.excel-course-page {
  --course-ink: #182b24;
  --course-muted: #58695f;
  --course-line: #d7e2da;
  --course-green: #176b4d;
  --course-green-dark: #104a37;
  --course-green-pale: #eaf4ee;
  --course-gold: #a76018;
  width: min(100%, 1760px);
  min-width: 0;
  margin: 0 auto;
  padding: clamp(14px, 2vw, 26px);
  color: var(--text, #24324a);
}

.excel-course-page a {
  color: var(--course-green-dark);
}

.excel-course-hero {
  margin: 0 clamp(0px, 1vw, 12px) 16px;
  padding: clamp(20px, 3vw, 34px);
  border: 1px solid var(--line, #d9e2ec);
  border-radius: 8px;
  background: #fff;
}

.excel-course-eyebrow {
  margin: 0 0 10px;
  color: var(--course-green-dark);
  font-size: 13px;
  font-weight: 800;
  text-transform: uppercase;
}

.excel-course-hero h1 {
  max-width: 900px;
  margin: 0;
  color: var(--course-ink);
  font-size: clamp(32px, 5vw, 54px);
  line-height: 1.08;
}

.excel-course-hero > p:last-of-type {
  max-width: 760px;
  color: var(--course-muted);
  font-size: 18px;
  line-height: 1.7;
}

.excel-course-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(220px, 270px) minmax(150px, 200px);
  gap: clamp(14px, 1.8vw, 24px);
  align-items: start;
}

.excel-course-index {
  position: sticky;
  top: 14px;
  grid-column: 2;
  grid-row: 1;
  max-height: max(220px, calc(100vh - 116px));
  overflow: auto;
  padding: 14px;
  border: 1px solid var(--line, #d9e2ec);
  border-radius: 8px;
  background: #f5f8fa;
  scrollbar-gutter: stable;
}

.excel-course-index h2 {
  margin: 0 0 12px;
  font-size: 19px;
}

.excel-course-index ol {
  display: grid;
  gap: 3px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.excel-course-index li {
  margin: 0;
  color: var(--course-muted);
  line-height: 1.35;
}

.excel-course-index a {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  min-height: 38px;
  padding: 8px 9px;
  border: 1px solid transparent;
  border-radius: 6px;
  color: var(--text, #24324a);
  font-size: 12px;
  line-height: 1.35;
  text-decoration: none;
}

.excel-course-index a::after {
  content: "→";
  color: #08715f;
}

.excel-course-index a:hover {
  border-color: var(--line, #d9e2ec);
  background: #fff;
}

.excel-course-index a[aria-current="page"] {
  border-color: #a9d3ca;
  color: #075849;
  background: #eaf6f1;
  font-weight: 800;
}

.excel-course-index a[aria-current="page"]::after {
  content: "✓";
}

.excel-course-progress {
  margin-top: 18px;
  padding-top: 14px;
  border-top: 1px solid var(--line, #d9e2ec);
  color: var(--course-muted);
  font-size: 14px;
}

.excel-course-content {
  grid-column: 1;
  grid-row: 1;
  min-width: 0;
  padding: clamp(18px, 3vw, 34px);
  border: 1px solid var(--line, #d9e2ec);
  border-radius: 8px;
  background: #fff;
}

.excel-course-ad-sidebar { grid-column: 3; grid-row: 1; }

.excel-course-content section {
  margin: 0 0 30px;
}

.excel-course-content h2 {
  margin: 0 0 12px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--course-line);
  color: var(--course-green-dark);
  font-size: 26px;
  line-height: 1.25;
}

.excel-course-content h3 {
  margin: 22px 0 8px;
  font-size: 19px;
}

.excel-course-content figure {
  margin: 18px 0;
}

.excel-course-content figure img {
  display: block;
  width: 100%;
  max-height: 360px;
  object-fit: contain;
  border: 1px solid var(--course-line);
  border-radius: 8px;
  background: #f4f8f5;
}

