/* =========================================================================
   nav.css — THANH DIEU HUONG + MENU DIEN THOAI + THANH TIEN DO CUON
   ========================================================================= */

/* ── Thanh tien do cuon (vach mong tren cung) ────────────────
   Dung scaleX chu khong dung width: doi width lam trinh duyet tinh lai bo cuc
   moi khung hinh, con transform thi khong. */
.progress {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: 3px;
  z-index: 120;
  background: linear-gradient(90deg, var(--accent), var(--accent-2), var(--accent-3));
  transform: scaleX(var(--p, 0));
  transform-origin: 0 50%;
  pointer-events: none;
}

/* ── Thanh nav ───────────────────────────────────────────── */
.nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 110;
  height: var(--nav-h);
  display: flex;
  align-items: center;
  background: transparent;
  border-bottom: 1px solid transparent;
  transition:
    background-color var(--dur) var(--ease),
    border-color var(--dur) var(--ease),
    box-shadow var(--dur) var(--ease),
    height var(--dur) var(--ease);
}
/* Da cuon xuong -> nen kinh mo + duong ke, cho chu khong dinh vao anh. */
.nav.is-stuck {
  background: var(--glass);
  -webkit-backdrop-filter: saturate(160%) blur(14px);
          backdrop-filter: saturate(160%) blur(14px);
  border-bottom-color: var(--border);
  box-shadow: var(--sh-sm);
}

.nav__inner {
  width: 100%;
  max-width: var(--maxw);
  margin-inline: auto;
  padding-inline: clamp(18px, 4vw, 32px);
  display: flex;
  align-items: center;
  gap: 20px;
}

/* ── Logo ───────────────────────────────────────────────── */
.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-weight: 750;
  font-size: 1.06rem;
  letter-spacing: -.02em;
  color: var(--text);
  margin-right: auto;
}
.brand:hover { color: var(--text); }
.brand__mark {
  width: 34px; height: 34px;
  display: grid;
  place-items: center;
  border-radius: 10px;
  background: var(--gold-grad);
  color: var(--accent-fg);
  box-shadow: 0 6px 16px rgba(232, 163, 23, .38);
  transition: transform var(--dur) var(--ease-spring);
}
.brand:hover .brand__mark { transform: rotate(-8deg) scale(1.06); }
.brand__name b { font-weight: 750; }
.brand__name span { color: var(--accent); }

/* ── Menu ────────────────────────────────────────────────── */
.nav__links {
  display: flex;
  align-items: center;
  gap: 4px;
  list-style: none;
  margin: 0; padding: 0;
}
.nav__links a {
  /* Them muc Dien dan + Tai lieu (8 muc, 06/09/2026): khong co dong nay thi tu
     1201px tro xuong chu bi be doi - "Tinh nang" thanh "Tinh"/"nang" - va thanh
     nav cao gap doi (49px -> 73px). Da do bang Chromium o 1201/1250/1300/1400px. */
  white-space: nowrap;
  position: relative;
  display: block;
  padding: 8px 14px;
  border-radius: var(--radius-pill);
  font-size: var(--fs-sm);
  font-weight: 600;
  color: var(--text-muted);
  transition: color var(--dur-fast) var(--ease), background-color var(--dur-fast) var(--ease);
}
.nav__links a:hover { color: var(--text); background: var(--surface-3); }

/* Gach chan chay tu giua ra — chi hien o muc dang xem. */
.nav__links a::after {
  content: "";
  position: absolute;
  left: 14px; right: 14px; bottom: 3px;
  height: 2px;
  border-radius: 2px;
  background: var(--accent);
  transform: scaleX(0);
  transition: transform var(--dur) var(--ease-out);
}
.nav__links a.is-active { color: var(--accent); }
.nav__links a.is-active::after { transform: scaleX(1); }

.nav__actions { display: flex; align-items: center; gap: 8px; }

/* ── Nut tron (doi giao dien, mo menu) ───────────────────── */
.icon-btn {
  width: 38px; height: 38px;
  display: grid;
  place-items: center;
  border: 1px solid var(--border);
  border-radius: 50%;
  background: var(--card);
  color: var(--text-muted);
  cursor: pointer;
  transition: color var(--dur-fast) var(--ease),
              border-color var(--dur-fast) var(--ease),
              transform var(--dur) var(--ease-spring);
}
.icon-btn:hover { color: var(--accent); border-color: var(--accent); transform: scale(1.06); }

/* Hai bieu tuong mat trang / mat troi chong len nhau, doi bang xoay + mo. */
.theme-btn svg { position: absolute; transition: transform var(--dur) var(--ease-spring), opacity var(--dur) var(--ease); }
.theme-btn { position: relative; }
.theme-btn .ico-sun  { opacity: 0; transform: rotate(-90deg) scale(.5); }
.theme-btn .ico-moon { opacity: 1; transform: none; }
:root[data-theme="dark"] .theme-btn .ico-sun  { opacity: 1; transform: none; }
:root[data-theme="dark"] .theme-btn .ico-moon { opacity: 0; transform: rotate(90deg) scale(.5); }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .theme-btn .ico-sun  { opacity: 1; transform: none; }
  :root:not([data-theme="light"]) .theme-btn .ico-moon { opacity: 0; transform: rotate(90deg) scale(.5); }
}

