:root{
  --bg:#0f1115;--bg2:#151820;--card:#1b1f28;--line:#2c323e;
  --text:#e8eaed;--muted:#a5adba;--accent:#ff7a1a;--accent2:#ffb020;
  --green:#7bd8a4;--blue:#85b7ff;--maxw:1040px
}
*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth;scroll-padding-top:84px}
body{background:var(--bg);color:var(--text);font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"Helvetica Neue",Arial,sans-serif;line-height:1.75;font-size:16px}
a{color:inherit;text-decoration:none}.wrap{max-width:var(--maxw);margin:0 auto;padding:0 24px}
.skip{position:absolute;left:16px;top:-60px;background:var(--accent);color:#111;padding:10px 16px;border-radius:8px;z-index:100}.skip:focus{top:12px}
nav{position:sticky;top:0;z-index:50;background:rgba(15,17,21,.9);backdrop-filter:blur(12px);border-bottom:1px solid var(--line)}
.navrow{height:64px;display:flex;align-items:center;justify-content:space-between;gap:20px}.brand{font-weight:700;letter-spacing:.02em}.brand span{color:var(--accent)}
.navlinks{display:flex;align-items:center;gap:22px;color:var(--muted);font-size:.9rem}.navlinks a:hover{color:var(--text)}.navlinks .active{color:var(--accent2)}
.nav-cv{border:1px solid var(--accent);color:var(--accent2);padding:7px 14px;border-radius:9px;font-size:.85rem;font-weight:700}.nav-cv:hover{background:var(--accent);color:#111}
.toggle{display:none;width:42px;height:38px;border:1px solid var(--line);border-radius:9px;background:transparent;color:var(--text);cursor:pointer}.mobile{display:none;padding:8px 24px 18px;background:rgba(15,17,21,.98);border-bottom:1px solid var(--line)}.mobile.open{display:grid}.mobile a{padding:10px 4px;border-bottom:1px solid var(--line);color:var(--muted)}
/* padding-top chứ KHÔNG dùng dạng viết tắt "padding:24px 0 0": viết tắt sẽ ghi đè cả
   lề ngang của .wrap, làm breadcrumb thụt ra trái 24px so với nav, h1 và nội dung. */
.breadcrumb{padding-top:24px;color:var(--muted);font-size:.87rem}.breadcrumb a:hover{color:var(--accent2)}.breadcrumb span{padding:0 7px;color:#606876}
.hero{padding:60px 0 66px;background:radial-gradient(760px 380px at 84% 0%,rgba(255,122,26,.17),transparent 68%),linear-gradient(180deg,#151820,var(--bg));border-bottom:1px solid var(--line)}
.eyebrow{color:var(--accent2);font-size:.78rem;font-weight:700;letter-spacing:.15em;text-transform:uppercase;margin-bottom:13px}
h1{font-size:clamp(1.95rem,3.4vw,3.05rem);line-height:1.2;font-weight:700;letter-spacing:-.02em;max-width:900px}.hero .lead{font-size:1.12rem;color:var(--muted);max-width:820px;margin-top:22px}
.tags{display:flex;gap:8px;flex-wrap:wrap;margin-top:24px}.tag{padding:5px 10px;border-radius:999px;background:rgba(133,183,255,.08);border:1px solid rgba(133,183,255,.22);color:var(--blue);font-size:.76rem;font-weight:700}.tag.live{color:var(--green);border-color:rgba(123,216,164,.24);background:rgba(123,216,164,.07)}
.quick{display:grid;grid-template-columns:repeat(4,1fr);gap:12px;margin-top:32px}.quick div{border:1px solid var(--line);background:rgba(255,255,255,.02);border-radius:12px;padding:16px}.quick b{display:block;color:var(--accent2);font-size:.76rem;letter-spacing:.08em;text-transform:uppercase;margin-bottom:4px}.quick span{font-size:.91rem;color:#d3d7dd}
.layout{display:grid;grid-template-columns:minmax(0,1fr) 250px;gap:52px;padding:64px 24px 84px}.content section{padding:0 0 52px;margin-bottom:52px;border-bottom:1px solid var(--line)}.content section:last-child{border-bottom:0;margin-bottom:0;padding-bottom:0}
h2{font-size:clamp(1.4rem,2.3vw,2.05rem);line-height:1.25;font-weight:700;letter-spacing:-.02em;margin-bottom:17px}h3{font-size:1.1rem;line-height:1.3;font-weight:650;margin:25px 0 9px}.content p{color:#c3c8d0;margin:0 0 15px}.content ul,.content ol{padding-left:22px;color:#c3c8d0;margin:12px 0 18px}.content li{margin:7px 0}.content strong{color:var(--text)}
h4{font-size:.84rem;line-height:1.4;font-weight:750;letter-spacing:.1em;text-transform:uppercase;color:var(--accent2);margin:28px 0 12px}
.callout{border-left:3px solid var(--accent);background:rgba(255,122,26,.06);padding:17px 20px;border-radius:0 12px 12px 0;margin:22px 0;color:#d9dde3}.warning{border-left-color:var(--accent2);background:rgba(255,176,32,.055)}
