/* ==========================================================================
   A Message from 1962? — Archival Paper & Early Computing Aesthetic
   ========================================================================== */

:root {
  --paper-bg: #ECE8DF;
  --paper-surface: #F4F1EA;
  --paper-elevated: #FAF8F3;
  --paper-inset: #E4DFD3;
  --ink-primary: #1E201D;
  --ink-secondary: #5B5E55;
  --ink-muted: #7C7E73;
  --phosphor-green: #264E36;
  --phosphor-dark: #1A3625;
  --phosphor-soft: #DCE3D8;
  --signal-vermilion: #C84B31;
  --signal-amber: #D96B27;
  --tape-manila: #F1DFAB;
  --tape-edge: #D1BD83;
  --hairline: #CFC9BC;
  --hairline-strong: #B8B1A2;

  --font-serif: "Instrument Serif", "Noto Serif SC", Georgia, serif;
  --font-sans: "Plus Jakarta Sans", -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-mono: "IBM Plex Mono", ui-monospace, SFMono-Regular, Menlo, monospace;
  --font-pixel: "VT323", "IBM Plex Mono", monospace;

  --radius-sm: 4px;
  --radius-md: 8px;
  --shadow-card: 0 1px 0 rgba(30, 32, 29, 0.05), 0 8px 24px rgba(30, 32, 29, 0.04);
  --max-width: 1180px;
}

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

html {
  background-color: var(--paper-bg);
  color: var(--ink-primary);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
}

body {
  margin: 0;
  min-height: 100vh;
  background-color: var(--paper-bg);
  background-image:
    radial-gradient(rgba(30, 32, 29, 0.035) 1px, transparent 0),
    radial-gradient(rgba(38, 78, 54, 0.025) 1px, transparent 0);
  background-size: 24px 24px;
  background-position: 0 0, 12px 12px;
  overflow-x: hidden;
}

[hidden] {
  display: none !important;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* ==========================================================================
   1. Retro Pixel Opening Overlay (Reference 1)
   ========================================================================== */

.intro-overlay {
  position: fixed;
  inset: 0;
  z-index: 1000;
  background-color: var(--paper-bg);
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  overflow: hidden;
}

.intro-overlay.is-hidden {
  visibility: hidden;
  pointer-events: none;
  opacity: 0;
}

.intro-canvas {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  z-index: 1;
}

.intro-topbar {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  z-index: 5;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 18px 28px;
}

.intro-tag {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--ink-muted);
}

.pixel-skip-btn {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--ink-secondary);
  background: var(--paper-surface);
  border: 1px solid var(--hairline-strong);
  padding: 6px 12px;
  cursor: pointer;
  transition: border-color 0.2s ease, color 0.2s ease;
}

.pixel-skip-btn:hover,
.pixel-skip-btn:focus-visible {
  border-color: var(--phosphor-green);
  color: var(--phosphor-green);
  outline: none;
}

.intro-stage {
  position: relative;
  z-index: 3;
  width: 312px;
  height: 214px;
}

.intro-stamps {
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 2;
}

.pixel-stamp {
  position: absolute;
  width: 28px;
  height: 28px;
  image-rendering: pixelated;
}

.pixel-window,
.pixel-window-clone {
  position: absolute;
  inset: 0;
  background: var(--paper-surface);
  border: 2px solid var(--phosphor-green);
  box-shadow: 4px 4px 0 rgba(38, 78, 54, 0.14);
}

.pixel-window-clone {
  opacity: 0;
  pointer-events: none;
  background: var(--paper-surface);
}

.pixel-window-clone::before {
  content: "";
  display: block;
  height: 28px;
  background: var(--phosphor-green);
}

.pixel-window {
  display: flex;
  flex-direction: column;
  z-index: 4;
}

.pixel-window-bar {
  height: 28px;
  background: var(--phosphor-green);
  color: var(--paper-surface);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 8px 0 10px;
}

.pixel-window-title {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
}

.pixel-close-x {
  appearance: none;
  background: transparent;
  border: none;
  color: var(--paper-surface);
  font-family: var(--font-mono);
  font-size: 16px;
  line-height: 1;
  padding: 2px 4px;
  cursor: pointer;
}

.pixel-window-body {
  flex: 1;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  padding: 20px 24px 22px;
  gap: 18px;
}

