/* ═══════════════════════════════════════════════════════════════════════
   BẬC TRÌ — kiểu trình bày
   Dùng lại bộ biến --gold/--paper/--ink của khung chuẩn (khai trong trang).
   ⚠ css/style.css có `button{width:100%}` — phải chặn lại, xem .bt-vung.
   ⚠ Mọi lưới dùng minmax(min(Xpx,100%),1fr) để không tràn ngang trên điện thoại.
   ═══════════════════════════════════════════════════════════════════════ */

.bt-vung{margin:0 0 40px;min-width:0;}
.bt-vung button{width:auto;}          /* chặn button{width:100%} của style.css */

.bt-trong{
  padding:22px;text-align:center;border:1px dashed var(--rule,rgba(60,40,10,.18));
  color:var(--ink-soft,rgba(26,18,8,.62));font-style:italic;
}

/* ═════════ KHỐI KHAI BÁO MỨC NGUỒN (đặt ở ĐẦU trang) ═════════ */
.bt-nguon-bao{
  border-left:4px solid var(--gold,#c9963b);
  background:var(--panel,#f0e8d5);
  padding:16px 20px;margin:0 0 34px;border-radius:0 3px 3px 0;
}
.bt-nguon-bao .bt-nb-nhan{
  display:block;font-family:var(--mono,'Montserrat',sans-serif);
  font-size:.56rem;font-weight:700;letter-spacing:.2em;text-transform:uppercase;
  color:var(--gold-dark,#8b6914);margin-bottom:8px;
}
.bt-nguon-bao p{margin:0 0 8px;font-size:.95rem;line-height:1.6;}
.bt-nguon-bao p:last-child{margin-bottom:0;}
.bt-nguon-bao.bt-nb-thieu{border-left-color:var(--accent,#7a1f1f);}
.bt-nguon-bao.bt-nb-thieu .bt-nb-nhan{color:var(--accent,#7a1f1f);}

/* ═════════ LƯỚI 5 BÀI HỌC ═════════ */
.bt-luoi{
  display:grid;gap:16px;margin:0 0 34px;
  grid-template-columns:repeat(auto-fit,minmax(min(240px,100%),1fr));
}
.bt-the{
  display:flex;flex-direction:column;min-width:0;
  padding:20px 18px 16px;border:1px solid var(--rule,rgba(60,40,10,.18));
  border-top:3px solid var(--gold,#c9963b);border-radius:3px;
  background:var(--paper,#faf7f2);text-decoration:none;color:inherit;
  transition:transform .16s ease, box-shadow .16s ease;
}
.bt-the:hover{transform:translateY(-3px);box-shadow:0 10px 26px rgba(60,40,10,.14);}
.bt-the-so{
  font-family:var(--mono,'Montserrat',sans-serif);font-size:.54rem;font-weight:700;
  letter-spacing:.2em;text-transform:uppercase;color:var(--gold-dark,#8b6914);
}
.bt-the-bieu{font-size:1.7rem;line-height:1;margin:8px 0 4px;color:var(--gold,#c9963b);}
.bt-the-ten{
  font-family:var(--display,'Playfair Display',Georgia,serif);
  font-size:1.24rem;line-height:1.25;margin:2px 0 8px;color:var(--ink,#1a1208);
}
.bt-the-mo{
  font-size:.9rem;line-height:1.55;margin:0 0 14px;flex:1;
  color:var(--ink-soft,rgba(26,18,8,.62));
}
.bt-the-chan{
  display:flex;justify-content:space-between;gap:10px;flex-wrap:wrap;
  border-top:1px solid var(--rule,rgba(60,40,10,.18));padding-top:10px;
  font-family:var(--mono,'Montserrat',sans-serif);font-size:.54rem;
  letter-spacing:.12em;text-transform:uppercase;
}
.bt-the-chan em{font-style:normal;color:var(--ink-soft,rgba(26,18,8,.62));}
.bt-the.bt-dangdoc{border-top-color:#b8860b;}
.bt-the.bt-xong{border-top-color:#2e6b3e;background:#f3f8f2;}
.bt-the.bt-xong .bt-trangthai{color:#2e6b3e;font-weight:700;}

