:root {
  --bg: #ffffff;
  --bg-alt: #f6f7f9;
  --fg: #111827;
  --muted: #6b7280;
  --border: #e5e7eb;
  --accent: #ff4400;
  --accent-fg: #ffffff;
  --radius: 12px;
  --container: 1120px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0b0c0f;
    --bg-alt: #14161a;
    --fg: #f3f4f6;
    --muted: #9ca3af;
    --border: #262a31;
  }
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font:
    16px / 1.55 system-ui,
    -apple-system,
    "Segoe UI",
    Roboto,
    "Helvetica Neue",
    Arial,
    sans-serif;
  -webkit-font-smoothing: antialiased;
}

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

a {
  color: inherit;
}

h1,
h2,
h3 {
  line-height: 1.2;
  margin: 0 0 0.5em;
  letter-spacing: -0.01em;
}

h1 {
  font-size: clamp(2rem, 5vw, 3.25rem);
}

h2 {
  font-size: clamp(1.5rem, 3vw, 2.25rem);
  margin-bottom: 1em;
}

h3 {
  font-size: 1.125rem;
}

p {
  margin: 0 0 1em;
}

.container {
  width: min(100% - 32px, var(--container));
  margin-inline: auto;
}

.narrow {
  max-width: 720px;
}

/* header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}

.nav {
  display: flex;
  align-items: center;
  gap: 24px;
  height: 64px;
}

.logo {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  text-decoration: none;
}

.menu {
  display: flex;
  gap: 20px;
  margin-left: auto;
}

.menu a {
  text-decoration: none;
  color: var(--muted);
}

.menu a:hover {
  color: var(--fg);
}

.burger {
  display: none;
  width: 40px;
  height: 40px;
  border: 0;
  background: none;
  flex-direction: column;
  justify-content: center;
  gap: 5px;
  cursor: pointer;
  margin-left: auto;
}

.burger span {
  display: block;
  height: 2px;
  background: var(--fg);
  border-radius: 2px;
}

/* buttons */
.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 22px;
  border-radius: 999px;
  background: var(--accent);
  color: var(--accent-fg);
  font-weight: 600;
  text-decoration: none;
  border: 1px solid var(--accent);
  cursor: pointer;
  font-size: 1rem;
  transition:
    transform 0.12s ease,
    opacity 0.12s ease;
}

.button:hover {
  opacity: 0.92;
  transform: translateY(-1px);
}

.button--ghost {
  background: transparent;
  color: var(--fg);
  border-color: var(--border);
}

.button--small {
  padding: 8px 16px;
  font-size: 0.9375rem;
}

/* hero */
.hero {
  padding: clamp(56px, 10vw, 120px) 0 clamp(40px, 8vw, 96px);
  background: radial-gradient(
    60% 60% at 70% 0%,
    color-mix(in srgb, var(--accent) 14%, transparent),
    transparent 70%
  );
}

.hero__inner {
  max-width: 760px;
}

/* главная: только слово «Привет» по центру экрана */
.only-hello {
  min-height: 100svh;
  display: grid;
  place-items: center;
  padding: 24px;
  overflow: clip;
}

.hello {
  font-size: clamp(3rem, 18vw, 12rem);
  font-weight: 800;
  letter-spacing: -0.04em;
  margin: 0;
}

/* надпись «praxis»: летает по экрану, отскакивает от краёв и крутится в 3D */
.flyer {
  position: fixed;
  top: 0;
  left: 0;
  pointer-events: none;
  user-select: none;
  will-change: transform;
  animation: fly-x 9s cubic-bezier(0.5, 0, 0.5, 1) infinite alternate;
}

.flyer__inner {
  display: block;
  padding: clamp(16px, 3vw, 28px);
  perspective: 700px;
  will-change: transform;
  animation: fly-y 5.5s cubic-bezier(0.5, 0, 0.5, 1) infinite alternate;
}

.flyer__spin {
  display: inline-block;
  transform-style: preserve-3d;
  backface-visibility: visible;
  font-size: clamp(1.75rem, 8vw, 5rem);
  font-weight: 900;
  letter-spacing: -0.03em;
  color: var(--accent);
  /* объёмная «экструзия» буквами вглубь + контактная тень */
  text-shadow:
    1px 1px 0 color-mix(in srgb, var(--accent) 72%, #000),
    2px 2px 0 color-mix(in srgb, var(--accent) 60%, #000),
    3px 3px 0 color-mix(in srgb, var(--accent) 50%, #000),
    4px 4px 0 color-mix(in srgb, var(--accent) 42%, #000),
    5px 5px 0 color-mix(in srgb, var(--accent) 34%, #000),
    6px 6px 0 color-mix(in srgb, var(--accent) 26%, #000),
    7px 7px 0 color-mix(in srgb, var(--accent) 18%, #000),
    8px 8px 14px rgba(0, 0, 0, 0.35);
  will-change: transform, filter;
  animation:
    spin 4.5s cubic-bezier(0.62, 0, 0.35, 1) infinite,
    glow 3.2s ease-in-out infinite;
}

