:root {
  --c-bg: #f6f6f4;
  --c-surface: #ededeb;
  --c-surface-strong: #dededb;
  --c-surface-raised: #ffffff;
  --c-text: #171717;
  --c-muted: #656563;
  --c-border: #d8d8d5;
  --c-border-strong: #8a8a8a;
  --c-inverse: #111111;
  --c-inverse-text: #ffffff;
  --font: "Noto Sans JP", "Hiragino Kaku Gothic ProN", "Yu Gothic", system-ui, sans-serif;
  --text-sm: 12px;
  --text-caption: 14px;
  --text-body: 16px;
  --text-lead: 20px;
  --text-h3: 20px;
  --text-h2: 28px;
  --text-h1: 40px;
  --line-body: 1.8;
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 24px;
  --space-6: 32px;
  --space-7: 48px;
  --space-8: 64px;
  --radius-sm: 10px;
  --radius: 16px;
  --radius-lg: 24px;
  --shadow-1: 0 1px 2px rgb(0 0 0 / 5%), 0 8px 24px rgb(0 0 0 / 4%);
  --shadow-2: 0 16px 48px rgb(0 0 0 / 14%);
  --topbar-height: 64px;
  --sidebar-width: 288px;
  --rail-width: 256px;
  --content-width: 720px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: auto;
}

*,
*::before,
*::after {
  animation: none !important;
  transition: none !important;
}

body {
  margin: 0;
  color: var(--c-text);
  background: var(--c-bg);
  font-family: var(--font);
  font-size: var(--text-body);
  font-weight: 400;
  line-height: 1.6;
  letter-spacing: 0.02em;
  -webkit-font-smoothing: antialiased;
}

button,
input,
textarea {
  color: inherit;
  font: inherit;
}

button,
a {
  -webkit-tap-highlight-color: transparent;
}

button {
  min-height: 44px;
}

a {
  color: inherit;
  text-underline-offset: 3px;
}

button:focus-visible,
a:focus-visible,
input:focus-visible,
textarea:focus-visible,
summary:focus-visible {
  outline: 3px solid var(--c-text);
  outline-offset: 3px;
}

.skip-link {
  position: fixed;
  z-index: 1000;
  top: var(--space-3);
  left: var(--space-3);
  padding: var(--space-3) var(--space-4);
  color: var(--c-inverse-text);
  background: var(--c-inverse);
  transform: translateY(-160%);
}

.skip-link:focus {
  transform: translateY(0);
}

.topbar {
  position: fixed;
  z-index: 50;
  inset: 0 0 auto;
  display: grid;
  grid-template-columns: var(--sidebar-width) 1fr auto;
  align-items: center;
  min-height: var(--topbar-height);
  background: rgb(255 255 255 / 94%);
  box-shadow: 0 1px 12px rgb(0 0 0 / 5%);
  backdrop-filter: blur(16px);
}

.brand {
  display: flex;
  gap: var(--space-3);
  align-items: center;
  height: var(--topbar-height);
  padding: 0 var(--space-5);
  border: 0;
  background: transparent;
  font-weight: 700;
  letter-spacing: 0.02em;
  cursor: pointer;
}

.brand-mark {
  display: grid;
  width: 32px;
  height: 32px;
  place-items: center;
  color: var(--c-inverse-text);
  background: var(--c-inverse);
  border-radius: var(--radius-sm);
  font-size: var(--text-caption);
}

.topbar-nav {
  display: flex;
  gap: var(--space-1);
  padding-left: var(--space-5);
}

.topbar-link,
.search-trigger,
.icon-button,
.plain-button {
  border: 0;
  background: transparent;
  cursor: pointer;
}

.topbar-link {
  min-height: 40px;
  padding: 0 var(--space-4);
  border-radius: 999px;
  color: var(--c-muted);
  font-size: var(--text-caption);
  font-weight: 700;
}

.topbar-link:hover,
.topbar-link[aria-current="page"] {
  color: var(--c-text);
  background: var(--c-surface);
}

.topbar-actions {
  display: flex;
  gap: var(--space-4);
  align-items: center;
  padding-right: var(--space-5);
}

.search-trigger {
  display: flex;
  gap: var(--space-5);
  align-items: center;
  min-width: 224px;
  padding: 0 var(--space-3);
  border: 0;
  border-radius: 999px;
  background: var(--c-surface);
  color: var(--c-muted);
  text-align: left;
}

kbd {
  margin-left: auto;
  padding: 2px 6px;
  border: 1px solid var(--c-border);
  border-radius: 4px;
  background: var(--c-surface);
  font-family: inherit;
  font-size: var(--text-sm);
}

