.course-back {
  flex: 0 0 auto;
  padding: 5px 9px;
  border: 1px solid var(--line);
  border-radius: 3px;
  color: var(--ac);
  font-family: var(--sans);
  font-size: 10px;
  white-space: nowrap;
  background: rgba(7, 10, 11, .72);
}
.course-back:hover, .course-back:focus-visible {
  border-color: var(--ac);
  color: var(--ink);
}
.course-back:focus-visible, .energy-figure a:focus-visible {
  outline: 2px solid var(--ac);
  outline-offset: 2px;
}
body.lang-en .tab em { display: none; }
.sec-h .en, body.lang-en .sec-h .en { margin: 0; font-family: var(--mono); font-size: 9px; line-height: inherit; color: inherit; }
.sec-h .zh { font-family: var(--mono); font-size: 9px; }
.part-t .en, body.lang-en .part-t .en { margin: 0; font-family: var(--sans); font-size: 13px; letter-spacing: .01em; color: var(--ink); }
.energy-figure {
  margin: 0 0 20px;
  border: 1px solid var(--line);
  border-radius: 4px;
  overflow: hidden;
  background: #0b1720;
}
.energy-figure a { display: block; }
.energy-figure img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 4 / 3;
  object-fit: cover;
}
.energy-figure figcaption { padding: 13px 14px 15px; }
.energy-figure strong {
  display: block;
  margin: 0 0 5px;
  font-size: 13px;
  font-weight: 500;
  color: var(--ink);
}
.energy-figure p { margin-top: 5px; }
.energy-figure small {
  display: block;
  margin-top: 9px;
  font-size: 10px;
  line-height: 1.6;
  color: var(--mut);
}
@media (max-width: 560px) {
  .course-back { padding: 5px 6px; font-size: 9px; }
}