/*
  Thanh Di Studio — Design System dùng chung cho toàn bộ trang con.
  Bảng màu / font đồng bộ với index.html & support.html (không đổi 2 trang đó).
*/

:root{
  --bg-1:#0b0f1f;
  --bg-2:#161b33;
  --accent:#ffb648;
  --accent-2:#ff7a3d;
  --zalo:#0068ff;
  --tg:#29a8e0;
  --online:#22d3a5;
  --offline:#f87171;
  --card:#11162b;
  --card-border:rgba(255,255,255,0.08);
  --text:#f3f4f8;
  --text-dim:#9aa3c0;
  --radius:18px;
}

*{box-sizing:border-box;margin:0;padding:0;}
html{scroll-behavior:smooth;}
body{
  font-family:'Be Vietnam Pro',system-ui,sans-serif;
  background:var(--bg-1);
  color:var(--text);
  min-height:100vh;
  overflow-x:hidden;
}
a{color:inherit;}
img{max-width:100%;}

.bg-glow{
  position:fixed;inset:0;z-index:-2;
  background:
    radial-gradient(circle at 15% 10%, rgba(255,122,61,0.2), transparent 40%),
    radial-gradient(circle at 85% 20%, rgba(0,104,255,0.18), transparent 40%),
    radial-gradient(circle at 50% 85%, rgba(255,182,72,0.12), transparent 50%),
    linear-gradient(160deg,var(--bg-1),var(--bg-2));
}

/* ══════════════ SITE NAV (thanh điều hướng chung mọi trang) ══════════════ */
.site-nav-wrap{
  position:sticky;top:0;z-index:100;
  padding-top:max(0px, env(safe-area-inset-top));
  backdrop-filter:blur(22px) saturate(160%);
  -webkit-backdrop-filter:blur(22px) saturate(160%);
  background:rgba(11,15,31,0.94);
  border-bottom:1px solid var(--card-border);
}
/* dùng trên trang có sẵn thanh sticky riêng (vd. index.html) để tránh chồng lấn */
.site-nav-wrap.no-sticky{
  position:relative;
  z-index:100;
}
.site-nav{
  position:relative;
  max-width:1080px;margin:0 auto;
  display:flex;align-items:center;justify-content:space-between;gap:14px;
  padding:10px 16px;
}
.site-nav .brand{
  display:flex;align-items:center;gap:8px;
  text-decoration:none;flex:none;
  font-weight:800;font-size:14px;color:var(--text);
}
.site-nav .brand img{
  width:26px;height:26px;border-radius:50%;
  border:2px solid var(--accent);object-fit:cover;flex:none;
}
.site-nav .brand .studio{color:var(--accent);}

/* ── Nút hamburger 3 gạch ── */
.nav-toggle{
  flex:none;
  width:38px;height:38px;
  display:flex;align-items:center;justify-content:center;
  background:rgba(255,255,255,0.05);
  border:1px solid var(--card-border);
  border-radius:10px;
  cursor:pointer;
  -webkit-tap-highlight-color:transparent;
  transition:background .2s, border-color .2s;
}
.nav-toggle:hover{ background:rgba(255,255,255,0.09); }
.nav-toggle svg{ width:19px;height:19px;color:var(--text);pointer-events:none; }
.nav-toggle .icon-close{ display:none; }
.nav-toggle.open .icon-bars{ display:none; }
.nav-toggle.open .icon-close{ display:block; }
.nav-toggle.open{ border-color:rgba(255,182,72,0.4);background:rgba(255,182,72,0.1); }

/* ── Menu xổ xuống ── */
.site-nav-links{
  position:absolute;
  top:calc(100% + 8px);right:16px;left:16px;
  max-width:340px;margin-left:auto;
  display:flex;flex-direction:column;gap:2px;
  background:rgba(11,15,31,0.98);
  border:1px solid var(--card-border);
  border-radius:16px;
  padding:10px;
  box-shadow:0 24px 48px -14px rgba(0,0,0,0.65);
  max-height:0;overflow:hidden;
  opacity:0;pointer-events:none;
  transform:translateY(-6px);
  transition:max-height .3s ease, opacity .2s ease, transform .25s ease;
  z-index:200;
}
.site-nav-links.open{
  max-height:80vh;opacity:1;pointer-events:auto;transform:translateY(0);
  overflow-y:auto;
}
.site-nav-links a{
  text-decoration:none;color:var(--text-dim);
  font-size:14.5px;font-weight:700;
  padding:12px 14px;border-radius:10px;
  transition:color .2s, background .2s;
}
.site-nav-links a:hover{ color:var(--text);background:rgba(255,255,255,0.05); }
.site-nav-links a.active{ color:var(--accent);background:rgba(255,182,72,0.14); }