/* ═════════ BẢNG TIẾN ĐỘ ═════════ */
.bt-tiendo{
  border:1px solid var(--rule,rgba(60,40,10,.18));border-radius:3px;
  padding:20px;margin:0 0 34px;background:var(--paper,#faf7f2);
}
.bt-td-dau{display:flex;justify-content:space-between;gap:12px;flex-wrap:wrap;margin-bottom:10px;}
.bt-td-nhan{
  font-family:var(--mono,'Montserrat',sans-serif);font-size:.58rem;font-weight:700;
  letter-spacing:.2em;text-transform:uppercase;color:var(--gold-dark,#8b6914);
}
.bt-td-so{font-family:var(--mono,'Montserrat',sans-serif);font-size:.62rem;color:var(--ink-soft,rgba(26,18,8,.62));}

.bt-thanh{height:9px;border-radius:9px;background:rgba(60,40,10,.12);overflow:hidden;}
.bt-thanh i{
  display:block;height:100%;border-radius:9px;
  background:linear-gradient(90deg,#c9963b,#8b6914);transition:width .35s ease;
}
.bt-thanh-nho{height:5px;margin:0 0 18px;}

.bt-td-luoi{
  display:grid;gap:10px;margin:16px 0 0;
  grid-template-columns:repeat(auto-fit,minmax(min(120px,45%),1fr));
}
.bt-td-luoi span{
  min-width:0;text-align:center;padding:14px 8px;border-radius:3px;
  background:linear-gradient(135deg,#2a2013,#43331c);color:#f5efe3;
  font-family:var(--mono,'Montserrat',sans-serif);font-size:.5rem;
  letter-spacing:.14em;text-transform:uppercase;line-height:1.5;
}
.bt-td-luoi b{
  display:block;font-family:var(--display,'Playfair Display',Georgia,serif);
  font-size:1.7rem;line-height:1;color:#ffd97a;margin-bottom:4px;
}
.bt-td-xong{
  margin:16px 0 0;padding:12px 14px;border-radius:3px;
  background:#eef6ee;border-left:3px solid #2e6b3e;font-size:.94rem;
}
.bt-td-ghi{
  margin:14px 0 0;font-size:.8rem;line-height:1.55;
  color:var(--ink-soft,rgba(26,18,8,.62));
}
.bt-xoa{
  margin-left:6px;padding:3px 10px;border:1px solid var(--rule,rgba(60,40,10,.18));
  background:transparent;border-radius:3px;cursor:pointer;
  font-family:var(--mono,'Montserrat',sans-serif);font-size:.55rem;
  letter-spacing:.12em;text-transform:uppercase;color:var(--ink-soft,rgba(26,18,8,.62));
}
.bt-xoa:hover{border-color:var(--accent,#7a1f1f);color:var(--accent,#7a1f1f);}

/* ═════════ TRẮC NGHIỆM ═════════ */
.bt-quiz{
  border:1px solid var(--rule,rgba(60,40,10,.18));border-top:3px solid var(--gold,#c9963b);
  border-radius:3px;padding:22px;margin:0 0 34px;background:var(--paper,#faf7f2);min-width:0;
}
.bt-quiz button{width:auto;}
.bt-quiz-dau{display:flex;justify-content:space-between;gap:12px;flex-wrap:wrap;margin-bottom:8px;}
.bt-quiz-dem,.bt-quiz-diem{
  font-family:var(--mono,'Montserrat',sans-serif);font-size:.56rem;font-weight:700;
  letter-spacing:.18em;text-transform:uppercase;color:var(--gold-dark,#8b6914);
}
.bt-quiz-diem{color:var(--ink-soft,rgba(26,18,8,.62));}
.bt-quiz-hoi{
  font-family:var(--display,'Playfair Display',Georgia,serif);
  font-size:1.3rem;line-height:1.4;margin:0 0 18px;color:var(--ink,#1a1208);
}

