:root {
  color-scheme: light;
  font: 16px/1.5 system-ui, sans-serif;
  color: #18263b;
  background: #f2f5fa;
  --muted: #506079;
  --line: #dce4ef;
  --accent: #2153b5;
  --accent-light: #edf3ff;
}
* { box-sizing: border-box; }
body { margin: 0; }
button, select { font: inherit; }
button { cursor: pointer; }
button:disabled { cursor: default; }
button:focus-visible, select:focus-visible, a:focus-visible {
  outline: 3px solid #3674e3;
  outline-offset: 3px;
}
.shell { max-width: 1120px; margin: auto; padding: 38px 24px 24px; }
.intro { margin-bottom: 24px; }
.intro p, .week-heading p { margin: 0; }
.intro p:last-child, footer { color: var(--muted); }
.course, .eyebrow {
  color: var(--accent);
  font-size: .78rem;
  font-weight: 750;
  letter-spacing: .08em;
  text-transform: uppercase;
}
.course span { margin-inline: 5px; }
h1 { margin: 6px 0 3px; font-size: clamp(1.9rem, 5vw, 2.65rem); line-height: 1.2; }
.layout { display: grid; grid-template-columns: 238px minmax(0, 1fr); gap: 20px; align-items: start; }
.weeks-panel, .quiz-panel { background: white; border: 1px solid var(--line); border-radius: 16px; }
.weeks-panel { padding: 15px; }
.weeks-panel h2 { font-size: .9rem; margin: 1px 5px 10px; }
#weeks { display: grid; gap: 6px; }
.week-button {
  display: grid;
  width: 100%;
  gap: 2px;
  text-align: left;
  padding: 10px 11px;
  border: 1px solid transparent;
  border-radius: 9px;
  color: inherit;
  background: #f7f9fc;
}
.week-button:hover { background: #f0f4fb; }
.week-button[aria-current="true"] { background: var(--accent-light); border-color: #9cb8ed; }
.week-button strong { font-size: .9rem; }
.week-button span { font-size: .8rem; color: var(--muted); }
.quiz-panel { padding: clamp(16px, 4vw, 28px); }
.week-heading { display: flex; justify-content: space-between; align-items: start; gap: 12px; }
.week-heading h2 { font-size: clamp(1.17rem, 3vw, 1.55rem); margin: 3px 0 0; line-height: 1.25; }
.progress-info { display: flex; justify-content: space-between; gap: 8px; margin: 17px 0 5px; color: var(--muted); font-size: .86rem; }
progress { width: 100%; height: 8px; vertical-align: top; border: 0; border-radius: 10px; background: #e5ebf4; }
progress::-webkit-progress-bar { background: #e5ebf4; border-radius: 10px; }
progress::-webkit-progress-value { background: #3265c7; border-radius: 10px; }
progress::-moz-progress-bar { background: #3265c7; border-radius: 10px; }
#question { margin-top: 17px; }
.question-meta { color: var(--muted); font-size: .84rem; margin: 0 0 6px; }
.prompt { margin: 0 0 15px; font-size: clamp(1.06rem, 2.6vw, 1.28rem); line-height: 1.4; }
.options { display: grid; gap: 8px; }
.option {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 12px;
  min-height: 49px;
  text-align: left;
  border: 1px solid var(--line);
  border-radius: 9px;
  background: white;
  color: inherit;
  line-height: 1.38;
}
.option:hover:not(:disabled) { background: var(--accent-light); border-color: #9cb8ed; }
.option .letter { flex: 0 0 28px; line-height: 28px; border-radius: 6px; font-weight: 700; text-align: center; background: #edf1f7; }
.option.correct { border-color: #4b9b72; background: #eaf7ee; color: #145633; }
.option.wrong { border-color: #cf787d; background: #fff0f1; color: #8f2028; }
.option.correct .letter { background: #d1eedc; }
.option.wrong .letter { background: #f9d9dc; }
.option .mark { margin-left: auto; padding-left: 6px; font-size: .82rem; font-weight: 700; }
.feedback-card { margin-top: 14px; padding: 12px 14px; border: 1px solid #b9d7c6; border-radius: 9px; background: #eef9f1; }
.feedback-card.incorrect { border-color: #e3b9bc; background: #fff5f5; }
.feedback-card p { margin: 5px 0 0; }
.feedback-card small { display: block; color: var(--muted); margin-top: 7px; }
.navigation { display: flex; align-items: center; justify-content: space-between; gap: 8px; border-top: 1px solid var(--line); margin-top: 18px; padding-top: 15px; }
.secondary, .primary, select { min-height: 39px; border: 1px solid var(--line); border-radius: 8px; padding: 6px 11px; background: white; color: inherit; }
.primary { background: var(--accent); border-color: var(--accent); color: white; font-weight: 650; }
.primary:hover:not(:disabled) { background: #173f91; }
.secondary:hover:not(:disabled) { background: #f1f5fc; }
.secondary:disabled, .primary:disabled { opacity: .55; }
#reset { font-size: .8rem; white-space: nowrap; }
.jump { color: var(--muted); font-size: .86rem; white-space: nowrap; }
.jump select { padding-inline: 5px; color: #18263b; }
footer { display: flex; justify-content: flex-end; flex-wrap: wrap; gap: 6px 18px; margin-top: 16px; font-size: .82rem; }
a { color: var(--accent); }
@media (max-width: 730px) {
  .shell { padding: 22px 13px; }
  .layout { grid-template-columns: minmax(0, 1fr); gap: 12px; }
  #weeks { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .weeks-panel { padding: 10px; }
  .week-button { padding: 7px 8px; }
  .week-button span { font-size: .75rem; }
}
@media (max-width: 380px) {
  .navigation { flex-wrap: wrap; }
  .jump { order: 1; width: 100%; text-align: center; }
}