/* ============ Vui Học — Trang hướng dẫn ============ */
:root { --primary: #ff7a59; --secondary: #4f8cff; --text: #22263a; --muted: #6f7690; --line: #e6e9f2; --bg: #f4f6fb; }
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; scroll-padding-top: 120px; }
body { margin: 0; font: 17px/1.65 "Nunito", "Segoe UI", system-ui, -apple-system, Roboto, Arial, sans-serif; color: var(--text); background: var(--bg); }
a { color: var(--secondary); }

.g-top { position: sticky; top: 0; z-index: 10; background: #fff; border-bottom: 1px solid var(--line); padding: 10px 16px; display: flex; flex-wrap: wrap; align-items: center; gap: 10px 18px; }
.g-brand { display: flex; align-items: center; gap: 8px; font-weight: 900; font-size: 1.15rem; color: var(--text); text-decoration: none; }
.g-brand img { height: 34px; }
.g-brand span { font-size: 1.6rem; }
.g-tabs { display: flex; gap: 6px; flex-wrap: wrap; }
.g-tabs a { padding: 7px 14px; border-radius: 99px; background: #f1f3fa; color: var(--text); font-weight: 800; text-decoration: none; font-size: .95rem; }
.g-tabs a.on { background: var(--primary); color: #fff; }

.g-wrap { max-width: 1120px; margin: 0 auto; padding: 20px 16px 40px; display: grid; grid-template-columns: 230px minmax(0, 1fr); gap: 24px; align-items: start; }
.g-toc { position: sticky; top: 90px; background: #fff; border: 1px solid var(--line); border-radius: 14px; padding: 14px; display: flex; flex-direction: column; gap: 2px; font-size: .92rem; }
.g-toc b { margin-bottom: 6px; }
.g-toc a { color: var(--text); text-decoration: none; padding: 5px 8px; border-radius: 8px; }
.g-toc a:hover { background: #f1f3fa; }
.g-print { margin-top: 10px; font: inherit; font-weight: 800; border: 0; border-radius: 10px; padding: 8px; background: #f1f3fa; cursor: pointer; }

.g-doc { background: #fff; border: 1px solid var(--line); border-radius: 18px; padding: 26px 32px; min-width: 0; }
.g-doc h1 { font-size: 1.9rem; line-height: 1.25; margin: 0 0 .6rem; }
.g-doc h2 { font-size: 1.4rem; margin: 2.2rem 0 .7rem; padding-top: 1rem; border-top: 2px dashed var(--line); }
.g-doc h2:first-of-type { border-top: 0; padding-top: 0; }
.g-doc h3 { font-size: 1.12rem; margin: 1.5rem 0 .4rem; }
.g-doc p { margin: .5rem 0 .8rem; }
.g-doc ul, .g-doc ol { padding-left: 1.4rem; margin: .4rem 0 1rem; }
.g-doc li { margin: .3rem 0; }
.g-doc ol > li::marker { font-weight: 900; color: var(--primary); }
.g-doc code { background: #fff3d6; color: #7a4d00; padding: 1px 7px; border-radius: 6px; font: 800 .95em ui-monospace, Menlo, Consolas, monospace; }
.g-doc hr { border: 0; border-top: 1px solid var(--line); margin: 1.5rem 0; }
.g-doc figure { margin: 1rem 0 1.4rem; text-align: center; }
.g-doc figure img { max-width: 100%; max-height: 640px; border-radius: 14px; border: 1px solid var(--line); box-shadow: 0 6px 20px rgba(30, 40, 90, .10); background: #fff; }
.g-doc figcaption { font-size: .9rem; color: var(--muted); margin-top: 6px; }
.g-doc li img { max-width: 100%; border-radius: 10px; border: 1px solid var(--line); margin: 6px 0; display: block; }
.callout { background: #eef5ff; border-left: 5px solid var(--secondary); border-radius: 12px; padding: 12px 16px; margin: 1rem 0; }
.table-wrap { overflow-x: auto; margin: .6rem 0 1.2rem; }
.g-doc table { border-collapse: collapse; width: 100%; font-size: .95rem; }
.g-doc th, .g-doc td { border: 1px solid var(--line); padding: 8px 10px; text-align: left; vertical-align: top; }
.g-doc th { background: #f6f8ff; }
.g-foot { text-align: center; color: var(--muted); font-size: .9rem; padding: 0 16px 30px; }

@media (max-width: 860px) {
  .g-top { position: static; }
  html { scroll-padding-top: 10px; }
  .g-wrap { grid-template-columns: 1fr; }
  .g-toc { position: static; }
  .g-doc { padding: 18px; border-radius: 14px; }
  .g-doc h1 { font-size: 1.5rem; }
}
@media print {
  body { background: #fff; font-size: 12pt; }
  .g-top, .g-toc, .g-foot { display: none; }
  .g-wrap { display: block; padding: 0; }
  .g-doc { border: 0; padding: 0; }
  .g-doc h2 { break-before: auto; }
  .g-doc figure, .callout, table { break-inside: avoid; }
  .g-doc figure img { max-height: 420px; box-shadow: none; }
}

/* ----- Trang "Các dạng câu hỏi": khung chơi thử ----- */
.demo-box { margin: .6rem 0 1.4rem; }
.demo-box iframe { width: 100%; max-width: 560px; height: 520px; border: 0; border-radius: 18px; transition: height .2s; box-shadow: 0 6px 20px rgba(30, 40, 90, .12); display: block; margin: 0 auto; background: #eef3ff; }
.demo-box .demo-print { display: none; }
@media print {
  .demo-box iframe { display: none; }
  .demo-box .demo-print { display: block; max-width: 100%; max-height: 420px; margin: 0 auto; border: 1px solid var(--line); border-radius: 12px; }
}