/* Trang danh mục: breadcrumb, hero, chip, bộ lọc, nhóm, SEO block — port từ bản mẫu (.page-intro/.subject-jump/.subject-head/.category-content) */
.b4t-breadcrumb{display:flex;gap:9px;align-items:center;padding:22px 0 12px;color:var(--b4t-color-muted);font-size:13px;white-space:nowrap;overflow-x:auto;scrollbar-width:none}
.b4t-breadcrumb a{color:var(--b4t-color-muted);text-decoration:none}
.b4t-breadcrumb a:hover{color:var(--b4t-color-primary)}
.b4t-breadcrumb .b4t-breadcrumb__sep{color:var(--b4t-color-line)}
.b4t-breadcrumb :last-child:not(a):not(.b4t-breadcrumb__sep){color:var(--b4t-color-primary);font-weight:600}
.b4t-eyebrow{display:inline-block;margin:0 0 var(--b4t-space-sm);color:var(--b4t-color-muted);font:700 12px/1.2 var(--b4t-font-sans);letter-spacing:.12em;text-transform:uppercase}
.b4t-eyebrow--dark{color:var(--b4t-color-accent)}
.b4t-hero{position:relative;overflow:hidden;min-height:245px;display:flex;justify-content:space-between;align-items:center;gap:var(--b4t-space-lg);padding:40px 48px;color:var(--b4t-color-on-primary);background:linear-gradient(115deg,var(--b4t-color-primary-strong),var(--b4t-color-primary));border-radius:4px 36px 4px 4px}
.b4t-hero::after{content:"";position:absolute;width:340px;height:340px;right:-80px;top:-110px;border:70px solid rgba(255,255,255,.07);border-radius:50%}
.b4t-hero__text{position:relative;z-index:1;max-width:700px}
.b4t-hero h1{margin:0 0 12px;font-size:clamp(31px,3.2vw,42px);line-height:1.16;color:inherit}
.b4t-hero h1 em{font-style:normal;color:var(--b4t-color-accent)}
.b4t-hero p{margin:0;max-width:660px;color:var(--b4t-color-primary-soft)}
.b4t-seal{position:relative;z-index:1;flex:none;width:124px;height:124px;display:flex;flex-direction:column;align-items:center;justify-content:center;border:1px solid rgba(255,255,255,.42);border-radius:50%;background:rgba(255,255,255,.08);box-shadow:inset 0 0 0 7px rgba(255,255,255,.06)}
.b4t-seal small{font-size:11px;letter-spacing:.18em;text-transform:uppercase}
.b4t-seal strong{font-size:40px;line-height:1}
.b4t-seal span{font-size:11px;color:var(--b4t-color-accent)}
.b4t-chips{position:sticky;top:72px;z-index:18;display:flex;gap:8px;overflow-x:auto;padding:14px 0 10px;background:rgba(245,248,250,.96);backdrop-filter:blur(8px);scrollbar-width:none;-webkit-mask-image:linear-gradient(90deg,#000 calc(100% - 28px),transparent)}
.b4t-chip{flex:none;display:inline-flex;align-items:center;min-height:var(--b4t-touch-min);padding:10px 18px;border:1px solid var(--b4t-color-line);border-radius:var(--b4t-radius-full);background:var(--b4t-color-paper);color:var(--b4t-color-ink);font-size:14px;font-weight:600;text-decoration:none;white-space:nowrap;transition:background-color .2s ease-out,color .2s ease-out}
.b4t-chip:hover,.b4t-chip.is-active{background:var(--b4t-color-primary);border-color:var(--b4t-color-primary);color:var(--b4t-color-on-primary)}
.b4t-filters{margin:var(--b4t-space-md) 0 0}
.b4t-filters>summary{display:inline-flex;align-items:center;gap:8px;min-height:var(--b4t-touch-min);padding:8px 14px;border-radius:var(--b4t-radius-sm);color:var(--b4t-color-primary);font-weight:600;font-size:14px;cursor:pointer;list-style:none}
.b4t-filters>summary::-webkit-details-marker{display:none}
.b4t-filters form{display:flex;flex-wrap:wrap;align-items:end;gap:var(--b4t-space-md);padding:var(--b4t-space-md);background:var(--b4t-color-paper);border:1px solid var(--b4t-color-line);border-radius:var(--b4t-radius-lg)}
.b4t-filters label{display:flex;flex-direction:column;gap:6px;font:600 13px/1.3 var(--b4t-font-sans);color:var(--b4t-color-muted)}
.b4t-filters input,.b4t-filters select{min-height:var(--b4t-touch-min);min-width:140px;padding:10px 12px;border:1px solid var(--b4t-color-line);border-radius:var(--b4t-radius-sm);background:var(--b4t-color-paper);color:var(--b4t-color-ink);font:500 15px var(--b4t-font-sans)}
