/* =========================================================
   MÔ HÌNH KINH DOANH – Giao diện đọc sách
   Tông chủ đạo (4e): GIẤY CŨ + XANH RỪNG + VÀNG ĐỒNG (theo style_reference.css)
   Giữ NGUYÊN tên biến cũ (--brand/--accent/--ink/--paper...) để toàn bộ
   module rd-* + landing + theme tự khớp; chỉ đổi GIÁ TRỊ sang palette mới.
   ========================================================= */

:root{
  /* nền & chữ */
  --ink:#2a1b10;
  --ink-soft:#725f49;
  --paper:#fffaf0;          /* mặt giấy (khung đọc, card)   */
  --paper-soft:#fbf1dd;
  --bg-1:#f3e3c3;           /* giấy cũ ấm (nền trang)        */
  --bg-2:#f6ecd5;           /* mặt phẳng nhạt cho card rd-*  */

  /* màu thương hiệu = XANH RỪNG (chủ đạo chrome/nút/heading) */
  --brand:#1e3a2f;          /* xanh rừng đậm */
  --brand-2:#15291f;        /* xanh rừng sẫm hơn (hover)     */
  --brand-soft:#e7ddc2;     /* nền nhạt ấm cho vùng nhấn     */

  /* màu nhấn = VÀNG ĐỒNG */
  --accent:#d5962a;         /* vàng đồng */
  --accent-2:#a85d24;       /* đồng nâu */
  --accent-soft:#f7e7c6;    /* vàng đồng rất nhạt */

  /* 4 cấp tiêu đề trong nội dung */
  --h1:#1e3a2f;             /* xanh rừng  – Chương            */
  --h2:#a85d24;             /* đồng nâu   – Mục chính          */
  --h3:#2f5d4d;             /* xanh ngọc  – Tiểu mục           */
  --h4:#8a4e1f;             /* nâu đồng   – Ý nhỏ              */

  --link:#1d4ed8;           /* xanh dương cho chú thích */
  --border:#dfc79f;
  --border-2:#ecd9b9;
  --highlight:#fff0a8;
  --shadow:0 22px 55px rgba(58,35,13,.14);
  --shadow-sm:0 12px 28px rgba(58,35,13,.10);

  --font-sans:Arial,"Segoe UI",system-ui,-apple-system,sans-serif;
  --font-serif:Georgia,"Times New Roman",serif;
}

*{box-sizing:border-box}
html{scroll-behavior:smooth}

body{
  margin:0;
  min-height:100vh;
  color:var(--ink);
  font-family:var(--font-serif);
  background:
    radial-gradient(circle at 12% 8%, rgba(213,150,42,.22), transparent 28%),
    radial-gradient(circle at 86% 12%, rgba(30,58,47,.16), transparent 30%),
    linear-gradient(135deg, var(--bg-1), #ead2a4);
}
/* lớp lưới giấy mờ trang trí */
body::before{
  content:"";position:fixed;inset:0;pointer-events:none;z-index:0;opacity:.26;
  background-image:
    linear-gradient(rgba(92,61,28,.08) 1px, transparent 1px),
    linear-gradient(90deg, rgba(92,61,28,.06) 1px, transparent 1px);
  background-size:42px 42px;
  -webkit-mask-image:linear-gradient(to bottom, rgba(0,0,0,.9), rgba(0,0,0,.12));
  mask-image:linear-gradient(to bottom, rgba(0,0,0,.9), rgba(0,0,0,.12));
}
a{color:inherit}
::selection{background:rgba(213,150,42,.34);color:var(--ink)}

.page-shell{position:relative;z-index:1;max-width:1220px;margin:0 auto;padding:24px 18px 40px}

.reader-layout{
  display:grid;
  grid-template-columns:312px minmax(0,1fr);
  gap:16px;
  align-items:start;
}