.pixel-greeting {
  margin: 0;
  font-family: var(--font-pixel);
  font-size: 31px;
  line-height: 1.05;
  color: var(--phosphor-green);
  text-align: left;
  width: 100%;
  max-width: 196px;
  letter-spacing: 0.03em;
}

.pixel-start-btn {
  width: 100%;
  max-width: 196px;
  padding: 7px 16px;
  background: transparent;
  border: 2px solid var(--phosphor-green);
  color: var(--phosphor-green);
  font-family: var(--font-pixel);
  font-size: 24px;
  line-height: 1;
  letter-spacing: 0.06em;
  cursor: pointer;
  transition: background-color 0.16s ease, color 0.16s ease, transform 0.12s ease;
}

.pixel-start-btn:hover,
.pixel-start-btn:focus-visible {
  background: var(--phosphor-green);
  color: var(--paper-surface);
  outline: none;
}

.pixel-start-btn:active {
  transform: translate(1px, 1px);
}

/* ==========================================================================
   2. Header & Navigation
   ========================================================================== */

.app-shell {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 40;
  background: rgba(236, 232, 223, 0.92);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--hairline);
}

.header-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 12px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
}

.brand-lockup {
  display: flex;
  align-items: center;
  gap: 10px;
}

.brand-dot {
  width: 8px;
  height: 8px;
  background: var(--phosphor-green);
  display: inline-block;
}

.brand-code {
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.08em;
  color: var(--ink-primary);
}

.brand-sub {
  font-size: 13px;
  color: var(--ink-secondary);
  border-left: 1px solid var(--hairline-strong);
  padding-left: 10px;
}

.stage-nav {
  display: flex;
  align-items: center;
  gap: 4px;
  background: var(--paper-inset);
  padding: 3px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--hairline);
}

.stage-tab {
  appearance: none;
  border: none;
  background: transparent;
  color: var(--ink-secondary);
  font-family: var(--font-sans);
  font-size: 13px;
  font-weight: 500;
  padding: 6px 12px;
  border-radius: 3px;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  transition: background-color 0.2s ease, color 0.2s ease;
}

.stage-tab .tab-num {
  font-family: var(--font-mono);
  font-size: 11px;
  opacity: 0.7;
}

.stage-tab:hover {
  color: var(--ink-primary);
}

.stage-tab.is-active {
  background: var(--paper-elevated);
  color: var(--phosphor-green);
  box-shadow: 0 1px 2px rgba(30, 32, 29, 0.08);
}

.utility-controls {
  display: flex;
  align-items: center;
  gap: 8px;
}

.util-btn {
  appearance: none;
  background: var(--paper-surface);
  border: 1px solid var(--hairline-strong);
  border-radius: var(--radius-sm);
  color: var(--ink-secondary);
  font-family: var(--font-mono);
  font-size: 12px;
  padding: 6px 10px;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  transition: border-color 0.2s ease, color 0.2s ease;
}

.util-btn:hover,
.util-btn:focus-visible {
  border-color: var(--phosphor-green);
  color: var(--ink-primary);
  outline: none;
}

.util-indicator {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--ink-muted);
}

.util-btn.is-on .util-indicator {
  background: var(--signal-vermilion);
}

.lang-switch {
  display: inline-flex;
  border: 1px solid var(--hairline-strong);
  border-radius: var(--radius-sm);
  overflow: hidden;
}

.lang-btn {
  appearance: none;
  border: none;
  background: var(--paper-surface);
  color: var(--ink-secondary);
  font-family: var(--font-mono);
  font-size: 12px;
  padding: 6px 10px;
  cursor: pointer;
}

.lang-btn.is-active {
  background: var(--phosphor-green);
  color: var(--paper-elevated);
}

/* ==========================================================================
   3. Main Layout & Hero
   ========================================================================== */

.main-content {
  flex: 1;
  max-width: var(--max-width);
  width: 100%;
  margin: 0 auto;
  padding: 36px 24px 72px;
}

.main-content:focus {
  outline: none;
}

.hero-band {
  padding-bottom: 28px;
  margin-bottom: 32px;
  border-bottom: 1px solid var(--hairline);
}

.hero-kicker {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
  margin-bottom: 12px;
}