.b4t-filters input:focus,.b4t-filters select:focus{outline:3px solid var(--b4t-color-focus);outline-offset:1px;border-color:var(--b4t-color-primary)}
.b4t-btn--secondary{background:var(--b4t-color-paper);color:var(--b4t-color-ink);border-color:var(--b4t-color-line)}
.b4t-btn--secondary:hover{background:var(--b4t-color-primary-soft);border-color:var(--b4t-color-primary);color:var(--b4t-color-primary)}
.b4t-group{scroll-margin-top:160px;margin-top:var(--b4t-space-xl)}
.b4t-group__head{display:flex;justify-content:space-between;align-items:end;gap:var(--b4t-space-md);margin-bottom:15px;padding-bottom:12px;border-bottom:1px solid var(--b4t-color-line)}
.b4t-group__head h2{margin:0;font-size:clamp(23px,2.4vw,27px);line-height:1.2}
.b4t-group__head h2 a{color:inherit;text-decoration:none}
.b4t-group__head h2 a:hover{color:var(--b4t-color-primary)}
.b4t-count{margin:0;color:var(--b4t-color-primary);font-size:13px;font-weight:600;white-space:nowrap}
a.b4t-count{display:inline-flex;align-items:center;min-height:var(--b4t-touch-min);text-decoration:none}
a.b4t-count:hover,a.b4t-count:focus-visible{text-decoration:underline}
.b4t-more{display:flex;margin:17px auto 0}
.b4t-more[aria-busy=true]{opacity:.6;cursor:progress}
.b4t-seo{margin:var(--b4t-space-2xl) 0 var(--b4t-space-3xl);padding:38px 42px;background:var(--b4t-color-paper);border:1px solid var(--b4t-color-line);border-radius:var(--b4t-radius-xl);box-shadow:var(--b4t-shadow-rest)}
.b4t-seo h2{margin:7px 0 15px;padding-left:16px;border-left:5px solid var(--b4t-color-primary);font-size:clamp(27px,2.6vw,32px);line-height:1.25}
.b4t-seo p,.b4t-seo li{color:var(--b4t-color-muted);max-width:1000px}
.b4t-seo li::marker{color:var(--b4t-color-primary);font-weight:700}
.b4t-seo [id^=muc-]{scroll-margin-top:170px} /* mục lục: không bị header + thanh chip (sticky) che */
.b4t-seo .b4t-toc{max-width:1000px}
.b4t-seo .b4t-toc li::marker{content:none}
@media (max-width:850px){.b4t-hero{padding:34px}.b4t-seal{width:105px;height:105px}.b4t-chips{top:60px}}
@media (max-width:600px){
  .b4t-hero{min-height:auto;padding:28px 22px;border-radius:3px 24px 3px 3px}
  .b4t-hero p{font-size:14px}
  .b4t-seal{display:none}
  .b4t-group__head{align-items:center}
  p.b4t-count{display:none}
  .b4t-filters form{gap:var(--b4t-space-sm)}
  .b4t-filters label{flex:1 1 calc(50% - 8px)}
  .b4t-filters input,.b4t-filters select{min-width:0;width:100%}
  .b4t-seo{padding:27px 22px}
}

/* Trang kết quả tìm kiếm + phân trang */
.b4t-search-page{margin-top:var(--b4t-space-lg)}
.b4t-search-page__title{margin:0;font-size:clamp(24px,2.6vw,30px)}
.b4t-chips--static{position:static;background:none;backdrop-filter:none;-webkit-mask-image:none;justify-content:center;flex-wrap:wrap;padding:var(--b4t-space-md) 0 0}
.b4t-pagination{margin:var(--b4t-space-xl) 0}
.b4t-pagination .nav-links{display:flex;justify-content:center;gap:6px;flex-wrap:wrap}
.b4t-pagination .page-numbers{display:inline-flex;align-items:center;justify-content:center;min-width:var(--b4t-touch-min);min-height:var(--b4t-touch-min);padding:0 12px;border:1px solid var(--b4t-color-line);border-radius:var(--b4t-radius-sm);background:var(--b4t-color-paper);color:var(--b4t-color-ink);text-decoration:none;font-weight:600}
.b4t-pagination .page-numbers.current{background:var(--b4t-color-primary);border-color:var(--b4t-color-primary);color:var(--b4t-color-on-primary)}
.b4t-pagination .page-numbers:hover:not(.current){background:var(--b4t-color-primary-soft)}
.b4t-pagination .screen-reader-text{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0)}

/* Trang chủ */
.b4t-home-hero{margin-top:var(--b4t-space-lg);min-height:300px}
.b4t-home-hero .b4t-hero__text{max-width:760px}
.b4t-search--hero{margin:var(--b4t-space-lg) 0 0;width:min(620px,100%);height:56px;background:var(--b4t-color-paper);border-color:transparent;padding-left:20px}
