:root {
  --vita-blue: #0067b1;
  --vita-red: #d71920;
  --ink: #1e2630;
  --muted: #5c6876;
  --line: #d9e1ea;
  --surface: #ffffff;
  --soft: #f4f7fb;
  --blue-soft: #e8f3fb;
  --red-soft: #fff0f0;
  --success: #1d7a4d;
  --warning: #a85700;
  --shadow: 0 18px 48px rgba(28, 47, 74, 0.14);
}

* {
  box-sizing: border-box;
}

html {
  min-height: 100%;
  font-size: 16px;
}

body {
  min-height: 100vh;
  margin: 0;
  color: var(--ink);
  background:
    linear-gradient(90deg, rgba(0, 103, 177, 0.08), rgba(215, 25, 32, 0.05)),
    var(--soft);
  font-family: Arial, Helvetica, sans-serif;
  letter-spacing: 0;
  overflow-x: hidden;
}

button,
input {
  font: inherit;
}

button {
  cursor: pointer;
}

img {
  display: block;
  max-width: 100%;
}

a {
  color: var(--vita-blue);
}

.app-shell {
  width: min(1180px, calc(100% - 32px));
  min-height: 100vh;
  margin: 0 auto;
  display: grid;
  grid-template-rows: auto 1fr auto;
  gap: 18px;
  padding: 18px 0;
}

.topbar {
  display: flex;
  align-items: center;
  gap: 18px;
  padding: 14px 18px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-top: 5px solid var(--vita-blue);
  border-radius: 8px;
  box-shadow: 0 6px 18px rgba(28, 47, 74, 0.08);
}

.brand {
  display: inline-flex;
  align-items: center;
  flex: 0 0 auto;
}

.brand img {
  width: 132px;
  max-height: 58px;
  object-fit: contain;
}

.course-label {
  min-width: 0;
  display: grid;
  gap: 2px;
  border-left: 4px solid var(--vita-red);
  padding-left: 14px;
}

.course-label span {
  color: var(--muted);
  font-size: 0.88rem;
  text-transform: uppercase;
}

.course-label strong {
  color: var(--ink);
  font-size: 1.08rem;
  line-height: 1.25;
}

.stage {
  min-height: 0;
  display: grid;
}

.lesson-view,
.quiz-view {
  display: grid;
  gap: 24px;
  align-items: stretch;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 8px;
  box-shadow: var(--shadow);
  overflow: hidden;
}

.lesson-view {
  grid-template-columns: minmax(0, 1.04fr) minmax(330px, 0.96fr);
}

.quiz-view {
  grid-template-columns: minmax(0, 1.04fr) minmax(330px, 0.96fr);
}

.lesson-copy,
.quiz-copy {
  min-width: 0;
}

.lesson-copy {
  padding: 32px;
  display: flex;
  flex-direction: column;
}

.page-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  margin-bottom: 14px;
  color: var(--muted);
  font-size: 0.9rem;
}

.page-meta span {
  padding: 5px 10px;
  background: var(--blue-soft);
  border: 1px solid #cde6f7;
  border-radius: 999px;
}

.page-meta span:first-child {
  color: var(--vita-red);
  background: var(--red-soft);
  border-color: #ffd0d0;
  font-weight: 700;
}

h1 {
  margin: 0 0 18px;
  color: var(--vita-blue);
  font-size: 2rem;
  line-height: 1.1;
  letter-spacing: 0;
  overflow-wrap: anywhere;
}

.page-body {
  display: grid;
  gap: 14px;
  font-size: 1.05rem;
  line-height: 1.58;
}

.page-body p,
.page-body ul,
.page-body ol {
  margin: 0;
}

.page-body ul,
.page-body ol {
  padding-left: 1.3rem;
}

.page-body li + li {
  margin-top: 8px;
}

.page-body strong {
  color: var(--vita-red);
}

.page-body .source-note {
  color: var(--muted);
  font-size: 0.95rem;
}

.step-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.96rem;
  line-height: 1.45;
  overflow-wrap: anywhere;
}

.step-table th,
.step-table td {
  padding: 10px;
  text-align: left;
  vertical-align: top;
  border: 1px solid var(--line);
}

.step-table th {
  color: var(--surface);
  background: var(--vita-blue);
}

.step-table tr:nth-child(even) td {
  background: #f8fbfd;
}

.visual-panel {
  min-width: 0;
  margin: 0;
  display: grid;
  grid-template-rows: 1fr auto;
  background: #eef3f8;
  border-left: 1px solid var(--line);
}

.visual-panel img {
  width: 100%;
  height: 100%;
  min-height: 420px;
  object-fit: cover;
}

.visual-panel figcaption {
  padding: 12px 18px 16px;
  color: var(--muted);
  background: var(--surface);
  border-top: 4px solid var(--vita-red);
  font-size: 0.95rem;
  line-height: 1.35;
  text-align: center;
  overflow-wrap: anywhere;
}

.download-list {
  display: grid;
  gap: 10px;
  padding: 0;
  margin: 0;
  list-style: none;
}

.download-list li {
  margin: 0;
}

.download-list a,
.empty-downloads {
  display: block;
  padding: 12px 14px;
  border: 1px solid var(--line);
  border-left: 5px solid var(--vita-blue);
  border-radius: 8px;
  background: #fbfdff;
  text-decoration: none;
  overflow-wrap: anywhere;
}

.empty-downloads {
  color: var(--muted);
}

.nav-panel {
  display: grid;
  gap: 12px;
  padding: 14px 18px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 8px;
  box-shadow: 0 6px 18px rgba(28, 47, 74, 0.08);
}

.progress-wrap {
  width: 100%;
}

.progress-track {
  height: 8px;
  background: #e5ecf4;
  border-radius: 999px;
  overflow: hidden;
}