.header-progress {
  display: grid;
  grid-template-columns: auto 72px;
  gap: var(--space-2);
  align-items: center;
  font-size: var(--text-sm);
  font-weight: 700;
}

.progress-track {
  display: block;
  width: 100%;
  height: 4px;
  overflow: hidden;
  background: var(--c-surface-strong);
  border-radius: 999px;
}

.progress-track > span {
  display: block;
  width: 0;
  height: 100%;
  background: var(--c-inverse);
}

.icon-button {
  display: grid;
  width: 44px;
  min-width: 44px;
  place-items: center;
  border: 0;
  border-radius: 50%;
  background: var(--c-surface);
  font-size: var(--text-lead);
  font-weight: 700;
}

.mobile-only {
  display: none;
}

.app-shell {
  display: grid;
  grid-template-columns: var(--sidebar-width) minmax(0, 1fr) var(--rail-width);
  min-height: 100vh;
  padding-top: var(--topbar-height);
}

.course-sidebar,
.context-rail {
  position: fixed;
  top: var(--topbar-height);
  bottom: 0;
  overflow-y: auto;
  background: #eeeeec;
  scrollbar-width: thin;
}

.course-sidebar {
  left: 0;
  width: var(--sidebar-width);
}

.context-rail {
  right: 0;
  width: var(--rail-width);
  padding: var(--space-5);
}

.sidebar-heading {
  padding: var(--space-5) var(--space-4) var(--space-3);
}

.sidebar-heading h2,
.context-rail h2 {
  margin: var(--space-1) 0 0;
  font-size: var(--text-body);
}

.eyebrow {
  margin: 0;
  color: var(--c-muted);
  font-size: var(--text-sm);
  font-weight: 700;
  letter-spacing: 0.12em;
}

.sidebar-group {
  padding: 0 var(--space-2) var(--space-1);
}

.sidebar-group summary {
  display: flex;
  min-height: 44px;
  padding: var(--space-3) var(--space-3);
  align-items: center;
  justify-content: space-between;
  cursor: pointer;
  font-size: var(--text-caption);
  font-weight: 700;
  list-style: none;
}

.sidebar-group summary::-webkit-details-marker {
  display: none;
}

.sidebar-group summary::after {
  content: "+";
  color: var(--c-muted);
}

.sidebar-group[open] summary::after {
  content: "−";
}

.sidebar-course {
  width: 100%;
  min-height: 48px;
  margin: 2px 0;
  padding: var(--space-2) var(--space-3);
  border: 0;
  border-radius: var(--radius-sm);
  background: transparent;
  text-align: left;
  cursor: pointer;
}

.sidebar-course:hover,
.sidebar-course[aria-current="page"] {
  background: var(--c-surface-raised);
  box-shadow: 0 1px 3px rgb(0 0 0 / 6%);
}

.sidebar-course-id {
  display: block;
  color: var(--c-muted);
  font-size: var(--text-sm);
  font-weight: 700;
}

.sidebar-course-title {
  display: block;
  margin-top: 2px;
  font-size: var(--text-caption);
  font-weight: 700;
  line-height: 1.45;
}

.sidebar-course-progress {
  display: block;
  margin-top: var(--space-1);
  color: var(--c-muted);
  font-size: var(--text-sm);
}

#main-content {
  grid-column: 2;
  min-width: 0;
  background: var(--c-bg);
}

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

.page {
  width: min(100%, 1040px);
  margin: 0 auto;
  padding: var(--space-6) var(--space-6) var(--space-8);
}

.page-narrow {
  width: min(100%, calc(var(--content-width) + 64px));
}

.page-header {
  margin-bottom: var(--space-7);
}

.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  align-items: center;
  margin-bottom: var(--space-5);
  color: var(--c-muted);
  font-size: var(--text-caption);
}

.breadcrumb button {
  min-height: 44px;
  padding: 0;
  border: 0;
  background: transparent;
  color: inherit;
  text-decoration: underline;
  text-underline-offset: 3px;
  cursor: pointer;
}

.page h1 {
  max-width: 820px;
  margin: var(--space-3) 0 var(--space-4);
  font-size: clamp(32px, 4vw, var(--text-h1));
  line-height: 1.3;
  letter-spacing: 0.01em;
}