.excel-course-content figcaption {
  margin-top: 8px;
  color: var(--course-muted);
  font-size: 14px;
}

.excel-course-content p,
.excel-course-content li {
  color: var(--course-muted);
  line-height: 1.7;
}

.excel-course-callout {
  margin: 18px 0;
  padding: 16px 18px;
  border-left: 4px solid var(--course-gold);
  background: #fff7e9;
}

.excel-course-callout p:last-child {
  margin-bottom: 0;
}

.excel-formula-search {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 10px;
  align-items: end;
  margin: 18px 0;
}

.excel-formula-search label {
  display: grid;
  gap: 6px;
  color: var(--course-ink);
  font-weight: 700;
}

.excel-formula-search input {
  width: 100%;
  min-height: 44px;
  padding: 9px 12px;
  border: 1px solid #9aada1;
  border-radius: 3px;
  font: inherit;
}

.excel-course-page button {
  min-height: 40px;
  padding: 8px 12px;
  border: 1px solid var(--course-green-dark);
  border-radius: 3px;
  background: var(--course-green-dark);
  color: #fff;
  font: inherit;
  font-weight: 700;
  cursor: pointer;
}

.excel-course-page button:focus-visible,
.excel-course-page a:focus-visible,
.excel-course-page input:focus-visible {
  outline: 3px solid #c9822b;
  outline-offset: 2px;
}

.excel-formula-table-wrap {
  overflow-x: auto;
  border: 1px solid var(--course-line);
}

.excel-formula-table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
}

.excel-formula-table th,
.excel-formula-table td {
  min-width: 150px;
  padding: 12px 14px;
  border-bottom: 1px solid var(--course-line);
  vertical-align: top;
  line-height: 1.55;
}

.excel-formula-table th {
  background: var(--course-green-pale);
  color: var(--course-ink);
}

.excel-formula-table td:first-child {
  min-width: 130px;
  color: var(--course-green-dark);
  font-weight: 800;
  white-space: nowrap;
}

.excel-formula-table code,
.excel-course-content code {
  color: #263c31;
  font-family: Consolas, "Courier New", monospace;
  font-size: 0.95em;
  overflow-wrap: anywhere;
}

.excel-formula-table tr[hidden] {
  display: none;
}

.excel-course-example {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 12px;
  align-items: center;
  margin: 10px 0;
  padding: 12px 14px;
  border: 1px solid var(--course-line);
  background: #fbfdfb;
}

.excel-course-example p {
  margin: 0;
}

.excel-course-example button {
  min-height: 34px;
  padding: 5px 9px;
  font-size: 13px;
}

.excel-course-actions {
  display: flex;
  gap: 10px;
  align-items: center;
  flex-wrap: wrap;
  padding: 16px 0;
  border-top: 1px solid var(--course-line);
}

.excel-course-actions p {
  margin: 0;
}

.excel-course-footer-nav {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  padding-top: 18px;
  border-top: 1px solid var(--course-line);
}

.excel-course-footer-nav a {
  font-weight: 800;
}

@media (min-width: 821px) and (max-width: 1100px) {
  .excel-course-layout {
    grid-template-columns: minmax(0, 1fr) minmax(200px, 240px);
  }

  .excel-course-ad-sidebar {
    display: none;
  }
}

@media (max-width: 820px) {
  .excel-course-layout {
    grid-template-columns: 1fr;
    gap: 20px;
  }

  .excel-course-content {
    grid-column: 1;
    grid-row: 1;
  }

  .excel-course-index {
    grid-column: 1;
    grid-row: 2;
    position: static;
    max-height: min(65vh, 620px);
  }
}

@media (max-width: 520px) {
  .excel-course-hero {
    padding: 22px 18px;
  }

  .excel-formula-search,
  .excel-course-example {
    grid-template-columns: 1fr;
  }

  .excel-course-footer-nav {
    flex-direction: column;
  }
}