:root{
  --bg:#f7f9fa; --paper:#ffffff; --ink:#231f20; --muted:#5f6b6c; --line:#d4e1df;
  --teal:#3fbfb7; --teal-ink:#126e68; --mint:#ebf6f7; --warn:#8a5a12; --warn-bg:#fbf1de;
  --f-body:"Manrope","Segoe UI",system-ui,sans-serif; --f-mono:"JetBrains Mono",ui-monospace,Consolas,monospace;
}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]){
  --bg:#111617; --paper:#182022; --ink:#eef4f3; --muted:#a3b3b2; --line:#2c3a3b;
  --teal:#4fcfc7; --teal-ink:#7fded8; --mint:#1d3133; --warn:#f0c27a; --warn-bg:#33291a; color-scheme:dark}}
:root[data-theme="dark"]{
  --bg:#111617; --paper:#182022; --ink:#eef4f3; --muted:#a3b3b2; --line:#2c3a3b;
  --teal:#4fcfc7; --teal-ink:#7fded8; --mint:#1d3133; --warn:#f0c27a; --warn-bg:#33291a; color-scheme:dark}
*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{background:var(--bg);color:var(--ink);font-family:var(--f-body);font-size:16px;line-height:1.6;padding-inline:16px;padding-block:28px 64px}
.wrap{max-width:820px;margin:0 auto;display:flex;flex-direction:column;gap:28px}
h1,h2,h3{text-wrap:balance;line-height:1.2;margin:0}
h1{font-size:clamp(28px,6vw,42px);font-weight:800;letter-spacing:-.02em}
h2{font-size:22px;font-weight:800}
h3{font-size:17px;font-weight:800}
p{margin:0;max-width:68ch}
.eyebrow{font-size:12px;font-weight:700;letter-spacing:.12em;text-transform:uppercase;color:var(--teal-ink)}
header{display:flex;flex-direction:column;gap:14px;border-bottom:2px solid var(--ink);padding-bottom:22px}
.lead{font-size:18px;color:var(--ink)}
.facts{display:flex;flex-wrap:wrap;gap:8px 18px;color:var(--muted);font-size:14px}
.facts b{color:var(--ink)}
.progress{position:sticky;top:env(safe-area-inset-top,0px);z-index:5;background:var(--bg);padding-block:10px;display:flex;align-items:center;gap:12px;font-size:14px;font-weight:700}
.bar{flex:1;height:10px;border-radius:5px;background:var(--line);overflow:hidden}
.bar i{display:block;height:100%;width:0;background:var(--teal);transition:width .3s}
.rules{display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:12px}
.rule{background:var(--mint);border-radius:10px;padding:14px 16px;display:flex;flex-direction:column;gap:6px;min-width:0}
.rule b{font-size:15px}
.rule p{font-size:14px;color:var(--muted)}
.stage{display:flex;flex-direction:column;gap:14px}
.stage-head{display:flex;align-items:baseline;gap:12px;flex-wrap:wrap}
.stage-num{font-family:var(--f-mono);font-size:13px;color:var(--paper);background:var(--ink);border-radius:6px;padding:2px 8px}
.stage-goal{color:var(--muted);font-size:15px}
.card{background:var(--paper);border:1.5px solid var(--line);border-radius:12px;padding:18px 18px 16px;display:flex;flex-direction:column;gap:12px;min-width:0}
.card.done{border-color:var(--teal)}
.card-top{display:flex;gap:12px;align-items:flex-start}
.card-top input{width:22px;height:22px;margin-top:2px;accent-color:var(--teal);flex:none;cursor:pointer}
.card-top label{cursor:pointer;display:flex;flex-direction:column;gap:2px;min-width:0}
.tid{font-family:var(--f-mono);font-size:12px;color:var(--teal-ink)}
.sec{display:grid;grid-template-columns:96px 1fr;gap:4px 14px;font-size:15px}
.sec dt{font-size:12px;font-weight:700;letter-spacing:.06em;text-transform:uppercase;color:var(--muted);padding-top:3px}
.sec dd{margin:0;min-width:0}
.sec ul{margin:0;padding-left:18px}
.prompt{position:relative;background:var(--mint);border-radius:8px;padding:38px 14px 12px;font-family:var(--f-mono);font-size:13.5px;line-height:1.55;white-space:pre-wrap;overflow-wrap:anywhere}
.copy{position:absolute;top:8px;right:8px;font:600 12px var(--f-body);background:var(--paper);color:var(--ink);border:1px solid var(--line);border-radius:6px;padding:3px 9px;cursor:pointer}
.copy:focus-visible,.card-top input:focus-visible{outline:2px solid var(--teal);outline-offset:2px}