.b4t-search--hero .b4t-search__submit{flex:none;width:auto;height:44px;min-height:44px;padding:0 22px;border-radius:var(--b4t-radius-full);background:var(--b4t-color-accent);color:var(--b4t-color-on-accent);font:600 14px/1 var(--b4t-font-sans);white-space:nowrap}
.b4t-search--hero .b4t-search__submit:hover{background:#e6a92f}
.b4t-search--hero .b4t-search__results{color:var(--b4t-color-ink)}
@media (max-width:360px){.b4t-home-hero{padding-left:16px;padding-right:16px}.b4t-search--hero{padding-left:10px}.b4t-search--hero .b4t-search__submit{padding:0 12px;font-size:13px}.b4t-search--hero{gap:0}} /* màn 320px: đủ chỗ cho placeholder */
/* ===== Trang chủ theo đề xuất khách (2026-09-28) ===== */
/* Block 1 Hero: chip gợi ý dưới ô tìm */
.b4t-hero__chips{display:flex;flex-wrap:wrap;gap:8px;margin-top:14px}
.b4t-hero__chips a{padding:6px 14px;border:1px solid rgba(255,255,255,.38);border-radius:var(--b4t-radius-full);color:#fff;font:600 13px/1.3 var(--b4t-font-sans);text-decoration:none;background:rgba(255,255,255,.06);transition:background-color .2s ease-out,border-color .2s ease-out}
.b4t-hero__chips a:hover,.b4t-hero__chips a:focus-visible{background:rgba(255,255,255,.18);border-color:#fff}
/* Block 2 SKKN theo cấp học: 5 cột (PC) → accordion (mobile) */
.b4t-lv{margin-top:var(--b4t-section-gap)}
.b4t-lv h2{margin-bottom:var(--b4t-space-md)}
.b4t-lv__grid{display:grid;grid-template-columns:repeat(5,minmax(0,1fr));gap:14px;align-items:stretch} /* cột cao bằng nhau */
.b4t-lv__col{background:var(--b4t-color-paper);border:1px solid var(--b4t-color-line);border-radius:var(--b4t-radius-lg);box-shadow:var(--b4t-shadow-rest);padding:16px}
.b4t-lv__head{display:flex;align-items:center;gap:12px;list-style:none;cursor:default;padding-bottom:12px;margin-bottom:6px;border-bottom:1px solid var(--b4t-color-line)}
.b4t-lv__head::-webkit-details-marker,.b4t-lv__item>summary::-webkit-details-marker{display:none}
.b4t-lv__head>.b4t-lv__caret{display:none}
.b4t-lv__num{flex:none;display:grid;place-items:center;width:38px;height:38px;border-radius:12px;font:700 13px/1 var(--b4t-font-sans);color:var(--b4t-color-ink)}
.b4t-lv__col--1 .b4t-lv__num{background:#fdf1d6}.b4t-lv__col--2 .b4t-lv__num{background:#e3f4e6}.b4t-lv__col--3 .b4t-lv__num{background:#fde7d9}.b4t-lv__col--4 .b4t-lv__num{background:#e1ecfb}.b4t-lv__col--5 .b4t-lv__num{background:#ece6fa}
.b4t-lv__title{display:flex;flex-direction:column;gap:2px;min-width:0}
.b4t-lv__title a{color:var(--b4t-color-ink);font:700 16px/1.25 var(--b4t-font-sans);text-decoration:none}
.b4t-lv__title a:hover{color:var(--b4t-color-primary)}
.b4t-lv__title small{color:var(--b4t-color-muted);font-size:12px;line-height:1.35}
.b4t-lv__link{display:block;padding:9px 2px;border-bottom:1px solid var(--b4t-color-line);color:var(--b4t-color-ink);font:600 13px/1.35 var(--b4t-font-sans);text-decoration:none}
.b4t-lv__link:last-child{border-bottom:0}
.b4t-lv__link:hover{color:var(--b4t-color-primary)}
.b4t-lv__item{border-bottom:1px solid var(--b4t-color-line)}
.b4t-lv__item:last-child{border-bottom:0}
.b4t-lv__item>summary{display:flex;align-items:center;justify-content:space-between;gap:8px;padding:9px 2px;list-style:none;cursor:pointer}
.b4t-lv__item>summary a{color:var(--b4t-color-ink);font:600 13px/1.35 var(--b4t-font-sans);text-decoration:none}
.b4t-lv__item>summary a:hover,.b4t-lv__item[open]>summary a{color:var(--b4t-color-primary)}
.b4t-lv__caret{flex:none;color:var(--b4t-color-muted);transition:transform .2s ease-out}
.b4t-lv__item[open]>summary .b4t-lv__caret{transform:rotate(180deg);color:var(--b4t-color-primary)}
.b4t-lv__chips{display:flex;flex-wrap:wrap;gap:6px;padding:2px 0 12px}
