/* ============================================================
   A9 BUSINESS — Design System (Wave 1 staging)
   Tokens + components. Nguồn màu/font: Nhận diện thương hiệu A9 BUSINESS.
   Style: professional · systematic · minimal.
   ============================================================ */

/* ---- Tokens: LIGHT (bare :root = complete light palette) ---- */
:root{
  --ground:#F7F8F6;
  --surface:#FFFFFF;
  --surface-2:#EDF2EE;
  --ink:#16232A;
  --ink-soft:#4C5B58;
  --ink-faint:#7A8A84;
  --line:#DBE4DD;
  --line-strong:#C4D1C7;
  --brand:#0F6E40;
  --brand-deep:#074A2A;
  --brand-forest:#04301C;
  --brand-forest-2:#0D5231;
  --accent:#B87C22;          /* "economics" — chỉ dùng cho số liệu/metric */
  --on-brand:#FFFFFF;
  --on-forest:#EAF3EC;

  --font-display:'Be Vietnam Pro',system-ui,'Segoe UI',Arial,sans-serif;
  --font-body:'Be Vietnam Pro',system-ui,'Segoe UI',Arial,sans-serif;
  --font-mono:'IBM Plex Mono',ui-monospace,'Cascadia Mono','Courier New',monospace;

  --step--1:0.82rem;
  --step-0:1.0625rem;
  --step-1:1.33rem;
  --step-2:1.66rem;
  --step-3:2.15rem;
  --step-4:2.9rem;

  --sp:1rem;
  --radius:10px;
  --radius-sm:6px;
  --shadow:0 1px 2px rgba(16,35,25,.06),0 8px 24px -12px rgba(16,35,25,.14);
  --maxw:1120px;
}

/* ---- Tokens: DARK via OS (only when no explicit light choice) ---- */
@media (prefers-color-scheme:dark){
  :root:not([data-theme="light"]){
    --ground:#0B120F;
    --surface:#121B17;
    --surface-2:#182420;
    --ink:#E9F0EB;
    --ink-soft:#AEBDB4;
    --ink-faint:#7E8E85;
    --line:#25332C;
    --line-strong:#33443A;
    --brand:#37B96E;
    --brand-deep:#0F6E40;
    --brand-forest:#031F13;
    --brand-forest-2:#0B4429;
    --accent:#E0A44A;
    --on-brand:#04180F;
    --on-forest:#EAF3EC;
    --shadow:0 1px 2px rgba(0,0,0,.4),0 10px 28px -14px rgba(0,0,0,.6);
  }
}
/* ---- Tokens: DARK via explicit toggle ---- */
:root[data-theme="dark"]{
  --ground:#0B120F;
  --surface:#121B17;
  --surface-2:#182420;
  --ink:#E9F0EB;
  --ink-soft:#AEBDB4;
  --ink-faint:#7E8E85;
  --line:#25332C;
  --line-strong:#33443A;
  --brand:#37B96E;
  --brand-deep:#0F6E40;
  --brand-forest:#031F13;
  --brand-forest-2:#0B4429;
  --accent:#E0A44A;
  --on-brand:#04180F;
  --on-forest:#EAF3EC;
  --shadow:0 1px 2px rgba(0,0,0,.4),0 10px 28px -14px rgba(0,0,0,.6);
}

*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{
  margin:0;
  background:var(--ground);
  color:var(--ink);
  font-family:var(--font-body);
  font-size:var(--step-0);
  line-height:1.6;
  -webkit-font-smoothing:antialiased;
}
img{max-width:100%;display:block}
a{color:var(--brand-deep);text-decoration:none}
a:hover{text-decoration:underline}
:focus-visible{outline:2px solid var(--brand);outline-offset:2px;border-radius:2px}

h1,h2,h3,h4{font-family:var(--font-display);line-height:1.15;text-wrap:balance;margin:0;font-weight:700;letter-spacing:-.01em}
h1{font-size:var(--step-4)}
h2{font-size:var(--step-3)}
h3{font-size:var(--step-1)}
p{margin:0}

.wrap{max-width:var(--maxw);margin-inline:auto;padding-inline:clamp(1.1rem,4vw,2rem)}
.prose{max-width:64ch}
.stack>*+*{margin-top:var(--sp)}

/* ---- Eyebrow (mono, systematic label) ---- */
.eyebrow{
  font-family:var(--font-mono);
  font-size:var(--step--1);
  text-transform:uppercase;
  letter-spacing:.16em;
  color:var(--brand-deep);
  font-weight:500;
  display:inline-flex;align-items:center;gap:.5rem;
}
.eyebrow::before{content:"";width:1.6rem;height:1px;background:var(--line-strong)}

