:root {
  color-scheme: dark;
  --navy-950: #060b18;
  --navy-900: #0b1224;
  --navy-850: #101a33;
  --navy-800: #15213f;
  --navy-700: #24345f;
  --ink: #f8fbff;
  --muted: #aeb9d4;
  --muted-strong: #ced6e8;
  --blue: #4f7cff;
  --blue-light: #7ca4ff;
  --teal: #25c9b2;
  --gold: #ffb52e;
  --gold-light: #ffd36a;
  --red: #ff7085;
  --border: rgba(159, 179, 225, 0.18);
  --border-strong: rgba(159, 179, 225, 0.32);
  --surface: rgba(18, 29, 57, 0.78);
  --surface-strong: #121d39;
  --shadow: 0 24px 80px rgba(0, 0, 0, 0.32);
  --radius-xl: 28px;
  --radius-lg: 20px;
  --radius-md: 14px;
  --max-width: 1140px;
}

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

html {
  scroll-behavior: smooth;
}

body {
  min-width: 320px;
  overflow-x: clip;
  margin: 0;
  color: var(--ink);
  background:
    radial-gradient(circle at 12% -4%, rgba(79, 124, 255, 0.24), transparent 30rem),
    radial-gradient(circle at 92% 12%, rgba(37, 201, 178, 0.13), transparent 26rem),
    linear-gradient(180deg, var(--navy-900), var(--navy-950) 75%);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  font-size: 16px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

body::before {
  position: fixed;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  content: "+   ×   =   −   ÷   ?";
  color: rgba(255, 255, 255, 0.018);
  font-size: clamp(3rem, 11vw, 10rem);
  font-weight: 900;
  letter-spacing: 0.11em;
  line-height: 2.1;
  overflow: hidden;
  transform: rotate(-9deg) scale(1.12);
}

a {
  color: var(--blue-light);
  text-underline-offset: 0.2em;
  text-decoration-thickness: 0.08em;
}

a:hover {
  color: #a9c2ff;
}

a:focus-visible,
button:focus-visible,
summary:focus-visible {
  outline: 3px solid var(--gold);
  outline-offset: 4px;
  border-radius: 5px;
}

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

h1,
h2,
h3 {
  margin-top: 0;
  color: var(--ink);
  line-height: 1.13;
  letter-spacing: -0.025em;
}

h1 {
  margin-bottom: 1.2rem;
  font-size: clamp(2.75rem, 7vw, 5.6rem);
  font-weight: 850;
}

h2 {
  margin-bottom: 1rem;
  font-size: clamp(1.8rem, 3.6vw, 2.8rem);
  font-weight: 800;
}

h3 {
  margin-bottom: 0.65rem;
  font-size: 1.18rem;
  font-weight: 760;
}

p {
  margin: 0 0 1rem;
}

ul,
ol {
  padding-left: 1.35rem;
}

li + li {
  margin-top: 0.45rem;
}

.skip-link {
  position: fixed;
  top: 0.75rem;
  left: 0.75rem;
  z-index: 100;
  padding: 0.7rem 1rem;
  color: var(--navy-950);
  background: var(--gold);
  border-radius: 10px;
  font-weight: 800;
  transform: translateY(-160%);
}

.skip-link:focus {
  transform: translateY(0);
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  border-bottom: 1px solid var(--border);
  background: rgba(6, 11, 24, 0.8);
  -webkit-backdrop-filter: blur(18px);
  backdrop-filter: blur(18px);
}

.header-inner,
.container {
  width: min(calc(100% - 2rem), var(--max-width));
  margin-inline: auto;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 74px;
  gap: 1.5rem;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.72rem;
  color: var(--ink);
  font-size: 1.18rem;
  font-weight: 850;
  letter-spacing: 0.06em;
  text-decoration: none;
  text-transform: uppercase;
}

