@font-face { font-family: "Be Vietnam Pro"; font-weight: 400; src: url(assets/fonts/BeVietnamPro-Regular.ttf); font-display: swap; }
@font-face { font-family: "Be Vietnam Pro"; font-weight: 500; src: url(assets/fonts/BeVietnamPro-Medium.ttf); font-display: swap; }
@font-face { font-family: "Be Vietnam Pro"; font-weight: 700; src: url(assets/fonts/BeVietnamPro-Bold.ttf); font-display: swap; }
@font-face { font-family: "Be Vietnam Pro"; font-weight: 900; src: url(assets/fonts/BeVietnamPro-Black.ttf); font-display: swap; }
:root { --or: #FF6A2B; --night: #06090E; --card: #11151f; --line: #1f2533; --paper: #F6F5F2; --mute: #9aa3b5; }
* { box-sizing: border-box; margin: 0; }
html { scroll-behavior: smooth; scroll-padding-top: 90px; }
body { background: var(--night); color: var(--paper); font: 400 16.5px/1.7 "Be Vietnam Pro", system-ui, sans-serif; -webkit-font-smoothing: antialiased; }
a { color: var(--or); text-decoration: underline; text-underline-offset: 3px; }
.top { position: fixed; top: 12px; left: 50%; transform: translateX(-50%); width: min(960px, calc(100% - 24px)); z-index: 10; display: flex; align-items: center; justify-content: space-between; padding: 10px 14px 10px 20px; border-radius: 999px; background: rgba(12,16,24,.8); border: 1px solid rgba(255,255,255,.08); backdrop-filter: blur(16px); }
.top img { height: 24px; display: block; }
.top .back { color: var(--paper); text-decoration: none; font-size: 14.5px; font-weight: 500; }
main.doc { max-width: 760px; margin: 0 auto; padding: 130px 24px 80px; }
h1 { font-size: clamp(2rem, 5vw, 3.2rem); font-weight: 900; letter-spacing: -.04em; line-height: 1.08; }
.upd { color: var(--mute); font-size: 14px; margin-top: 10px; }
.intro { margin-top: 22px; color: #cfd5e2; }
.toc { display: flex; flex-wrap: wrap; gap: 8px; margin: 28px 0 8px; }
.toc a { text-decoration: none; color: var(--mute); border: 1px solid var(--line); border-radius: 999px; padding: 6px 14px; font-size: 13.5px; }
.toc a:hover { color: var(--paper); border-color: var(--or); }
section { margin-top: 38px; }
h2 { font-size: 1.3rem; font-weight: 700; letter-spacing: -.02em; margin-bottom: 10px; }
p, li { color: #c3cadb; }
p + p { margin-top: 12px; }
ul { padding-left: 20px; display: grid; gap: 10px; }
li::marker { color: var(--or); }
b { color: var(--paper); font-weight: 700; }
.others { margin-top: 56px; padding-top: 20px; border-top: 1px solid var(--line); font-size: 14.5px; color: var(--mute); }

/* ô thông tin còn trống: tô đỏ để không bị sót */
.todo { background: rgba(229,50,45,.2); color: #ff8f8a !important; border-radius: 4px; padding: 0 5px; text-decoration: none; }

footer.site { border-top: 1px solid var(--line); padding: 44px 0 28px; color: var(--mute); font-size: 14.5px; }
.wrap { max-width: 1180px; margin: 0 auto; padding: 0 24px; }
.fgrid { display: grid; grid-template-columns: 1.6fr 1fr 1fr; gap: 36px; }
.fco img { display: block; margin-bottom: 14px; }
.fco p { line-height: 1.75; }
.fco b { color: var(--paper); }
.flinks h4 { color: var(--paper); font-size: 14px; margin-bottom: 12px; }
.flinks a, .flinks span { display: block; color: var(--mute); text-decoration: none; margin-bottom: 8px; }
.flinks a:hover { color: var(--paper); }
.fbot { margin-top: 32px; padding-top: 18px; border-top: 1px solid var(--line); display: flex; justify-content: space-between; flex-wrap: wrap; gap: 8px; font-size: 13.5px; }
@media (max-width: 760px) { .fgrid { grid-template-columns: 1fr; } main.doc { padding-top: 110px; } }