.progress-fill {
  width: 0;
  height: 100%;
  background: linear-gradient(90deg, var(--vita-blue), var(--vita-red));
  transition: width 180ms ease;
}

.nav-buttons {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 10px;
}

.icon-button,
.primary-button,
.quiz-action {
  min-height: 44px;
  border: 1px solid var(--line);
  border-radius: 8px;
  color: var(--ink);
  background: var(--surface);
  transition: transform 120ms ease, border-color 120ms ease, background 120ms ease;
}

.icon-button {
  width: 48px;
  font-weight: 800;
}

.primary-button,
.quiz-action {
  min-width: 138px;
  padding: 0 18px;
  color: var(--surface);
  background: var(--vita-blue);
  border-color: var(--vita-blue);
  font-weight: 700;
}

.nav-step-button {
  min-width: 138px;
}

.primary-button:hover,
.quiz-action:hover,
.icon-button:hover {
  transform: translateY(-1px);
  border-color: var(--vita-red);
}

.primary-button:focus-visible,
.quiz-action:focus-visible,
.icon-button:focus-visible,
.option-card input:focus-visible + span {
  outline: 3px solid rgba(215, 25, 32, 0.32);
  outline-offset: 2px;
}

.primary-button:disabled,
.quiz-action:disabled,
.icon-button:disabled {
  cursor: not-allowed;
  opacity: 0.48;
  transform: none;
}

.nav-step-button:disabled {
  color: var(--surface);
  background: var(--vita-blue);
  border-color: var(--vita-blue);
  opacity: 1;
}

.quiz-copy {
  width: min(840px, 100%);
  margin: 0;
  display: grid;
  align-content: start;
  gap: 18px;
  padding: 32px;
}

.quiz-prompt {
  margin: 0;
  font-size: 1.18rem;
  line-height: 1.55;
}

.quiz-options {
  display: grid;
  gap: 12px;
}

.option-card {
  display: grid;
}

.option-card input {
  position: absolute;
  opacity: 0;
  pointer-events: none;
}

.option-card span {
  display: block;
  padding: 14px 16px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #fbfdff;
  line-height: 1.45;
  overflow-wrap: anywhere;
}

.option-card input:checked + span {
  border-color: var(--vita-blue);
  box-shadow: inset 5px 0 0 var(--vita-blue);
  background: var(--blue-soft);
}

.option-card.correct span {
  border-color: var(--success);
  box-shadow: inset 5px 0 0 var(--success);
  background: #eefaf4;
}

.option-card.incorrect span {
  border-color: var(--vita-red);
  box-shadow: inset 5px 0 0 var(--vita-red);
  background: var(--red-soft);
}

.quiz-feedback {
  padding: 14px 16px;
  border-radius: 8px;
  border: 1px solid var(--line);
  background: #fbfdff;
  line-height: 1.5;
}

.quiz-feedback.correct {
  border-color: #b9e4cd;
  background: #effaf4;
  color: #155b39;
}

.quiz-feedback.incorrect {
  border-color: #ffd0d0;
  background: var(--red-soft);
  color: #772024;
}

.closing-panel {
  display: grid;
  gap: 18px;
  padding-top: 12px;
}

.score-panel {
  display: grid;
  gap: 6px;
  padding: 18px;
  border-left: 6px solid var(--vita-red);
  border-radius: 8px;
  background: #fbfdff;
}

.score-panel strong {
  color: var(--vita-blue);
  font-size: 1.45rem;
}

.credit-panel {
  display: grid;
  gap: 6px;
  padding: 16px 18px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--blue-soft);
}

.credit-panel p {
  margin: 0;
  line-height: 1.45;
}

.credit-panel strong {
  color: var(--vita-red);
}

.partner-logos {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 18px;
}

.partner-logos img {
  max-height: 76px;
  width: auto;
  object-fit: contain;
}

.license-text {
  display: grid;
  gap: 8px;
  color: var(--muted);
  font-size: 0.95rem;
  line-height: 1.5;
}

[hidden] {
  display: none !important;
}

@media (max-width: 880px) {
  .app-shell {
    width: min(calc(100% - 20px), 720px);
    gap: 12px;
    padding: 10px 0;
  }

  .topbar {
    align-items: flex-start;
  }

  .brand img {
    width: 112px;
  }

  .lesson-view,
  .quiz-view {
    grid-template-columns: 1fr;
  }

  .lesson-copy,
  .quiz-copy {
    padding: 24px;
  }

  .visual-panel {
    border-left: 0;
    border-top: 1px solid var(--line);
  }

  .visual-panel img {
    min-height: auto;
    max-height: 420px;
    aspect-ratio: 16 / 10;
  }

  h1 {
    font-size: 1.65rem;
  }

  .page-body,
  .quiz-prompt {
    font-size: 1rem;
  }
}

@media (max-width: 560px) {
  .app-shell {
    width: calc(100% - 28px);
  }

  .topbar {
    flex-direction: column;
  }

  .course-label {
    border-left: 0;
    border-top: 4px solid var(--vita-red);
    padding: 10px 0 0;
  }

  .lesson-copy,
  .quiz-copy {
    padding: 20px 30px 20px 18px;
  }

  h1 {
    font-size: 1.32rem;
  }

  .page-body,
  .quiz-prompt {
    font-size: 0.98rem;
  }

  .page-body,
  .quiz-prompt,
  .quiz-options,
  .quiz-feedback {
    max-width: 320px;
  }

  .nav-buttons {
    display: grid;
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .primary-button {
    min-width: 0;
    padding: 0 12px;
  }

  .nav-step-button {
    min-width: 0;
  }

  .icon-button {
    width: auto;
  }

  .step-table {
    display: block;
    overflow-x: auto;
  }
}