/* ---------- Sidebar / mục lục (xanh rừng đậm) ---------- */
.sidebar{
  position:sticky;top:18px;max-height:calc(100vh - 36px);overflow:auto;
  padding:6px 0 4px;
  border:1px solid rgba(255,240,200,.15);
  border-radius:24px;
  color:#fff8e7;
  background:
    linear-gradient(180deg, rgba(30,58,47,.97), rgba(45,27,12,.96)),
    radial-gradient(circle at 20% 0%, rgba(213,150,42,.30), transparent 42%);
  box-shadow:var(--shadow);
  font-family:var(--font-sans);
}
.sidebar::-webkit-scrollbar{width:8px}
.sidebar::-webkit-scrollbar-thumb{background:rgba(213,150,42,.55);border-radius:999px}
.sidebar h2{
  margin:0;padding:18px 18px 12px;font-size:17px;letter-spacing:.08em;text-transform:uppercase;
  display:flex;align-items:center;gap:9px;
}
.sidebar h2::before{
  content:"☰";display:grid;place-items:center;width:30px;height:30px;flex:0 0 auto;
  color:#2a1b10;background:var(--accent);border-radius:10px;font-size:15px;
}
.sidebar nav{padding:0 12px 16px;display:flex;flex-direction:column;gap:6px}

/* link đơn (trang lẻ) */
.sidebar nav > a{
  display:block;padding:9px 12px;border-radius:12px;
  color:rgba(255,248,231,.80);text-decoration:none;line-height:1.35;font-size:14px;
  border:1px solid rgba(255,248,231,.07);background:rgba(255,248,231,.04);
  transition:background .15s,color .15s,transform .15s;
}
.sidebar nav > a:hover{background:rgba(255,248,231,.13);color:#fff8e7;transform:translateX(3px)}
.sidebar nav > a.active{color:#2a1b10;background:linear-gradient(135deg,#ffe4a3,var(--accent));font-weight:700;border-color:transparent}

/* chương: xổ ra */
.sidebar details{margin:0}
.sidebar summary{
  list-style:none;cursor:pointer;
  display:flex;justify-content:space-between;align-items:flex-start;gap:8px;
  padding:9px 12px;border-radius:12px;
  color:rgba(255,248,231,.86);font-size:14px;line-height:1.35;
  border:1px solid rgba(255,248,231,.07);background:rgba(255,248,231,.04);
  transition:background .15s;
}
.sidebar summary::-webkit-details-marker{display:none}
.sidebar summary::after{content:"▸";opacity:.85;transition:transform .15s;flex:0 0 auto;margin-top:1px}
.sidebar details[open] > summary::after{transform:rotate(90deg)}
.sidebar summary:hover{background:rgba(255,248,231,.13)}
.sidebar details.active-chap > summary{color:#2a1b10;background:linear-gradient(135deg,#ffe4a3,var(--accent));font-weight:700;border-color:transparent}

/* heading con trong sidebar */
.nav-subs{display:flex;flex-direction:column;padding:4px 0 6px;gap:2px}
.nav-subs a{
  display:block;color:rgba(255,248,231,.72);text-decoration:none;
  font-size:13px;line-height:1.35;padding:6px 10px;border-radius:9px;
  border-left:2px solid rgba(255,248,231,.12);margin-left:8px;
  transition:background .15s,color .15s;
}
.nav-subs a:hover{background:rgba(255,248,231,.12);color:#fff8e7}
.nav-subs a.active{background:rgba(213,150,42,.30);color:#fff8e7;font-weight:700;border-left-color:var(--accent)}
.nav-subs a.s2{padding-left:14px}
.nav-subs a.s3{padding-left:30px}
.nav-subs a.s4{padding-left:46px}
.nav-subs a.chap-top{color:#ffe9bc;font-style:italic;opacity:.92}

