.shell {
  width: min(760px, 100% - var(--space-5) * 2);
  margin-inline: auto;
  padding-block: var(--space-4) var(--space-8);
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
}

/* --- masthead --- */

.masthead {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: var(--space-4);
  flex-wrap: wrap;
}

.masthead__brand {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  min-width: 0;
}

.masthead__logo { height: 36px; width: auto; max-width: 180px; flex: none; object-fit: contain; }
/* Most logos are drawn for white paper; on a dark page they get a white plate. */
@media (prefers-color-scheme: dark) {
  .masthead__logo { background: #fff; padding: 4px 6px; border-radius: 6px; box-sizing: content-box; height: 28px; }
}

.masthead__title {
  font-size: var(--size-small);
  font-weight: 650;
  letter-spacing: -0.005em;
}

.masthead__tagline {
  font-size: var(--size-tiny);
  color: var(--color-muted);
  line-height: 1.4;
}

/* --- progress --- */

.progress { display: flex; flex-direction: column; gap: var(--space-2); }

.progress__track {
  height: 6px;
  border-radius: 999px;
  background: var(--color-border-soft);
  overflow: hidden;
}

.progress__bar {
  height: 100%;
  width: 0;
  border-radius: inherit;
  background: var(--color-primary);
  transition: width 0.3s ease;
}

.progress__label {
  font-size: var(--size-tiny);
  color: var(--color-muted);
  font-variant-numeric: tabular-nums;
}

/* --- panels --- */

.panel {
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-panel);
  padding: var(--space-6);
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
}

.colophon {
  font-size: var(--size-tiny);
  color: var(--color-muted);
  text-align: center;
}

@media (max-width: 480px) {
  .shell { width: calc(100% - var(--space-4) * 2); padding-block: var(--space-4) var(--space-7); }
  .panel { padding: var(--space-5) var(--space-4); border-radius: var(--radius); }
}