/* ── Nut ba gach ─────────────────────────────────────────── */
.burger { display: none; }
.burger span {
  display: block;
  width: 18px; height: 2px;
  background: currentColor;
  border-radius: 2px;
  transition: transform var(--dur) var(--ease-spring), opacity var(--dur-fast) var(--ease);
}
.burger span + span { margin-top: 4px; }
.burger.is-open span:nth-child(1) { transform: translateY(6px) rotate(45deg); }
.burger.is-open span:nth-child(2) { opacity: 0; }
.burger.is-open span:nth-child(3) { transform: translateY(-6px) rotate(-45deg); }

/* ── Ngan keo tren dien thoai ────────────────────────────── */
.drawer {
  position: fixed;
  inset: var(--nav-h) 0 auto 0;
  z-index: 105;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  box-shadow: var(--sh-lg);
  padding: 16px clamp(18px, 4vw, 32px) 24px;
  /* An bang scaleY + opacity thay vi display:none de con chuyen dong. */
  transform-origin: top center;
  transform: translateY(-8px) scaleY(.96);
  opacity: 0;
  visibility: hidden;
  transition: transform var(--dur) var(--ease-out), opacity var(--dur) var(--ease), visibility var(--dur);
}
.drawer.is-open { transform: none; opacity: 1; visibility: visible; }
.drawer ul { list-style: none; margin: 0 0 16px; padding: 0; display: grid; gap: 2px; }
.drawer a {
  display: block;
  padding: 12px 14px;
  border-radius: var(--radius-sm);
  font-weight: 600;
  color: var(--text);
}
.drawer a:hover { background: var(--surface-3); }

/* O tai khoan trong ngan keo: MAC DINH AN.
   Tu 701px tro len thanh nav con du cho cho nut tai khoan, ma ngan keo van
   hien den 1200px — khong an thi tu 701 den 1200 nguoi dung thay HAI nut
   "Đăng nhập". shared/css/mobile.css bat no len lai o duoi 700px. */
.drawer__acct { display: none; }

/* Nut doi linh vuc trong ngan keo: MAC DINH AN, cung ly do voi .drawer__acct
   — tu 701px tro len thanh nav da co nut nay roi, hien ca hai la trung. */
.drawer__dom { display: none; }

/* Nguong doi sang nut ba gach: 1200px, KHONG phai 940px.
   Thanh nav co 9 muc + nut ngon ngu + tai khoan + tim + doi giao dien + nut
   Tai ve. Duoi ~1200px chung khong con du cho, bat dau tran ra ngoai va day
   ca trang lech sang phai. Duoi nguong nay dua het vao ngan keo. */
@media (max-width: 1200px) {
  .nav__links { display: none; }
  .burger { display: grid; }
  .nav__actions .btn--nav { display: none; }
}
@media (min-width: 1201px) {
  .drawer { display: none; }

  /* Khoang 1201-1400px: bop nhe khoang cach va le trong de 9 muc vua khit. */
  @media (max-width: 1400px) {
    .nav__inner { gap: 12px; }
    .nav__links a { padding: 8px 10px; }
    .nav__links { gap: 0; }
  }
}

/* ── Nut chuyen ngon ngu ─────────────────────────────────────
   Hai o VI | EN dinh nhau thanh mot khoi. Cai dang chon co nen dam.
   Chu ngan (2 ky tu) nen khong can dich — dung nguyen ma ngon ngu. */
.langsw {
  display: inline-flex;
  border: var(--hair, 1px) solid var(--border);
  border-radius: 5px;
  overflow: hidden;
  background: var(--card);
}
.langsw button {
  padding: 7px 10px;
  border: 0;
  background: transparent;
  color: var(--text-muted);
  font: inherit;
  font-family: var(--font-mono);
  font-size: .72rem;
  font-weight: 700;
  letter-spacing: .06em;
  cursor: pointer;
  transition: background-color var(--dur-fast) var(--ease), color var(--dur-fast) var(--ease);
}
.langsw button + button { border-left: 1px solid var(--border); }
.langsw button:hover { color: var(--text); background: var(--surface-3); }
.langsw button.is-active { background: var(--accent-solid); color: var(--accent-fg); }

/* Man hinh hep: nut ngon ngu van giu lai (khac nut "Tải về" bi an), vi doi
   ngon ngu la viec nguoi dung can lam ngay o man hinh dau. */
@media (max-width: 420px) {
  .langsw button { padding: 6px 8px; font-size: .66rem; }
}