.b4t-lv__chips a{padding:4px 10px;border-radius:var(--b4t-radius-full);background:var(--b4t-color-bg);border:1px solid var(--b4t-color-line);color:var(--b4t-color-ink);font:500 12px/1.3 var(--b4t-font-sans);text-decoration:none}
.b4t-lv__chips a:hover{background:var(--b4t-color-primary);border-color:var(--b4t-color-primary);color:#fff}
@media (max-width:1199px){.b4t-lv__grid{grid-template-columns:repeat(3,minmax(0,1fr))}}
@media (max-width:849px){.b4t-lv__grid{grid-template-columns:repeat(2,minmax(0,1fr))}}
@media (max-width:600px){
  .b4t-lv__grid{grid-template-columns:1fr;gap:10px}
  .b4t-lv__col{padding:12px 14px}
  .b4t-lv__head{cursor:pointer;margin-bottom:0;padding-bottom:0;border-bottom:0}
  .b4t-lv__col[open]>.b4t-lv__head{padding-bottom:12px;margin-bottom:6px;border-bottom:1px solid var(--b4t-color-line)}
  .b4t-lv__head>.b4t-lv__caret{display:block;margin-left:auto}
  .b4t-lv__col[open]>.b4t-lv__head>.b4t-lv__caret{transform:rotate(180deg);color:var(--b4t-color-primary)}
}
/* Block 3 Đề tài theo xu hướng: 6 thẻ 3×2 */
.b4t-trend{position:relative;margin-top:var(--b4t-section-gap);padding:36px 0 8px}
.b4t-trend::before{content:"";position:absolute;right:0;top:12px;width:120px;height:80px;background:radial-gradient(var(--b4t-color-line) 1.5px,transparent 1.6px) 0 0/14px 14px;opacity:.9;pointer-events:none}
.b4t-trend__head{text-align:center;max-width:720px;margin:0 auto var(--b4t-space-lg)}
.b4t-trend__head h2{margin:0 0 10px;font:700 clamp(28px,3vw,38px)/1.2 var(--b4t-font-serif);color:var(--b4t-color-primary-strong)}
.b4t-trend__head h2 em{display:block;font-style:normal;color:var(--b4t-color-accent)}
.b4t-trend__head p{margin:0;color:var(--b4t-color-muted)}
.b4t-trend__grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px}
.b4t-trend__card{display:flex;align-items:center;gap:14px;padding:16px 18px;background:var(--b4t-color-paper);border:1px solid var(--b4t-color-line);border-radius:var(--b4t-radius-lg);box-shadow:var(--b4t-shadow-rest);color:var(--b4t-color-ink);text-decoration:none;transition:box-shadow .2s ease-out,transform .2s ease-out,border-color .2s ease-out}
.b4t-trend__card:hover,.b4t-trend__card:focus-visible{box-shadow:var(--b4t-shadow-hover);transform:translateY(-2px);border-color:var(--b4t-color-primary)}
.b4t-trend__icon{flex:none;display:grid;place-items:center;width:52px;height:52px;border-radius:50%;background:var(--b4t-color-primary-soft);color:var(--b4t-color-primary)}
.b4t-trend__icon svg{width:26px;height:26px}
.b4t-trend__text{flex:1;display:flex;flex-direction:column;gap:3px;min-width:0}
.b4t-trend__text strong{font:700 15px/1.3 var(--b4t-font-sans)}
.b4t-trend__text small{color:var(--b4t-color-muted);font-size:13px;line-height:1.4}
.b4t-trend__go{flex:none;display:grid;place-items:center;width:30px;height:30px;border-radius:50%;border:1px solid var(--b4t-color-line);color:var(--b4t-color-primary);font-size:18px;line-height:1}
@media (max-width:1023px){.b4t-trend__grid{grid-template-columns:repeat(2,minmax(0,1fr))}}
@media (max-width:600px){.b4t-trend__grid{grid-template-columns:1fr;gap:10px}.b4t-trend::before{display:none}.b4t-trend{padding-top:8px}}
@media (prefers-reduced-motion:reduce){.b4t-trend__card{transition:none}.b4t-trend__card:hover{transform:none}}
/* Block 5 SKKN nổi bật theo cấp học: tab (5 panel render sẵn) */
.b4t-feat__tabs{display:flex;gap:8px;overflow-x:auto;scrollbar-width:none;padding:2px 2px 14px}
.b4t-feat__tabs::-webkit-scrollbar{display:none}
.b4t-feat__tabs [role=tab]{flex:none;min-height:var(--b4t-touch-min);padding:10px 18px;border:1px solid var(--b4t-color-line);border-radius:var(--b4t-radius-full);background:var(--b4t-color-paper);color:var(--b4t-color-ink);font:600 14px/1.2 var(--b4t-font-sans);cursor:pointer}
.b4t-feat__tabs [role=tab][aria-selected=true],.b4t-feat__tabs [role=tab]:hover{background:var(--b4t-color-primary);border-color:var(--b4t-color-primary);color:var(--b4t-color-on-primary)}