@keyframes fly-x {
  to {
    transform: translateX(calc(100vw - 100%));
  }
}

@keyframes fly-y {
  to {
    transform: translateY(calc(100svh - 100%));
  }
}

/* «вжух»: разгон, полный оборот с наклоном и наездом на зрителя, мягкая посадка */
@keyframes spin {
  0% {
    transform: rotateX(0deg) rotateY(0deg) rotateZ(0deg) scale(1);
  }
  18% {
    transform: rotateX(-10deg) rotateY(38deg) rotateZ(-3deg) scale(1.06);
  }
  42% {
    transform: rotateX(12deg) rotateY(208deg) rotateZ(5deg) scale(1.3);
  }
  62% {
    transform: rotateX(-8deg) rotateY(318deg) rotateZ(-4deg) scale(1.12);
  }
  82% {
    transform: rotateX(4deg) rotateY(372deg) rotateZ(2deg) scale(0.96);
  }
  100% {
    transform: rotateX(0deg) rotateY(360deg) rotateZ(0deg) scale(1);
  }
}

@keyframes glow {
  0%,
  100% {
    filter: drop-shadow(0 0 6px color-mix(in srgb, var(--accent) 45%, transparent)) hue-rotate(0deg);
  }
  50% {
    filter: drop-shadow(0 0 26px color-mix(in srgb, var(--accent) 80%, transparent)) hue-rotate(35deg);
  }
}

/* мобильный: короче тень, слабее перспектива — чтобы не тормозило и не вылезало за экран */
@media (max-width: 760px) {
  .flyer__inner {
    perspective: 380px;
  }

  .flyer__spin {
    text-shadow:
      1px 1px 0 color-mix(in srgb, var(--accent) 70%, #000),
      2px 2px 0 color-mix(in srgb, var(--accent) 55%, #000),
      3px 3px 0 color-mix(in srgb, var(--accent) 40%, #000),
      4px 4px 10px rgba(0, 0, 0, 0.35);
    animation-duration: 5.5s, 3.2s;
  }

  .flyer {
    animation-duration: 7s;
  }

  .flyer__inner {
    animation-duration: 4.5s;
  }
}

@media (prefers-reduced-motion: reduce) {
  .flyer,
  .flyer__inner,
  .flyer__spin {
    animation: none;
  }
}

.eyebrow {
  display: inline-block;
  padding: 4px 12px;
  border-radius: 999px;
  border: 1px solid var(--border);
  color: var(--muted);
  font-size: 0.8125rem;
  margin-bottom: 20px;
}

.lead {
  font-size: 1.125rem;
  color: var(--muted);
  max-width: 60ch;
}

.hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin: 28px 0 16px;
}

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

/* sections */
.section {
  padding: clamp(48px, 7vw, 88px) 0;
}

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

.grid {
  display: grid;
  gap: 20px;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
}

.grid--3 {
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
}

.card {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
}

.card__icon {
  font-size: 1.5rem;
  margin-bottom: 12px;
}

.card p {
  color: var(--muted);
  margin: 0;
}

.steps {
  counter-reset: step;
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  gap: 16px;
  max-width: 720px;
}

.steps li {
  position: relative;
  padding-left: 52px;
  min-height: 40px;
}

.steps li::before {
  counter-increment: step;
  content: counter(step);
  position: absolute;
  left: 0;
  top: 0;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  display: grid;
  place-items: center;
  background: var(--accent);
  color: var(--accent-fg);
  font-weight: 700;
}

/* pricing */
.plan ul {
  list-style: none;
  padding: 0;
  margin: 16px 0 24px;
  color: var(--muted);
  display: grid;
  gap: 8px;
}

.plan .button {
  width: 100%;
}

.plan--featured {
  border-color: var(--accent);
  box-shadow: 0 8px 32px color-mix(in srgb, var(--accent) 18%, transparent);
}

.price {
  font-size: 2rem;
  font-weight: 700;
  margin: 8px 0 0;
}

.price span {
  font-size: 1rem;
  font-weight: 400;
  color: var(--muted);
}

/* faq */
.faq-item {
  border-bottom: 1px solid var(--border);
  padding: 14px 0;
}

summary {
  cursor: pointer;
  font-weight: 600;
  list-style: none;
  display: flex;
  justify-content: space-between;
  gap: 16px;
}

summary::after {
  content: "+";
  color: var(--muted);
}

.faq-item[open] summary::after {
  content: "−";
}

.faq-item p {
  margin: 10px 0 0;
  color: var(--muted);
}

/* form */
.form {
  display: grid;
  gap: 14px;
  max-width: 480px;
}

.form label {
  display: grid;
  gap: 6px;
  font-size: 0.9375rem;
}

.form input {
  font: inherit;
  padding: 12px 14px;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--fg);
}

.form input:focus {
  outline: 2px solid var(--accent);
  outline-offset: 1px;
}

.form input[aria-invalid="true"] {
  border-color: #dc2626;
}

.form__status {
  min-height: 1.5em;
  margin: 0;
  color: var(--muted);
}

.form__status.is-error {
  color: #dc2626;
}

.form__status.is-ok {
  color: #16a34a;
}

/* footer */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 28px 0;
  color: var(--muted);
  font-size: 0.875rem;
}

.footer {
  display: flex;
  flex-wrap: wrap;
  gap: 12px 24px;
  justify-content: space-between;
}

.footer p {
  margin: 0;
}

.footer nav {
  display: flex;
  gap: 16px;
}

/* mobile */
@media (max-width: 760px) {
  .menu {
    display: none;
    position: absolute;
    inset: 64px 0 auto 0;
    flex-direction: column;
    gap: 0;
    background: var(--bg);
    border-bottom: 1px solid var(--border);
    padding: 8px 16px 16px;
  }

  .menu a {
    padding: 12px 0;
  }

  .site-header.is-open .menu {
    display: flex;
  }

  .nav .button--small {
    display: none;
  }

  .burger {
    display: flex;
  }

  .plan .button {
    width: 100%;
  }
}