@media (max-width:480px){
  .site-nav{ gap:10px;padding:9px 14px; }
  .site-nav .brand{ font-size:12.5px;gap:6px; }
  .site-nav .brand img{ width:22px;height:22px; }
  .site-nav-links{ left:14px;right:14px;max-width:none; }
}
.site-nav-cta{
  flex:none;
  display:inline-flex;align-items:center;gap:6px;
  background:linear-gradient(120deg,var(--accent),var(--accent-2));
  color:#1a1206;font-weight:800;font-size:13px;
  padding:9px 16px;border-radius:11px;text-decoration:none;
  box-shadow:0 8px 18px -8px rgba(255,122,61,0.6);
  white-space:nowrap;
}

/* ══════════════ LAYOUT ══════════════ */
.page{ max-width:760px;margin:0 auto;padding:0 18px 60px; }
.page-wide{ max-width:1080px;margin:0 auto;padding:0 18px 60px; }

/* ══════════════ BREADCRUMB ══════════════ */
.breadcrumb{
  display:flex;flex-wrap:wrap;align-items:center;gap:6px;
  padding:16px 0 0;font-size:12.5px;color:var(--text-dim);font-weight:600;
}
.breadcrumb a{ color:var(--text-dim);text-decoration:none; }
.breadcrumb a:hover{ color:var(--accent); }
.breadcrumb .sep{ opacity:.4; }
.breadcrumb .current{ color:var(--text); }

/* ══════════════ PAGE HEADER (giống support.html) ══════════════ */
.page-header{
  padding:26px 0 28px;
  border-bottom:1px solid var(--card-border);
  margin-bottom:28px;
}
.page-header .eyebrow{
  font-size:11px;font-weight:800;letter-spacing:2.5px;text-transform:uppercase;
  color:var(--accent);opacity:.75;margin-bottom:10px;
}
.page-header h1{
  font-size:clamp(26px,7vw,40px);font-weight:900;line-height:1.15;letter-spacing:-.5px;
  background:linear-gradient(95deg,#93c5fd,#3b82f6);
  -webkit-background-clip:text;background-clip:text;color:transparent;
  margin-bottom:12px;
}
.page-header h1 .accent{ color:var(--accent);background:none;-webkit-background-clip:unset;background-clip:unset; }
.page-header p{ color:var(--text-dim);font-size:14.5px;font-weight:500;line-height:1.65;max-width:600px; }
.page-header .meta-row{
  display:flex;flex-wrap:wrap;gap:10px;margin-top:16px;font-size:12.5px;color:var(--text-dim);
}
.page-header .meta-row span{ display:flex;align-items:center;gap:5px; }

/* ══════════════ SECTION TITLE ══════════════ */
.section-title{ display:flex;align-items:center;gap:12px;margin:34px 0 18px; }
.section-title span:first-child{ font-size:16px;font-weight:800;white-space:nowrap; }
.section-title .line{ flex:1;height:1px;background:var(--card-border); }

/* ══════════════ CARDS ══════════════ */
.card{
  background:linear-gradient(160deg,var(--card),rgba(17,22,43,0.6));
  border:1px solid var(--card-border);
  border-radius:20px;padding:22px;margin-bottom:18px;
  transition:border-color .3s, box-shadow .3s;
}
.card:hover{ border-color:rgba(255,255,255,0.16); }
.card h3{ font-size:17px;font-weight:800;margin-bottom:8px; }
.card p{ color:var(--text-dim);font-size:14px;line-height:1.65; }

.grid-2{ display:grid;grid-template-columns:1fr;gap:14px; }
@media(min-width:600px){ .grid-2{ grid-template-columns:1fr 1fr; } }
.grid-3{ display:grid;grid-template-columns:1fr;gap:14px; }
@media(min-width:640px){ .grid-3{ grid-template-columns:1fr 1fr; } }
@media(min-width:900px){ .grid-3{ grid-template-columns:1fr 1fr 1fr; } }

