:root {
  color-scheme: light;
  --paper: #f3f6f3;
  --paper-strong: #ffffff;
  --ink: #18332d;
  --ink-soft: #557069;
  --line: #ccd8d3;
  --line-strong: #9db2aa;
  --green: #25685a;
  --green-deep: #174b41;
  --green-pale: #dcece6;
  --blue-pale: #e3edf3;
  --orange: #aa542e;
  --orange-pale: #f4e6df;
  --danger: #a73d3d;
  --shadow: 0 12px 36px rgba(24, 51, 45, 0.1);
  --radius: 10px;
  --body-font: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", sans-serif;
  --display-font: "Songti SC", "STSong", serif;
  --data-font: ui-monospace, "SFMono-Regular", Menlo, monospace;
}

[data-theme="dark"] {
  color-scheme: dark;
  --paper: #172320;
  --paper-strong: #1e2d29;
  --ink: #e8f0ed;
  --ink-soft: #a6b9b3;
  --line: #344b45;
  --line-strong: #56746b;
  --green: #71b5a4;
  --green-deep: #b5dfd3;
  --green-pale: #25453d;
  --blue-pale: #283f4b;
  --orange: #e09a73;
  --orange-pale: #4a3128;
  --danger: #ff9b9b;
  --shadow: 0 14px 36px rgba(0, 0, 0, 0.28);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  min-width: 320px;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--body-font);
  font-size: 16px;
  line-height: 1.75;
  letter-spacing: 0;
}
button, input, textarea { font: inherit; }
button { color: inherit; }
button, a { -webkit-tap-highlight-color: transparent; }
button:focus-visible, a:focus-visible, input:focus-visible, textarea:focus-visible {
  outline: 3px solid color-mix(in srgb, var(--orange) 58%, transparent);
  outline-offset: 3px;
}

.app-shell { min-height: 100vh; }
.course-rail {
  position: fixed;
  inset: 0 auto 0 0;
  z-index: 20;
  display: flex;
  width: 310px;
  flex-direction: column;
  overflow-y: auto;
  border-right: 1px solid var(--line);
  background: var(--paper-strong);
}
.rail-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 24px 22px 18px;
}
.brand {
  display: flex;
  gap: 12px;
  align-items: center;
  color: var(--ink);
  text-decoration: none;
}
.brand strong { display: block; font-size: 16px; line-height: 1.3; }
.brand small { display: block; margin-top: 3px; color: var(--ink-soft); font-size: 12px; }
.brand-mark {
  position: relative;
  display: grid;
  width: 34px;
  height: 34px;
  place-items: center;
  border: 1px solid var(--line-strong);
  border-radius: 50%;
}
.brand-mark span { position: absolute; width: 5px; height: 5px; border-radius: 50%; background: var(--green); }
.brand-mark span:nth-child(1) { transform: translate(-8px, 4px); }
.brand-mark span:nth-child(2) { transform: translate(0, -5px); }
.brand-mark span:nth-child(3) { transform: translate(8px, 5px); background: var(--orange); }
.brand-mark::after { content: ""; width: 19px; height: 12px; border-bottom: 1px solid var(--green); transform: rotate(4deg); }

.icon-button {
  display: inline-grid;
  width: 42px;
  height: 42px;
  flex: 0 0 42px;
  place-items: center;
  border: 0;
  border-radius: 8px;
  background: transparent;
  cursor: pointer;
}
.icon-button:hover { background: var(--green-pale); }
.icon-button svg, .text-button svg { width: 20px; height: 20px; fill: none; stroke: currentColor; stroke-linecap: round; stroke-linejoin: round; stroke-width: 1.8; }
.rail-close, .menu-button { display: none; }

.progress-block { margin: 2px 22px 20px; padding: 16px 0 18px; border-block: 1px solid var(--line); }
.progress-copy { display: flex; align-items: baseline; justify-content: space-between; font-size: 13px; }
.progress-copy strong { font-family: var(--data-font); font-size: 13px; }
.progress-track { height: 4px; margin-top: 10px; overflow: hidden; background: var(--line); }
.progress-track span { display: block; width: 100%; height: 100%; background: var(--orange); transform: scaleX(0); transform-origin: left center; transition: transform 300ms ease-out; }
.progress-block p, .rail-foot p { margin: 10px 0 0; color: var(--ink-soft); font-size: 12px; line-height: 1.6; }

