/* ============================================================
   desktop.css v2 — Base Reset + Desktop Layout (≥ 768px)
   深海蓝顶/底栏 · 暖米白内容区
   ============================================================ */

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

html {
  height: 100%;
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
}
body {
  height: 100%;
  font-family: var(--font-sans);
  background: var(--bg-base);
  color: var(--text-primary);
  -webkit-font-smoothing: antialiased;
  overflow: hidden;
  user-select: none;
}

/* ── Loader ── */
#loader {
  position: fixed; inset: 0; z-index: 9999;
  display: flex; flex-direction: column;
  align-items: center; justify-content: center;
  background: var(--navy);
  transition: opacity 0.4s ease, visibility 0.4s ease;
}
body:not(.loading) #loader { opacity: 0; visibility: hidden; pointer-events: none; }
.loader-ring {
  width: 32px; height: 32px;
  border: 1.5px solid rgba(201,169,110,0.25);
  border-top-color: var(--gold);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}
.loader-text {
  margin-top: var(--sp-4);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--text-on-dark-muted);
}
@keyframes spin { to { transform: rotate(360deg); } }

/* ── Top Bar · Navy ── */
#top-bar {
  position: fixed; top: 0; left: 0; right: 0;
  height: var(--topbar-h); z-index: 200;
  display: flex; align-items: center;
  padding: 0 var(--sp-8);
  background: var(--navy);
  border-bottom: 1px solid var(--border-dk-subtle);
}
.topbar-left  { flex: 0 0 auto; }
.topbar-center { flex: 1; text-align: center; }
.topbar-right  { flex: 0 0 auto; display: flex; align-items: center; gap: var(--sp-5); }

/* Brand mark */
.brand {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: var(--fw-medium);
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--text-on-dark-muted);
}
.brand-accent { color: var(--gold); }

/* Chapter name in top bar */
#slide-chapter {
  font-family: var(--font-sans);
  font-size: var(--text-xs);
  font-weight: var(--fw-normal);
  letter-spacing: 0.06em;
  color: var(--text-on-dark-muted);
}

/* Progress dots (desktop) */
#progress-dots { display: flex; align-items: center; gap: 5px; }
.pdot {
  width: 6px; height: 6px;
  border-radius: var(--r-full);
  background: rgba(255,255,255,0.18);
  border: none; cursor: pointer; padding: 0;
  transition: width 0.3s var(--ease-out), background 0.25s;
  outline: none;
  position: relative;
}
/* Active dot stretches to an ellipse */
.pdot.is-active  { width: 14px; background: var(--gold); border-radius: 3px; }
.pdot.is-visited { background: rgba(255,255,255,0.35); }
.pdot:hover      { background: var(--gold-lt); width: 10px; }

/* Tooltip for dot */
.pdot::after {
  content: attr(title);
  position: absolute; bottom: calc(100% + 8px); left: 50%;
  transform: translateX(-50%);
  background: var(--navy-light); border: 1px solid var(--border-dk-default);
  color: var(--text-on-dark); font-family: var(--font-sans);
  font-size: var(--text-2xs); padding: 3px 8px;
  border-radius: var(--r-sm); white-space: nowrap;
  pointer-events: none; opacity: 0;
  transition: opacity var(--ease-fast);
}
.pdot:hover::after { opacity: 1; }

#progress-counter { display: none; }

/* ── Stage ── */
#stage {
  position: fixed;
  top: var(--topbar-h); left: 0; right: 0;
  height: var(--stage-h);
  overflow: hidden;
  background: var(--bg-base);
}
#slide-content { width: 100%; height: 100%; }

/* Slide transitions */
#slide-content.is-exiting { opacity: 0; transition: opacity 0.18s ease; }
#slide-content.is-entering {
  animation: slideEnter 0.85s var(--ease-spring) forwards;
}
@keyframes slideEnter {
  from { opacity: 0; transform: translateY(28px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ── Bottom Bar · Navy ── */
#bottom-bar {
  position: fixed; bottom: 0; left: 0; right: 0;
  height: var(--bottombar-h); z-index: 200;
  display: flex; align-items: center; justify-content: space-between;
  padding: 0 var(--sp-8);
  background: var(--navy);
  border-top: 1px solid var(--border-dk-subtle);
}