.kicker-badge {
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 3px 8px;
  background: var(--phosphor-soft);
  color: var(--phosphor-green);
  border: 1px solid rgba(38, 78, 54, 0.25);
  border-radius: 2px;
}

.kicker-meta {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--ink-muted);
}

.hero-title {
  margin: 0 0 12px;
  font-family: var(--font-serif);
  font-size: clamp(2.4rem, 5vw, 4rem);
  font-weight: 400;
  line-height: 1.05;
  letter-spacing: -0.01em;
  color: var(--ink-primary);
}

.hero-lead {
  margin: 0;
  max-width: 68ch;
  font-size: 16px;
  color: var(--ink-secondary);
}

.shared-banner {
  margin-top: 20px;
  padding: 14px 18px;
  background: var(--paper-elevated);
  border: 1px solid var(--phosphor-green);
  border-left: 4px solid var(--phosphor-green);
  border-radius: var(--radius-sm);
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
}

.shared-banner[hidden] {
  display: none;
}

.shared-banner-text {
  display: flex;
  flex-direction: column;
  gap: 2px;
  font-size: 14px;
}

.shared-banner-text strong {
  color: var(--phosphor-green);
}

/* ==========================================================================
   4. Shared Section Headers, Cards & Buttons
   ========================================================================== */

.stage-section[hidden] {
  display: none;
}

.section-header-row {
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  gap: 24px;
  flex-wrap: wrap;
  margin-bottom: 24px;
}

.step-label {
  display: block;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--phosphor-green);
  margin-bottom: 4px;
}

.section-title {
  margin: 0;
  font-family: var(--font-serif);
  font-size: clamp(1.75rem, 3vw, 2.35rem);
  font-weight: 400;
  line-height: 1.15;
}

.section-note,
.apparatus-disclaimer {
  margin: 0;
  max-width: 46ch;
  font-size: 14px;
  color: var(--ink-secondary);
}

.apparatus-disclaimer {
  padding: 8px 12px;
  background: var(--paper-surface);
  border: 1px solid var(--hairline);
  border-left: 3px solid var(--signal-amber);
  border-radius: var(--radius-sm);
  font-size: 13px;
}

.panel-card {
  background: var(--paper-surface);
  border: 1px solid var(--hairline);
  border-radius: var(--radius-md);
  padding: 20px;
  box-shadow: var(--shadow-card);
}

.panel-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-bottom: 12px;
  margin-bottom: 16px;
  border-bottom: 1px solid var(--hairline);
}

.panel-code {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--ink-muted);
}

.btn-primary,
.btn-secondary,
.btn-ghost {
  appearance: none;
  font-family: var(--font-sans);
  font-size: 14px;
  font-weight: 500;
  padding: 10px 18px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  transition: background-color 0.2s ease, border-color 0.2s ease, color 0.2s ease, transform 0.12s ease;
}

.btn-primary {
  background: var(--phosphor-green);
  color: var(--paper-elevated);
  border: 1px solid var(--phosphor-green);
}

.btn-primary:hover,
.btn-primary:focus-visible {
  background: var(--phosphor-dark);
  border-color: var(--phosphor-dark);
  outline: none;
}

.btn-secondary {
  background: var(--paper-elevated);
  color: var(--ink-primary);
  border: 1px solid var(--hairline-strong);
}

.btn-secondary:hover,
.btn-secondary:focus-visible {
  border-color: var(--phosphor-green);
  color: var(--phosphor-green);
  outline: none;
}

.btn-ghost {
  background: transparent;
  color: var(--ink-secondary);
  border: 1px solid var(--hairline);
}

.btn-ghost:hover,
.btn-ghost:focus-visible {
  border-color: var(--ink-secondary);
  color: var(--ink-primary);
  outline: none;
}

.btn-sm {
  padding: 7px 12px;
  font-size: 13px;
}

.btn-xs {
  padding: 4px 9px;
  font-size: 12px;
  font-family: var(--font-mono);
}

.link-btn {
  appearance: none;
  background: none;
  border: none;
  padding: 0;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--phosphor-green);
  text-decoration: underline;
  text-underline-offset: 3px;
  cursor: pointer;
}