.lesson-nav { position: relative; padding: 0 14px 18px; }
.lesson-nav::before { content: ""; position: absolute; top: 25px; bottom: 42px; left: 35px; width: 1px; background: var(--line); }
.nav-item {
  position: relative;
  display: grid;
  width: 100%;
  min-height: 62px;
  grid-template-columns: 32px 1fr;
  gap: 10px;
  align-items: center;
  padding: 7px 10px 7px 6px;
  border: 0;
  border-radius: 8px;
  background: transparent;
  text-align: left;
  cursor: pointer;
}
.nav-item:hover { background: color-mix(in srgb, var(--green-pale) 62%, transparent); }
.nav-item[aria-current="page"] { background: var(--green-pale); color: var(--green-deep); }
.nav-node {
  z-index: 1;
  display: grid;
  width: 30px;
  height: 30px;
  place-items: center;
  border: 1px solid var(--line-strong);
  border-radius: 50%;
  background: var(--paper-strong);
  color: var(--ink-soft);
  font-family: var(--data-font);
  font-size: 11px;
}
.nav-item.is-complete .nav-node { border-color: var(--green); background: var(--green); color: white; }
.nav-copy strong { display: block; font-size: 14px; font-weight: 600; line-height: 1.4; }
.nav-copy small { display: block; margin-top: 2px; overflow: hidden; color: var(--ink-soft); font-size: 11px; text-overflow: ellipsis; white-space: nowrap; }
.rail-foot { margin-top: auto; padding: 16px 22px 24px; border-top: 1px solid var(--line); }
.text-button { display: inline-flex; gap: 8px; align-items: center; margin-top: 12px; padding: 7px 0; border: 0; background: transparent; color: var(--green-deep); font-size: 13px; font-weight: 600; cursor: pointer; }
.text-button:hover { color: var(--orange); }
.me-link { display: block; margin-top: 12px; color: var(--green-deep); font-size: 13px; font-weight: 650; text-decoration: none; }

.reading-pane { min-height: 100vh; margin-left: 310px; }
.topbar {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  min-height: 76px;
  align-items: center;
  gap: 16px;
  padding: 10px max(28px, calc((100vw - 310px - 860px) / 2));
  border-bottom: 1px solid color-mix(in srgb, var(--line) 82%, transparent);
  background: color-mix(in srgb, var(--paper) 92%, transparent);
  backdrop-filter: blur(14px);
}
.location { min-width: 0; }
.location span { display: block; color: var(--orange); font-family: var(--data-font); font-size: 11px; }
.location strong { display: block; overflow: hidden; font-size: 14px; text-overflow: ellipsis; white-space: nowrap; }
.topbar-actions { display: flex; align-items: center; gap: 4px; margin-left: auto; }
.save-status { margin-right: 8px; color: var(--ink-soft); font-size: 12px; }
.quick-button, .install-button { display: inline-flex; min-height: 38px; align-items: center; gap: 7px; padding: 7px 11px; border: 1px solid var(--green); border-radius: 8px; background: var(--green); color: #fff; font-size: 12px; font-weight: 650; cursor: pointer; }
.quick-button:hover, .install-button:hover { background: var(--green-deep); border-color: var(--green-deep); }
.install-button { border-color: var(--line-strong); background: transparent; color: var(--green-deep); }
.quick-button svg, .install-button svg { width: 16px; height: 16px; fill: none; stroke: currentColor; stroke-linecap: round; stroke-linejoin: round; stroke-width: 1.8; }
.theme-sun { display: none; }
[data-theme="dark"] .theme-moon { display: none; }
[data-theme="dark"] .theme-sun { display: block; }

.lesson { width: min(100% - 48px, 820px); margin: 0 auto; padding: 62px 0 80px; }
.lesson-header { position: relative; padding-bottom: 42px; border-bottom: 1px solid var(--line-strong); }
.lesson-kicker { margin: 0 0 12px; color: var(--orange); font-family: var(--data-font); font-size: 12px; }
.lesson h1 { max-width: 12em; margin: 0; font-family: var(--display-font); font-size: clamp(36px, 5vw, 58px); font-weight: 700; line-height: 1.15; letter-spacing: 0; }
.lesson-summary { max-width: 650px; margin: 20px 0 0; color: var(--ink-soft); font-size: 18px; line-height: 1.75; }
.lesson-time { display: inline-flex; gap: 7px; align-items: center; margin-top: 22px; color: var(--ink-soft); font-size: 13px; }
.lesson-time svg { width: 17px; height: 17px; fill: none; stroke: currentColor; stroke-width: 1.8; }

