* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  background: #000;
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, sans-serif;
}

/* ── Error overlay ───────────────────────────────────────────── */
#error-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 99999;
  display: none;
  background: rgba(160, 0, 0, 0.92);
  color: #fff;
  font-family: monospace;
  font-size: 12px;
  padding: 12px 16px;
  max-height: 50%;
  overflow-y: auto;
  white-space: pre-wrap;
}

/* ── Splash screen ───────────────────────────────────────────── */
#splash {
  position: fixed;
  inset: 0;
  z-index: 1000;
  background: #000;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 40px 32px;
  gap: 12px;
  opacity: 1;
  transition: opacity 0.5s ease;
}

#splash.fade-out {
  opacity: 0;
  pointer-events: none;
}

.splash-title {
  color: #fff;
  font-size: 52px;
  font-weight: 700;
  letter-spacing: -1.5px;
  line-height: 1;
}

.splash-divider {
  width: 40px;
  height: 2px;
  background: rgba(255, 255, 255, 0.25);
  border-radius: 2px;
  margin: 8px 0;
}

.splash-subtitle {
  color: rgba(255, 255, 255, 0.5);
  font-size: 15px;
  line-height: 1.6;
  text-align: center;
  max-width: 260px;
}

#start-btn {
  margin-top: 32px;
  padding: 16px 52px;
  font-size: 17px;
  font-weight: 600;
  font-family: inherit;
  color: #000;
  background: #fff;
  border: none;
  border-radius: 50px;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
  transition: transform 0.12s ease, opacity 0.12s ease;
}

#start-btn:active {
  transform: scale(0.95);
  opacity: 0.8;
}

.splash-hint {
  color: rgba(255, 255, 255, 0.25);
  font-size: 12px;
  text-align: center;
  margin-top: 8px;
}

/* ── Minimalist scan UI ──────────────────────────────────────── */
#scan-ui {
  position: fixed;
  inset: 0;
  z-index: 500;
  display: none; /* shown after splash dismissed */
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 20px;
  pointer-events: none; /* pass touches through to camera */
  opacity: 1;
  transition: opacity 0.3s ease;
}

#scan-ui.hidden {
  opacity: 0;
}

/* Corner-bracket frame sized to postcard ratio (6:4 landscape) */
.scan-frame {
  position: relative;
  width: 72vw;
  height: calc(72vw * 0.667);
  animation: scan-pulse 2.4s ease-in-out infinite;
}

@keyframes scan-pulse {
  0%, 100% { opacity: 0.5; }
  50%       { opacity: 1;   }
}

/* Four L-shaped corners */
.scan-corner {
  position: absolute;
  width: 18px;
  height: 18px;
  border: 2px solid #fff;
}

.scan-corner.tl { top: 0;    left: 0;  border-right: none; border-bottom: none; }
.scan-corner.tr { top: 0;    right: 0; border-left:  none; border-bottom: none; }
.scan-corner.bl { bottom: 0; left: 0;  border-right: none; border-top:    none; }
.scan-corner.br { bottom: 0; right: 0; border-left:  none; border-top:    none; }

.scan-label {
  color: rgba(255, 255, 255, 0.45);
  font-size: 12px;
  letter-spacing: 1.5px;
  text-transform: uppercase;
}

/* ── Download button ─────────────────────────────────────────── */
#download-btn {
  position: fixed;
  bottom: calc(28px + env(safe-area-inset-bottom));
  left: 50%;
  transform: translateX(-50%);
  z-index: 600;
  display: none; /* shown after splash dismissed */
  padding: 12px 28px;
  background: rgba(255, 255, 255, 0.12);
  color: rgba(255, 255, 255, 0.85);
  font-size: 14px;
  font-weight: 500;
  font-family: inherit;
  text-decoration: none;
  border-radius: 50px;
  border: 1px solid rgba(255, 255, 255, 0.18);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  white-space: nowrap;
  -webkit-tap-highlight-color: transparent;
  transition: background 0.15s ease;
}

#download-btn:active {
  background: rgba(255, 255, 255, 0.22);
}