.bt-dapan{display:flex;flex-direction:column;gap:9px;}
.bt-da{
  display:flex;align-items:flex-start;gap:12px;width:100%;min-width:0;
  padding:13px 15px;text-align:left;cursor:pointer;
  border:1px solid var(--rule,rgba(60,40,10,.18));border-radius:3px;
  background:#fff;color:var(--ink,#1a1208);
  font-family:var(--sans,'Be Vietnam Pro',sans-serif);font-size:.97rem;line-height:1.5;
  transition:border-color .14s ease, background .14s ease;
}
.bt-da:hover:not(:disabled){border-color:var(--gold,#c9963b);background:#fffdf7;}
.bt-da:disabled{cursor:default;}
.bt-da-chu{
  flex:0 0 auto;width:24px;height:24px;border-radius:50%;
  display:flex;align-items:center;justify-content:center;
  background:var(--panel,#f0e8d5);color:var(--gold-dark,#8b6914);
  font-family:var(--mono,'Montserrat',sans-serif);font-size:.62rem;font-weight:700;
}
.bt-da-noi{min-width:0;}
.bt-da-dung{border-color:#2e6b3e;background:#eef6ee;}
.bt-da-dung .bt-da-chu{background:#2e6b3e;color:#fff;}
.bt-da-sai{border-color:var(--accent,#7a1f1f);background:#fbf0f0;}
.bt-da-sai .bt-da-chu{background:var(--accent,#7a1f1f);color:#fff;}

.bt-giai{margin:16px 0 0;padding:15px 17px;border-radius:3px;border-left:3px solid var(--gold,#c9963b);background:var(--panel,#f0e8d5);}
.bt-giai-dung{border-left-color:#2e6b3e;background:#eef6ee;}
.bt-giai-sai{border-left-color:var(--accent,#7a1f1f);background:#fbf0f0;}
.bt-giai-nhan{
  display:block;font-family:var(--mono,'Montserrat',sans-serif);font-size:.58rem;
  font-weight:700;letter-spacing:.18em;text-transform:uppercase;margin-bottom:7px;
}
.bt-giai-dung .bt-giai-nhan{color:#2e6b3e;}
.bt-giai-sai .bt-giai-nhan{color:var(--accent,#7a1f1f);}
.bt-giai p{margin:0 0 8px;font-size:.95rem;line-height:1.62;}
.bt-nguon{
  font-family:var(--mono,'Montserrat',sans-serif);font-size:.62rem;
  letter-spacing:.05em;color:var(--ink-soft,rgba(26,18,8,.62));
}
.bt-tiep{
  margin-top:6px;padding:9px 20px;border:none;border-radius:3px;cursor:pointer;
  background:var(--ink,#1a1208);color:#f5efe3;
  font-family:var(--mono,'Montserrat',sans-serif);font-size:.6rem;font-weight:700;
  letter-spacing:.16em;text-transform:uppercase;
}
.bt-tiep:hover{background:var(--gold-dark,#8b6914);}

/* ── kết quả ── */
.bt-ketqua{text-align:center;}
.bt-kq-nhan{
  display:block;font-family:var(--mono,'Montserrat',sans-serif);font-size:.58rem;
  font-weight:700;letter-spacing:.22em;text-transform:uppercase;
  color:var(--gold-dark,#8b6914);margin-bottom:6px;
}
.bt-kq-so{
  display:block;font-family:var(--display,'Playfair Display',Georgia,serif);
  font-size:3.4rem;line-height:1;color:var(--ink,#1a1208);
}
.bt-kq-so em{font-size:1.5rem;font-style:normal;color:var(--ink-soft,rgba(26,18,8,.62));}
.bt-kq-hang{
  display:inline-block;margin:10px 0 4px;padding:5px 16px;border-radius:20px;
  font-family:var(--mono,'Montserrat',sans-serif);font-size:.6rem;font-weight:700;
  letter-spacing:.16em;text-transform:uppercase;
}
.bt-hang-xs .bt-kq-hang{background:#2e6b3e;color:#fff;}
.bt-hang-g  .bt-kq-hang{background:#4a8a3f;color:#fff;}
.bt-hang-k  .bt-kq-hang{background:var(--gold,#c9963b);color:#1a1208;}
.bt-hang-tb .bt-kq-hang{background:#b8860b;color:#fff;}
.bt-hang-cl .bt-kq-hang{background:var(--accent,#7a1f1f);color:#fff;}
.bt-kq-tron{margin:16px 0 0;font-style:italic;color:#2e6b3e;}

.bt-xemlai{margin:24px 0 0;text-align:left;}
.bt-xemlai-nhan{
  display:block;font-family:var(--mono,'Montserrat',sans-serif);font-size:.56rem;
  font-weight:700;letter-spacing:.18em;text-transform:uppercase;
  color:var(--accent,#7a1f1f);margin-bottom:10px;
}
.bt-xemlai ul{list-style:none;margin:0;padding:0;}
.bt-xemlai li{
  padding:12px 14px;margin:0 0 9px;border-radius:3px;
  background:#fff;border-left:3px solid var(--accent,#7a1f1f);
}
.bt-xemlai li b{display:block;font-weight:600;font-size:.95rem;line-height:1.5;margin-bottom:5px;}
.bt-xemlai li span{display:block;font-size:.86rem;line-height:1.5;color:var(--ink-soft,rgba(26,18,8,.62));}