.lesson-section { padding: 40px 0; border-bottom: 1px solid var(--line); }
.lesson-section h2 { margin: 0 0 16px; font-family: var(--display-font); font-size: 26px; line-height: 1.35; }
.lesson-section h3 { margin: 30px 0 10px; font-size: 17px; line-height: 1.5; }
.lesson-section p { max-width: 72ch; margin: 0 0 14px; }
.lesson-section ul, .lesson-section ol { margin: 14px 0; padding-left: 1.4em; }
.lesson-section li { margin: 8px 0; padding-left: 0.25em; }
.lesson-section li::marker { color: var(--orange); font-weight: 700; }
.lesson-section strong { font-weight: 650; }
.note {
  margin: 24px 0;
  padding: 18px 20px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--blue-pale);
}
.note.warning { background: var(--orange-pale); }
.note.danger { color: var(--danger); }
.note p:last-child { margin-bottom: 0; }
.quote { margin: 24px 0; padding: 4px 0 4px 22px; border-left: 1px solid var(--orange); color: var(--green-deep); font-family: var(--display-font); font-size: 20px; line-height: 1.7; }

.cycle-map {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1px;
  margin: 24px 0 8px;
  overflow: hidden;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius);
  background: var(--line);
}
.cycle-step { position: relative; min-height: 122px; padding: 18px 16px; background: var(--paper-strong); }
.cycle-step small { color: var(--orange); font-family: var(--data-font); font-size: 10px; }
.cycle-step strong { display: block; margin-top: 24px; font-size: 15px; }
.cycle-step:not(:last-child)::after { content: ""; position: absolute; top: 24px; right: -5px; z-index: 1; width: 8px; height: 8px; border-top: 1px solid var(--orange); border-right: 1px solid var(--orange); transform: rotate(45deg); }

.experiment { margin-top: 34px; overflow: hidden; border-radius: var(--radius); background: var(--paper-strong); box-shadow: var(--shadow); }
.experiment-head { display: flex; align-items: start; justify-content: space-between; gap: 20px; padding: 22px 24px; background: var(--green-deep); color: var(--paper-strong); }
[data-theme="dark"] .experiment-head { color: #12211d; }
.experiment-head h2 { margin: 0 0 4px; font-family: var(--display-font); font-size: 24px; }
.experiment-head p { margin: 0; opacity: 0.8; font-size: 13px; }
.autosave { flex: 0 0 auto; font-family: var(--data-font); font-size: 10px; opacity: 0.72; }
.form-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; padding: 24px; }
.field { display: grid; gap: 7px; }
.field.full { grid-column: 1 / -1; }
.field label { color: var(--ink-soft); font-size: 13px; font-weight: 600; }
.field input, .field textarea {
  width: 100%;
  border: 0;
  border-bottom: 1px solid var(--line-strong);
  border-radius: 0;
  background: transparent;
  color: var(--ink);
  line-height: 1.65;
  resize: vertical;
}
.field input { min-height: 42px; padding: 7px 2px; }
.field textarea { min-height: 86px; padding: 9px 2px; }
.field input::placeholder, .field textarea::placeholder { color: color-mix(in srgb, var(--ink-soft) 78%, transparent); }
.form-actions { display: flex; align-items: center; justify-content: space-between; gap: 14px; padding: 18px 24px 22px; border-top: 1px solid var(--line); }
.complete-toggle { display: inline-flex; align-items: center; gap: 10px; cursor: pointer; }
.complete-toggle input { position: absolute; opacity: 0; }
.check-box { display: grid; width: 24px; height: 24px; place-items: center; border: 1px solid var(--line-strong); border-radius: 6px; }
.check-box svg { width: 15px; fill: none; stroke: white; stroke-width: 2.2; opacity: 0; }
.complete-toggle input:checked + .check-box { border-color: var(--green); background: var(--green); }
.complete-toggle input:checked + .check-box svg { opacity: 1; }
.complete-toggle input:focus-visible + .check-box { outline: 3px solid color-mix(in srgb, var(--orange) 58%, transparent); outline-offset: 3px; }
.complete-toggle span:last-child { font-size: 14px; font-weight: 600; }
.clear-button { border: 0; background: transparent; color: var(--ink-soft); font-size: 12px; cursor: pointer; }
.clear-button:hover { color: var(--danger); }