.link-btn:hover {
  color: var(--signal-vermilion);
}

/* ==========================================================================
   5. Stage 1 & 2: Compose & Letter Comparison
   ========================================================================== */

.compose-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1.12fr);
  gap: 24px;
  align-items: start;
}

.meta-inputs {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-bottom: 14px;
}

.field-group {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.field-label {
  font-size: 13px;
  font-weight: 500;
  color: var(--ink-secondary);
}

.text-input,
.textarea-input {
  width: 100%;
  font-family: var(--font-sans);
  font-size: 15px;
  color: var(--ink-primary);
  background: var(--paper-elevated);
  border: 1px solid var(--hairline-strong);
  border-radius: var(--radius-sm);
  padding: 9px 12px;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.textarea-input {
  resize: vertical;
  min-height: 118px;
  line-height: 1.6;
}

.text-input:focus,
.textarea-input:focus,
.letter-textarea:focus {
  outline: none;
  border-color: var(--phosphor-green);
  box-shadow: 0 0 0 3px rgba(38, 78, 54, 0.12);
}

.char-counter {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--ink-muted);
}

.samples-block {
  margin-top: 14px;
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}

.samples-label {
  font-size: 12px;
  color: var(--ink-muted);
}

.sample-chips {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}

.sample-chip {
  appearance: none;
  background: var(--paper-bg);
  border: 1px solid var(--hairline-strong);
  border-radius: 99px;
  padding: 4px 11px;
  font-size: 12px;
  color: var(--ink-secondary);
  cursor: pointer;
  transition: border-color 0.2s ease, color 0.2s ease, background-color 0.2s ease;
}

.sample-chip:hover {
  border-color: var(--phosphor-green);
  color: var(--phosphor-green);
  background: var(--paper-elevated);
}

.original-echo {
  margin-top: 18px;
  padding: 12px 14px;
  background: var(--paper-inset);
  border-radius: var(--radius-sm);
  border: 1px dashed var(--hairline-strong);
}

.echo-label {
  display: block;
  font-family: var(--font-mono);
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--ink-muted);
  margin-bottom: 4px;
}

.echo-text {
  margin: 0;
  font-size: 14px;
  color: var(--ink-secondary);
  white-space: pre-wrap;
  word-break: break-word;
}

/* 1962 Letter Paper Sheet */

.letter-paper {
  background: #FAF7EE;
  border: 1px solid var(--hairline-strong);
  border-radius: var(--radius-sm);
  padding: 18px;
  background-image: repeating-linear-gradient(
    to bottom,
    transparent,
    transparent 29px,
    rgba(184, 177, 162, 0.25) 30px
  );
}

.letter-paper-head {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 10px;
}

.postmark-stamp {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  color: var(--signal-vermilion);
  border: 1px solid rgba(200, 75, 49, 0.45);
  padding: 2px 7px;
  border-radius: 2px;
}

.edited-badge {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--phosphor-green);
  background: var(--phosphor-soft);
  padding: 2px 7px;
  border-radius: 2px;
}

.letter-textarea {
  width: 100%;
  border: 1px solid transparent;
  background: transparent;
  font-family: var(--font-serif);
  font-size: 20px;
  line-height: 30px;
  color: var(--ink-primary);
  resize: vertical;
  min-height: 240px;
  padding: 0 2px;
}

html[lang="zh-CN"] .letter-textarea,
html[lang="zh-CN"] .decoded-text {
  font-family: "Noto Serif SC", Georgia, serif;
  font-size: 16px;
  line-height: 30px;
}

.tone-footnote {
  margin: 10px 0 0;
  font-size: 12px;
  color: var(--ink-muted);
}

.compose-actions {
  margin-top: 16px;
  display: flex;
  justify-content: flex-end;
}

.dispatch-panel {
  margin-top: 18px;
  padding: 16px;
  background: var(--paper-elevated);
  border: 1px solid var(--phosphor-green);
  border-radius: var(--radius-sm);
}

.dispatch-panel[hidden] {
  display: none;
}

.dispatch-status {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 14px;
  font-weight: 500;
  color: var(--phosphor-green);
  margin-bottom: 12px;
}

.status-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--phosphor-green);
}

.dispatch-buttons {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}

.share-url-row {
  margin-top: 12px;
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}