.bt-kq-nut{display:flex;gap:10px;justify-content:center;flex-wrap:wrap;margin:24px 0 0;}
.bt-lai{
  padding:11px 24px;border:none;border-radius:3px;cursor:pointer;text-decoration:none;
  background:var(--gold-dark,#8b6914);color:#fff;
  font-family:var(--mono,'Montserrat',sans-serif);font-size:.6rem;font-weight:700;
  letter-spacing:.16em;text-transform:uppercase;
}
.bt-lai:hover{background:var(--ink,#1a1208);color:#fff;}
.bt-lai-phu{background:transparent;color:var(--gold-dark,#8b6914);border:1px solid var(--gold,#c9963b);}
.bt-lai-phu:hover{background:var(--gold,#c9963b);color:#1a1208;}

/* ═════════ CÂU HỎI THẢO LUẬN ═════════ */
ol.bt-thao{counter-reset:bt;list-style:none;margin:0 0 34px;padding:0;}
ol.bt-thao li{
  counter-increment:bt;position:relative;
  padding:16px 18px 14px 54px;margin:0 0 12px;
  border:1px solid var(--rule,rgba(60,40,10,.18));border-radius:3px;
  background:var(--paper,#faf7f2);
}
ol.bt-thao li::before{
  content:counter(bt);position:absolute;left:16px;top:16px;
  width:26px;height:26px;border-radius:50%;
  display:flex;align-items:center;justify-content:center;
  background:var(--gold,#c9963b);color:#1a1208;
  font-family:var(--mono,'Montserrat',sans-serif);font-size:.64rem;font-weight:700;
}
.bt-thao-hoi{margin:0 0 8px;font-size:1rem;line-height:1.55;font-weight:500;}
.bt-thao-y summary{
  cursor:pointer;font-family:var(--mono,'Montserrat',sans-serif);
  font-size:.56rem;font-weight:700;letter-spacing:.16em;text-transform:uppercase;
  color:var(--gold-dark,#8b6914);
}
.bt-thao-y p{margin:8px 0 0;font-size:.92rem;line-height:1.6;color:var(--ink-soft,rgba(26,18,8,.62));}

/* ═════════ NÚT ĐÁNH DẤU ĐÃ ĐỌC ═════════ */
.bt-danhdau{
  width:auto;padding:11px 22px;border-radius:3px;cursor:pointer;
  border:1px solid var(--gold,#c9963b);background:transparent;color:var(--gold-dark,#8b6914);
  font-family:var(--mono,'Montserrat',sans-serif);font-size:.6rem;font-weight:700;
  letter-spacing:.16em;text-transform:uppercase;
}
.bt-danhdau:hover{background:var(--gold,#c9963b);color:#1a1208;}
.bt-danhdau.bt-da-danhdau{border-color:#2e6b3e;color:#2e6b3e;background:#eef6ee;}

/* ═════════ VIDEO YOUTUBE ═════════ */
.bt-video{
  display:grid;gap:20px;margin:0 0 34px;
  grid-template-columns:repeat(auto-fit,minmax(min(300px,100%),1fr));
}
.bt-vid{min-width:0;}
.bt-vid-khung{
  position:relative;width:100%;padding-top:56.25%;
  background:#1a1208;border-radius:3px;overflow:hidden;
}
.bt-vid-khung iframe{position:absolute;inset:0;width:100%;height:100%;border:0;}
.bt-vid-ten{
  display:block;margin:10px 0 2px;font-family:var(--display,'Playfair Display',Georgia,serif);
  font-size:1.02rem;line-height:1.35;color:var(--ink,#1a1208);
}
.bt-vid-kenh{
  display:block;font-family:var(--mono,'Montserrat',sans-serif);font-size:.56rem;
  letter-spacing:.14em;text-transform:uppercase;color:var(--ink-soft,rgba(26,18,8,.62));
}
.bt-vid-co{
  display:inline-block;margin-bottom:6px;padding:2px 9px;border-radius:2px;
  background:var(--panel,#f0e8d5);color:var(--gold-dark,#8b6914);
  font-family:var(--mono,'Montserrat',sans-serif);font-size:.52rem;font-weight:700;
  letter-spacing:.16em;text-transform:uppercase;
}