.b4t-feat__panel+.b4t-feat__panel{margin-top:var(--b4t-space-lg)}
.b4t-feat.is-tabbed .b4t-feat__panel{margin-top:0}
.b4t-feat__panel[hidden]{display:none}
@media (min-width:1200px){.b4t-feat .b4t-feat__grid{grid-template-columns:repeat(5,minmax(0,1fr))}}
.b4t-feat__more{margin:var(--b4t-space-md) 0 0;text-align:center}
/* 2 hàng (team 2026-10-02): PC 5 cột × 2 = 10; 3 cột → 9; 2 cột → 6 (không lẻ thẻ, đỡ cuộn trên điện thoại) */
@media (min-width:850px) and (max-width:1199px){.b4t-feat__grid>.b4t-card:nth-child(n+10){display:none}}
@media (max-width:849px){.b4t-feat__grid>.b4t-card:nth-child(n+7){display:none}}

/* Block 1 Hero — "Con Số Ấn Tượng" bên phải (team 2026-10-02, thay khối "Giá trị mang lại") */
.b4t-home-hero .b4t-hero__text{flex:1 1 auto;min-width:0}
.b4t-hero__stats{position:relative;z-index:1;flex:0 0 380px;background:var(--b4t-color-paper);border-radius:var(--b4t-radius-xl);box-shadow:var(--b4t-shadow-pop);padding:24px}
.b4t-hero__stats-title{margin:0 0 16px;text-align:center;font:800 19px/1.2 var(--b4t-font-sans);color:var(--b4t-color-ink)}
.b4t-hero__nums{display:grid;grid-template-columns:1fr 1fr;gap:12px}
.b4t-stat{background:var(--b4t-color-bg);border-radius:var(--b4t-radius-lg);padding:18px 12px;text-align:center}
.b4t-stat strong{display:block;font:800 clamp(24px,2.6vw,32px)/1 var(--b4t-font-sans)}
.b4t-stat .is-teal,.b4t-stat strong.is-teal{color:var(--b4t-color-primary)}
.b4t-stat .is-gold,.b4t-stat strong.is-gold{color:var(--b4t-color-accent)}
.b4t-stat span{display:block;margin-top:8px;color:var(--b4t-color-muted);font-size:13px}
@media (max-width:1100px){.b4t-home-hero{flex-direction:column;align-items:stretch}.b4t-hero__stats{flex-basis:auto}.b4t-hero__nums{grid-template-columns:repeat(4,minmax(0,1fr))}}
@media (max-width:600px){
  .b4t-hero__stats{padding:16px 14px}
  .b4t-hero__stats-title{font-size:16px;margin-bottom:12px}
  .b4t-hero__nums{grid-template-columns:repeat(2,minmax(0,1fr));gap:8px}
  .b4t-stat{padding:12px 8px}
  .b4t-stat span{font-size:12px;margin-top:6px}
}

/* Trang chủ — "Cam kết chất lượng" (yc5). Nền sáng tươi (teal nhạt), card trắng. */
.b4t-commit{background:linear-gradient(160deg,#f2faf9 0%,var(--b4t-color-primary-soft) 100%);color:var(--b4t-color-ink);padding:60px 0}
.b4t-commit__head{text-align:center;max-width:640px;margin:0 auto 40px}
.b4t-commit__badge{display:inline-block;padding:6px 14px;border-radius:var(--b4t-radius-full);background:var(--b4t-color-accent);color:#14343a;font-weight:700;font-size:12px;letter-spacing:.12em;text-transform:uppercase}
.b4t-commit__head h2{margin:16px 0 0;font:800 clamp(24px,3.2vw,34px)/1.2 var(--b4t-font-sans);color:var(--b4t-color-ink);display:inline-block}
.b4t-commit__head h2::after{content:"";display:block;width:64px;height:3px;background:var(--b4t-color-accent);border-radius:2px;margin:12px auto 0}
.b4t-commit__head p{margin:14px 0 0;color:var(--b4t-color-muted);font-size:15px;line-height:1.6}
.b4t-commit__grid{display:grid;grid-template-columns:repeat(3,1fr);gap:24px}
.b4t-commit__card{background:var(--b4t-color-paper);border:1px solid var(--b4t-color-line);border-radius:var(--b4t-radius-xl);box-shadow:var(--b4t-shadow-rest);padding:28px;display:flex;flex-direction:column;transition:box-shadow .2s ease-out,transform .2s ease-out}
.b4t-commit__card:hover{box-shadow:var(--b4t-shadow-hover);transform:translateY(-2px)}
.b4t-commit__icon{display:grid;place-items:center;width:52px;height:52px;border-radius:14px;background:var(--b4t-color-primary);color:#fff;margin-bottom:18px}
.b4t-commit__icon svg{width:26px;height:26px}
.b4t-commit__card h3{margin:0 0 10px;font:800 18px/1.3 var(--b4t-font-sans);color:var(--b4t-color-ink)}
.b4t-commit__card h3::before{content:"+ ";color:var(--b4t-color-accent)}
