/* De co loi giai (de.php). Mau theo :root cua trang; dung chung lp.css + cc.css. */
.de-nl { font-weight: 700; font-size: 14.5px; text-decoration: none; color: var(--ink2); }
@media (max-width: 640px) { .de-nl { display: none; } }
.de-crumb { font-size: 13.5px; color: var(--ink2); padding-top: 18px; }
.de-crumb a { color: var(--ink2); }
.de-head { padding-top: 14px; padding-bottom: 6px; max-width: 900px; }
.de-head h1 { font-size: clamp(26px, 4vw, 40px); margin: 12px 0 10px; line-height: 1.2; }
.de-head .lead { font-size: clamp(15.5px, 1.8vw, 17.5px); }
.de-meta { display: flex; flex-wrap: wrap; gap: 8px; margin: 14px 0 4px; }
.de-main { padding-top: 14px; padding-bottom: 40px; }
.de-paper { background: var(--card); border: 1px solid var(--line); border-radius: 22px; padding: clamp(16px, 3.4vw, 34px); max-width: 900px; }
.de-sec + .de-sec { margin-top: 26px; }
.de-sh { font-size: 18.5px; margin: 0 0 12px; line-height: 1.35; }
.de-sh small { font-weight: 600; color: var(--ink2); font-size: 14px; }
.de-sh .de-pt { background: var(--soft); border-radius: 99px; padding: 2px 9px; margin-left: 4px; white-space: nowrap; }
.de-pass { background: var(--bg); border-left: 4px solid var(--pri); border-radius: 10px; padding: 12px 16px; line-height: 1.65; margin-bottom: 14px; white-space: normal; }
.de-box, .de-words { display: flex; flex-wrap: wrap; gap: 8px; margin: 6px 0 12px; }
.de-box span, .de-words span { border: 1.5px solid var(--line); background: var(--bg); border-radius: 10px; padding: 4px 10px; font-weight: 600; }
.de-it { padding: 12px 0; border-top: 1px dashed var(--line); }
.de-sec .de-it:first-of-type { border-top: 0; }
.de-q { line-height: 1.6; }
.de-opts { margin: 8px 0 4px; padding-left: 26px; display: grid; grid-template-columns: repeat(auto-fit, minmax(180px, 1fr)); gap: 4px 18px; }
.de-opts li { line-height: 1.5; }
.de-hints { margin: 8px 0; color: var(--ink2); }
.de-sol { margin-top: 8px; }
.de-sol > summary { cursor: pointer; display: inline-block; font-weight: 700; font-size: 14px; color: var(--pri); padding: 4px 12px; border-radius: 99px; background: var(--soft); list-style: none; }
.de-sol > summary::-webkit-details-marker { display: none; }
.de-sol[open] > summary { background: var(--pri); color: #fff; }
.de-sol-b { margin-top: 8px; background: #F0FDF4; border: 1px solid #BBF7D0; border-radius: 12px; padding: 10px 14px; }
.de-sol-b p { margin: 4px 0; line-height: 1.6; }
.de-script { margin-bottom: 12px; }
.de-script > summary { cursor: pointer; font-weight: 700; color: var(--ink2); }
.de-script > div { margin-top: 8px; background: var(--bg); border-radius: 10px; padding: 10px 14px; line-height: 1.6; }
.de-ai { margin-top: 26px; }
.de-video { max-width: 900px; margin-bottom: 18px; }
.de-yt { position: relative; aspect-ratio: 16 / 9; border-radius: 18px; overflow: hidden; background: #000; }
.de-yt button { all: unset; cursor: pointer; display: block; width: 100%; height: 100%; position: relative; }
.de-yt img { width: 100%; height: 100%; object-fit: cover; opacity: .9; }
.de-yt span { position: absolute; inset: 0; margin: auto; width: 74px; height: 52px; border-radius: 14px; background: #E11D2F; color: #fff; font-size: 26px; display: grid; place-items: center; }
.de-yt iframe { width: 100%; height: 100%; border: 0; }
.de-up { display: grid; grid-template-columns: 1.3fr 1fr; gap: 20px; align-items: center; background: var(--ink); color: #fff; border-radius: 26px; padding: clamp(20px, 4vw, 36px); margin: 26px 0; max-width: 900px; }
.de-up h2 { color: #fff; font-size: clamp(20px, 2.6vw, 28px); }
.de-up .lead { color: rgba(255,255,255,.82); font-size: 15.5px; margin-top: 8px; }
.de-up .btn.alt { background: rgba(255,255,255,.1); color: #fff; box-shadow: inset 0 0 0 1.5px rgba(255,255,255,.3); }
.de-up .cta-row { margin-top: 0; }
@media (max-width: 820px) { .de-up { grid-template-columns: 1fr; } }
.de-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(250px, 1fr)); gap: 14px; }
.de-card { display: flex; flex-direction: column; gap: 6px; background: var(--card); border: 1px solid var(--line); border-radius: 18px; padding: 16px 18px; text-decoration: none; color: var(--ink); transition: transform .15s, box-shadow .15s; }
.de-card:hover { transform: translateY(-3px); box-shadow: 0 20px 40px -26px rgba(0,0,0,.35); }
.de-card b { font-size: 16.5px; line-height: 1.35; }
.de-tag { font-size: 12.5px; font-weight: 700; color: var(--ink2); }
.de-vid { font-size: 13px; font-weight: 700; color: #E11D2F; }
.de-card .go { margin-top: auto; padding-top: 6px; font-weight: 800; color: var(--pri); font-size: 14px; }
.de-blk { margin-bottom: 30px; }
.de-blk h2 a { color: inherit; }
.de-chips { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 12px; }
.de-chips .cc-chip { text-decoration: none; }
.de-grades { display: grid; grid-template-columns: repeat(auto-fill, minmax(160px, 1fr)); gap: 12px; }
.de-gc { display: flex; flex-direction: column; gap: 4px; background: var(--card); border: 1px solid var(--line); border-radius: 18px; padding: 16px; text-decoration: none; color: var(--ink); }
.de-gc b { font-size: 22px; font-family: 'Baloo 2', var(--hf); }
.de-gc span { font-size: 13.5px; color: var(--ink2); }
.de-gc em { font-style: normal; font-weight: 800; color: var(--pri); font-size: 14px; margin-top: 4px; }
.de-rel { max-width: 900px; }
@media print {
  .no-print, nav, footer { display: none !important; }
  body { background: #fff; }
  .de-paper { border: 0; padding: 0; }
  .de-sol, .de-script { display: none !important; }
  body.de-print-key .de-sol { display: block !important; }
}