/* PC限定 2画面参照モード（問題ページから開く解説ペイン） */

.split-toggle-row {
  display: none;
  justify-content: flex-end;
  margin: 0 0 14px;
}

.split-toggle-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

.split-toggle-btn__icon {
  font-weight: 900;
}

.split-toggle-btn.is-active {
  background: var(--brand-navy, #0d1420);
  color: #fff;
  border-color: #111;
}

.split-explain-pane {
  display: none;
  --split-pane-top: 64px;
  --split-pane-height: calc(100vh - 80px);
}

@media (min-width: 901px) {
  .split-toggle-row {
    display: flex;
  }

  .container--problem:has(.problem-split-layout.is-split) {
    max-width: min(1480px, calc(100vw - 32px));
  }

  .problem-split-layout.is-split {
    display: grid;
    grid-template-columns: minmax(380px, 42%) minmax(0, 1fr);
    gap: 24px;
    align-items: start;
  }

  .problem-split-layout.is-split .split-explain-pane {
    display: block;
  }
}

/* ===== 解説ペイン本体 ===== */
.split-explain-pane {
  align-self: start;
  min-width: 0;
}

.problem-split-layout.is-split .split-explain-pane {
  height: var(--split-pane-height);
}

.split-explain-pane__inner {
  border: 2px solid #111;
  background: #fff;
  box-shadow: 4px 4px 0 #111;
  display: flex;
  flex-direction: column;
  padding: clamp(14px, 2vw, 20px);
  box-sizing: border-box;
}

@media (min-width: 901px) {
  .problem-split-layout.is-split .split-explain-pane__inner {
    position: fixed;
    top: var(--split-pane-top);
    left: var(--split-pane-left, 16px);
    width: var(--split-pane-width, 420px);
    height: var(--split-pane-height);
    z-index: 20;
  }
}

.split-explain-pane__head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  flex: 0 0 auto;
  gap: 12px;
  margin: 0 0 14px;
  padding-bottom: 12px;
  border-bottom: 2px dashed #c5cad3;
}

.split-explain-pane__label {
  display: block;
  margin-bottom: 4px;
  font-size: 0.7rem;
  font-weight: 900;
  letter-spacing: 0.08em;
  color: #00a2ff;
}

.split-explain-pane__title {
  margin: 0;
  font-size: 1.05rem;
  font-weight: 900;
  color: #111;
  line-height: 1.4;
}

.split-explain-pane__actions {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
}

.split-explain-pane__full-link {
  font-size: 0.76rem;
  font-weight: 900;
  color: #0a66c2;
  text-decoration: underline;
  text-underline-offset: 3px;
  white-space: nowrap;
}

.split-explain-pane__close {
  width: 28px;
  height: 28px;
  flex-shrink: 0;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 2px solid #111;
  background: #fff;
  color: #111;
  font-size: 0.85rem;
  font-weight: 900;
  cursor: pointer;
  transition: background 0.12s ease, color 0.12s ease;
}

.split-explain-pane__close:hover {
  background: #111;
  color: #fff;
}

.split-explain-pane__body {
  flex: 1 1 auto;
  min-height: 0;
  overflow-y: auto;
  padding-right: 6px;
  font-size: 0.92rem;
}

/* lesson_blocks.html の要素を、狭いペイン向けに縮小 */
.split-explain-pane__body .chat-item {
  margin: 12px 0;
  font-size: 0.9rem;
}

.split-explain-pane__body .chat-icon {
  width: 40px;
  height: 40px;
  border-radius: 50%;
}

.split-explain-pane__body .chat-item.left .chat-icon {
  margin-right: 8px;
}

.split-explain-pane__body .chat-item.right .chat-icon {
  margin-left: 8px;
}

.split-explain-pane__body .chat-item p {
  max-width: 100%;
  padding: 8px 12px;
  border-radius: 12px;
}

.split-explain-pane__body .code-block {
  margin: 14px 0;
}

.split-explain-pane__body .code-block pre code {
  font-size: 0.78rem;
}

.split-explain-pane__body .image-container {
  margin: 14px 0;
}

.split-explain-pane__body .image-container--linked img,
.split-explain-pane__body .lesson-media-link img {
  max-width: min(180px, 70%);
}

.split-explain-pane__body .explain-table th,
.split-explain-pane__body .explain-table td {
  font-size: 0.8rem;
  padding: 8px;
}