/* ═════════ NGUYÊN VĂN TÀI LIỆU + TAB VI/EN ═════════ */
.bt-tab{display:flex;gap:6px;margin:0 0 0;flex-wrap:wrap;}
.bt-tab button{
  width:auto;padding:9px 20px;border:1px solid var(--rule,rgba(60,40,10,.18));
  border-bottom:none;border-radius:3px 3px 0 0;cursor:pointer;
  background:var(--panel,#f0e8d5);color:var(--ink-soft,rgba(26,18,8,.62));
  font-family:var(--mono,'Montserrat',sans-serif);font-size:.58rem;font-weight:700;
  letter-spacing:.16em;text-transform:uppercase;
}
.bt-tab button.bt-tab-on{background:var(--paper,#faf7f2);color:var(--gold-dark,#8b6914);border-bottom:1px solid var(--paper,#faf7f2);}
.bt-goc{
  border:1px solid var(--rule,rgba(60,40,10,.18));border-radius:0 3px 3px 3px;
  padding:26px 28px;margin:0 0 34px;background:var(--paper,#faf7f2);min-width:0;
}
.bt-goc h3{
  font-family:var(--display,'Playfair Display',Georgia,serif);
  font-size:1.3rem;margin:26px 0 10px;color:var(--ink,#1a1208);
}
.bt-goc h3:first-child{margin-top:0;}
.bt-goc h4{
  font-family:var(--mono,'Montserrat',sans-serif);font-size:.62rem;font-weight:700;
  letter-spacing:.18em;text-transform:uppercase;color:var(--gold-dark,#8b6914);
  margin:22px 0 8px;
}
.bt-goc p{margin:0 0 13px;font-size:1rem;line-height:1.75;}
.bt-goc ul,.bt-goc ol{margin:0 0 14px;padding-left:22px;}
.bt-goc li{margin:0 0 7px;line-height:1.68;}
.bt-goc blockquote{
  margin:0 0 15px;padding:2px 0 2px 18px;border-left:3px solid var(--gold,#c9963b);
  font-family:var(--serif,'EB Garamond',Georgia,serif);font-style:italic;font-size:1.06rem;line-height:1.65;
}
.bt-goc .bt-tacgia{
  font-family:var(--mono,'Montserrat',sans-serif);font-size:.58rem;font-weight:700;
  letter-spacing:.16em;text-transform:uppercase;color:var(--ink-soft,rgba(26,18,8,.62));
  margin:0 0 20px;
}
.bt-an{display:none;}

/* ═════════ ĐIỀU HƯỚNG BÀI TRƯỚC / SAU ═════════ */
.bt-dieuhuong{
  display:grid;gap:12px;margin:34px 0 0;
  grid-template-columns:repeat(auto-fit,minmax(min(220px,100%),1fr));
}
.bt-dh{
  display:flex;flex-direction:column;gap:4px;min-width:0;
  padding:15px 18px;border:1px solid var(--rule,rgba(60,40,10,.18));border-radius:3px;
  background:var(--paper,#faf7f2);text-decoration:none;color:inherit;
}
.bt-dh:hover{border-color:var(--gold,#c9963b);background:#fffdf7;}
.bt-dh span{
  font-family:var(--mono,'Montserrat',sans-serif);font-size:.54rem;font-weight:700;
  letter-spacing:.16em;text-transform:uppercase;color:var(--gold-dark,#8b6914);
}
.bt-dh b{font-family:var(--display,'Playfair Display',Georgia,serif);font-size:1.04rem;font-weight:400;line-height:1.3;}
.bt-dh-sau{text-align:right;}

/* ═════════ ĐIỆN THOẠI ═════════ */
@media screen and (max-width:736px){
  .bt-goc{padding:20px 17px;}
  .bt-quiz{padding:17px;}
  .bt-quiz-hoi{font-size:1.13rem;}
  .bt-kq-so{font-size:2.7rem;}
  .bt-da{font-size:.94rem;padding:12px 13px;}
  .bt-dh-sau{text-align:left;}
  ol.bt-thao li{padding:14px 15px 12px 48px;}
}