/* Visual design follows OmniTools (MIT) – see /gioi-thieu/. Values mirror its MUI theme. */
@font-face { font-family:"Quicksand"; font-weight:100 900; font-style:normal; font-display:swap; src:url("/assets/Quicksand-VariableFont_wght.ttf") format("truetype"); }
:root { color-scheme:light; --bg:#F5F5FA; --hover:#FAFAFD; --light:#EBF5FF; --dark:#5581b5; --primary:#1976d2; --link:#1c76ce; --ink:rgba(0,0,0,.87); --muted:rgba(0,0,0,.6); --line:rgba(0,0,0,.23); --shadow1:0 2px 1px -1px rgba(0,0,0,.2),0 1px 1px 0 rgba(0,0,0,.14),0 1px 3px 0 rgba(0,0,0,.12); font-family:"Quicksand",system-ui,sans-serif; color:var(--ink); background:var(--bg); }
* { box-sizing:border-box; }
body { margin:0; font-size:16px; line-height:1.5; letter-spacing:.00938em; background:var(--bg); }
body.home-bg { background:var(--bg) url("/assets/background.svg"); }
a { color:var(--link); text-decoration:none; }
a:hover { color:#030362; }
button,input,textarea,select { font:inherit; letter-spacing:inherit; color:inherit; }
:focus-visible { outline:2px solid var(--primary); outline-offset:2px; }
[hidden] { display:none!important; }
.sr-only { position:absolute; width:1px; height:1px; overflow:hidden; clip-path:inset(50%); white-space:nowrap; }
.skip { position:absolute; left:16px; top:-90px; padding:10px; background:#fff; z-index:5; }
.skip:focus { top:8px; }
h1,h2,h3,p { margin-top:0; }
h1,h2,h3 { font-weight:inherit; }
svg { flex:none; }

/* Header */
.topbar { display:flex; align-items:center; justify-content:space-between; gap:16px; min-height:64px; margin:16px 150px 0; padding:0 24px; }
.logo { font-size:30px; font-weight:700; color:var(--link); letter-spacing:-.5px; white-space:nowrap; }
.topbar nav { display:flex; align-items:center; gap:24px; }
.topbar nav > a:not(.btn) { color:var(--ink); }
.topbar nav > a:not(.btn):hover,.topbar nav > a[aria-current] { color:var(--link); }
.lang { display:inline-flex; align-items:center; gap:4px; color:var(--ink); }
.lang svg { width:22px; height:22px; }
.lang select { max-width:130px; padding:4px 2px; border:0; border-radius:4px; background:none; cursor:pointer; }
.lang select:hover { background:rgba(0,0,0,.04); }

/* Buttons and chips */
.btn { display:inline-flex; align-items:center; justify-content:center; gap:8px; min-height:36.5px; padding:6px 16px; border-radius:4px; border:1px solid transparent; font-size:14px; font-weight:500; line-height:1.75; letter-spacing:.02857em; cursor:pointer; background:none; color:var(--primary); text-align:center; transition:background .25s,box-shadow .25s; }
.btn svg { width:20px; height:20px; }
.btn.contained { background:var(--primary); color:#fff; box-shadow:0 3px 1px -2px rgba(0,0,0,.2),0 2px 2px 0 rgba(0,0,0,.14),0 1px 5px 0 rgba(0,0,0,.12); }
.btn.contained:hover { background:#1565c0; color:#fff; }
.btn.outlined { border-color:rgba(25,118,210,.5); }
.btn.outlined:hover { border-color:var(--primary); background:rgba(25,118,210,.04); color:var(--primary); }
.btn.paper { background:var(--bg); }
.btn.text { padding:6px 8px; }
.btn.text:hover { background:rgba(25,118,210,.04); }
.btn:disabled { color:rgba(0,0,0,.26); cursor:default; background:none; }
.chip { display:inline-flex; align-items:center; height:24px; padding:0 8px; border-radius:16px; background:rgba(0,0,0,.08); font-size:13px; color:var(--ink); align-self:flex-start; }
.small { font-size:14px; color:var(--muted); }
.title { font-size:30px; line-height:1.5; color:var(--primary); margin-bottom:16px; }
.title span { display:block; font-size:16px; color:var(--muted); }