.trap{background:var(--warn-bg);color:var(--ink);border-radius:8px;padding:10px 14px;font-size:14px}
.trap b{color:var(--warn)}
.boss{border:2px solid var(--ink);box-shadow:6px 6px 0 var(--teal)}
footer{border-top:1px solid var(--line);padding-top:18px;display:flex;flex-direction:column;gap:12px;font-size:15px}
table{border-collapse:collapse;width:100%;font-size:14px}
th,td{border-bottom:1px solid var(--line);padding:8px 10px;text-align:left;vertical-align:top}
th{font-size:12px;letter-spacing:.06em;text-transform:uppercase;color:var(--muted)}
.tbl{overflow-x:auto}
@media (max-width:520px){.sec{grid-template-columns:1fr}.sec dt{padding-top:6px}}
@media (prefers-reduced-motion:reduce){.bar i{transition:none}}
.part{display:flex;flex-direction:column;gap:6px;padding:18px 20px;border-radius:12px;background:var(--ink);color:var(--paper)}
.part .eyebrow{color:var(--teal)}
.part p{color:var(--paper);opacity:.85;font-size:15px}
.map{display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:12px}
.map div{border:1.5px solid var(--line);border-radius:10px;padding:14px 16px;background:var(--paper);display:flex;flex-direction:column;gap:4px;min-width:0}
.map b{font-size:15px}
.map span{font-size:13px;color:var(--teal-ink);font-weight:700}
.map p{font-size:14px;color:var(--muted)}
.skilltag{font-size:14px;background:var(--mint);border-left:3px solid var(--teal);padding:6px 12px;border-radius:0 6px 6px 0}
.skilltag b{color:var(--teal-ink)}
.note{font-size:14px;color:var(--muted)}
/* các bước làm */
ol.steps{margin:0;padding:0;list-style:none;counter-reset:st;display:flex;flex-direction:column;gap:8px}
ol.steps li{counter-increment:st;display:block;position:relative;padding-left:36px;min-height:26px}
ol.steps li::before{content:counter(st);position:absolute;left:0;top:1px;width:24px;height:24px;border-radius:50%;background:var(--ink);color:var(--paper);font:700 13px/24px var(--f-body);text-align:center}
.k{display:inline-block;font:600 13px var(--f-body);border:1.5px solid var(--ink);border-radius:6px;padding:0 7px;background:var(--paper);white-space:nowrap}
/* hình minh hoạ */
figure{margin:0;display:flex;flex-direction:column;gap:6px}
figcaption{font-size:13px;color:var(--muted)}
.mock{--m-bg:#f4f6f6;--m-pn:#ffffff;--m-ln:#d9e2e1;--m-tx:#231f20;--m-mu:#7b8786;background:var(--m-bg);color:var(--m-tx);border:1.5px solid var(--ink);border-radius:10px;overflow:hidden;font-size:13px;line-height:1.4;position:relative}
.mock .tb{display:flex;align-items:center;gap:6px;padding:7px 10px;background:var(--m-pn);border-bottom:1px solid var(--m-ln)}
.mock .tb i{width:9px;height:9px;border-radius:50%;background:var(--m-ln)}
.mock .tb span{margin-left:8px;color:var(--m-mu);font-size:12px;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.mock .body{display:grid;grid-template-columns:120px 1fr;min-height:180px}
.mock .side{background:var(--m-pn);border-right:1px solid var(--m-ln);padding:10px 8px;display:flex;flex-direction:column;gap:6px;font-size:12px}
.mock .main{padding:12px;display:flex;flex-direction:column;gap:10px;min-width:0}
.mock .btn{position:relative;display:inline-flex;align-items:center;gap:4px;border:1px solid var(--m-ln);background:var(--m-pn);border-radius:6px;padding:4px 8px;font-weight:600;font-size:12px;width:max-content;max-width:100%}
.mock .btn.pri{background:#231f20;color:#fff;border-color:#231f20}
.mock .row{display:flex;gap:8px;align-items:center;flex-wrap:wrap}
.mock .box{position:relative;background:var(--m-pn);border:1px solid var(--m-ln);border-radius:8px;padding:8px 10px}
.mock .muted{color:var(--m-mu)}
.mock .hl{outline:2.5px dashed #e0533d;outline-offset:2px}
.pin{position:absolute;top:-10px;right:-10px;width:22px;height:22px;border-radius:50%;background:#e0533d;color:#fff;font:800 12px/22px var(--f-body);text-align:center;box-shadow:0 0 0 2px #fff;z-index:2}
