/* Layout only. Colours come exclusively from semantic variables (themes/*.css). */
html, body, .reveal-viewport { margin: 0; height: 100%; background: var(--bg); color: var(--ink);
  font-family: Inter, "Microsoft YaHei", "PingFang SC", "Noto Sans SC", system-ui, sans-serif; }
.reveal { color: var(--ink); }
.reveal .slides > section { text-align: left; background: var(--bg); width: 1920px; height: 1080px; box-sizing: border-box;
  padding: 0 120px; }
.shell { display: flex; flex-direction: column; justify-content: center; height: 100%; gap: 24px; }
.shell h1 { font-size: 80px; line-height: 1.1; margin: 0; color: var(--ink); text-transform: none; }
.shell-tag { font-size: 28px; letter-spacing: .12em; color: var(--accent); margin: 0; }
.shell-meta { font-size: 32px; color: var(--ink-muted); margin: 0; }
.ph { font-size: 32px; color: var(--ink-muted); border: 2px dashed var(--card-border); padding: 12px 20px;
  width: fit-content; margin: 0; }
.demo-badge { position: absolute; left: 120px; right: 120px; bottom: 56px; display: flex; flex-wrap: wrap; gap: 12px 24px;
  font-size: 28px; color: var(--ink-muted); border-top: 1px solid var(--card-border); padding-top: 16px; }
.demo-badge b { color: var(--accent); }
.demo-badge .unconfirmed { color: var(--ink); background: var(--card); border: 1px solid var(--card-border); padding: 0 12px; }
#dev-badge, #tier-tag, #toast { position: fixed; z-index: 50; font-size: 16px; font-family: inherit; }
#dev-badge { top: 8px; left: 8px; padding: 2px 8px; background: var(--card); color: var(--ink-muted);
  border: 1px solid var(--card-border); }
#tier-tag { top: 8px; right: 8px; color: var(--accent); }
#tier-tag:empty { display: none; }
#toast { left: 50%; bottom: 24px; transform: translateX(-50%); padding: 8px 16px; background: var(--card);
  color: var(--ink); border: 1px solid var(--card-border); opacity: 0; transition: opacity .2s; pointer-events: none; }
#toast.show { opacity: 1; }
.reveal.overview .slides > section[data-tier="optional"],
.reveal.overview .slides > section[data-tier="appendix"] { outline: 4px dashed var(--accent); }

#step-hint { position: fixed; right: 16px; bottom: 14px; z-index: 50; font: 600 15px Inter, system-ui, sans-serif; color: var(--ink); background: var(--card);
  border: 1px solid var(--card-border); padding: 4px 10px; border-radius: 999px; opacity: 0; transition: opacity .4s; pointer-events: none; }
#step-hint.show { opacity: .85; }
@media print { #step-hint { display: none; } }