.app-shell {
  min-height: 100vh;
}

.sidebar {
  position: fixed;
  inset: 0 auto 0 0;

  z-index: 30;

  display: flex;
  flex-direction: column;

  width: var(--sidebar-width);
  padding: 28px 18px 20px;

  background: var(--color-surface);

  border-right: 1px solid var(--color-border);
}

.brand {
  display: flex;
  align-items: center;
  gap: 11px;

  padding: 0 10px;

  font-size: 1.35rem;
  font-weight: 700;
  letter-spacing: -0.7px;
}

.brand-icon {
  display: grid;
  place-items: center;

  width: 38px;
  height: 38px;

  color: white;
  background: var(--color-primary);

  border-radius: 12px;
}

.brand-icon svg {
  width: 23px;
  height: 23px;
}

.sidebar-section {
  margin-top: 52px;
}

.sidebar-label {
  padding: 0 12px;

  color: var(--color-text-muted);

  font-size: var(--font-size-xs);
  font-weight: 700;
  letter-spacing: 1.2px;
}

.sidebar-nav {
  display: grid;
  gap: 7px;

  margin-top: 18px;
}

.main-area {
  min-height: 100vh;
  margin-left: var(--sidebar-width);
}

.topbar {
  position: sticky;
  top: 0;

  z-index: 20;

  display: flex;
  align-items: center;
  justify-content: space-between;

  height: var(--topbar-height);
  padding: 0 42px;

  background: rgba(255, 255, 255, 0.94);

  border-bottom: 1px solid var(--color-border);

  backdrop-filter: blur(12px);
}

.breadcrumb {
  display: flex;
  align-items: center;
  gap: 12px;

  color: var(--color-text-secondary);

  font-size: var(--font-size-sm);
}

.breadcrumb-divider {
  color: var(--color-border-strong);
}

.breadcrumb strong {
  color: var(--color-text);
  font-weight: 600;
}

.topbar-right {
  display: flex;
  align-items: center;
}

.page-content {
  width: min(100%, 1120px);

  margin: 0 auto;
  padding: 55px 48px 80px;
}

.page-heading {
  margin-bottom: 42px;
}

.page-heading h1 {
  margin: 9px 0 12px;

  font-size: var(--font-size-3xl);
  line-height: 1.2;
  letter-spacing: -1.2px;
}

.page-description {
  max-width: 600px;

  margin: 0;

  color: var(--color-text-secondary);

  line-height: 1.7;
}

.import-section,
.reader-section {
  width: 100%;
}

.section-heading {
  display: flex;
  align-items: center;
  justify-content: space-between;

  margin-bottom: 18px;
}

.section-heading h2 {
  margin: 0 0 5px;

  font-size: var(--font-size-xl);
  letter-spacing: -0.5px;
}

.section-heading p {
  margin: 0;

  color: var(--color-text-secondary);

  font-size: var(--font-size-sm);
}

.import-card {
  padding: 28px;

  background: var(--color-surface);

  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);

  box-shadow: var(--shadow-sm);
}

.sample-section {
  margin-top: 36px;
}

.sample-heading {
  display: flex;
  align-items: center;
  justify-content: space-between;

  margin-bottom: 14px;
}

.sample-heading h3 {
  margin: 0;

  font-size: var(--font-size-base);
}

.reader-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;

  margin-bottom: 24px;
}

.reader-tools {
  display: flex;
  align-items: center;
  gap: 8px;
}

.reading-card {
  padding: 54px 65px;

  background: var(--color-surface);

  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);

  box-shadow: var(--shadow-sm);
}

.reading-title {
  margin: 24px 0;

  font-size: clamp(1.7rem, 4vw, 2.3rem);
  line-height: 1.3;
  letter-spacing: -0.8px;
}

.reading-divider {
  height: 1px;
  background: var(--color-border);
}

.reading-content {
  max-width: 720px;

  margin: 34px auto 0;

  font-family: var(--font-reading);
  font-size: var(--reading-font-size, 19px);
  line-height: var(--reading-line-height, 1.9);

  color: #414458;
}

.reading-content p {
  margin: 0 0 25px;
}

.reader-bottom-note {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;

  margin-top: 22px;

  color: var(--color-text-secondary);

  font-size: var(--font-size-sm);
}

.sidebar-bottom {
  margin-top: auto;
}

.sidebar-message {
  display: flex;
  align-items: flex-start;
  gap: 12px;

  padding: 16px 13px;

  background: var(--color-surface-soft);

  border-radius: var(--radius-md);
}

.sidebar-message strong {
  font-size: var(--font-size-sm);
}

.sidebar-message p {
  margin: 5px 0 0;

  color: var(--color-text-secondary);

  font-size: var(--font-size-xs);
  line-height: 1.6;
}

.sidebar-footer {
  display: flex;
  flex-direction: column;
  gap: 5px;

  padding: 24px 8px 0;

  color: var(--color-text-muted);

  font-size: var(--font-size-xs);
}

.mobile-overlay,
.mobile-menu-button {
  display: none;
}