.mock .tree{font-family:var(--f-mono);font-size:12px;line-height:1.7}
.mock .tree .on{background:#fdecc8;border-radius:4px;padding:0 4px}
.mock .seg{border-left:4px solid;padding:4px 8px;margin:4px 0;background:#fff}
.frames{display:grid;grid-template-columns:repeat(4,1fr);gap:8px}
.frames img{width:100%;border-radius:8px;border:1px solid var(--line);display:block}
.duo{display:grid;grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:12px}
.duo img{width:100%;border-radius:10px;border:1px solid var(--line);display:block}
.phone{position:relative;width:180px;aspect-ratio:9/16;border:2px solid var(--ink);border-radius:16px;background:#f2f2f2;overflow:hidden;margin:0 auto}
.phone .safe{position:absolute;left:8%;right:20%;top:9%;bottom:24%;border:2px dashed #2a9d8f;background:rgba(63,191,183,.15);display:flex;align-items:center;justify-content:center;text-align:center;font-size:11px;font-weight:700;color:#126e68;padding:4px}
.phone .rail{position:absolute;right:3%;top:38%;width:12%;bottom:24%;display:flex;flex-direction:column;gap:8px;align-items:center}
.phone .rail i{width:20px;height:20px;border-radius:50%;background:#bbb}
.phone .cap{position:absolute;left:5%;right:22%;bottom:5%;height:14%;background:rgba(0,0,0,.18);border-radius:6px;font-size:10px;color:#333;padding:4px}
.agents{display:flex;flex-direction:column;align-items:center;gap:0}
.agents .lead{padding:8px 14px;border:2px solid #231f20;background:#fff;border-radius:8px;font-weight:700}
.agents .stem{width:2px;height:16px;background:#231f20}
.agents .bus{display:grid;grid-template-columns:repeat(3,1fr);gap:8px;width:100%;border-top:2px solid #231f20;padding-top:14px;position:relative}
.agents .bus div{background:#fff;border:1.5px solid var(--m-ln);border-radius:8px;padding:6px;text-align:center;font-size:12px}
.agents .bus b{display:block;font-size:11px;color:#126e68}
@media (max-width:520px){.mock .body{grid-template-columns:1fr}.mock .side{flex-direction:row;flex-wrap:wrap;border-right:0;border-bottom:1px solid var(--m-ln)}.frames{grid-template-columns:repeat(2,1fr)}}

/* Phần riêng của ứng dụng: thanh trên, biểu mẫu, nút, thông báo, bài kiểm tra, bảng xếp hạng */
img{max-width:100%;height:auto}
a{color:var(--teal-ink)}
.top{display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:8px 16px;padding-bottom:14px;border-bottom:2px solid var(--ink)}
.brand{font-weight:800;font-size:17px;color:var(--ink);text-decoration:none}
.top nav{display:flex;flex-wrap:wrap;align-items:center;gap:6px 14px;font-size:14px;font-weight:600}
.top nav a{color:var(--ink);text-decoration:none}
.top nav a:hover{text-decoration:underline}
.top form{display:inline;margin:0}
.who{color:var(--muted);font-weight:600}
.linkbtn{background:none;border:0;padding:0;font:inherit;font-weight:600;color:var(--teal-ink);cursor:pointer;text-decoration:underline}
.btn-main,.btn-ghost{display:inline-block;font:700 15px var(--f-body);border-radius:8px;padding:10px 18px;cursor:pointer;text-decoration:none;text-align:center;border:2px solid var(--ink);min-height:44px}
.btn-main{background:var(--ink);color:var(--paper)}
.btn-ghost{background:var(--paper);color:var(--ink)}
.btn-main:focus-visible,.btn-ghost:focus-visible,.linkbtn:focus-visible,a:focus-visible,input:focus-visible{outline:2px solid var(--teal);outline-offset:2px}
.flash{border-radius:8px;padding:10px 14px;font-size:15px;background:var(--mint);border-left:4px solid var(--teal)}
.flash.error{background:var(--warn-bg);border-left-color:var(--warn)}
.form{display:flex;flex-direction:column;gap:14px;max-width:420px}
.form label{display:flex;flex-direction:column;gap:4px;font-size:14px;font-weight:700}