/* ---------- Vùng nội dung ---------- */
.content{display:grid;gap:14px;min-width:0}
.article{
  position:relative;overflow:hidden;
  padding:clamp(26px,4vw,56px);
  border:1px solid rgba(223,199,159,.9);
  border-radius:28px;
  background:
    radial-gradient(circle at 8% 0%, rgba(213,150,42,.12), transparent 34%),
    linear-gradient(180deg, var(--paper), var(--paper-soft));
  box-shadow:var(--shadow);
}
.article::before{
  content:"";position:absolute;inset:18px;pointer-events:none;
  border:1px solid rgba(174,117,43,.14);border-radius:20px;
}
.article > *{position:relative;z-index:1}

/* ---------- 4 cấp tiêu đề ---------- */
/* H1 – Chương */
.article h1{
  margin:0 0 28px;padding-bottom:22px;
  color:var(--h1);font-family:var(--font-sans);
  font-size:clamp(30px,4.4vw,52px);line-height:1.16;
  letter-spacing:-.03em;text-transform:uppercase;font-weight:800;
  border-bottom:2px solid rgba(213,150,42,.30);
}
/* H2 – Mục chính: thanh trái vàng đồng + nền nhạt */
.article h2{
  margin:40px 0 16px;padding:15px 18px;
  border-left:7px solid var(--accent);border-radius:0 18px 18px 0;
  background:linear-gradient(90deg, rgba(213,150,42,.16), transparent);
  color:var(--ink);font-family:var(--font-sans);
  font-size:clamp(24px,3vw,33px);font-weight:800;line-height:1.28;letter-spacing:-.02em;
}
/* H3 – Tiểu mục: thanh trái xanh ngọc */
.article h3{
  margin:32px 0 13px;padding-left:16px;
  border-left:4px solid var(--h3);color:var(--h3);
  font-family:var(--font-sans);font-size:clamp(20px,2vw,25px);font-weight:700;line-height:1.34;
}
/* H4 – Ý nhỏ */
.article h4{
  margin:24px 0 10px;color:var(--h4);
  font-family:var(--font-sans);font-size:19px;font-weight:700;line-height:1.35;
}

/* ---------- Đoạn văn ---------- */
.article p{margin:0 0 18px;font-size:19px;line-height:1.7;text-align:justify;text-wrap:pretty}
.article p:has(> img){text-align:center}
.article p.caption,.article .fig-caption,.article .tbl-caption{
  text-align:center;font-style:italic;color:var(--ink-soft);margin:6px 0 18px;
}
.article em strong,.article strong em{color:var(--accent-2)}
.article strong{color:var(--brand)}
.article a:not(.footnote-ref){color:var(--accent-2);font-weight:700;border-bottom:1px dashed rgba(168,93,36,.45)}

/* ---------- Trích dẫn ---------- */
.article blockquote{
  margin:24px 0;padding:18px 22px;border-left:7px solid var(--accent);
  background:rgba(213,150,42,.12);color:var(--brand);border-radius:18px;
}
.article blockquote p{margin:0}

/* ---------- Danh sách ---------- */
.article ol,.article ul{margin:12px 0 20px;padding-left:26px;font-size:19px;line-height:1.7}
.article li{margin:8px 0}
.article li::marker{color:var(--accent-2);font-weight:900}

/* ---------- Ảnh ---------- */
.article img{
  display:block;max-width:min(100%,720px);height:auto!important;margin:18px auto 26px;
  padding:14px;border:1px solid rgba(223,199,159,.85);border-radius:20px;background:var(--paper);
  box-shadow:var(--shadow-sm);object-fit:contain;
}

/* ---------- Bảng ---------- */
.article table{
  width:100%;border-collapse:separate;border-spacing:0;margin:24px auto;
  font-family:var(--font-sans);font-size:15px;line-height:1.5;
  border-radius:18px;overflow:hidden;box-shadow:var(--shadow-sm);border:1px solid var(--border);background:var(--paper);
}
.article th,.article td{padding:13px 16px;vertical-align:top;border-bottom:1px solid rgba(223,199,159,.75)}
.article tr:last-child td{border-bottom:none}
.article thead th,.article tr:first-child th{
  color:#fff8e7;text-align:left;font-weight:700;letter-spacing:.3px;
  background:linear-gradient(135deg,var(--brand) 0%,var(--brand-2) 100%);border-bottom:none;
}
.article tbody tr:nth-child(even) td,.article tr:nth-child(even) td{background:rgba(213,150,42,.07)}
.article tbody tr:hover td,.article tr:hover td{background:var(--accent-soft);transition:background .15s}