.brand:hover {
  color: var(--ink);
}

.brand-mark {
  display: grid;
  width: 40px;
  aspect-ratio: 1;
  place-items: center;
  color: white;
  background: linear-gradient(145deg, #6090ff, #355bd5);
  border: 1px solid rgba(255, 255, 255, 0.22);
  border-radius: 12px;
  box-shadow: 0 8px 25px rgba(59, 98, 223, 0.35), inset 0 1px rgba(255, 255, 255, 0.35);
  font-size: 1.28rem;
  line-height: 1;
}

.site-nav {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 0.25rem;
}

.site-nav a {
  padding: 0.55rem 0.75rem;
  color: var(--muted-strong);
  border-radius: 9px;
  font-size: 0.92rem;
  font-weight: 700;
  text-decoration: none;
}

.site-nav a:hover,
.site-nav a[aria-current="page"] {
  color: white;
  background: rgba(124, 164, 255, 0.11);
}

.language-link {
  margin-left: 0.45rem;
  border: 1px solid var(--border-strong);
}

.hero {
  position: relative;
  display: grid;
  grid-template-columns: minmax(0, 1.15fr) minmax(280px, 0.85fr);
  align-items: center;
  min-height: calc(100vh - 74px);
  padding-block: 5.5rem;
  gap: clamp(3rem, 7vw, 7rem);
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  margin-bottom: 1.3rem;
  color: var(--teal);
  font-size: 0.82rem;
  font-weight: 800;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

.eyebrow::before {
  width: 2rem;
  height: 2px;
  content: "";
  background: currentColor;
  border-radius: 999px;
}

.gradient-text {
  color: transparent;
  background: linear-gradient(100deg, var(--blue-light), var(--teal) 58%, var(--gold-light));
  -webkit-background-clip: text;
  background-clip: text;
}

.hero-copy > p {
  max-width: 41rem;
  color: var(--muted-strong);
  font-size: clamp(1.08rem, 2vw, 1.28rem);
}

.actions {
  display: flex;
  flex-wrap: wrap;
  margin-top: 2rem;
  gap: 0.8rem;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 50px;
  padding: 0.75rem 1.2rem;
  color: white;
  background: linear-gradient(145deg, #456bd4, #355bd5);
  border: 1px solid rgba(255, 255, 255, 0.16);
  border-radius: 13px;
  box-shadow: 0 12px 30px rgba(61, 100, 220, 0.26);
  font-weight: 800;
  text-decoration: none;
}

.button:hover {
  color: white;
  transform: translateY(-1px);
}

.button-secondary {
  color: var(--muted-strong);
  background: rgba(20, 32, 62, 0.7);
  border-color: var(--border-strong);
  box-shadow: none;
}

.button-secondary:hover {
  color: white;
}

.game-preview {
  position: relative;
  width: min(100%, 410px);
  margin-inline: auto;
  padding: clamp(1rem, 3vw, 1.6rem);
  background: linear-gradient(160deg, rgba(27, 43, 81, 0.95), rgba(8, 15, 32, 0.96));
  border: 1px solid rgba(124, 164, 255, 0.24);
  border-radius: 36px;
  box-shadow: var(--shadow), inset 0 1px rgba(255, 255, 255, 0.08);
  transform: rotate(2deg);
}

.game-preview::after {
  position: absolute;
  inset: 8% 0 -8% 15%;
  z-index: -1;
  content: "";
  background: rgba(37, 201, 178, 0.12);
  filter: blur(45px);
  border-radius: 50%;
}

.preview-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1.2rem;
  color: var(--muted);
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.stars {
  color: var(--gold);
  letter-spacing: 0.13rem;
}

.tile-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0.65rem;
}

.tile {
  display: grid;
  aspect-ratio: 1;
  place-items: center;
  color: white;
  background: linear-gradient(145deg, #5f8dff, #365dd6);
  border: 1px solid rgba(255, 255, 255, 0.16);
  border-radius: 17px;
  box-shadow: inset 0 5px rgba(255, 255, 255, 0.12), 0 8px 16px rgba(0, 0, 0, 0.18);
  font-size: clamp(1.05rem, 3.3vw, 1.75rem);
  font-weight: 900;
}