.b4t-commit__card>p{margin:0 0 20px;color:var(--b4t-color-muted);font-size:14px;line-height:1.6;flex:1}
.b4t-commit__foot{border-top:1px solid var(--b4t-color-line);padding-top:14px;color:var(--b4t-color-muted);font-size:13px}
.b4t-commit__foot::before{content:"✓ ";color:var(--b4t-color-primary);font-weight:700}
@media (max-width:900px){.b4t-commit__grid{grid-template-columns:1fr;gap:16px}}
/* Block 6 Quy trình biên tập & Hội đồng chuyên môn (2026-09-30) */
.b4t-edit{margin-top:var(--b4t-section-gap)}
.b4t-edit>h2{margin:0 0 var(--b4t-space-lg)}
.b4t-edit__grid{display:grid;grid-template-columns:minmax(0,.9fr) minmax(0,1.6fr);gap:20px;align-items:stretch}
.b4t-edit__process,.b4t-edit__board{background:var(--b4t-color-paper);border:1px solid var(--b4t-color-line);border-radius:var(--b4t-radius-xl);box-shadow:var(--b4t-shadow-rest);padding:24px}
.b4t-edit__process{display:flex;flex-direction:column;background:linear-gradient(160deg,#f2faf9 0%,var(--b4t-color-primary-soft) 100%)}
.b4t-edit h3{margin:0 0 16px;font:700 18px/1.3 var(--b4t-font-sans);color:var(--b4t-color-primary-strong)}
.b4t-edit__steps{list-style:none;margin:0 0 20px;padding:0;display:flex;flex-direction:column;gap:0}
.b4t-edit__steps li{position:relative;display:flex;align-items:center;gap:14px;padding:12px 0}
.b4t-edit__steps li+li::before{content:"";position:absolute;left:18px;top:-12px;height:24px;border-left:2px dashed var(--b4t-color-line)}
.b4t-edit__num{flex:none;display:grid;place-items:center;width:38px;height:38px;border-radius:50%;background:var(--b4t-color-primary);color:#fff;font:700 15px/1 var(--b4t-font-sans);position:relative;z-index:1}
.b4t-edit__steps strong{font:600 15px/1.35 var(--b4t-font-sans);color:var(--b4t-color-ink)}
.b4t-edit__cta{margin-top:auto;align-self:flex-start}
.b4t-edit__board-head{display:flex;justify-content:space-between;align-items:baseline;gap:12px;flex-wrap:wrap;margin-bottom:4px}
.b4t-edit__members{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:12px}
.b4t-member{display:flex;align-items:center;gap:14px;padding:14px;border:1px solid var(--b4t-color-line);border-radius:var(--b4t-radius-lg);background:var(--b4t-color-paper);color:var(--b4t-color-ink);text-decoration:none;transition:box-shadow .2s ease-out,border-color .2s ease-out}
.b4t-member:hover,.b4t-member:focus-visible{box-shadow:var(--b4t-shadow-hover);border-color:var(--b4t-color-primary)}
.b4t-member__photo{flex:none;width:72px;height:72px;border-radius:50%;overflow:hidden;background:var(--b4t-color-primary-soft)}
.b4t-member__photo img{width:100%;height:100%;object-fit:cover;object-position:center 25%}
.b4t-member__text{display:flex;flex-direction:column;gap:2px;min-width:0}
.b4t-member__text strong{font:700 15px/1.3 var(--b4t-font-sans)}
.b4t-member__text small{color:var(--b4t-color-muted);font-size:12.5px;line-height:1.4}
.b4t-member__deg{color:var(--b4t-color-ink)!important;font-weight:600}
.b4t-member__area{align-self:flex-start;margin-top:6px;padding:3px 10px;border-radius:var(--b4t-radius-full);background:var(--b4t-color-primary-soft);color:var(--b4t-color-primary);font:600 12px/1.3 var(--b4t-font-sans)}
@media (max-width:1023px){.b4t-edit__grid{grid-template-columns:minmax(0,1fr)}}
@media (max-width:600px){.b4t-edit__members{grid-template-columns:minmax(0,1fr)}.b4t-edit__process,.b4t-edit__board{padding:18px}}
/* Block 7 Thầy cô nói gì (2026-09-30): bố cục thẻ "case study", màu dự án (nền teal đậm, nhấn hổ phách) */
.b4t-fb{margin-top:var(--b4t-section-gap);padding:56px 0;background:linear-gradient(160deg,var(--b4t-color-primary-strong) 0%,#0f3f42 100%);color:#fff}
.b4t-fb__head{text-align:center;margin-bottom:28px}
.b4t-fb__eyebrow{margin:0 0 8px;color:var(--b4t-color-accent);font:700 12px/1.2 var(--b4t-font-sans);letter-spacing:.14em;text-transform:uppercase}