.course-title {
  word-break: keep-all;
  overflow-wrap: normal;
}

.page-lead {
  max-width: 720px;
  margin: 0;
  color: var(--c-muted);
  font-size: var(--text-lead);
  line-height: 1.7;
}

.meta-row {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3) var(--space-5);
  margin-top: var(--space-5);
  color: var(--c-muted);
  font-size: var(--text-caption);
}

.button-row {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
  margin-top: var(--space-6);
}

.button {
  display: inline-flex;
  min-height: 48px;
  padding: 0 var(--space-5);
  align-items: center;
  justify-content: center;
  border: 0;
  border-radius: 999px;
  background: var(--c-surface-strong);
  color: var(--c-text);
  font-weight: 700;
  text-decoration: none;
  cursor: pointer;
}

.button-primary {
  background: var(--c-inverse);
  color: var(--c-inverse-text);
  box-shadow: 0 4px 12px rgb(0 0 0 / 14%);
}

.button:hover {
  filter: brightness(0.94);
}

.button[disabled] {
  border-color: var(--c-border);
  color: var(--c-muted);
  background: var(--c-surface);
  cursor: not-allowed;
}

.continue-panel {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: var(--space-6);
  align-items: end;
  padding: var(--space-6);
  border-radius: var(--radius-lg);
  background: var(--c-surface-raised);
  box-shadow: var(--shadow-1);
}

.home-page {
  padding-top: var(--space-6);
}

.continue-label,
.course-kicker {
  margin: 0;
  color: var(--c-muted);
  font-size: var(--text-caption);
  font-weight: 700;
}

.continue-panel h2 {
  margin: var(--space-2) 0 var(--space-1);
  font-size: var(--text-h2);
  line-height: 1.4;
}

.continue-panel p {
  margin: 0;
  color: var(--c-muted);
}

.section-heading {
  display: flex;
  gap: var(--space-5);
  align-items: end;
  justify-content: space-between;
  margin: var(--space-7) 0 var(--space-4);
}

.section-heading h2 {
  margin: var(--space-1) 0 0;
  font-size: var(--text-h2);
}

.section-heading p {
  max-width: 520px;
  margin: 0;
  color: var(--c-muted);
}

.course-group + .course-group {
  margin-top: var(--space-8);
}

.level-heading {
  display: flex;
  align-items: start;
  justify-content: space-between;
  gap: var(--space-5);
  margin-bottom: var(--space-4);
}

.level-number {
  margin: 0 0 var(--space-1);
  color: var(--c-muted);
  font-size: var(--text-sm);
  font-weight: 700;
  letter-spacing: 0.08em;
}

.level-heading h2 {
  margin: 0;
  font-size: var(--text-h2);
}

.level-description {
  max-width: 640px;
  margin: var(--space-2) 0 0;
  color: var(--c-muted);
}

.level-count {
  flex: 0 0 auto;
  padding-top: var(--space-5);
  color: var(--c-muted);
  font-size: var(--text-caption);
}

.level-completion {
  display: flex;
  gap: var(--space-4);
  align-items: baseline;
  margin: 0 0 var(--space-3);
  padding: var(--space-4);
  border-radius: var(--radius);
  background: var(--c-surface);
}

.level-completion strong {
  flex: 0 0 auto;
  font-size: var(--text-caption);
}

.level-selection-note {
  margin: calc(var(--space-3) * -1) 0 var(--space-3);
  padding: var(--space-3) var(--space-4) var(--space-4);
  color: var(--c-muted);
  background: var(--c-surface);
  border-radius: 0 0 var(--radius) var(--radius);
  font-size: var(--text-caption);
}

.course-list {
  display: grid;
  gap: var(--space-2);
}

.course-row {
  display: grid;
  grid-template-columns: 160px minmax(0, 1fr) 120px 32px;
  gap: var(--space-4);
  align-items: center;
  width: 100%;
  min-height: 112px;
  padding: var(--space-3) var(--space-4);
  border: 0;
  border-radius: var(--radius);
  background: var(--c-surface-raised);
  text-align: left;
  cursor: pointer;
}

.course-thumbnail {
  display: block;
  overflow: hidden;
  border-radius: var(--radius-sm);
  background: var(--c-surface);
}

.course-thumbnail img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 16 / 9;
  object-fit: cover;
}