.share-url-input {
  flex: 1;
  min-width: 200px;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--ink-secondary);
  background: var(--paper-bg);
  border: 1px solid var(--hairline);
  border-radius: var(--radius-sm);
  padding: 6px 10px;
}

.copy-feedback {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--phosphor-green);
}

/* ==========================================================================
   6. Stage 3: Contemporary Ferranti Sirius Interactive Machine
   ========================================================================== */

.sirius-console {
  background: #E6E1D5;
  border: 1px solid var(--hairline-strong);
  border-radius: var(--radius-md);
  padding: 20px;
  box-shadow: var(--shadow-card);
}

.console-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
  padding-bottom: 16px;
  margin-bottom: 20px;
  border-bottom: 1px solid var(--hairline-strong);
}

.console-nameplate {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.plate-title {
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.08em;
  color: var(--ink-primary);
}

.plate-model {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--ink-muted);
}

.decimal-strip {
  display: flex;
  align-items: center;
  gap: 10px;
  background: #232622;
  padding: 6px 12px;
  border-radius: var(--radius-sm);
  border: 1px solid #3A3E38;
}

.strip-label {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.08em;
  color: #93988C;
}

.lamp-row {
  display: flex;
  gap: 4px;
}

.lamp {
  width: 20px;
  height: 20px;
  display: grid;
  place-items: center;
  font-family: var(--font-mono);
  font-size: 11px;
  color: #6B7065;
  background: #171916;
  border-radius: 2px;
  border: 1px solid #30342E;
  transition: color 0.12s ease, background-color 0.12s ease;
}

.lamp.is-lit {
  color: #FFE7BD;
  background: #9B4D18;
  border-color: var(--signal-amber);
}

.console-workspace {
  display: grid;
  grid-template-columns: minmax(0, 1.3fr) minmax(0, 0.9fr);
  gap: 22px;
  align-items: start;
}

/* Paper Tape Reader */

.reader-housing {
  background: var(--paper-surface);
  border: 1px solid var(--hairline-strong);
  border-radius: var(--radius-sm);
  padding: 16px;
}

.reader-meta-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--ink-secondary);
  margin-bottom: 10px;
}

.tape-percent {
  color: var(--phosphor-green);
  font-weight: 600;
}

.tape-viewport {
  position: relative;
  height: 118px;
  background: #232622;
  border: 2px solid #3E433B;
  border-radius: var(--radius-sm);
  overflow: hidden;
  display: flex;
  align-items: center;
  touch-action: none;
  user-select: none;
}

.optical-head {
  position: absolute;
  left: 34px;
  top: 0;
  bottom: 0;
  width: 44px;
  z-index: 6;
  background: rgba(26, 54, 37, 0.85);
  border-left: 2px solid #8A9182;
  border-right: 2px solid #8A9182;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: space-between;
  padding: 4px 0;
  pointer-events: none;
}

.head-tag {
  font-family: var(--font-mono);
  font-size: 7px;
  letter-spacing: 0.04em;
  color: #D2D8CC;
  text-align: center;
  line-height: 1.05;
}

.head-sensors {
  display: flex;
  flex-direction: column;
  gap: 5px;
  align-items: center;
  margin-bottom: 6px;
}

.sensor-led {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: #3F463D;
  border: 1px solid #636C5F;
  transition: background-color 0.08s ease;
}

.sensor-led.is-sprocket {
  width: 4px;
  height: 4px;
}

.sensor-led.is-lit {
  background: var(--signal-amber);
  box-shadow: 0 0 6px rgba(217, 107, 39, 0.85);
}

.tape-ribbon {
  position: relative;
  display: flex;
  align-items: center;
  height: 84px;
  will-change: transform;
  transform: translate3d(56px, 0, 0);
}

.tape-holes-wrap {
  height: 84px;
  background: var(--tape-manila);
  border-top: 1px solid var(--tape-edge);
  border-bottom: 1px solid var(--tape-edge);
  box-shadow: inset 0 2px 0 rgba(255, 255, 255, 0.4), inset 0 -2px 0 rgba(0, 0, 0, 0.06);
  display: flex;
  align-items: center;
}