.b4t-fb__head h2{margin:0;color:#fff;font:800 clamp(26px,3.2vw,38px)/1.2 var(--b4t-font-sans);text-transform:uppercase;letter-spacing:.01em}
.b4t-fb__head h2 em{font-style:normal;color:var(--b4t-color-accent)}
.b4t-fb__wrap{position:relative}
.b4t-fb__track{display:grid;grid-auto-flow:column;grid-auto-columns:calc((100% - 2*20px)/3);gap:20px;overflow-x:auto;scroll-snap-type:x mandatory;scrollbar-width:none;padding:2px}
.b4t-fb__track::-webkit-scrollbar{display:none}
.b4t-fb__card{margin:0;scroll-snap-align:start;display:flex;flex-direction:column;border-radius:var(--b4t-radius-xl);overflow:hidden;background:rgba(255,255,255,.06);border:1px solid rgba(255,255,255,.14)}
.b4t-fb__shot{display:block;padding:0;border:0;background:#fff;cursor:zoom-in;aspect-ratio:16/10;overflow:hidden}
.b4t-fb__shot img{width:100%;height:100%;object-fit:cover;object-position:top;display:block;transition:transform .3s ease-out}
.b4t-fb__shot:hover img,.b4t-fb__shot:focus-visible img{transform:scale(1.03)}
.b4t-fb__card figcaption{flex:1;display:flex;align-items:center;justify-content:space-between;gap:12px;padding:16px 18px}
.b4t-fb__text{display:flex;flex-direction:column;gap:4px;min-width:0}
.b4t-fb__text strong{font:700 15px/1.3 var(--b4t-font-sans);color:#fff;margin-bottom:4px}
.b4t-fb__text span{font-size:13px;line-height:1.45;color:rgba(255,255,255,.78)}
.b4t-fb__badge{flex:none;max-width:42%;padding:6px 10px;border-radius:var(--b4t-radius-md);background:var(--b4t-color-accent);color:var(--b4t-color-on-accent);font:800 13px/1.25 var(--b4t-font-sans);text-align:center}
.b4t-fb__nav{position:absolute;top:30%;z-index:2;width:42px;height:42px;border-radius:50%;border:0;background:#fff;color:var(--b4t-color-primary);font-size:24px;line-height:1;cursor:pointer;box-shadow:var(--b4t-shadow-pop)}
.b4t-fb__nav--prev{left:-18px}.b4t-fb__nav--next{right:-18px}
.b4t-fb__nav[disabled]{opacity:0;pointer-events:none}
.b4t-fb__dlg{padding:0;border:0;border-radius:var(--b4t-radius-lg);max-width:min(1000px,94vw);max-height:92vh;background:#fff}
.b4t-fb__dlg::backdrop{background:rgba(8,30,32,.78)}
.b4t-fb__dlg img{display:block;max-width:100%;max-height:92vh;object-fit:contain}
.b4t-fb__close{position:absolute;top:8px;right:8px;width:40px;height:40px;border-radius:50%;border:0;background:rgba(0,0,0,.6);color:#fff;font-size:24px;cursor:pointer}
@media (max-width:1023px){.b4t-fb__track{grid-auto-columns:calc((100% - 20px)/2)}}
@media (max-width:600px){.b4t-fb{padding:40px 0}.b4t-fb__track{grid-auto-columns:86%;gap:12px}.b4t-fb__nav{display:none}}
@media (prefers-reduced-motion:reduce){.b4t-fb__shot img{transition:none}}
/* Block 8 Cẩm nang viết SKKN (2026-09-30): 6 thẻ bài viết có ảnh, ngày, tiêu đề, 1 dòng mô tả */
.b4t-guide{margin-top:var(--b4t-section-gap)}
.b4t-guide .b4t-group__head{align-items:flex-end}
.b4t-guide__sub{margin:6px 0 0;color:var(--b4t-color-muted);font-size:14px}
.b4t-guide__grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:18px}
.b4t-guide__card{display:flex;flex-direction:column;background:var(--b4t-color-paper);border:1px solid var(--b4t-color-line);border-radius:var(--b4t-radius-xl);overflow:hidden;box-shadow:var(--b4t-shadow-rest);color:var(--b4t-color-ink);text-decoration:none;transition:transform .2s ease-out,box-shadow .2s ease-out,border-color .2s ease-out}
.b4t-guide__card:hover,.b4t-guide__card:focus-visible{transform:translateY(-3px);box-shadow:var(--b4t-shadow-hover);border-color:var(--b4t-color-primary)}
.b4t-guide__media{position:relative;display:block;aspect-ratio:16/9;background:var(--b4t-color-primary-soft);overflow:hidden}
.b4t-guide__media img{width:100%;height:100%;object-fit:cover;display:block;transition:transform .3s ease-out}
.b4t-guide__card:hover .b4t-guide__media img{transform:scale(1.04)}
