/* base */
.callout {
  border: 1px solid #ddd;
  border-left: 4px solid #444;
  padding: 12px 16px;
  margin: 1.5em 0;
  border-radius: 4px;
  background: #fff;
}

[data-theme="dark"] .callout {
  background: transparent;        /* bỏ nền card */
  border: 1px solid #333;                 /* bỏ box */
  border-left: 3px solid #888;    /* chỉ giữ line trái */
  padding: 0.6em 1em;
  margin: 1.2em 0;
  color: #e0e0e0;
}

[data-theme="dark"] .callout * {
  color: inherit;
}

/* title */
.callout-title {
  font-weight: 600;
  font-family: "Georgia", "Times New Roman", serif;
  margin-bottom: 6px;
}

/* content */
.callout-content {
  font-family: "Georgia", "Times New Roman", serif;
  line-height: 1.6;
}

/* từng loại (rất subtle) */
.definition { border-left-color: #000; }
.theorem    { border-left-color: #222; }
.lemma      { border-left-color: #444; }
.proof      { border-left-color: #666; }
.example    { border-left-color: #888; }
.intuition  { border-left-color: #aaa; }
.remark     { border-left-color: #bbb; }
.pitfall    { border-left-color: #999; }
.algorithm  { border-left-color: #333; }
.notation   { border-left-color: #555; }

/* nested nhẹ nhàng */
.callout .callout {
  margin-top: 10px;
  border-left-width: 3px;
  background: #fafafa;
}