/* Hero + search */
.home,.hero-wrap { display:flex; flex-direction:column; align-items:center; padding:40px; }
.hero { width:60%; }
.hero-title { font-size:30px; line-height:1.5; margin:0; }
.hero-title span { color:var(--primary); }
.hero-desc { font-size:20px; line-height:1.5; margin-bottom:16px; }
.search { position:relative; display:flex; align-items:center; background:#fff; border:1px solid var(--line); border-radius:16px; }
.search:hover { border-color:var(--ink); }
.search:focus-within { border-color:var(--primary); box-shadow:inset 0 0 0 1px var(--primary); }
.search input { flex:1; min-width:0; height:54px; padding:0 14px; border:0; outline:0; background:none; font-size:16px; }
.search > svg { width:24px; height:24px; margin-right:12px; }
.listbox { position:absolute; z-index:6; top:calc(100% + 4px); left:0; right:0; max-height:40vh; overflow:auto; padding:8px 0; background:#fff; border-radius:4px; box-shadow:0 5px 5px -3px rgba(0,0,0,.2),0 8px 10px 1px rgba(0,0,0,.14),0 3px 14px 2px rgba(0,0,0,.12); }
.listbox .group { position:sticky; top:-8px; padding:4px 10px; color:var(--primary); background:#e3eefa; }
.listbox [role="option"] { display:flex; align-items:center; gap:10px; padding:6px 16px; color:var(--ink); }
.listbox [role="option"] svg { width:24px; height:24px; }
.listbox [role="option"] span { display:flex; flex-direction:column; }
.listbox [role="option"] small { font-size:12px; }
.listbox [role="option"]:hover,.listbox [aria-selected="true"] { background:rgba(0,0,0,.04); }
.none { padding:14px 16px; margin:0; color:var(--muted); }
.quick-grid { display:grid; grid-template-columns:repeat(3,1fr); gap:16px; list-style:none; margin:16px 0 0; padding:0; }
.quick { display:flex; align-items:center; justify-content:center; height:100%; padding:16px; border:1px solid rgba(0,0,0,.12); border-radius:12px; background:#fff; color:var(--ink); text-align:center; }
.quick:hover { background:var(--hover); color:var(--ink); }

/* Home categories */
.categories { width:80%; display:grid; grid-template-columns:repeat(2,1fr); gap:16px; margin-top:24px; }
.cat-card { display:flex; flex-direction:column; padding:16px 16px 24px; background:#fff; border-radius:4px; box-shadow:var(--shadow1); transition:background .3s; }
.cat-card:hover { background:var(--hover); }
.cat-head { display:flex; align-items:center; gap:12px; }
.cat-head svg { width:60px; height:60px; }
.cat-head h2 { font-size:20px; font-weight:700; margin:0; }
.cat-card p { flex:1; margin:16px 0; }
.cat-actions { display:grid; grid-template-columns:1fr 1fr; gap:16px; }
.home-posts { width:80%; margin-top:40px; }
.section-head { display:flex; align-items:baseline; justify-content:space-between; gap:12px; }

/* Category page */
.divider { margin:0; border:0; border-top:1px solid var(--primary); }
.category { margin:24px 0 0 24px; padding:24px; }
.category-bar { display:flex; align-items:center; justify-content:space-between; gap:16px; margin-bottom:24px; }
.category-bar h1 { display:flex; align-items:center; gap:8px; font-size:22px; color:var(--primary); margin:0; }
.category-bar p { margin:4px 0 0 48px; color:var(--muted); max-width:760px; }
.back { display:grid; place-items:center; width:40px; height:40px; border-radius:50%; color:var(--primary); }
.back:hover { background:rgba(25,118,210,.04); }
.back svg { width:24px; height:24px; }
.small-search { width:400px; max-width:100%; }
.tile-grid,.grid-3 { display:grid; grid-template-columns:repeat(3,1fr); gap:16px; }
.tool-tile { display:flex; align-items:center; gap:16px; padding:16px; background:#fff; border-radius:8px; box-shadow:5px 4px 2px #E9E9ED; color:var(--ink); transition:background .3s; }
.tool-tile:hover { background:var(--hover); color:var(--ink); }
.tool-tile > svg { width:60px; height:60px; }
.tile-name { display:block; font-size:20px; color:var(--link); }
.tile-desc { display:block; color:var(--muted); }

/* Generic page + breadcrumb */
.page { width:85%; margin:0 auto; padding:24px 0 40px; }
.crumbs ol { display:flex; flex-wrap:wrap; list-style:none; margin:0 0 16px; padding:0; color:var(--muted); }
.crumbs li + li::before { content:"/"; margin:0 8px; }
.page-head h1,.post-head h1 { font-size:30px; color:var(--primary); line-height:1.5; margin-bottom:8px; }
.lead { font-size:20px; }