/* Nav buttons in bottom bar */
.nav-btn {
  display: flex; align-items: center; gap: var(--sp-2);
  padding: var(--sp-2) var(--sp-5);
  min-width: 130px; height: 34px;
  border: 1px solid var(--border-dk-default);
  border-radius: var(--r-sm);
  background: transparent;
  color: var(--text-on-dark-muted);
  font-family: var(--font-sans); font-size: var(--text-xs);
  font-weight: var(--fw-medium);
  cursor: pointer; outline: none;
  transition: border-color 0.2s, color 0.2s, background 0.2s;
  white-space: nowrap;
}
.nav-btn svg { width: 14px; height: 14px; flex-shrink: 0; }
.nav-btn:hover:not(:disabled) {
  border-color: var(--gold-border);
  color: var(--gold-lt);
  background: var(--gold-dim);
}
.nav-btn:disabled { opacity: 0.25; cursor: not-allowed; }

/* Next button — gold accent */
.nav-btn-next {
  border-color: var(--gold-border);
  color: var(--gold);
  background: var(--gold-dim);
  justify-content: flex-end;
}
.nav-btn-next:hover:not(:disabled) {
  background: var(--gold);
  border-color: var(--gold);
  color: var(--navy);
}

/* Page counter */
#page-counter {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--text-on-dark-muted);
  letter-spacing: 0.08em;
  min-width: 52px; text-align: center;
}

/* Step dots */
#step-dots { display: flex; align-items: center; gap: 6px; }
.sdot {
  width: 6px; height: 6px;
  border-radius: var(--r-full);
  background: rgba(255,255,255,0.18);
  transition: width 0.3s var(--ease-out), background 0.25s;
}
.sdot.is-active { width: 14px; background: var(--gold); border-radius: 3px; }
.sdot.is-done   { background: rgba(255,255,255,0.38); }

/* ── Reveal System (desktop) ──
   Step > 0 blocks are invisible (layout preserved).
   On shown: spring animation plays once. */
.reveal-block[data-step]:not([data-step="0"]):not(.is-shown) {
  opacity: 0;
  transform: translateY(24px);
  pointer-events: none;
  /* No transition here — spring animation handles the shown state */
}
.reveal-block[data-step].is-shown {
  opacity: 1 !important;
  transform: translateY(0) !important;
  pointer-events: auto !important;
  animation: springReveal 0.75s var(--ease-spring) forwards;
}
/* Staggered children within a revealed block */
.reveal-block.is-shown > *:nth-child(1) { animation-delay: 0ms; }
.reveal-block.is-shown > *:nth-child(2) { animation-delay: 90ms; }
.reveal-block.is-shown > *:nth-child(3) { animation-delay: 180ms; }
.reveal-block.is-shown > *:nth-child(4) { animation-delay: 270ms; }

@keyframes springReveal {
  from { opacity: 0; transform: translateY(24px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ── Slide structure utilities ── */
.slide-wrap {
  width: 100%; height: 100%;
  display: flex; flex-direction: column;
  padding: var(--sp-8) var(--sp-12);
  overflow: hidden; position: relative;
  background: var(--bg-base);
}
.slide-head { flex-shrink: 0; margin-bottom: var(--sp-5); }
.slide-body {
  flex: 1; min-height: 0;
  display: flex; flex-direction: column;
  gap: var(--sp-4);
}

/* Layout grid helpers */
.l-two-col   { display: grid; grid-template-columns: 1fr 1fr; gap: var(--sp-5); }
.l-three-col { display: grid; grid-template-columns: 1fr 1fr 1fr; gap: var(--sp-4); }
.l-60-40     { display: grid; grid-template-columns: 3fr 2fr; gap: var(--sp-5); }
.l-40-60     { display: grid; grid-template-columns: 2fr 3fr; gap: var(--sp-5); }
.l-center    { display: flex; flex-direction: column; align-items: center; justify-content: center; }
.l-fill      { flex: 1; }
.l-row       { display: flex; gap: var(--sp-4); }
.l-col       { display: flex; flex-direction: column; gap: var(--sp-3); }