.flow{display:flex;align-items:stretch;gap:7px;flex-wrap:wrap;margin:22px 0}.flow span{display:flex;align-items:center;background:var(--card);border:1px solid var(--line);border-radius:9px;padding:9px 12px;font-size:.86rem;color:#d5d9df}.flow i{font-style:normal;color:var(--accent);align-self:center}
.metrics{display:grid;grid-template-columns:repeat(2,1fr);gap:12px;margin:22px 0}.metric{border:1px solid var(--line);background:var(--card);border-radius:12px;padding:19px}.metric b{display:block;font-size:1.35rem;color:var(--accent2);line-height:1.2;margin-bottom:6px}.metric span{color:var(--muted);font-size:.88rem}
.proof{display:grid;grid-template-columns:repeat(2,1fr);gap:12px}.proof>div,.proof>.proof-link{border:1px dashed #3a414d;border-radius:12px;padding:18px;color:var(--muted);font-size:.91rem}.proof b{display:block;color:var(--text);margin-bottom:5px}.proof-link{display:block;text-decoration:none;transition:border-color .18s ease,background .18s ease,transform .18s ease}.proof-link:hover{border-color:var(--blue);background:rgba(133,183,255,.06);transform:translateY(-1px)}.proof-open{display:block;margin-top:12px;color:var(--blue);font-size:.78rem;font-weight:750}
.visual-card{border:1px solid var(--line);border-radius:16px;background:linear-gradient(145deg,rgba(27,31,40,.96),rgba(17,20,26,.98));padding:22px;margin:26px 0;overflow:hidden}.visual-card figcaption{color:var(--muted);font-size:.84rem;line-height:1.55;margin-top:16px}.visual-kicker{font-size:.72rem;font-weight:750;letter-spacing:.12em;text-transform:uppercase;color:var(--accent2);margin-bottom:14px}
.product-shot{margin:24px 0 0}.product-shot-frame{overflow:hidden;border:1px solid #343b48;border-radius:14px;background:#f5f6f8}.product-shot img{display:block;width:100%;height:auto}.product-shot figcaption{margin-top:12px;color:var(--muted);font-size:.84rem;line-height:1.55}.product-shot figcaption a{color:var(--blue);text-decoration:underline;text-underline-offset:3px}.product-shot figcaption a:hover{color:var(--text)}
.evidence-actions{display:flex;flex-wrap:wrap;gap:10px;margin:16px 0 0}.evidence-actions a{display:inline-flex;align-items:center;gap:7px;border:1px solid rgba(133,183,255,.38);border-radius:9px;padding:9px 13px;background:rgba(133,183,255,.075);color:var(--blue);font-size:.82rem;font-weight:700;text-decoration:none}.evidence-actions a::after{content:"↗";font-size:.9em}.evidence-actions a:hover{border-color:var(--blue);background:rgba(133,183,255,.13);color:var(--text)}
.decision-track,.roadmap-track{display:grid;grid-template-columns:1fr auto 1fr auto 1fr;align-items:stretch;gap:9px}.decision-track>i,.roadmap-track>i{font-style:normal;color:var(--accent);align-self:center}.decision-node,.roadmap-stage{display:flex;flex-direction:column;min-width:0;border:1px solid #343b48;border-radius:12px;padding:15px;background:rgba(255,255,255,.02)}.decision-node>span{font-size:.7rem;font-weight:800;letter-spacing:.1em;color:var(--blue)}.decision-node>b,.roadmap-stage>b{margin:4px 0;color:var(--text);line-height:1.3}.decision-node>small,.roadmap-stage>small{color:var(--muted);line-height:1.45}.decision-node.accent-node{border-color:rgba(255,122,26,.65);background:rgba(255,122,26,.07)}
.roadmap-stage{position:relative;padding-top:42px}.stage-status{position:absolute;top:12px;left:14px;font-size:.64rem;line-height:1;padding:5px 7px;border-radius:999px;color:var(--muted);background:#242a35}.roadmap-stage.current{border-color:rgba(123,216,164,.55);background:rgba(123,216,164,.055)}.roadmap-stage.current .stage-status{color:var(--green);background:rgba(123,216,164,.1)}
.funnel-steps{list-style:none;padding:0!important;margin:14px 0 20px!important;display:grid;gap:9px}.funnel-steps li{display:grid;grid-template-columns:34px 1fr;gap:12px;align-items:start;border:1px solid var(--line);border-radius:12px;padding:13px 15px;margin:0!important;background:rgba(255,255,255,.018)}.funnel-steps li>span{display:grid;place-items:center;width:30px;height:30px;border-radius:50%;background:rgba(255,122,26,.12);color:var(--accent2);font-weight:800}.funnel-steps b{display:block;color:var(--text);margin-bottom:2px}.funnel-steps small{display:block;color:var(--muted);line-height:1.5}.input-chips{display:flex;flex-wrap:wrap;gap:8px;margin:0 0 20px}.input-chips span{border:1px solid rgba(133,183,255,.25);background:rgba(133,183,255,.065);color:var(--blue);font-size:.78rem;font-weight:650;padding:6px 10px;border-radius:999px}