.top .tools { display: flex; align-items: center; gap: 8px; }
.top .back { margin-right: 6px; }
.nbtn { width: 36px; height: 36px; border-radius: 50%; border: 1px solid rgba(255,255,255,.14); background: rgba(255,255,255,.05); color: var(--paper); display: grid; place-items: center; cursor: pointer; font: 700 12px "Be Vietnam Pro", system-ui, sans-serif; text-decoration: none; }
.top a.nbtn { color: var(--paper); }
.nbtn:hover { border-color: var(--or); }
.nbtn svg { width: 17px; height: 17px; fill: currentColor; stroke: currentColor; }
.nbtn .sun { display: none; fill: none; } .nbtn .sun circle { fill: currentColor; stroke: none; }
html[data-theme="light"] .nbtn .moon { display: none; } html[data-theme="light"] .nbtn .sun { display: inline; }
.skip { position: fixed; left: 12px; top: -60px; z-index: 50; background: var(--or); color: #fff; padding: 10px 16px; border-radius: 10px; font-weight: 700; text-decoration: none; }
.skip:focus { top: 12px; }
:focus-visible { outline: 2px solid var(--or); outline-offset: 3px; border-radius: 6px; }
html[data-theme="light"] { --night: #fcfcfb; --card: #fff; --line: #e4e4e0; --paper: #0f1218; --mute: #5d6678; color-scheme: light; }
html[data-theme="light"] body { background: var(--night); color: var(--paper); }
html[data-theme="light"] .top { background: rgba(255,255,255,.8); border-color: rgba(0,0,0,.08); }
html[data-theme="light"] .top .back { color: var(--paper); }
html[data-theme="light"] .top img, html[data-theme="light"] .fco img { filter: brightness(0); }
html[data-theme="light"] .nbtn { border-color: rgba(0,0,0,.14); background: rgba(0,0,0,.03); }
html[data-theme="light"] p, html[data-theme="light"] li, html[data-theme="light"] .intro { color: #3d4452; }
html[data-theme="light"] b { color: #0f1218; }
html[data-theme="light"] a { color: #C2410C; }
html[data-theme="light"] .flinks a, html[data-theme="light"] .flinks span { color: var(--mute); }

/* biểu mẫu gửi yêu cầu (trang hỗ trợ) */
.reqform form { display: grid; gap: 14px; margin-top: 14px; background: var(--card); border: 1px solid var(--line); border-radius: 20px; padding: 22px; }
.reqform label { display: grid; gap: 6px; font-size: 14px; color: var(--mute); font-weight: 500; }
.reqform .two { display: grid; grid-template-columns: 1fr 1fr; gap: 14px; }
@media (max-width: 600px) { .reqform .two { grid-template-columns: 1fr; } }
.reqform input, .reqform select, .reqform textarea { font: inherit; color: var(--paper); background: rgba(255,255,255,.04); border: 1px solid var(--line); border-radius: 12px; padding: 11px 13px; width: 100%; }
.reqform input:focus, .reqform select:focus, .reqform textarea:focus { outline: 2px solid var(--or); outline-offset: 1px; }
.reqform .chk { display: flex; gap: 10px; align-items: flex-start; }
.reqform .chk input { width: auto; margin-top: 5px; accent-color: var(--or); }
.reqform .hp { position: absolute; left: -9999px; width: 1px; height: 1px; opacity: 0; }
.reqform .fnote { font-size: 13px; color: var(--mute); }
.reqform .fbtn { justify-self: start; font: 700 15px "Be Vietnam Pro", sans-serif; color: #fff; background: var(--or); border: 0; border-radius: 999px; padding: 12px 28px; cursor: pointer; }
.reqform .fbtn[disabled] { opacity: .6; cursor: wait; }
.reqform .fstat { font-weight: 500; }
.reqform .fstat.ok { color: #6fd08c; }
.reqform .fstat.bad { color: #ff8f8a; }

[data-opt][hidden] { display: none !important; }   /* ô tuỳ chọn trống: chân trang đặt display cho span nên phải ép ẩn */