:root {
  --bg-top: #050816;
  --bg-bottom: #0b1220;

  --card-border: rgba(148, 163, 184, 0.35);
  --ink: #f1f5f9;
  --muted: #9ca3af;

  --puzzle-main: #6366f1;
  --puzzle-soft: #818cf8;
  --accent: #a5b4fc;

  --shadow: 0 18px 40px rgba(15, 23, 42, 0.85);
}

/* RESET */
* { box-sizing: border-box; }
html, body { height: 100%; margin: 0; padding: 0; }

body.puzzle-bg {
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
    Roboto, Helvetica, Arial, sans-serif;
  color: var(--ink);
  background:
    radial-gradient(circle at 20% 0%, rgba(99,102,241,0.35), transparent 55%),
    radial-gradient(circle at 85% 10%, rgba(129,140,248,0.30), transparent 60%),
    linear-gradient(180deg, var(--bg-top), var(--bg-bottom));
}

/* HERO */
.hero {
  text-align: center;
  padding: 32px 16px 18px;
  position: relative;
  overflow: hidden;
}

.puzzle-hero::before,
.puzzle-hero::after {
  content: "";
  position: absolute;
  inset: auto -10% -40px -10%;
  height: 90px;
  background:
    radial-gradient(circle at 10% 0%, rgba(248,250,252,0.16), transparent 60%),
    radial-gradient(circle at 90% 0%, rgba(199,210,254,0.22), transparent 60%),
    repeating-linear-gradient(
      -45deg,
      rgba(99,102,241,0.75) 0px,
      rgba(99,102,241,0.75) 6px,
      rgba(15,23,42,0.95) 6px,
      rgba(15,23,42,0.95) 12px
    );
  opacity: 0.55;
  filter: blur(2px);
  pointer-events: none;
}

.logo {
  font-size: 44px;
  line-height: 1;
  text-shadow: 0 0 18px rgba(15,23,42,0.9);
}

.title {
  margin: 8px 0 4px;
  font-size: clamp(28px, 5vw, 44px);
  letter-spacing: 1.2px;
  font-weight: 900;
  color: #ffffff;
  text-shadow:
    0 0 12px rgba(15,23,42,0.9),
    0 0 30px rgba(99,102,241,0.9);
}

.subtitle {
  margin: 0;
  color: var(--puzzle-soft);
  font-weight: 700;
  letter-spacing: 0.6px;
}

/* LANGUAGE SWITCHER */
.lang-nav {
  display: flex;
  gap: 10px;
  justify-content: center;
  align-items: center;
  padding: 10px 0 18px;
}

.lang-nav a {
  color: #eef2ff;
  text-decoration: none;
  font-weight: 700;
  background: rgba(99,102,241,0.10);
  border: 1px solid rgba(129,140,248,0.55);
  padding: 6px 14px;
  border-radius: 999px;
  backdrop-filter: blur(6px);
  transition:
    background 0.15s ease-out,
    transform 0.1s ease-out,
    box-shadow 0.15s ease-out;
}

.lang-nav a:hover {
  background: rgba(129,140,248,0.22);
  box-shadow: 0 8px 18px rgba(15,23,42,0.6);
  transform: translateY(-1px);
}

.lang-nav span {
  color: rgba(148,163,184,0.8);
}

/* LAYOUT */
.container {
  max-width: 880px;
  margin: 0 auto;
  padding: 0 16px 42px;
}

/* CARDS */
.card {
  background:
    radial-gradient(circle at top, rgba(79,70,229,0.35), transparent 60%),
    linear-gradient(145deg, rgba(15,23,42,0.95), rgba(15,23,42,0.98));
  border-radius: 18px;
  box-shadow: var(--shadow);
  padding: 18px 18px 10px;
  margin: 14px 0;
  border: 1px solid var(--card-border);
  position: relative;
  overflow: hidden;
}

.card-puzzle::before {
  content: "";
  position: absolute;
  inset: 0;
  background:
    radial-gradient(circle at 0% 0%, rgba(99,102,241,0.22), transparent 55%),
    radial-gradient(circle at 100% 0%, rgba(129,140,248,0.20), transparent 55%),
    linear-gradient(
      135deg,
      rgba(99,102,241,0.14),
      transparent 40%,
      transparent 60%,
      rgba(165,180,252,0.14)
    );
  mix-blend-mode: screen;
  opacity: 0.9;
  pointer-events: none;
}

/* TEXT */
h2 {
  margin: 6px 0 10px;
  font-size: clamp(20px, 3.2vw, 26px);
  color: var(--accent);
}

h3 {
  margin: 18px 0 8px;
  color: #c7d2fe;
}

p {
  color: var(--ink);
  line-height: 1.65;
}

ul {
  margin: 6px 0 12px 20px;
  line-height: 1.6;
}

a {
  color: #c7d2fe;
}

a:hover {
  color: #eef2ff;
}

/* META */
.meta {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  grid-template-columns: 1fr;
  gap: 6px;
}

.meta strong { color: var(--accent); }

.meta .editable {
  background: rgba(15,23,42,0.65);
  padding: 0 6px;
  border-radius: 6px;
  border: 1px solid rgba(129,140,248,0.35);
}

/* CODE */
code {
  background: rgba(15,23,42,0.9);
  border: 1px solid rgba(129,140,248,0.45);
  padding: 2px 6px;
  border-radius: 6px;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace;
  font-size: 0.95em;
  color: #e0e7ff;
}

/* FOOTER */
.footer-note {
  text-align: center;
}

.footer-note p {
  color: var(--muted);
  font-size: 14px;
}

/* RESPONSIVE */
@media (min-width: 640px) {
  .meta {
    grid-template-columns: 1fr 1fr;
  }
}