/* ---------- Chú thích cuối chương ---------- */
.article .footnotes{margin-top:40px;padding-top:18px;border-top:2px dashed rgba(213,150,42,.4);font-size:15px}
.article .footnotes h2{border:none;background:none;padding:0;color:var(--brand);font-size:20px;margin:0 0 10px}
.article .footnotes p,.article .footnotes li{font-size:15px;text-align:left}
.article a.footnote-ref,.article sup a,.article .footnote-back{color:var(--link);text-decoration:none;font-weight:700}
.article a.footnote-ref:hover,.article .footnote-back:hover{text-decoration:underline}
.article .footnotes li:target,.article li.fn-target{background:var(--highlight);border-radius:6px;box-shadow:0 0 0 6px var(--highlight)}

/* ---------- Thanh điều hướng dưới ---------- */
.bottom-nav{display:flex;flex-wrap:wrap;gap:12px;justify-content:center;margin-top:6px;font-family:var(--font-sans)}
.nav-link{
  display:inline-flex;align-items:center;justify-content:center;min-height:44px;padding:0 20px;
  border-radius:999px;border:1px solid var(--border);background:rgba(255,250,240,.9);color:var(--brand);
  text-decoration:none;font-weight:800;font-size:14px;box-shadow:var(--shadow-sm);transition:transform .12s;
}
.nav-link:hover{transform:translateY(-2px)}
.nav-link.primary{color:#fff8e7;background:linear-gradient(135deg,var(--brand),var(--accent-2));border-color:transparent}

/* ---------- Trang Mục lục (đen, thụt theo cấp, KHÔNG đánh số) ---------- */
.toc{font-family:var(--font-sans)}
.toc a{display:block;color:#2a1b10;text-decoration:none;padding:4px 8px;line-height:1.45;border-radius:10px}
.toc a:hover{color:var(--brand);background:rgba(213,150,42,.13)}
.toc .toc-front{font-weight:700;font-size:17px;margin-top:6px}
.toc .toc-chap{font-weight:800;font-size:18px;margin-top:18px;color:var(--brand)}
.toc .toc-l2{padding-left:24px;font-weight:600}
.toc .toc-l3{padding-left:48px;font-weight:400}
.toc .toc-l4{padding-left:72px;font-size:15px;color:var(--ink-soft)}

/* ---------- Trang bìa ---------- */
.cover-wrap{display:flex;flex-wrap:wrap;gap:28px;justify-content:center;align-items:flex-start}
.cover-item{text-align:center;max-width:380px}
.cover-item img{width:100%;max-width:375px;height:auto;border-radius:14px;box-shadow:var(--shadow);border:1px solid var(--border)}
.cover-item figcaption{margin-top:10px;font-family:var(--font-sans);font-weight:700;color:var(--brand)}

/* ---------- Trang trách nhiệm ---------- */
.imprint{font-family:var(--font-serif)}
.imprint p{text-align:center;font-size:16px;line-height:1.5;margin:6px 0}
.imprint .imprint-logo img{max-width:230px;box-shadow:none;border:none;background:none;padding:0}

/* ---------- Responsive ---------- */
@media(max-width:980px){
  .page-shell{padding:16px 12px 28px}
  .reader-layout{grid-template-columns:1fr}
  .sidebar{position:static;max-height:none}
  .article{padding:24px 18px;border-radius:22px}
  .article::before{inset:10px;border-radius:16px}
  .article p,.article ol,.article ul{font-size:18px}
  .toc .toc-l2{padding-left:18px}
  .toc .toc-l3{padding-left:36px}
  .toc .toc-l4{padding-left:54px}
}