inline-block;
  animation: tokIn .5s var(--ease)
}

.token-sentence .tok.new {
  color: var(--amber)
}

.token-sentence .caret {
  display: inline-block;
  width: 2px;
  height: 1.2em;
  background: var(--amber);
  vertical-align: -.2em;
  margin-left: 3px;
  animation: blink 1s steps(2) infinite
}

.prob-row {
  display: grid;
  grid-template-columns: 110px 1fr 44px;
  align-items: center;
  gap: .8rem;
  margin-top: .7rem;
  font-size: .95rem
}

.prob-bar {
  height: 10px;
  border-radius: 99px;
  background: rgba(255, 255, 255, .12);
  overflow: hidden
}

.prob-bar span {
  display: block;
  height: 100%;
  width: 0;
  border-radius: 99px;
  background: var(--periwinkle);
  transition: width .9s var(--ease)
}

.prob-row.top .prob-bar span {
  background: var(--amber)
}

.prob-row.top {
  font-weight: 700
}

.prob-val {
  text-align: right;
  color: #C8CFF8;
  font-variant-numeric: tabular-nums
}

@keyframes tokIn {
  from {
    opacity: 0;
    transform: translateY(8px)
  }

  to {
    opacity: 1;
    transform: none
  }
}

@keyframes blink {
  50% {
    opacity: 0
  }
}

/* ===== Статья ===== */
.article-body p {
  margin-bottom: 1.4rem
}

.pullquote {
  border-left: 4px solid var(--cobalt);
  padding: .4rem 0 .4rem 1.5rem;
  margin: 2.5rem 0;
  font-family: var(--font-serif);
  font-size: 1.6rem;
  line-height: 1.4;
  font-style: italic
}

.fig {
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  padding: 1rem;
  margin: 0
}

.fig img {
  border-radius: var(--radius-md);
  width: 100%;
  height: auto
}

.fig figcaption {
  padding: .8rem .6rem .2rem;
  color: var(--ink-soft);
  font-size: .92rem
}

/* Три шага (это действительно последовательность) */
.steps {
  counter-reset: step
}

.step {
  position: relative;
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  padding: 2rem 1.6rem;
  height: 100%
}

.step::before {
  counter-increment: step;
  content: counter(step);
  position: absolute;
  top: -18px;
  left: 1.4rem;
  width: 38px;
  height: 38px;
  border-radius: 50%;
  background: var(--cobalt);
  color: #fff;
  font-weight: 800;
  display: grid;
  place-items: center
}

.step i {
  font-size: 1.8rem;
  color: var(--cobalt)
}

.step p {
  color: var(--ink-soft);
  margin: 0
}

/* Хронология */
.timeline {
  position: relative;
  margin: 0;
  padding: 0;
  list-style: none
}

.timeline::before {
  content: "";
  position: absolute;
  left: 11px;
  top: 6px;
  bottom: 6px;
  width: 2px;
  background: var(--line)
}

.tl-item {
  position: relative;
  padding: 0 0 2.2rem 3rem
}

.tl-item::before {
  content: "";
  position: absolute;
  left: 3px;
  top: 6px;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--white);
  border: 4px solid var(--cobalt)
}

.tl-item.key::before {
  border-color: var(--amber);
  background: var(--amber)
}

.tl-year {
  font-weight: 800;
  color: var(--cobalt)
}

.tl-item h3 {
  font-size: 1.25rem;
  margin: .1rem 0 .3rem
}

.tl-item p {
  color: var(--ink-soft);
  margin: 0;
  max-width: 60ch
}

/* Применение */
.use {
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  padding: 1.8rem;
  height: 100%;
  transition: border-color .25s
}

.use:hover {
  border-color: var(--cobalt)
}

.use .ico {
  width: 52px;
  height: 52px;
  border-radius: 14px;
  display: grid;
  place-items: center;
  background: #E8EBFF;
  color: var(--cobalt);
  font-size: 1.5rem;
  margin-bottom: 1.1rem
}

.use p {
  color: var(--ink-soft);
  margin: 0
}

/* Ограничения */
.dark-band {
  background: var(--indigo);
  color: #fff;
  border-radius: var(--radius-lg);
  padding: clamp(2rem, 5vw, 4rem)
}

.dark-band .lead-text {
  color: #C8CFF8
}

.limit {
  display: flex;
  gap: 1rem;
  padding: 1.1rem 0;
  border-top: 1px solid rgba(255, 255, 255, .14)
}

.limit i {
  color: var(--amber);
  font-size: 1.4rem;
  line-height: 1.3
}

.limit h3 {
  font-size: 1.1rem;
  margin: 0 0 .2rem
}

.limit p {
  margin: 0;
  color: #C8CFF8
}

/* FAQ */
.accordion {
  --bs-accordion-border-color: var(--line);
  --bs-accordion-active-bg: #EEF1FF;
  --bs-accordion-active-color: var(--ink);
  --bs-accordion-btn-focus-box-shadow: 0 0 0 3px var(--amber)
}

.accordion-item {
  border-radius: var(--radius-md) !important;
  overflow: hidden;
  margin-bottom: .8rem;
  border: 1px solid var(--line)
}

.accordion-button {
  font-weight: 700;
  padding: 1.2rem 1.4rem
}

.accordion-body {
  font-family: var(--font-serif);
  font-size: 1.1rem;
  line-height: 1.7;
  color: var(--ink-soft)
}

/* CTA и футер */
.cta {
  background: linear-gradient(135deg, var(--cobalt), var(--indigo-2));
  color: #fff;
  border-radius: var(--radius-lg);
  padding: clamp(2.5rem, 6vw, 4.5rem);
  text-align: center
}

.cta p {
  color: #D5DAFF;
  max-width: 52ch;
  margin: 0 auto 1.8rem
}

footer {
  padding: 3rem 0;
  color: var(--ink-soft);
  font-size: .95rem
}

footer a {
  color: var(--ink-soft)
}

/* Кнопка «Наверх» */
#backToTop {
  position: fixed;
  right: 1.2rem;
  bottom: 1.2rem;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  border: 0;
  background: var(--cobalt);
  color: #fff;
  font-size: 1.3rem;
  box-shadow: 0 10px 24px rgba(59, 75, 255, .4);
  opacity: 0;
  visibility: hidden;
  transform: translateY(12px);
  transition: .3s var(--ease);
  z-index: 1030
}

#backToTop.show {
  opacity: 1;
  visibility: visible;
  transform: none
}

#backToTop:hover {
  background: var(--indigo-2)
}

/* Появление блоков (Intersection Observer) */
.reveal {
  opacity: 0;
  transform: translateY(28px);
  transition: opacity .8s var(--ease), transform .8s var(--ease);
  transition-delay: var(--d, 0s)
}

.reveal.visible {
  opacity: 1;
  transform: none
}

.no-js .reveal {
  opacity: 1;
  transform: none
}

@media(max-width:575.98px) {
  .hero {
    padding: 7.5rem 0 4rem
  }

  .prob-row {
    grid-template-columns: 90px 1fr 40px
  }

  .token-sentence {
    font-size: 1.3rem
  }
}

@media(prefers-reduced-motion:reduce) {
  html {
    scroll-behavior: auto
  }

  *,
  *::before,
  *::after {
    animation: none !important;
    transition: none !important
  }

  .reveal {
    opacity: 1;
    transform: none
  }
}