/* Link-card dùng cho hub/index (huong-dan, su-kien...) */
.link-card{
  display:block;text-decoration:none;color:var(--text);
  background:var(--card);border:1px solid var(--card-border);
  border-radius:16px;padding:18px 20px;
  transition:border-color .25s, transform .2s, background .25s;
}
.link-card:hover{ border-color:rgba(255,182,72,0.4);background:rgba(255,182,72,0.05);transform:translateY(-2px); }
.link-card .lc-tag{
  display:inline-block;font-size:11px;font-weight:800;color:var(--accent);
  background:rgba(255,182,72,0.12);padding:3px 10px;border-radius:99px;margin-bottom:10px;
}
.link-card h3{ font-size:15.5px;font-weight:800;margin-bottom:6px;line-height:1.4; }
.link-card p{ font-size:13px;color:var(--text-dim);line-height:1.6; }

/* Server badge colors */
.tag-td{ color:var(--accent);background:rgba(255,182,72,0.12); }
.tag-ncd{ color:#67b3ff;background:rgba(0,104,255,0.14); }
.tag-cindy{ color:#c084fc;background:rgba(124,58,237,0.14); }

/* ══════════════ BUTTONS ══════════════ */
.btn-row{ display:flex;gap:10px;margin-top:18px;flex-wrap:wrap; }
.btn{
  flex:1;min-width:130px;text-align:center;padding:13px 16px;border-radius:13px;
  font-weight:700;font-size:14.5px;text-decoration:none;color:#fff;border:1px solid transparent;
  transition:transform .2s, filter .2s;display:inline-flex;align-items:center;justify-content:center;gap:7px;
}
.btn:active{ transform:scale(.96); }
.btn svg{ width:16px;height:16px;flex:none; }
.btn-primary{
  background:linear-gradient(120deg,var(--accent),var(--accent-2));
  box-shadow:0 10px 22px -8px rgba(255,122,61,0.55);
}
.btn-primary:hover{ filter:brightness(1.08); }
.btn-outline{
  background:rgba(255,255,255,0.04);border-color:var(--card-border);color:var(--text);
}
.btn-outline:hover{ background:rgba(255,255,255,0.08); }
.btn-zalo{
  background:rgba(0,104,255,0.12);border-color:rgba(0,104,255,0.45);color:#67b3ff;
}
.btn-zalo:hover{ background:rgba(0,104,255,0.2); }

/* ══════════════ ARTICLE / PROSE (bài hướng dẫn, sự kiện) ══════════════ */
.article{
  background:var(--card);border:1px solid var(--card-border);
  border-radius:var(--radius);padding:26px 22px;margin-bottom:8px;
}
.article h2{ font-size:20px;font-weight:800;margin:28px 0 12px; }
.article h2:first-child{ margin-top:0; }
.article h3{ font-size:16.5px;font-weight:800;margin:22px 0 10px;color:var(--accent); }
.article p{ font-size:14.5px;line-height:1.8;color:var(--text-dim);margin-bottom:14px; }
.article ul, .article ol{ margin:0 0 16px 20px;color:var(--text-dim);font-size:14.5px;line-height:1.85; }
.article li{ margin-bottom:6px; }
.article strong{ color:var(--text);font-weight:700; }
.article a{ color:var(--accent);text-decoration:underline;text-underline-offset:2px; }
.article table{ width:100%;border-collapse:collapse;margin:8px 0 18px;font-size:13.5px; }
.article th,.article td{ text-align:left;padding:9px 12px;border-bottom:1px solid var(--card-border); }
.article th{ color:var(--text);font-weight:800;background:rgba(255,255,255,0.03); }
.article td{ color:var(--text-dim); }

.tip-box{
  display:flex;gap:12px;background:rgba(255,182,72,0.06);
  border-left:3px solid var(--accent);border-radius:0 12px 12px 0;
  padding:14px 16px;margin:18px 0;font-size:13.5px;color:var(--text-dim);line-height:1.7;
}
.tip-box .ti{ font-size:19px;flex:none; }
.warn-box{
  display:flex;gap:12px;background:rgba(248,113,113,0.06);
  border-left:3px solid var(--offline);border-radius:0 12px 12px 0;
  padding:14px 16px;margin:18px 0;font-size:13.5px;color:var(--text-dim);line-height:1.7;
}
.warn-box .ti{ font-size:19px;flex:none; }

/* TOC (mục lục) */
.toc{
  background:var(--card);border:1px solid var(--card-border);
  border-radius:16px;padding:16px 18px;margin-bottom:24px;
}
.toc-title{ font-size:12px;font-weight:800;letter-spacing:1px;text-transform:uppercase;color:var(--accent);margin-bottom:10px; }
.toc ol{ margin:0;padding-left:18px;color:var(--text-dim);font-size:13.5px;line-height:2; }
.toc a{ color:var(--text-dim);text-decoration:none; }
.toc a:hover{ color:var(--accent); }