.course-row-body {
  display: grid;
  gap: var(--space-1);
  align-content: center;
}

.course-row:hover,
.course-row:focus-visible {
  background: #e9e9e6;
}

.course-code {
  font-size: var(--text-caption);
  font-weight: 700;
}

.course-row-title {
  display: block;
  font-size: var(--text-lead);
  font-weight: 700;
  word-break: auto-phrase;
}

.course-progress-track {
  display: block;
  width: min(160px, 60%);
  height: 4px;
  margin-top: var(--space-2);
  overflow: hidden;
  border-radius: 999px;
  background: var(--c-surface-strong);
}

.course-progress-track > span {
  display: block;
  height: 100%;
  border-radius: inherit;
  background: var(--c-inverse);
}

.course-row-progress {
  text-align: right;
  font-size: var(--text-caption);
}

.course-row-arrow {
  font-size: var(--text-lead);
  text-align: right;
}

.learning-summary {
  display: flex;
  gap: var(--space-5);
  margin: var(--space-4) var(--space-2) 0;
  color: var(--c-muted);
  font-size: var(--text-caption);
}

.learning-summary strong {
  color: var(--c-text);
  font-size: var(--text-body);
}

.outcome-list {
  display: grid;
  gap: var(--space-3);
  margin: var(--space-5) 0;
  padding: 0;
  list-style: none;
}

.outcome-list li {
  padding-left: var(--space-5);
  position: relative;
}

.outcome-list li::before {
  position: absolute;
  left: 0;
  content: "—";
}

.course-orientation {
  margin-bottom: var(--space-5);
  padding: var(--space-6);
  border-radius: var(--radius-lg);
  background: var(--c-inverse);
  color: var(--c-inverse-text);
}

.orientation-label {
  margin: 0 0 var(--space-3);
  color: #bdbdb9;
  font-size: var(--text-sm);
  font-weight: 700;
  letter-spacing: 0.12em;
}

.course-orientation h2 {
  margin: 0 0 var(--space-4);
  font-size: var(--text-h2);
  line-height: 1.45;
}

.orientation-message {
  max-width: 760px;
  margin: 0;
  color: #ededeb;
  font-size: var(--text-lead);
  line-height: 1.8;
}

.course-guide {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: var(--space-3);
  margin-bottom: var(--space-5);
}

.course-guide > div {
  padding: var(--space-5);
  border-radius: var(--radius);
  background: var(--c-surface);
}

.course-guide h2 {
  margin: 0 0 var(--space-4);
  font-size: var(--text-h3);
}

.course-guide ul {
  margin: 0;
  padding-left: 1.25em;
}

.course-guide li + li {
  margin-top: var(--space-2);
}

.surface-section {
  padding: var(--space-5);
  border-radius: var(--radius);
  background: var(--c-surface-raised);
}

.surface-section .section-heading {
  margin-top: 0;
}

.lesson-list {
  display: grid;
  gap: var(--space-2);
  counter-reset: lesson;
}

.lesson-row {
  display: grid;
  grid-template-columns: 56px minmax(0, 1fr) auto;
  gap: var(--space-4);
  align-items: center;
  width: 100%;
  min-height: 72px;
  padding: var(--space-3) var(--space-4);
  border: 0;
  border-radius: var(--radius);
  background: var(--c-surface-raised);
  text-align: left;
  cursor: pointer;
}

.lesson-row:hover {
  background: #e9e9e6;
}

.lesson-number {
  display: grid;
  width: 40px;
  height: 40px;
  place-items: center;
  border: 0;
  background: var(--c-surface);
  border-radius: 50%;
  font-size: var(--text-caption);
  font-weight: 700;
}

.lesson-row.is-complete .lesson-number {
  color: var(--c-inverse-text);
  background: var(--c-inverse);
  border-color: var(--c-inverse);
}

.lesson-title {
  display: block;
  font-weight: 700;
}

.lesson-meta {
  display: block;
  margin-top: var(--space-1);
  color: var(--c-muted);
  font-size: var(--text-caption);
}

.status-label {
  color: var(--c-muted);
  font-size: var(--text-sm);
  font-weight: 700;
}

.resource-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: var(--space-3);
}

.resource-button {
  min-height: 64px;
  padding: var(--space-3) var(--space-4);
  border: 0;
  border-radius: var(--radius);
  background: var(--c-surface-raised);
  text-align: left;
  font-weight: 700;
  cursor: pointer;
}