.completion { display: grid; grid-template-columns: 130px 1fr; gap: 22px; align-items: start; margin-top: 34px; padding: 22px 0; border-block: 1px solid var(--line-strong); }
.completion strong { color: var(--orange); font-family: var(--data-font); font-size: 12px; }
.completion p { margin: 0; }
.lesson-footer { display: grid; grid-template-columns: 1fr auto 1fr; align-items: center; gap: 18px; padding-top: 38px; }
.nav-button { display: inline-flex; min-height: 44px; align-items: center; gap: 8px; border: 0; background: transparent; color: var(--green-deep); font-weight: 650; cursor: pointer; }
.nav-button:last-child { justify-self: end; }
.nav-button:disabled { opacity: 0.28; cursor: default; }
.nav-button svg { width: 18px; fill: none; stroke: currentColor; stroke-width: 1.8; }
.lesson-footer small { color: var(--ink-soft); text-align: center; }
.toast { position: fixed; right: 24px; bottom: 24px; z-index: 40; padding: 10px 14px; border-radius: 8px; background: var(--ink); color: var(--paper-strong); box-shadow: var(--shadow); font-size: 13px; opacity: 0; transform: translateY(8px); pointer-events: none; transition: 180ms ease-out; }
.toast.is-visible { opacity: 1; transform: translateY(0); }