.tile.op {
  background: linear-gradient(145deg, #37d7c0, #139b8d);
  border-radius: 50%;
}

.tile.equal {
  color: #302009;
  background: linear-gradient(145deg, #ffc54d, #ee9209);
  border-radius: 30%;
}

.tile.empty {
  background: rgba(150, 167, 207, 0.055);
  border-color: rgba(150, 167, 207, 0.06);
  box-shadow: none;
}

.preview-equation {
  margin: 1rem 0 0;
  padding: 0.75rem 1rem;
  color: var(--gold-light);
  background: rgba(255, 181, 46, 0.08);
  border: 1px solid rgba(255, 181, 46, 0.2);
  border-radius: 12px;
  font-size: 0.95rem;
  font-weight: 800;
  text-align: center;
}

.section {
  padding-block: clamp(4.5rem, 9vw, 7.5rem);
}

.section-muted {
  border-block: 1px solid var(--border);
  background: rgba(12, 20, 40, 0.56);
}

.section-heading {
  max-width: 44rem;
  margin-bottom: 2.5rem;
}

.section-heading p,
.lead {
  color: var(--muted-strong);
  font-size: 1.08rem;
}

.feature-grid,
.support-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
}

.card {
  padding: clamp(1.25rem, 3vw, 1.7rem);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  box-shadow: 0 15px 45px rgba(0, 0, 0, 0.12);
}

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

.card p,
.card li {
  color: var(--muted-strong);
}

.icon-chip {
  display: grid;
  width: 46px;
  aspect-ratio: 1;
  margin-bottom: 1.15rem;
  place-items: center;
  color: var(--navy-950);
  background: linear-gradient(145deg, var(--teal), #63e3d1);
  border-radius: 14px;
  box-shadow: inset 0 1px rgba(255, 255, 255, 0.5);
  font-size: 1.25rem;
  font-weight: 950;
}

.card:nth-child(2) .icon-chip {
  background: linear-gradient(145deg, var(--blue-light), #adc4ff);
}

.card:nth-child(3) .icon-chip {
  background: linear-gradient(145deg, var(--gold), var(--gold-light));
}

.faq-list {
  display: grid;
  max-width: 850px;
  gap: 0.75rem;
}

details {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
}

summary {
  padding: 1.1rem 1.25rem;
  cursor: pointer;
  font-weight: 780;
}

details p {
  padding: 0 1.25rem 1.15rem;
  color: var(--muted-strong);
}

.contact-panel {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: clamp(1.6rem, 4vw, 3rem);
  background:
    radial-gradient(circle at 100% 0, rgba(37, 201, 178, 0.2), transparent 20rem),
    linear-gradient(145deg, rgba(36, 52, 95, 0.9), rgba(16, 29, 57, 0.95));
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-xl);
  gap: 2rem;
}

.contact-panel h2 {
  margin-bottom: 0.45rem;
}

.contact-panel p {
  margin-bottom: 0;
  color: var(--muted-strong);
}

.site-footer {
  padding-block: 2rem;
  color: var(--muted);
  border-top: 1px solid var(--border);
  font-size: 0.9rem;
}

.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
}

.footer-links a {
  color: var(--muted-strong);
}

/* Policy pages */
.policy-shell {
  display: grid;
  grid-template-columns: 240px minmax(0, 800px);
  align-items: start;
  padding-block: clamp(3.5rem, 7vw, 6rem);
  gap: clamp(2rem, 5vw, 4.5rem);
}

.policy-nav {
  position: sticky;
  top: 104px;
  padding: 1.1rem;
  background: rgba(16, 26, 51, 0.72);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
}