.tape-canvas {
  display: block;
  height: 84px;
}

.tape-handle {
  flex-shrink: 0;
  height: 84px;
  min-width: 72px;
  padding: 0 12px;
  background: var(--signal-vermilion);
  color: var(--paper-elevated);
  border: none;
  border-left: 2px dashed rgba(255, 255, 255, 0.65);
  clip-path: polygon(0 0, calc(100% - 12px) 0, 100% 50%, calc(100% - 12px) 100%, 0 100%);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 2px;
  cursor: grab;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.08em;
}

.tape-handle:active {
  cursor: grabbing;
  background: #AE3D26;
}

.handle-grip {
  font-size: 14px;
  letter-spacing: 2px;
  opacity: 0.85;
}

.tape-controls-row {
  margin-top: 12px;
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
}

.tape-scrubber {
  flex: 1;
  min-width: 160px;
  accent-color: var(--phosphor-green);
  cursor: pointer;
}

.tape-btn-group {
  display: flex;
  gap: 8px;
}

.drag-hint {
  margin: 10px 0 0;
  font-size: 13px;
  color: var(--ink-secondary);
}

/* Teleprinter Sheet */

.teleprinter-frame {
  margin-top: 16px;
  background: #FAF7EE;
  border: 1px solid var(--hairline-strong);
  border-radius: var(--radius-sm);
  padding: 16px 18px;
}

.teleprinter-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--ink-muted);
  padding-bottom: 10px;
  border-bottom: 1px solid var(--hairline);
}

.letter-sheet {
  min-height: 210px;
  padding: 16px 0 12px;
  position: relative;
}

.decoded-text {
  margin: 0;
  display: inline;
  white-space: pre-wrap;
  word-break: break-word;
  font-family: var(--font-serif);
  font-size: 21px;
  line-height: 1.5;
  color: var(--ink-primary);
}

.decoded-cursor {
  display: inline-block;
  font-family: var(--font-mono);
  font-weight: 700;
  color: var(--phosphor-green);
  margin-left: 2px;
}

@media (prefers-reduced-motion: no-preference) {
  .decoded-cursor.is-active {
    animation: cursor-blink 0.9s steps(2, start) infinite;
  }
}

@keyframes cursor-blink {
  to {
    opacity: 0;
  }
}

.tape-empty-prompt {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--ink-muted);
}

.letter-compare-toggle {
  padding-top: 10px;
  border-top: 1px dashed var(--hairline);
}

.receive-original-box {
  margin: 10px 0 0;
  padding: 10px 12px;
  background: var(--paper-inset);
  border-radius: var(--radius-sm);
  font-size: 13px;
  color: var(--ink-secondary);
  white-space: pre-wrap;
}

/* Delay-Line Loop Monitor */

.loop-card {
  background: var(--paper-surface);
  border: 1px solid var(--hairline-strong);
  border-radius: var(--radius-sm);
  padding: 18px;
}

.loop-card-top {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 10px;
  margin-bottom: 14px;
}

.loop-title {
  margin: 4px 0 0;
  font-family: var(--font-serif);
  font-size: 22px;
  font-weight: 400;
  line-height: 1.15;
}

.process-states {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
  margin-bottom: 14px;
}

.process-pill {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 9px 10px;
  background: var(--paper-elevated);
  border: 1px solid var(--hairline);
  border-radius: var(--radius-sm);
  transition: border-color 0.2s ease, background-color 0.2s ease;
}

.pill-dot {
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--ink-muted);
  flex-shrink: 0;
}

.process-pill.is-reading {
  border-color: var(--signal-amber);
  background: #FDF5EC;
}

.process-pill.is-reading .pill-dot {
  background: var(--signal-amber);
}

.process-pill.is-paused {
  border-color: var(--hairline-strong);
  background: var(--paper-inset);
}

.process-pill.is-paused .pill-dot {
  background: var(--ink-muted);
}

.process-pill.is-circulating {
  border-color: var(--phosphor-green);
  background: #EEF4EE;
}

.process-pill.is-circulating .pill-dot {
  background: var(--phosphor-green);
}

.pill-copy {
  display: flex;
  flex-direction: column;
  line-height: 1.25;
}

.pill-name {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--ink-secondary);
}

.pill-status {
  font-size: 12px;
  font-weight: 600;
  color: var(--ink-primary);
}