.is-immediate .course-rail, .is-immediate .topbar { display: none; }
.is-immediate .reading-pane { margin-left: 0; }
.is-immediate .lesson { width: 100%; padding: 0; }
.immediate-screen { display: flex; min-height: 100svh; flex-direction: column; padding: max(18px, env(safe-area-inset-top)) max(18px, env(safe-area-inset-right)) max(20px, env(safe-area-inset-bottom)) max(18px, env(safe-area-inset-left)); background: var(--paper); }
.immediate-head { display: flex; min-height: 44px; align-items: center; justify-content: space-between; }
.immediate-brand { font-size: 15px; }
.immediate-exit { width: 44px; height: 44px; border: 0; border-radius: 8px; background: transparent; color: var(--ink-soft); font-size: 26px; cursor: pointer; }
.immediate-exit:hover { background: var(--green-pale); }
.immediate-progress { height: 2px; overflow: hidden; background: var(--line); }
.immediate-progress span { display: block; width: 100%; height: 100%; background: var(--orange); transform: scaleX(var(--progress)); transform-origin: left; transition: transform 240ms ease-out; }
.immediate-stage { display: flex; width: min(100%, 440px); flex: 1; flex-direction: column; justify-content: center; margin: 0 auto; padding: 44px 0 24px; }
.immediate-kicker { margin: 0 0 10px; color: var(--orange); font-family: var(--data-font); font-size: 11px; }
.immediate-stage h1 { max-width: 11em; margin: 0; font-family: var(--display-font); font-size: 38px; line-height: 1.2; }
.immediate-copy { max-width: 26em; margin: 14px 0 0; color: var(--ink-soft); font-size: 17px; line-height: 1.75; }
.immediate-rationale { margin: 16px 0 0; padding-left: 12px; border-left: 2px solid var(--orange); color: var(--green-deep); font-size: 14px; line-height: 1.6; }
.immediate-input-label { display: block; margin-top: 28px; color: var(--ink-soft); font-size: 13px; font-weight: 650; }
.immediate-input { width: 100%; min-height: 92px; margin-top: 8px; padding: 13px 14px; resize: vertical; border: 1px solid var(--line-strong); border-radius: 8px; background: var(--paper-strong); color: var(--ink); font: inherit; line-height: 1.6; }
.immediate-input:focus { outline: 2px solid color-mix(in srgb, var(--green) 45%, transparent); outline-offset: 2px; border-color: var(--green); }
.immediate-anchor { position: relative; display: grid; width: 156px; height: 156px; place-items: center; margin: 34px auto; border: 1px solid var(--line-strong); border-radius: 50%; }
.immediate-anchor::before, .immediate-anchor::after { content: ""; position: absolute; background: var(--green); opacity: .42; }
.immediate-anchor::before { width: 1px; height: 68%; }
.immediate-anchor::after { width: 68%; height: 1px; }
.immediate-anchor span { z-index: 1; width: 18px; height: 18px; border-radius: 50%; background: var(--green); box-shadow: 0 7px 22px color-mix(in srgb, var(--green) 24%, transparent); }
.immediate-anchor[data-anchor="support"]::before, .immediate-anchor[data-anchor="support"]::after { opacity: 0; }
.immediate-anchor[data-anchor="choice"] { width: 112px; height: 112px; margin-block: 24px; opacity: .56; }
.immediate-anchor[data-anchor="action"]::before { width: 68%; height: 1px; }
.immediate-anchor[data-anchor="action"]::after { display: none; }
.immediate-anchor[data-anchor="finish"] { border-color: transparent; }
.immediate-anchor[data-anchor="finish"]::before { width: 86%; height: 1px; }
.immediate-anchor[data-anchor="finish"]::after { display: none; }
.immediate-primary { width: 100%; min-height: 52px; padding: 10px 18px; border: 1px solid var(--green); border-radius: 8px; background: var(--green); color: #fff; font-weight: 650; cursor: pointer; }
.immediate-primary:hover { border-color: var(--green-deep); background: var(--green-deep); }
.immediate-secondary, .immediate-back { min-height: 44px; border: 0; background: transparent; color: var(--ink-soft); cursor: pointer; }
.immediate-secondary { margin-top: 8px; }
.immediate-back { margin-top: 2px; font-size: 13px; }
.immediate-choices { display: grid; gap: 10px; margin-top: 28px; }
.immediate-choices button { min-height: 52px; padding: 12px 14px; border: 1px solid var(--line); border-radius: 8px; background: var(--paper-strong); color: var(--ink); text-align: left; cursor: pointer; }
.immediate-choices button:hover { border-color: var(--green); }
.immediate-suggestions { display: grid; gap: 8px; margin-top: 24px; }
.immediate-suggestions button { min-height: 48px; padding: 11px 13px; border: 1px solid var(--line); border-radius: 8px; background: var(--paper-strong); color: var(--ink); text-align: left; line-height: 1.5; cursor: pointer; }
.immediate-suggestions button:hover, .immediate-suggestions button[aria-pressed="true"] { border-color: var(--green); background: var(--green-pale); }
.immediate-suggestions small { display: block; margin-bottom: 2px; color: var(--orange); font-family: var(--data-font); font-size: 10px; }
.immediate-feedback { display: grid; grid-template-columns: 1fr 1fr; gap: 8px; margin: 28px 0 18px; }
.immediate-feedback p { grid-column: 1 / -1; margin: 0 0 4px; color: var(--ink-soft); font-size: 13px; }
.immediate-feedback button { min-height: 44px; border: 1px solid var(--line); border-radius: 8px; background: transparent; color: var(--ink); cursor: pointer; }
.immediate-feedback button[aria-pressed="true"] { border-color: var(--green); background: var(--green-pale); }
.memory-candidate { margin: 20px 0 16px; padding-top: 18px; border-top: 1px solid var(--line); }
.memory-candidate p { margin: 0 0 8px; color: var(--ink-soft); font-size: 13px; }
.memory-candidate textarea, .memory-item textarea { width: 100%; padding: 10px 12px; border: 1px solid var(--line-strong); border-radius: 8px; background: var(--paper-strong); color: var(--ink); font: inherit; resize: vertical; }
.memory-candidate div, .memory-item div { display: flex; gap: 8px; margin-top: 8px; }
.memory-candidate button, .memory-item button { min-height: 38px; padding: 7px 11px; border: 1px solid var(--line); border-radius: 8px; background: transparent; color: var(--ink); cursor: pointer; }