.menu-icon {
  display: grid;
  gap: 4px;
  width: 18px;
}

.menu-icon i {
  display: block;
  height: 2px;
  border-radius: 999px;
  background: currentColor;
}

.resource-button:hover {
  background: #e9e9e6;
}

.lesson-header {
  max-width: var(--content-width);
  margin: 0 auto var(--space-7);
}

.lesson-kicker {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2) var(--space-4);
  align-items: center;
  color: var(--c-muted);
  font-size: var(--text-caption);
  font-weight: 700;
}

.lesson-content {
  max-width: var(--content-width);
  margin: 0 auto;
  font-size: 17px;
  line-height: var(--line-body);
}

.lesson-content h1 {
  display: none;
}

.lesson-content h2 {
  margin: var(--space-8) 0 var(--space-4);
  padding-top: var(--space-4);
  font-size: var(--text-h2);
  line-height: 1.5;
}

.lesson-content h3 {
  margin: var(--space-6) 0 var(--space-3);
  font-size: var(--text-h3);
  line-height: 1.5;
}

.lesson-content p,
.lesson-content ul,
.lesson-content ol,
.lesson-content blockquote,
.lesson-content table,
.lesson-content pre {
  margin: 0 0 var(--space-5);
}

.lesson-content ul,
.lesson-content ol {
  padding-left: 1.5em;
}

.lesson-content li + li {
  margin-top: var(--space-2);
}

.lesson-content blockquote {
  padding: var(--space-4) var(--space-5);
  border-left: 0;
  border-radius: var(--radius-sm);
  background: var(--c-surface);
}

.lesson-content blockquote p:last-child {
  margin-bottom: 0;
}

.lesson-content code {
  padding: 2px 5px;
  border-radius: 4px;
  background: var(--c-surface);
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.9em;
  letter-spacing: 0;
}

.lesson-content pre {
  overflow-x: auto;
  padding: var(--space-5);
  border: 1px solid var(--c-border);
  background: var(--c-inverse);
  color: var(--c-inverse-text);
}

.lesson-content pre code {
  padding: 0;
  background: transparent;
  color: inherit;
  white-space: pre-wrap;
  overflow-wrap: break-word;
}

.table-wrap {
  margin-bottom: var(--space-5);
  overflow-x: auto;
}

.lesson-content table {
  width: 100%;
  border-collapse: collapse;
  font-size: var(--text-caption);
}

.lesson-content th,
.lesson-content td {
  padding: var(--space-3);
  border: 1px solid var(--c-border);
  vertical-align: top;
  text-align: left;
}

.lesson-content th {
  background: var(--c-surface);
  font-weight: 700;
}

.lesson-content img {
  max-width: 100%;
  height: auto;
}

.lesson-content hr {
  margin: var(--space-8) 0;
  border: 0;
  border-top: 1px solid var(--c-border);
}

.lesson-actions {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: var(--space-4);
  max-width: var(--content-width);
  margin: var(--space-8) auto 0;
  padding: var(--space-4);
  border-radius: var(--radius);
  background: var(--c-surface-raised);
  box-shadow: var(--shadow-1);
}

.lesson-actions .button:last-child {
  min-width: 208px;
}

.rail-section + .rail-section {
  margin-top: var(--space-6);
}

.rail-section {
  padding: var(--space-4);
  border-radius: var(--radius);
  background: rgb(255 255 255 / 70%);
}

.rail-section h2 {
  margin-bottom: var(--space-3);
}

.outline-list {
  margin: 0;
  padding: 0;
  list-style: none;
}

.outline-list a {
  display: block;
  min-height: 44px;
  padding: var(--space-2) var(--space-2);
  border-radius: var(--radius-sm);
  color: var(--c-muted);
  font-size: var(--text-sm);
  line-height: 1.5;
  text-decoration: none;
}

.outline-list a:hover,
.outline-list a[aria-current="location"] {
  color: var(--c-text);
  background: var(--c-surface-raised);
  text-decoration: none;
}

.memo-label {
  display: block;
  margin-bottom: var(--space-2);
  font-size: var(--text-caption);
  font-weight: 700;
}

.memo-field {
  width: 100%;
  min-height: 144px;
  padding: var(--space-3);
  resize: vertical;
  border: 1px solid var(--c-border);
  border-radius: var(--radius-sm);
  background: var(--c-bg);
  font-size: var(--text-caption);
  line-height: 1.6;
}