/* Tool page */
.tool-head { display:flex; align-items:center; justify-content:space-between; gap:24px; margin-bottom:32px; }
.tool-head h1 { font-size:30px; color:var(--primary); margin-bottom:8px; }
.tool-desc { font-size:20px; margin-bottom:16px; }
.tool-art { width:250px; height:250px; }
.io { display:grid; grid-template-columns:1fr 1fr; gap:16px; }
.io > div { min-width:0; }
.io-title { font-size:30px; color:var(--primary); margin-bottom:8px; }
.io-title label { cursor:inherit; }
textarea { display:block; width:100%; min-height:258px; resize:vertical; padding:16.5px 14px; border:1px solid var(--line); border-radius:4px; background:#fff; line-height:1.4375em; }
textarea:hover { border-color:var(--ink); }
textarea:focus { outline:0; border-color:var(--primary); box-shadow:inset 0 0 0 1px var(--primary); }
textarea[aria-invalid="true"] { border-color:#d32f2f; }
.io-foot { display:flex; flex-wrap:wrap; gap:16px; margin-top:8px; }
.result-box { display:grid; grid-template-columns:1fr 1fr; gap:1px; min-height:258px; margin:0; overflow:hidden; border:1px solid var(--line); border-radius:4px; background:var(--line); }
.result-box div { display:flex; flex-direction:column; justify-content:center; padding:16px; background:#fff; }
.result-box dt { color:var(--muted); }
.result-box dd { margin:0; font-size:34px; color:var(--primary); font-variant-numeric:tabular-nums; }
.drop { display:flex; flex-direction:column; align-items:center; justify-content:center; gap:12px; min-height:258px; padding:24px; border:1px dashed var(--line); border-radius:4px; background:#fff; color:var(--muted); text-align:center; }
.drop svg { width:48px; height:48px; color:var(--primary); }
a.drop:hover, .drop.over { border-color:var(--primary); background:#f0f6fd; }
.drop.demo { background:#fff radial-gradient(rgba(0,0,0,.12) 1px,transparent 1px) 0 0/16px 16px; }
.drop.demo span { font-size:70px; color:#FFD400; filter:drop-shadow(0 3px 0 #fff) drop-shadow(0 -3px 0 #fff) drop-shadow(3px 0 0 #fff) drop-shadow(-3px 0 0 #fff) drop-shadow(0 6px 6px rgba(0,0,0,.2)); transform:rotate(-12deg); }
.status { min-height:24px; margin:8px 0 0; color:#d32f2f; }
.opt-desc { margin:0 0 0 16px; font-size:12px; color:var(--muted); }
.options { margin-top:24px; padding:20px; border-radius:8px; background:var(--light); box-shadow:var(--shadow1); }
.options h2 { display:flex; align-items:center; gap:8px; font-size:20px; margin-bottom:8px; }
.options h2 svg { width:24px; height:24px; }
.opt-groups { display:grid; grid-template-columns:repeat(3,1fr); gap:16px; }
.opt-group { margin:0; padding:0; border:0; min-width:0; }
.opt-group legend { font-size:22px; padding:0; margin-bottom:8px; }
.radio { display:flex; align-items:center; gap:4px; margin:16px 0 8px; cursor:pointer; }
.radio input,.fake-radio { appearance:none; flex:none; width:42px; height:42px; margin:0; display:grid; place-items:center; border-radius:50%; cursor:pointer; background:radial-gradient(circle,transparent 8px,currentColor 8.5px,currentColor 10px,transparent 10.5px); color:var(--muted); }
.radio input:hover { background-color:rgba(25,118,210,.04); }
.radio input:checked,.fake-radio.on { color:var(--primary); background:radial-gradient(circle,currentColor 4.5px,transparent 5px,transparent 8px,currentColor 8.5px,currentColor 10px,transparent 10.5px); }
.info { margin-top:32px; }
.info h2 { font-size:30px; color:var(--primary); margin-bottom:16px; }
.info p { font-size:20px; }
.sep { margin:24px 0; border:0; height:2px; background:var(--dark); }
.examples,.guides,.all-tools { margin-top:16px; }
.ex-card { display:flex; flex-direction:column; gap:8px; padding:16px; background:#fff; border-radius:4px; box-shadow:0 3px 3px -2px rgba(0,0,0,.2),0 3px 4px 0 rgba(0,0,0,.14),0 1px 8px 0 rgba(0,0,0,.12); cursor:pointer; transition:background .3s,transform .3s; }
.ex-card:hover { background:var(--hover); transform:scale(1.02); }
.ex-card h3 { font-size:20px; font-weight:500; margin:0; }
.ex-card p { color:var(--muted); font-size:14px; margin:0; }
.ex-box { padding:8px; border-radius:4px; background:var(--bg); }
.ex-box pre { margin:0; padding:8px 14px; min-height:40px; border:1px solid rgba(0,0,0,.12); border-radius:4px; background:#fff; color:rgba(0,0,0,.38); font:inherit; white-space:pre-wrap; overflow-wrap:anywhere; }
.ex-arrow { align-self:center; width:24px; height:24px; }
.ex-opts .opt-group legend { font-size:16px; }
.ex-opts .radio { margin:4px 0; }
.ex-opts .opt-desc { display:none; }
.tool-card { display:flex; flex-direction:column; gap:8px; padding:16px; border-radius:8px; background:var(--dark); color:#fff; box-shadow:6px 6px 12px #b8b9be,-6px -6px 12px #fff; transition:transform .3s; }
.tool-card:hover { color:#fff; transform:scale(1.05); }
.tool-card-head { display:flex; align-items:center; gap:8px; }
.tool-card-head svg { width:24px; height:24px; }
.tool-card-head strong { flex:1; font-size:20px; font-weight:500; }
.tool-card-desc { color:rgba(255,255,255,.85); }