.loop-visual-box {
  background: var(--paper-elevated);
  border: 1px solid var(--hairline);
  border-radius: var(--radius-sm);
  padding: 6px;
  display: flex;
  justify-content: center;
}

.loop-canvas {
  width: 100%;
  max-width: 380px;
  height: auto;
  display: block;
}

.pause-callout {
  margin-top: 12px;
  padding: 11px 13px;
  background: #EEF4EE;
  border: 1px solid rgba(38, 78, 54, 0.35);
  border-left: 3px solid var(--phosphor-green);
  border-radius: var(--radius-sm);
  font-size: 13px;
}

.pause-callout[hidden] {
  display: none;
}

.pause-callout strong {
  display: block;
  color: var(--phosphor-green);
  margin-bottom: 3px;
}

.pause-callout p {
  margin: 0;
  color: var(--ink-secondary);
}

.cycle-telemetry {
  margin-top: 14px;
  padding-top: 12px;
  border-top: 1px solid var(--hairline);
}

.telemetry-row {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin-bottom: 6px;
}

.telemetry-label {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--ink-secondary);
}

.telemetry-value {
  font-family: var(--font-mono);
  font-size: 18px;
  font-weight: 600;
  color: var(--phosphor-green);
}

.telemetry-disclaimer {
  margin: 0;
  font-size: 12px;
  line-height: 1.45;
  color: var(--ink-muted);
  background: var(--paper-inset);
  padding: 8px 10px;
  border-radius: var(--radius-sm);
}

.complete-card {
  margin-top: 14px;
  padding: 16px;
  background: var(--paper-elevated);
  border: 1px solid var(--phosphor-green);
  border-radius: var(--radius-sm);
}

.complete-card[hidden] {
  display: none;
}

.complete-text {
  margin: 0 0 12px;
  font-size: 14px;
  color: var(--ink-primary);
}

/* ==========================================================================
   7. Stage 4: Real History & Museum Portal
   ========================================================================== */

.history-layout {
  display: grid;
  grid-template-columns: minmax(0, 1.15fr) minmax(0, 0.95fr);
  gap: 24px;
  align-items: start;
}

.museum-photo-frame {
  margin: 0;
  background: var(--paper-surface);
  border: 1px solid var(--hairline-strong);
  border-radius: var(--radius-md);
  padding: 14px;
  box-shadow: var(--shadow-card);
}

.photo-plate-wrap {
  position: relative;
  background: #23221F;
  border-radius: var(--radius-sm);
  overflow: hidden;
}

.sirius-archive-canvas,
.sirius-uploaded-photo {
  width: 100%;
  height: auto;
  display: block;
}

.sirius-uploaded-photo {
  max-height: 440px;
  object-fit: cover;
  filter: sepia(0.18) contrast(1.04);
}

.plate-catalog-tag {
  position: absolute;
  left: 12px;
  bottom: 12px;
  background: rgba(30, 32, 29, 0.84);
  color: #EAE5D9;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  padding: 4px 8px;
  border-radius: 2px;
}

.photo-caption-row {
  margin-top: 12px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
  font-size: 13px;
  color: var(--ink-secondary);
}

.upload-photo-label {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--phosphor-green);
  border: 1px solid var(--phosphor-green);
  border-radius: var(--radius-sm);
  padding: 4px 9px;
  cursor: pointer;
  white-space: nowrap;
}

.upload-photo-label:hover {
  background: var(--phosphor-green);
  color: var(--paper-elevated);
}

.history-cards {
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.history-card {
  background: var(--paper-surface);
  border: 1px solid var(--hairline);
  border-radius: var(--radius-md);
  padding: 18px 20px;
}

.card-num {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--signal-vermilion);
  letter-spacing: 0.08em;
}

.history-card h3 {
  margin: 4px 0 8px;
  font-family: var(--font-serif);
  font-size: 22px;
  font-weight: 400;
  line-height: 1.2;
}

.history-card p {
  margin: 0;
  font-size: 14px;
  color: var(--ink-secondary);
}

.museum-visit-banner {
  margin-top: 28px;
  background: var(--paper-elevated);
  border: 1px solid var(--hairline-strong);
  border-radius: var(--radius-md);
  padding: 24px;
  box-shadow: var(--shadow-card);
}

.visit-info-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) minmax(0, 1fr);
  gap: 24px;
  align-items: center;
}