.form input[type=text],.form input[type=email],.form input[type=password]{font:400 16px var(--f-body);color:var(--ink);background:var(--paper);border:1.5px solid var(--line);border-radius:8px;padding:10px 12px;width:100%;min-height:44px}
.form .hint{font-size:13px;font-weight:400;color:var(--muted)}
.form-links{display:flex;flex-wrap:wrap;gap:6px 16px;font-size:14px}
.hero{display:flex;flex-direction:column;gap:12px}
.hero .lead{font-size:17px}
.me{display:flex;flex-direction:column;gap:6px}
.stage-list{display:flex;flex-direction:column;gap:10px}
.item{display:flex;gap:12px;align-items:flex-start;background:var(--paper);border:1.5px solid var(--line);border-radius:12px;padding:12px 14px;text-decoration:none;color:var(--ink);min-width:0}
.item:hover{border-color:var(--teal)}
.item.done{border-color:var(--teal)}
.item .tick{flex:none;width:22px;height:22px;border-radius:50%;border:2px solid var(--line);margin-top:1px;display:flex;align-items:center;justify-content:center;font-size:13px;font-weight:800;color:var(--paper)}
.item.done .tick{background:var(--teal);border-color:var(--teal)}
.item .meta{display:flex;flex-direction:column;gap:4px;min-width:0}
.item b{font-size:16px}
.badge{display:inline-block;width:max-content;max-width:100%;font-size:12px;font-weight:700;color:var(--teal-ink);background:var(--mint);border-radius:999px;padding:2px 10px}
.stage-count{font-size:13px;color:var(--muted);font-weight:700}
.page{display:flex;flex-direction:column;gap:18px}
.title-row{display:flex;flex-direction:column;gap:8px}
.blocks{display:flex;flex-direction:column;gap:14px}
.sec .prompt+.why{margin-top:10px}
.why{background:var(--mint);border-left:3px solid var(--teal);border-radius:0 8px 8px 0;padding:10px 14px;font-size:14px}
.why b{display:block;color:var(--teal-ink);margin-bottom:4px;font-size:13px}
.quiz{display:flex;flex-direction:column;gap:16px;border-top:2px solid var(--ink);padding-top:18px}
.q{border:1.5px solid var(--line);border-radius:12px;padding:14px 16px;margin:0;display:flex;flex-direction:column;gap:8px;min-width:0}
.q.wrong{border-color:var(--warn);background:var(--warn-bg)}
.q legend{font-weight:800;font-size:15px;padding:0 6px}
.q label{display:flex;gap:10px;align-items:flex-start;font-size:15px;cursor:pointer;padding:4px 0}
.q input{width:20px;height:20px;margin-top:2px;accent-color:var(--teal);flex:none}
.q-static{list-style:none;margin:0;padding:0;display:flex;flex-direction:column;gap:12px}
.q-static li{border:1.5px solid var(--line);border-radius:12px;padding:12px 16px;display:flex;flex-direction:column;gap:6px}
.q-static ul{margin:0;padding-left:20px;font-size:15px}
.ok{background:var(--mint);border:2px solid var(--teal);border-radius:12px;padding:14px 16px;display:flex;flex-direction:column;gap:10px}
.ok b{font-size:17px}
.board{width:100%}
.board td.num,.board th.num{width:56px;text-align:right}
.board td.pts,.board th.pts{width:72px;text-align:right}
.board tr.me-row td{background:var(--mint);font-weight:800}
.foot{border-top:1px solid var(--line);padding-top:14px;font-size:13px;color:var(--muted)}
.bar-wrap{display:flex;align-items:center;gap:12px;font-size:14px;font-weight:700}
.stage-note{font-size:14px;color:var(--muted)}
.prog-sticky{position:sticky;top:0;z-index:5}
.check-line{display:flex;gap:10px;align-items:center;font-size:14px;font-weight:700}
.item.done .tick::after{content:"";width:5px;height:10px;border:solid #fff;border-width:0 2.5px 2.5px 0;transform:rotate(45deg) translate(-1px,-1px)}
.item .state{font-size:12px;font-weight:700;color:var(--muted)}
.item.done .state{color:var(--teal-ink)}
.quiz-ro{display:flex;flex-direction:column;gap:10px;border-top:1px dashed var(--line);padding-top:12px}
.quiz-ro h4{margin:0;font-size:14px}
.cl-inline{display:flex;gap:8px 10px;align-items:center;flex-wrap:wrap}