.me-header { margin-bottom: 10px; }
.settings-section { padding: 30px 0; border-bottom: 1px solid var(--line); }
.settings-section h2 { margin: 0; font-family: var(--display-font); font-size: 24px; }
.section-heading { display: flex; align-items: start; justify-content: space-between; gap: 16px; margin-bottom: 18px; }
.section-heading p { margin: 6px 0 0; color: var(--ink-soft); font-size: 14px; }
.setting-row { display: flex; align-items: center; justify-content: space-between; gap: 20px; padding: 18px 0; border-bottom: 1px solid var(--line); cursor: pointer; }
.setting-row span { min-width: 0; }
.setting-row strong, .setting-row small { display: block; }
.setting-row small { margin-top: 4px; color: var(--ink-soft); }
.setting-row input { width: 44px; height: 24px; accent-color: var(--green); }
.memory-list { display: grid; gap: 12px; }
.memory-item { padding: 14px; border: 1px solid var(--line); border-radius: 8px; }
.memory-item button:last-child { color: var(--danger); }
.empty-state { margin: 18px 0 0; color: var(--ink-soft); }

@media (max-width: 900px) {
  .course-rail { width: min(88vw, 320px); transform: translateX(-102%); transition: transform 220ms ease-out; }
  .course-rail.is-open { transform: translateX(0); }
  .rail-close, .menu-button { display: inline-grid; }
  .rail-scrim { position: fixed; inset: 0; z-index: 15; background: rgba(10, 24, 20, 0.38); opacity: 0; pointer-events: none; transition: opacity 220ms ease-out; }
  .rail-scrim.is-visible { opacity: 1; pointer-events: auto; }
  .reading-pane { margin-left: 0; }
  .topbar { padding: 10px 18px; }
  .save-status { display: none; }
  .lesson { width: min(100% - 36px, 740px); padding-top: 42px; }
}

@media (max-width: 620px) {
  body { font-size: 15px; }
  .topbar { min-height: 64px; gap: 8px; padding-inline: 10px; }
  .topbar-actions { gap: 0; }
  .topbar .icon-button { width: 40px; height: 40px; flex-basis: 40px; }
  #printButton { display: none; }
  .install-button { display: none; }
  .quick-button { min-height: 36px; padding-inline: 9px; font-size: 11px; }
  .quick-button svg { display: none; }
  .location span { font-size: 10px; }
  .location strong { max-width: 43vw; font-size: 13px; }
  .lesson { width: min(100% - 30px, 560px); padding: 34px 0 60px; }
  .lesson-header { padding-bottom: 30px; }
  .lesson h1 { font-size: 38px; }
  .lesson-summary { font-size: 16px; }
  .lesson-section { padding: 32px 0; }
  .lesson-section h2 { font-size: 23px; }
  .cycle-map { grid-template-columns: 1fr 1fr; }
  .cycle-step { min-height: 105px; }
  .cycle-step:nth-child(2)::after { display: none; }
  .form-grid { grid-template-columns: 1fr; padding: 20px; }
  .field.full { grid-column: auto; }
  .experiment-head, .form-actions { padding-inline: 20px; }
  .experiment-head { display: block; }
  .autosave { display: block; margin-top: 8px; }
  .form-actions { align-items: flex-start; flex-direction: column; }
  .completion { grid-template-columns: 1fr; gap: 6px; }
  .lesson-footer { grid-template-columns: 1fr 1fr; }
  .lesson-footer small { display: none; }
}

@media (max-width: 380px) {
  .immediate-stage { padding-top: 28px; }
  .immediate-stage h1 { font-size: 32px; }
  .immediate-copy { font-size: 15px; }
  .immediate-anchor { width: 128px; height: 128px; margin-block: 24px; }
  .immediate-choices { gap: 8px; margin-top: 20px; }
  .immediate-choices button { min-height: 48px; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition-duration: 0.01ms !important; animation-duration: 0.01ms !important; }
  .immediate-progress span { transition: none; }
}

@media print {
  :root { --paper: #fff; --paper-strong: #fff; --ink: #111; --ink-soft: #444; --line: #bbb; --line-strong: #777; }
  .course-rail, .topbar, .lesson-footer, .toast { display: none !important; }
  .reading-pane { margin: 0; }
  .lesson { width: 100%; padding: 0; }
  .lesson-section, .lesson-header { break-inside: avoid; }
  .experiment { box-shadow: none; border: 1px solid #777; }
  .experiment-head { background: #eee; color: #111; }
  .immediate-screen { display: none !important; }
}