.branch-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:12px}.branch-grid>div{border:1px solid var(--line);border-radius:12px;padding:17px;background:var(--card)}.branch-grid b{display:block;margin-bottom:5px}.branch-grid p{font-size:.88rem;margin:0}.validation-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:8px;margin-bottom:22px}.validation-grid span{position:relative;border:1px dashed #39414d;border-radius:10px;padding:10px 12px 10px 31px;color:var(--muted);font-size:.82rem;line-height:1.4}.validation-grid span:before{content:"✓";position:absolute;left:11px;color:var(--green);font-weight:800}
.test-head{display:flex;justify-content:space-between;align-items:center;gap:20px;padding-bottom:18px;border-bottom:1px solid var(--line)}.test-head>div{display:flex;flex-direction:column}.test-head span{color:var(--muted);font-size:.66rem;font-weight:750;letter-spacing:.1em}.test-head b{font-size:1.1rem;margin-top:3px}.test-head>strong{color:var(--green);font-size:1.1rem;letter-spacing:.12em;border:1px solid rgba(123,216,164,.45);background:rgba(123,216,164,.08);padding:8px 12px;border-radius:9px}.test-metrics{display:grid;grid-template-columns:repeat(4,1fr);gap:9px;margin:18px 0}.test-metrics>div{border:1px solid #323946;border-radius:10px;padding:13px;text-align:center}.test-metrics b{display:block;color:var(--accent2);font-size:1.3rem}.test-metrics small{display:block;color:var(--muted);font-size:.72rem;line-height:1.35}.test-log{display:grid;grid-template-columns:auto 1fr auto;align-items:center;gap:7px 10px;color:var(--muted);font-size:.78rem}.test-log i{height:1px;background:#343b47}.test-log b{color:var(--green);font-size:.72rem}
.side{position:relative}.toc{position:sticky;top:88px;border:1px solid var(--line);background:var(--card);border-radius:14px;padding:19px}.toc b{display:block;color:var(--accent2);font-size:.78rem;letter-spacing:.1em;text-transform:uppercase;margin-bottom:10px}.toc a{display:block;color:var(--muted);font-size:.88rem;padding:6px 0;border-bottom:1px solid rgba(44,50,62,.7)}.toc a:last-child{border-bottom:0}.toc a:hover{color:var(--text)}
.case-nav{display:grid;grid-template-columns:1fr auto 1fr;gap:12px;align-items:stretch;padding:0 24px 72px;max-width:var(--maxw);margin:0 auto}.case-nav a{border:1px solid var(--line);background:var(--card);border-radius:12px;padding:16px 18px;font-size:.9rem;color:var(--muted)}.case-nav a:hover{border-color:var(--accent);color:var(--text)}.case-nav a:nth-child(2){display:flex;align-items:center;text-align:center;color:var(--accent2);font-weight:600;letter-spacing:.01em}.case-nav .next{text-align:right}
.back-top{position:fixed;right:22px;bottom:22px;z-index:40;border:1px solid rgba(255,122,26,.5);background:rgba(27,31,40,.96);color:var(--accent2);border-radius:999px;padding:10px 15px;font-weight:600;cursor:pointer;box-shadow:0 8px 24px rgba(0,0,0,.3);opacity:0;visibility:hidden;transform:translateY(10px);transition:.2s}.back-top.show{opacity:1;visibility:visible;transform:none}.back-top:hover{background:var(--accent);color:#111}
footer{padding:30px 0;border-top:1px solid var(--line);color:var(--muted);text-align:center;font-size:.85rem}footer b{color:var(--accent)}
:focus-visible{outline:3px solid rgba(255,176,32,.65);outline-offset:3px}
@media(max-width:880px){.layout{grid-template-columns:1fr}.side{display:none}.quick{grid-template-columns:repeat(2,1fr)}}
@media(max-width:720px){.navlinks,.nav-cv{display:none}.toggle{display:block}.hero{padding:44px 0 54px}.hero h1{line-height:1.18;letter-spacing:-.015em}.layout{padding-top:48px}.metrics,.proof,.branch-grid,.validation-grid{grid-template-columns:1fr}.decision-track,.roadmap-track{grid-template-columns:1fr}.decision-track>i,.roadmap-track>i{transform:rotate(90deg);justify-self:center}.test-metrics{grid-template-columns:repeat(2,1fr)}.case-nav{grid-template-columns:1fr}.case-nav a:nth-child(2){justify-content:center;order:3}.case-nav .next{text-align:left}.back-top{right:14px;bottom:14px}}
@media(max-width:480px){.wrap,.layout,.case-nav{padding-left:18px;padding-right:18px}.quick{grid-template-columns:1fr}.flow{display:grid}.flow i{display:none}.visual-card{padding:17px}.test-head{align-items:flex-start}.test-head>strong{font-size:.9rem}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}.back-top{transition:none}}