.visit-kicker {
  font-family: var(--font-mono);
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--phosphor-green);
}

.visit-headline {
  margin: 4px 0 8px;
  font-family: var(--font-serif);
  font-size: 26px;
  font-weight: 400;
}

.visit-desc {
  margin: 0;
  font-size: 14px;
  color: var(--ink-secondary);
}

.visit-facts {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
}

.fact-item {
  background: var(--paper-surface);
  border: 1px solid var(--hairline);
  border-radius: var(--radius-sm);
  padding: 12px;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.fact-label {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--ink-muted);
  text-transform: uppercase;
}

.fact-val {
  font-size: 13px;
  font-weight: 600;
  color: var(--ink-primary);
}

.visit-cta-row {
  margin-top: 20px;
  padding-top: 16px;
  border-top: 1px solid var(--hairline);
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

/* ==========================================================================
   8. Footer & Native Modal Dialog
   ========================================================================== */

.site-footer {
  border-top: 1px solid var(--hairline);
  background: var(--paper-surface);
  padding: 16px 24px;
}

.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--ink-muted);
}

.visit-dialog {
  width: min(560px, calc(100vw - 32px));
  border: 1px solid var(--phosphor-green);
  border-radius: var(--radius-md);
  background: var(--paper-elevated);
  color: var(--ink-primary);
  padding: 0;
  box-shadow: 0 24px 60px rgba(30, 32, 29, 0.28);
}

.visit-dialog::backdrop {
  background: rgba(26, 30, 25, 0.56);
  backdrop-filter: blur(2px);
}

.dialog-shell {
  padding: 22px 24px;
}

.dialog-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 16px;
  padding-bottom: 14px;
  border-bottom: 1px solid var(--hairline);
}

.dialog-title {
  margin: 4px 0 0;
  font-family: var(--font-serif);
  font-size: 26px;
  font-weight: 400;
}

.dialog-close-btn {
  appearance: none;
  background: transparent;
  border: 1px solid var(--hairline-strong);
  border-radius: var(--radius-sm);
  padding: 5px 10px;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--ink-secondary);
  cursor: pointer;
}

.dialog-close-btn:hover {
  border-color: var(--phosphor-green);
  color: var(--phosphor-green);
}

.dialog-body {
  padding: 16px 0;
  font-size: 14px;
  color: var(--ink-secondary);
}

.dialog-details {
  margin: 14px 0 0;
  display: grid;
  gap: 10px;
}

.dialog-details > div {
  background: var(--paper-surface);
  border: 1px solid var(--hairline);
  border-radius: var(--radius-sm);
  padding: 10px 12px;
}

.dialog-details dt {
  font-family: var(--font-mono);
  font-size: 11px;
  text-transform: uppercase;
  color: var(--phosphor-green);
  margin-bottom: 2px;
}

.dialog-details dd {
  margin: 0;
  color: var(--ink-primary);
}

.dialog-footer {
  padding-top: 12px;
  border-top: 1px solid var(--hairline);
  display: flex;
  justify-content: flex-end;
}

/* ==========================================================================
   9. Responsive Breakpoints & Reduced Motion
   ========================================================================== */

@media (max-width: 1040px) {
  .brand-sub {
    display: none;
  }
}

@media (max-width: 960px) {
  .compose-grid,
  .console-workspace,
  .history-layout,
  .visit-info-grid {
    grid-template-columns: 1fr;
  }

  .visit-facts {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 640px) {
  .header-inner {
    padding: 10px 16px;
  }

  .stage-nav {
    order: 3;
    width: 100%;
    justify-content: space-between;
  }

  .stage-tab {
    flex: 1;
    justify-content: center;
    padding: 6px 6px;
    font-size: 12px;
  }

  .main-content {
    padding: 24px 16px 56px;
  }

  .meta-inputs,
  .process-states {
    grid-template-columns: 1fr;
  }

  .decimal-strip {
    width: 100%;
    justify-content: space-between;
    overflow-x: auto;
  }

  .intro-stage {
    width: 280px;
    height: 196px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .btn-primary,
  .btn-secondary,
  .btn-ghost,
  .pixel-start-btn,
  .stage-tab {
    transition-property: background-color, border-color, color;
  }
}