.memo-status {
  margin: var(--space-2) 0 0;
  color: var(--c-muted);
  font-size: var(--text-sm);
}

.bookmark-button {
  width: 100%;
  margin-top: var(--space-3);
}

.search-dialog {
  width: min(720px, calc(100vw - 32px));
  max-height: min(720px, calc(100vh - 48px));
  padding: 0;
  overflow: hidden;
  border: 0;
  border-radius: var(--radius-lg);
  background: var(--c-surface-raised);
  box-shadow: var(--shadow-2);
}

.search-dialog::backdrop {
  background: rgb(0 0 0 / 45%);
}

.search-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-5);
}

.search-header h2 {
  margin: var(--space-1) 0 0;
  font-size: var(--text-h3);
}

.search-field {
  display: block;
  padding: var(--space-5) var(--space-5) 0;
}

.search-field input {
  width: 100%;
  min-height: 52px;
  padding: 0 var(--space-4);
  border: 0;
  border-radius: 999px;
  background: var(--c-surface);
  font-size: var(--text-body);
}

.search-help {
  margin: var(--space-2) var(--space-5) var(--space-4);
  color: var(--c-muted);
  font-size: var(--text-sm);
}

.search-results {
  max-height: 480px;
  overflow-y: auto;
  padding: var(--space-2);
}

.search-result {
  display: block;
  width: 100%;
  min-height: 64px;
  padding: var(--space-3) var(--space-5);
  border: 0;
  border-radius: var(--radius-sm);
  background: transparent;
  text-align: left;
  cursor: pointer;
}

.search-result:hover,
.search-result:focus-visible {
  background: var(--c-surface);
}

.search-result small {
  display: block;
  margin-bottom: var(--space-1);
  color: var(--c-muted);
}

.search-result strong {
  display: block;
}

.empty-state,
.error-state {
  max-width: 640px;
  margin: var(--space-8) auto;
  padding: var(--space-6);
  border-radius: var(--radius);
  background: var(--c-surface-raised);
}

.empty-state h2,
.error-state h1 {
  margin-top: 0;
  font-size: var(--text-h2);
}

.loading-state {
  width: min(720px, calc(100% - 48px));
  margin: var(--space-8) auto;
}

.loading-line {
  display: block;
  width: 72%;
  height: 16px;
  margin-bottom: var(--space-4);
  background: var(--c-surface-strong);
}

.loading-line-wide {
  width: 92%;
  height: 40px;
}

.loading-state p {
  color: var(--c-muted);
}

.toast {
  position: fixed;
  z-index: 100;
  right: var(--space-5);
  bottom: var(--space-5);
  max-width: 360px;
  padding: var(--space-3) var(--space-4);
  border: 1px solid var(--c-inverse);
  border-radius: var(--radius-sm);
  background: var(--c-inverse);
  color: var(--c-inverse-text);
}

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

.noscript {
  margin: 96px auto;
  max-width: 640px;
  padding: var(--space-5);
  border: 1px solid var(--c-text);
}

.mobile-backdrop {
  position: fixed;
  z-index: 55;
  inset: var(--topbar-height) 0 0;
  background: rgb(0 0 0 / 45%);
}

@media (max-width: 1180px) {
  .app-shell {
    grid-template-columns: var(--sidebar-width) minmax(0, 1fr);
  }

  .context-rail {
    display: none;
  }
}

@media (max-width: 880px) {
  :root {
    --text-h1: 32px;
    --text-h2: 24px;
  }

  .topbar {
    grid-template-columns: 1fr auto;
  }

  .brand {
    border-right: 0;
  }

  .topbar-nav,
  .header-progress,
  .search-trigger span,
  .search-trigger kbd {
    display: none;
  }

  .topbar-actions {
    gap: var(--space-2);
    padding-right: var(--space-3);
  }

  .search-trigger {
    min-width: 44px;
    width: 44px;
    padding: 0;
    justify-content: center;
  }

  .search-trigger::before {
    content: "検索";
    font-size: var(--text-sm);
    font-weight: 700;
  }

  .mobile-only {
    display: grid;
  }

  .app-shell {
    display: block;
  }

  .course-sidebar {
    z-index: 60;
    width: min(88vw, 336px);
    transform: translateX(-102%);
  }