.policy-nav strong {
  display: block;
  margin-bottom: 0.65rem;
  font-size: 0.78rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.policy-nav a {
  display: block;
  padding: 0.38rem 0.5rem;
  color: var(--muted-strong);
  border-radius: 7px;
  font-size: 0.88rem;
  text-decoration: none;
}

.policy-nav a:hover {
  color: white;
  background: rgba(124, 164, 255, 0.1);
}

.policy-content {
  min-width: 0;
  overflow-wrap: anywhere;
}

.policy-content h1 {
  margin-bottom: 0.75rem;
  font-size: clamp(2.35rem, 6vw, 4.4rem);
}

.policy-meta {
  margin-bottom: 2.5rem;
  color: var(--muted);
}

.policy-summary {
  margin-bottom: 2.5rem;
  padding: 1.3rem 1.5rem;
  color: var(--muted-strong);
  background: rgba(37, 201, 178, 0.075);
  border: 1px solid rgba(37, 201, 178, 0.22);
  border-radius: var(--radius-md);
}

.policy-section {
  padding-top: 1rem;
  margin-bottom: 2.8rem;
  scroll-margin-top: 100px;
}

.policy-section h2 {
  font-size: clamp(1.45rem, 3vw, 2rem);
}

.policy-section h3 {
  margin-top: 1.6rem;
}

.policy-section p,
.policy-section li {
  color: var(--muted-strong);
}

.policy-section strong {
  color: var(--ink);
}

.data-table-wrap {
  overflow-x: auto;
  margin-block: 1.2rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.92rem;
}

th,
td {
  padding: 0.9rem 1rem;
  border-bottom: 1px solid var(--border);
  text-align: left;
  vertical-align: top;
}

th {
  color: var(--ink);
  background: rgba(124, 164, 255, 0.08);
  font-size: 0.8rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

td {
  color: var(--muted-strong);
}

tr:last-child td {
  border-bottom: 0;
}

.notice {
  padding: 1rem 1.15rem;
  color: var(--muted-strong);
  background: rgba(255, 181, 46, 0.075);
  border-left: 3px solid var(--gold);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
}

.external-list a::after {
  content: " ↗";
  font-size: 0.78em;
}

.legal-contact {
  padding: 1.3rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
}

@media (max-width: 900px) {
  .hero {
    grid-template-columns: 1fr;
    min-height: auto;
    padding-block: 5rem;
  }

  .game-preview {
    width: min(100%, 370px);
    transform: none;
  }

  .feature-grid,
  .support-grid {
    grid-template-columns: 1fr;
  }

  .policy-shell {
    grid-template-columns: minmax(0, 1fr);
  }

  .policy-nav {
    position: static;
    display: flex;
    flex-wrap: wrap;
    padding: 0.65rem;
    gap: 0.2rem;
    white-space: normal;
  }

  .policy-nav strong {
    display: none;
  }

  .policy-nav a {
    flex: 0 0 auto;
  }
}

@media (max-width: 680px) {
  .header-inner {
    min-height: 66px;
  }

  .site-nav a:not(.language-link) {
    display: none;
  }

  .hero {
    padding-block: 3.8rem;
  }

  .actions,
  .button {
    width: 100%;
  }

  .contact-panel,
  .footer-inner {
    align-items: stretch;
    flex-direction: column;
  }

  .contact-panel .button {
    width: 100%;
  }

  .policy-shell {
    width: min(calc(100% - 1.25rem), var(--max-width));
  }

  th,
  td {
    min-width: 9rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
  }
}

@media print {
  :root {
    color-scheme: light;
  }

  body {
    color: #111;
    background: white;
  }

  body::before,
  .site-header,
  .policy-nav,
  .site-footer {
    display: none;
  }

  .policy-shell {
    display: block;
    width: 100%;
    padding: 0;
  }

  .policy-content h1,
  .policy-content h2,
  .policy-content h3,
  .policy-section strong {
    color: #111;
  }

  .policy-meta,
  .policy-section p,
  .policy-section li,
  td {
    color: #222;
  }

  a {
    color: #111;
  }
}