/* Author / meta box for E-E-A-T */
.author-box{
  display:flex;align-items:center;gap:12px;
  background:var(--card);border:1px solid var(--card-border);
  border-radius:16px;padding:14px 16px;margin:18px 0 28px;
}
.author-box img{ width:42px;height:42px;border-radius:50%;object-fit:cover;flex:none;border:2px solid var(--card-border); }
.author-box .a-name{ font-size:13.5px;font-weight:800; }
.author-box .a-role{ font-size:11.5px;color:var(--text-dim); }

/* Related posts */
.related-grid{ display:grid;grid-template-columns:1fr;gap:12px; }
@media(min-width:560px){ .related-grid{ grid-template-columns:1fr 1fr; } }

/* ══════════════ FAQ ══════════════ */
.faq-list{ display:flex;flex-direction:column;gap:8px; }
.faq-item{ background:var(--card);border:1px solid var(--card-border);border-radius:14px;overflow:hidden; }
.faq-q{
  width:100%;background:none;border:none;color:var(--text);text-align:left;cursor:pointer;
  display:flex;align-items:center;justify-content:space-between;gap:12px;padding:15px 18px;
  font-family:inherit;font-size:14px;font-weight:700;-webkit-tap-highlight-color:transparent;
}
.faq-q:hover{ color:var(--accent); }
.faq-chevron{ width:18px;height:18px;flex:none;transition:transform .25s;color:var(--text-dim); }
.faq-item.open .faq-chevron{ transform:rotate(180deg); }
.faq-a{ max-height:0;overflow:hidden;transition:max-height .3s ease; }
.faq-item.open .faq-a{ max-height:400px; }
.faq-a-inner{ padding:0 18px 16px;font-size:13.5px;color:var(--text-dim);line-height:1.7;font-weight:500; }

/* ══════════════ FOOTER (mở rộng, dùng cho các trang con) ══════════════ */
.site-footer{
  margin-top:50px;padding:40px 18px 28px;border-top:1px solid var(--card-border);color:var(--text-dim);font-size:13px;
}
.site-footer-grid{
  max-width:1080px;margin:0 auto;
  display:grid;grid-template-columns:1.4fr 1fr 1fr 1fr;gap:28px;
}
@media(max-width:760px){ .site-footer-grid{ grid-template-columns:1fr 1fr; } }
@media(max-width:460px){ .site-footer-grid{ grid-template-columns:1fr; } }
.site-footer .fname{
  font-weight:800;font-size:16px;color:var(--text);margin-bottom:8px;
  background:linear-gradient(95deg,#fff,var(--accent));-webkit-background-clip:text;background-clip:text;
}
.site-footer .fdesc{ font-size:12.5px;line-height:1.7;max-width:280px; }
.site-footer .fcol-title{ font-size:11.5px;font-weight:800;letter-spacing:1px;text-transform:uppercase;color:var(--text);margin-bottom:12px;opacity:.8; }
.site-footer .fcol a{ display:block;color:var(--text-dim);text-decoration:none;font-size:13px;font-weight:500;margin-bottom:9px;transition:color .2s; }
.site-footer .fcol a:hover{ color:var(--accent); }
.site-footer .fbottom{
  max-width:1080px;margin:32px auto 0;padding-top:20px;border-top:1px solid var(--card-border);
  display:flex;flex-wrap:wrap;justify-content:space-between;gap:10px;font-size:12px;
}
.site-footer .disclaimer{ margin-top:6px;font-size:11.5px;color:#5d6388;line-height:1.6;max-width:1080px;margin-left:auto;margin-right:auto; }

/* ══════════════ MISC ══════════════ */
.top-btn{
  position:fixed;right:16px;bottom:16px;width:46px;height:46px;border-radius:50%;
  background:linear-gradient(150deg,var(--accent),var(--accent-2));
  display:flex;align-items:center;justify-content:center;
  box-shadow:0 10px 22px -6px rgba(255,122,61,0.6);
  opacity:0;pointer-events:none;transform:translateY(10px);
  transition:opacity .3s ease, transform .3s ease;z-index:10;border:none;cursor:pointer;
}
.top-btn.show{ opacity:1;pointer-events:auto;transform:translateY(0); }
.top-btn svg{ width:20px;height:20px; }

.reveal{ opacity:0;transform:translateY(18px);transition:opacity .5s ease, transform .5s ease; }
.reveal.visible{ opacity:1;transform:translateY(0); }

@media(prefers-reduced-motion:reduce){
  .reveal{ opacity:1;transform:none;transition:none; }
}