  .course-sidebar.is-open {
    transform: translateX(0);
  }

  #main-content {
    width: 100%;
  }

  .page {
    padding: var(--space-6) var(--space-5) 112px;
  }

  .continue-panel {
    grid-template-columns: 1fr;
    align-items: start;
  }

  .course-row {
    grid-template-columns: 120px minmax(0, 1fr) 24px;
  }

  .course-row-progress {
    display: none;
  }

  .lesson-actions {
    position: fixed;
    z-index: 40;
    right: 0;
    bottom: 0;
    left: 0;
    grid-template-columns: 120px minmax(0, 1fr);
    margin: 0;
    padding: var(--space-3) var(--space-4);
    border-radius: var(--radius) var(--radius) 0 0;
    background: var(--c-surface-raised);
    box-shadow: 0 -8px 28px rgb(0 0 0 / 8%);
  }

  .lesson-actions .button {
    min-width: 0;
    padding: 0 var(--space-3);
    white-space: nowrap;
  }
}

@media (max-width: 560px) {
  .brand {
    padding-left: var(--space-4);
  }

  .brand-mark {
    width: 28px;
    height: 28px;
  }

  .page {
    padding-right: var(--space-4);
    padding-left: var(--space-4);
  }

  .page h1 {
    font-size: 28px;
  }

  .page-lead {
    font-size: var(--text-body);
  }

  .learning-summary {
    gap: var(--space-4);
    overflow-x: auto;
    white-space: nowrap;
  }

  .resource-grid {
    grid-template-columns: 1fr;
  }

  .section-heading {
    display: block;
  }

  .section-heading p {
    margin-top: var(--space-2);
  }

  .level-heading {
    display: block;
  }

  .level-count {
    display: block;
    padding-top: var(--space-2);
  }

  .level-completion {
    display: block;
  }

  .level-completion span {
    display: block;
    margin-top: var(--space-1);
  }

  .course-row {
    min-height: 80px;
    grid-template-columns: 112px minmax(0, 1fr) 24px;
  }

  .course-row-title {
    font-size: var(--text-body);
  }

  .course-row-description {
    display: none;
  }

  .lesson-row {
    grid-template-columns: 48px minmax(0, 1fr);
  }

  .lesson-row .status-label {
    display: none;
  }

  .lesson-content {
    font-size: 16px;
    line-height: 1.8;
  }

  .lesson-content h2 {
    margin-top: var(--space-7);
    font-size: 24px;
  }

  .button-row .button {
    width: 100%;
  }
}

@media print {
  .topbar,
  .course-sidebar,
  .context-rail,
  .lesson-actions,
  .toast {
    display: none !important;
  }

  .app-shell,
  #main-content {
    display: block;
    padding: 0;
  }

  .page {
    max-width: none;
    padding: 0;
  }
}

/* Curriculum review mode */
.topbar {
  display: flex;
  padding: 0 max(var(--space-4), calc((100vw - 1040px) / 2));
}

.brand {
  padding: 0;
}

.app-shell {
  display: block;
}

#main-content {
  width: 100%;
}

.course-row {
  grid-template-columns: 160px minmax(0, 1fr) auto 32px;
}

.course-row-meta {
  color: var(--c-muted);
  font-size: var(--text-caption);
  white-space: nowrap;
}

.resource-actions {
  display: flex;
}

@media (max-width: 880px) {
  .topbar {
    display: flex;
    padding: 0 var(--space-4);
  }

  .page {
    padding-bottom: var(--space-8);
  }

  .course-row {
    grid-template-columns: 120px minmax(0, 1fr) 24px;
  }

  .course-row-meta {
    display: none;
  }

  .lesson-row {
    grid-template-columns: 48px minmax(0, 1fr) 24px;
  }

  .lesson-actions {
    position: static;
    grid-template-columns: 1fr 1fr;
    margin: var(--space-8) auto 0;
    padding: var(--space-3);
    border-radius: var(--radius);
    box-shadow: var(--shadow-1);
  }

  .lesson-actions .button:last-child {
    min-width: 0;
  }

  .course-guide {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 560px) {
  .brand {
    padding-left: 0;
  }

  .brand > span:last-child {
    font-size: var(--text-caption);
  }

  .course-orientation {
    padding: var(--space-5);
  }

  .course-orientation h2 {
    font-size: 24px;
  }

  .orientation-message {
    font-size: var(--text-body);
  }
}