.b4t-guide__ico{position:absolute;left:14px;bottom:-22px;z-index:1;display:grid;place-items:center;width:46px;height:46px;border-radius:14px;background:var(--b4t-color-accent);color:var(--b4t-color-on-accent);box-shadow:var(--b4t-shadow-rest)}
.b4t-guide__ico svg{width:24px;height:24px}
.b4t-guide__media{overflow:visible}
.b4t-guide__media img{border-radius:0}
.b4t-guide__media--ph{background:linear-gradient(135deg,var(--b4t-color-primary) 0%,var(--b4t-color-primary-strong) 100%)}
.b4t-guide__media--ph::after{content:"";position:absolute;inset:0;background:radial-gradient(circle at 85% 20%,rgba(239,185,93,.35) 0,transparent 45%),radial-gradient(rgba(255,255,255,.12) 1.5px,transparent 1.6px) 0 0/16px 16px}
.b4t-guide__phtxt{position:absolute;inset:0;z-index:1;display:grid;place-items:center;padding:18px 24px;text-align:center;color:#fff;font:700 clamp(20px,2vw,26px)/1.25 var(--b4t-font-serif);text-shadow:0 2px 12px rgba(0,0,0,.18)}
.b4t-guide__body{flex:1;display:flex;flex-direction:column;gap:6px;padding:32px 18px 18px}
.b4t-guide__body time{color:var(--b4t-color-muted);font-size:12px}
.b4t-guide__body strong{font:700 17px/1.3 var(--b4t-font-sans)}
.b4t-guide__body small{color:var(--b4t-color-muted);font-size:13.5px;line-height:1.5}
.b4t-guide__more{margin-top:auto;padding-top:8px;color:var(--b4t-color-primary);font:600 13px/1.3 var(--b4t-font-sans)}
@media (max-width:1023px){.b4t-guide__grid{grid-template-columns:repeat(2,minmax(0,1fr))}}
@media (max-width:600px){.b4t-guide__grid{grid-auto-flow:column;grid-template-columns:none;grid-auto-columns:84%;overflow-x:auto;scroll-snap-type:x mandatory;scrollbar-width:none;gap:12px;padding-bottom:6px}.b4t-guide__grid::-webkit-scrollbar{display:none}.b4t-guide__card{scroll-snap-align:start}.b4t-guide .b4t-group__head{flex-wrap:wrap}}
@media (prefers-reduced-motion:reduce){.b4t-guide__card,.b4t-guide__media img{transition:none}.b4t-guide__card:hover{transform:none}}
/* Block 9 Câu hỏi thường gặp (2026-09-30): accordion <details>, câu trả lời có sẵn HTML + FAQPage JSON-LD */
.b4t-faq{margin-top:var(--b4t-section-gap)}
.b4t-faq__head{text-align:center;margin-bottom:var(--b4t-space-lg)}
.b4t-faq__head h2{margin:0}
.b4t-faq__list{max-width:860px;margin:0 auto;display:flex;flex-direction:column;gap:12px}
.b4t-faq__item{background:var(--b4t-color-paper);border:1px solid var(--b4t-color-line);border-radius:var(--b4t-radius-lg);box-shadow:var(--b4t-shadow-rest);transition:border-color .2s ease-out}
.b4t-faq__item[open]{border-color:var(--b4t-color-primary)}
.b4t-faq__item>summary{display:flex;align-items:center;justify-content:space-between;gap:16px;padding:18px 22px;list-style:none;cursor:pointer;font:700 16px/1.4 var(--b4t-font-sans);color:var(--b4t-color-ink)}
.b4t-faq__item>summary::-webkit-details-marker{display:none}
.b4t-faq__item>summary:hover,.b4t-faq__item[open]>summary{color:var(--b4t-color-primary)}
.b4t-faq__icon{position:relative;flex:none;width:28px;height:28px;border-radius:50%;background:var(--b4t-color-primary-soft)}
.b4t-faq__icon::before,.b4t-faq__icon::after{content:"";position:absolute;left:50%;top:50%;width:12px;height:2px;margin:-1px 0 0 -6px;border-radius:2px;background:var(--b4t-color-primary);transition:transform .2s ease-out}
.b4t-faq__icon::after{transform:rotate(90deg)}
.b4t-faq__item[open] .b4t-faq__icon{background:var(--b4t-color-primary)}
.b4t-faq__item[open] .b4t-faq__icon::before,.b4t-faq__item[open] .b4t-faq__icon::after{background:#fff}
.b4t-faq__item[open] .b4t-faq__icon::after{transform:rotate(0)}
.b4t-faq__a{padding:0 22px 18px;color:var(--b4t-color-muted);line-height:1.65}
.b4t-faq__a p{margin:0}
.b4t-faq__a a{color:var(--b4t-color-primary);font-weight:600}
@media (max-width:600px){.b4t-faq__item>summary{padding:15px 16px;font-size:15px}.b4t-faq__a{padding:0 16px 15px}}
@media (prefers-reduced-motion:reduce){.b4t-faq__icon::before,.b4t-faq__icon::after{transition:none}}