/* Blog */
.post-card { display:flex; flex-direction:column; overflow:hidden; background:#fff; border-radius:4px; box-shadow:var(--shadow1); color:var(--ink); transition:background .3s; }
.post-card:hover { background:var(--hover); color:var(--ink); }
.cover { display:grid; place-items:center; aspect-ratio:16/9; background:var(--light) radial-gradient(#fff 1.5px,transparent 1.5px) 0 0/18px 18px; }
.cover svg { width:72px; height:72px; }
.cover-lg { aspect-ratio:21/7; border-radius:8px; margin-bottom:8px; }
.cover-lg svg { width:120px; height:120px; }
.post-body { display:flex; flex-direction:column; flex:1; gap:8px; padding:16px; }
.post-body h3 { font-size:20px; font-weight:700; color:var(--link); margin:0; }
.post-body p { flex:1; margin:0; color:var(--muted); }
.post-head { max-width:820px; margin-bottom:24px; }
.post-head .chip { margin-bottom:8px; }
.post-layout { display:grid; grid-template-columns:minmax(0,1fr) 260px; gap:48px; align-items:start; }
.post-layout:not(:has(.toc)) { display:block; }
.toc { order:2; position:sticky; top:24px; margin-top:32px; padding:20px; border-radius:8px; background:var(--light); box-shadow:var(--shadow1); }
.toc ol { margin:8px 0 0; padding-left:18px; }
.toc li { margin-bottom:6px; }
.tool-cta { margin-top:32px; }
.prose { max-width:820px; margin:32px 0; font-size:18px; line-height:1.7; }
.prose h2 { font-size:26px; color:var(--primary); line-height:1.4; margin-top:32px; scroll-margin-top:24px; }
.prose li { margin-bottom:8px; }
.prose code { padding:2px 5px; border-radius:4px; background:rgba(0,0,0,.06); overflow-wrap:anywhere; }
.prose table { display:block; overflow-x:auto; margin:20px 0; border-collapse:collapse; font-size:16px; }
.prose th,.prose td { padding:8px 12px; border:1px solid rgba(0,0,0,.12); text-align:left; vertical-align:top; }
.prose th { background:var(--light); }
details { padding:12px 0; border-bottom:1px solid rgba(0,0,0,.12); }
summary { cursor:pointer; font-weight:600; }
details p { margin:8px 0 0; color:var(--muted); }

footer { display:flex; flex-wrap:wrap; justify-content:space-between; gap:8px 24px; margin-top:24px; padding:24px 40px; border-top:1px solid rgba(0,0,0,.12); font-size:14px; color:var(--muted); }
footer p { margin:0; }
footer a { color:var(--muted); }

@media (max-width:1199px) { .hero { width:80%; } .topbar { margin-inline:24px; } }
@media (max-width:899px) {
  .topbar { margin:8px 0 0; padding:0 16px; flex-wrap:wrap; }
  .topbar nav { flex-wrap:wrap; gap:4px 16px; font-size:14px; }
  .home,.hero-wrap { padding:16px 8px; }
  .hero,.categories,.home-posts { width:100%; }
  .categories,.io,.post-layout { grid-template-columns:1fr; }
  .tile-grid,.grid-3,.opt-groups { grid-template-columns:repeat(2,1fr); }
  .tool-art { display:none; }
  .page { width:auto; margin:0 16px; }
  .category { margin:8px 0 0; padding:16px; }
  .category-bar { flex-direction:column; align-items:stretch; }
  .category-bar p { margin-left:0; }
  .small-search { width:100%; }
  .toc { position:static; order:0; }
  footer { padding:24px 16px; }
}
@media (max-width:599px) {
  .quick-grid,.tile-grid,.grid-3,.opt-groups,.cat-actions { grid-template-columns:1fr; }
  .quick-grid { grid-template-columns:1fr 1fr; gap:8px; }
  .quick { padding:12px 8px; font-size:14px; }
  .topbar nav > a:not(.btn) { font-size:14px; }
  .cover-lg { aspect-ratio:16/9; }
}
@media (prefers-reduced-motion:reduce) { *,*::before,*::after { transition:none!important; } }