:root {
  --bg: #f3f3f3;
  --text: #111;
  --border: #111;
  --shadow: 0 10px 30px rgba(0,0,0,.08);
  --radius: 18px;
  --gap: 1rem;
  --box-size: min(42vw, 260px);
  --font: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

* { box-sizing: border-box; }

html, body {
  height: 100%;
  margin: 0;
}

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  min-height: 100dvh;
  padding: 2rem;
}

main {
  width: 100%;
  max-width: 760px;
  min-height: calc(100dvh - 4rem);
  margin: 0 auto;
  position: relative;
  display: flex;
  flex-direction: column;
  justify-content: center;
  text-align: center;
  padding-bottom: 3rem;
}

h1 {
  margin: 0 0 0.75rem;
  font-size: clamp(1.8rem, 3vw, 2.6rem);
  line-height: 1.1;
  font-weight: 700;
  letter-spacing: -0.02em;
}

p.lead {
  margin: 0 0 2rem;
  font-size: 1rem;
  color: #444;
}

.stage {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: var(--gap);
  flex-wrap: wrap;
  margin-bottom: 1.5rem;
}

.panel {
  position: relative;
  width: var(--box-size);
  height: var(--box-size);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
  cursor: pointer;
  transition: transform .18s ease, box-shadow .18s ease;
}

.panel:hover,
.panel:focus-visible {
  transform: translateY(-2px);
  box-shadow: 0 14px 36px rgba(0,0,0,.12);
  outline: none;
}

.panel.black {
  background: #000;
  color: #fff;
}

.panel.white {
  background: #fff;
  color: #000;
}

.face {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  padding: 1.25rem;
  text-align: center;
  transition: opacity .22s ease;
}

.face.hidden {
  opacity: 0;
  pointer-events: none;
}

.face.visible {
  opacity: 1;
  pointer-events: auto;
}

.message {
  max-width: 16rem;
  line-height: 1.45;
  font-size: 1rem;
}

.hint {
  font-size: 0.95rem;
  color: #555;
  margin: 0 0 1.25rem;
}

footer {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  font-size: 0.9rem;
  color: #666;
}

footer a {
  color: inherit;
  text-underline-offset: 0.15em;
}

@media (max-width: 560px) {
  .stage {
    flex-direction: column;
    align-items: center;
  }
}

@media (prefers-reduced-motion: reduce) {
  .panel,
  .face {
    transition: none;
  }
}

.stage {
  display: flex;
  justify-content: center;
  gap: 1rem;
  flex-wrap: wrap;
  margin-bottom: 1.5rem;
}

.panel {
  width: min(42vw, 260px);
  height: min(42vw, 260px);
  border: 1px solid #111;
  border-radius: 18px;
  box-shadow: 0 10px 30px rgba(0,0,0,.08);
  cursor: pointer;
  padding: 1.25rem;
  display: grid;
  place-items: center;
  text-align: center;
  transition:
    background-color .2s ease,
    color .2s ease,
    transform .18s ease,
    box-shadow .18s ease;
}

.panel:hover,
.panel:focus-visible {
  transform: translateY(-2px);
  box-shadow: 0 14px 36px rgba(0,0,0,.12);
  outline: none;
}

.panel.active {
  background: #fff;
  color: #000;
}

.panel.inactive {
  background: #000;
  color: #000; /* egal, Text wird ausgeblendet */
}

.panel .message {
  max-width: 16rem;
  line-height: 1.45;
  font-size: 1rem;
  transition: opacity .15s ease;
}

.panel.inactive .message {
  opacity: 0;
  pointer-events: none;
}