:root {
  --ink: #090909;
  --paper: #fbfbf8;
  --accent: #ff4b12;
  --muted: rgba(9, 9, 9, 0.5);
}

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

html {
  min-width: 320px;
  min-height: 100%;
  background: var(--paper);
}

body {
  min-height: 100svh;
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: Arial, "Helvetica Neue", Helvetica, sans-serif;
  -webkit-font-smoothing: antialiased;
}

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

.site-header {
  position: fixed;
  top: 0;
  right: 0;
  left: 0;
  z-index: 10;
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto minmax(0, 1fr);
  align-items: center;
  padding: clamp(22px, 3vw, 42px);
}

.wordmark {
  justify-self: start;
  font-size: 0.73rem;
  font-weight: 800;
  letter-spacing: 0.015em;
  text-transform: uppercase;
}

.language-nav {
  display: flex;
  align-items: center;
  grid-column: 2;
  flex-shrink: 0;
  gap: clamp(32px, 3vw, 48px);
  justify-self: center;
  color: var(--muted);
  font-size: clamp(1.35rem, 2.2vw, 1.8rem);
  letter-spacing: 0.02em;
}

.language-nav a {
  position: relative;
  padding: 10px 0;
  white-space: nowrap;
}

.language-nav a[aria-current="page"] {
  color: var(--ink);
}

.language-nav a[aria-current="page"]::after {
  position: absolute;
  right: 0;
  bottom: 0;
  left: 0;
  height: 3px;
  background: var(--accent);
  content: "";
}

.language-nav a:hover,
.language-nav a:focus-visible {
  color: var(--ink);
}

main {
  display: grid;
  place-items: center;
  padding: clamp(118px, 12vh, 150px) 24px clamp(72px, 7vw, 110px);
}

.referral-entry {
  width: min(100%, 640px);
}

.return-login-link {
  display: grid;
  min-height: clamp(138px, 16vw, 166px);
  padding: clamp(24px, 4vw, 36px);
  border: 3px solid var(--ink);
  border-radius: 22px;
  background: var(--ink);
  box-shadow: 8px 8px 0 var(--accent);
  color: #fff;
  column-gap: 24px;
  grid-template-areas:
    "kicker arrow"
    "title arrow";
  grid-template-columns: minmax(0, 1fr) auto;
  grid-template-rows: auto 1fr;
  outline: none;
  transition: background 160ms ease, color 160ms ease, box-shadow 160ms ease, transform 160ms ease;
}

.return-login-kicker {
  align-self: end;
  color: var(--accent);
  font-size: clamp(0.82rem, 1.4vw, 0.95rem);
  font-weight: 800;
  grid-area: kicker;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.return-login-title {
  align-self: end;
  min-width: 0;
  font-size: clamp(3rem, 7.5vw, 5.2rem);
  font-weight: 700;
  grid-area: title;
  letter-spacing: -0.065em;
  line-height: 0.9;
  white-space: nowrap;
}

.return-login-arrow {
  display: grid;
  width: clamp(56px, 7vw, 70px);
  height: clamp(56px, 7vw, 70px);
  align-self: center;
  border-radius: 50%;
  background: #fff;
  color: var(--ink);
  font-size: clamp(1.65rem, 3vw, 2.15rem);
  grid-area: arrow;
  place-items: center;
}

.return-login-link:hover,
.return-login-link:focus-visible {
  background: var(--accent);
  box-shadow: 8px 8px 0 var(--ink);
  color: var(--ink);
  transform: translate(-2px, -2px);
}

.return-login-link:hover .return-login-kicker,
.return-login-link:focus-visible .return-login-kicker {
  color: var(--ink);
}

.signup-divider {
  display: flex;
  align-items: center;
  gap: 16px;
  margin: clamp(30px, 5vw, 44px) 0;
  color: var(--muted);
  font-size: 0.82rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.signup-divider::before,
.signup-divider::after {
  height: 1px;
  background: rgba(9, 9, 9, 0.18);
  content: "";
  flex: 1;
}

.signup-divider span {
  flex: 0 1 auto;
  text-align: center;
}

.referral-form,
.referral-control {
  width: 100%;
}

.referral-control {
  position: relative;
}

h1 {
  max-width: 620px;
  margin: 0 0 clamp(26px, 4vw, 40px);
  font-size: clamp(2.25rem, 4.4vw, 4.6rem);
  font-weight: 400;
  letter-spacing: -0.055em;
  line-height: 1.02;
}

.referral-input {
  width: 100%;
  height: clamp(66px, 7vw, 78px);
  padding: 0 88px 0 28px;
  border: 1.5px solid var(--ink);
  border-radius: 999px;
  outline: none;
  background: transparent;
  color: var(--ink);
  font: inherit;
  font-size: clamp(1rem, 1.35vw, 1.18rem);
  letter-spacing: 0.01em;
  transition: border-color 160ms ease, box-shadow 160ms ease, background 160ms ease;
}

.referral-input::placeholder {
  color: var(--muted);
  opacity: 1;
}

.referral-input:hover {
  background: #fff;
}

.referral-input:focus {
  border-color: var(--accent);
  background: #fff;
  box-shadow: 0 0 0 4px rgba(255, 75, 18, 0.14);
}

.referral-input[aria-invalid="true"] {
  border-color: #b42318;
}

.referral-submit {
  position: absolute;
  top: 50%;
  right: 9px;
  display: grid;
  width: clamp(48px, 5.5vw, 58px);
  height: clamp(48px, 5.5vw, 58px);
  padding: 0;
  border: 0;
  border-radius: 50%;
  background: var(--ink);
  color: #fff;
  cursor: pointer;
  font: inherit;
  font-size: 1.45rem;
  place-items: center;
  transform: translateY(-50%);
  transition: background 160ms ease, color 160ms ease, transform 160ms ease;
}

.referral-submit:hover,
.referral-submit:focus-visible {
  background: var(--accent);
  color: var(--ink);
}

.referral-submit:active {
  transform: translateY(-50%) scale(0.96);
}

.referral-error {
  min-height: 1.25em;
  margin: 12px 24px 0;
  color: #b42318;
  font-size: 0.9rem;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

@media (max-width: 600px) {
  .site-header {
    grid-template-columns: minmax(0, 1fr) auto minmax(0, 1fr);
    padding: 22px 20px;
  }

  .wordmark {
    max-width: 72px;
    line-height: 1.05;
  }

  main {
    align-items: center;
    padding: 96px 20px 72px;
  }

  h1 {
    margin-bottom: 26px;
    font-size: clamp(2.1rem, 11vw, 3.4rem);
  }

  .return-login-link {
    min-height: 140px;
    padding: 24px 22px;
    border-radius: 18px;
    box-shadow: 6px 6px 0 var(--accent);
    column-gap: 16px;
  }

  .return-login-title {
    font-size: clamp(2.8rem, 13vw, 3.4rem);
  }

  html[lang="zh-CN"] .return-login-title {
    font-size: clamp(2.25rem, 11vw, 2.75rem);
    letter-spacing: -0.04em;
  }

  .signup-divider {
    margin: 30px 0;
    font-size: 0.72rem;
  }

  .referral-input {
    padding: 0 76px 0 22px;
  }
}