/* ---- Header / nav ---- */
.site-header{
  position:sticky;top:0;z-index:50;
  background:color-mix(in srgb,var(--ground) 88%,transparent);
  backdrop-filter:saturate(1.4) blur(10px);
  border-bottom:1px solid var(--line);
}
.nav{display:flex;align-items:center;gap:1.5rem;height:64px}
.brand{display:flex;align-items:center;gap:.6rem;font-family:var(--font-display);font-weight:800;letter-spacing:-.02em;color:var(--ink);font-size:1.15rem}
.brand:hover{text-decoration:none}
.brand .mark{
  width:30px;height:30px;border-radius:7px;flex:none;
  background:radial-gradient(120% 120% at 65% 30%,var(--brand-forest-2),var(--brand-forest));
  display:grid;place-items:center;color:#fff;font-weight:800;font-size:.85rem;font-family:var(--font-mono)
}
.brand small{font-family:var(--font-mono);font-weight:500;font-size:.6rem;letter-spacing:.14em;color:var(--ink-faint);text-transform:uppercase}
.nav-links{display:flex;gap:1.35rem;margin-left:auto;align-items:center}
.nav-links a{color:var(--ink-soft);font-size:.95rem;font-weight:500}
.nav-links a:hover{color:var(--ink);text-decoration:none}
@media(max-width:860px){.nav-links a:not(.btn){display:none}}

/* ---- Buttons ---- */
.btn{
  display:inline-flex;align-items:center;gap:.5rem;
  font-family:var(--font-display);font-weight:600;font-size:.98rem;
  padding:.7rem 1.25rem;border-radius:var(--radius-sm);
  border:1px solid transparent;cursor:pointer;transition:transform .08s ease,background .15s ease;
}
.btn:hover{text-decoration:none;transform:translateY(-1px)}
.btn-primary{background:var(--brand);color:var(--on-brand)}
.btn-primary:hover{background:var(--brand-deep)}
.btn-ghost{background:transparent;color:var(--ink);border-color:var(--line-strong)}
.btn-ghost:hover{background:var(--surface-2)}
.btn-on-forest{background:var(--on-forest);color:var(--brand-forest)}
.btn-lg{padding:.85rem 1.6rem;font-size:1.05rem}

/* ---- Sections ---- */
section{padding-block:clamp(3rem,7vw,5.5rem)}
.section-head{max-width:60ch;margin-bottom:2.2rem}
.section-head h2{margin-top:.7rem}
.section-head p{color:var(--ink-soft);margin-top:.6rem}
.divider{height:1px;background:var(--line);border:0}

/* ---- Hero ---- */
.hero{padding-top:clamp(2.5rem,6vw,4rem)}
.hero h1{max-width:16ch}
.hero .lede{font-size:var(--step-1);color:var(--ink-soft);max-width:52ch;margin-top:1.1rem;font-weight:400}
.hero .cta-row{display:flex;flex-wrap:wrap;gap:.75rem;margin-top:1.8rem}
.hero .tag{margin-top:1.6rem;font-family:var(--font-mono);font-size:var(--step--1);color:var(--ink-faint);letter-spacing:.04em}

/* ---- Painpoints ---- */
.grid-3{display:grid;grid-template-columns:repeat(3,1fr);gap:1rem}
@media(max-width:800px){.grid-3{grid-template-columns:1fr}}
.pain{padding:1.4rem;border:1px solid var(--line);border-radius:var(--radius);background:var(--surface)}
.pain .n{font-family:var(--font-mono);font-size:var(--step--1);color:var(--accent);letter-spacing:.1em}
.pain h3{margin:.6rem 0 .4rem;font-size:1.15rem}
.pain p{color:var(--ink-soft);font-size:.98rem}

/* ---- Funnel steps ---- */
.steps{display:grid;grid-template-columns:repeat(3,1fr);gap:1rem;counter-reset:s}
@media(max-width:800px){.steps{grid-template-columns:1fr}}
.step{position:relative;padding:1.4rem;border:1px solid var(--line);border-radius:var(--radius);background:var(--surface)}
.step::before{counter-increment:s;content:"0" counter(s);font-family:var(--font-mono);font-size:.8rem;color:var(--brand);letter-spacing:.1em}
.step h3{margin:.5rem 0 .3rem;font-size:1.1rem}
.step p{color:var(--ink-soft);font-size:.95rem}
.step .out{margin-top:.7rem;font-family:var(--font-mono);font-size:.78rem;color:var(--ink-faint)}

/* ---- Forest band (dark proof/cta) ---- */
.band{background:linear-gradient(160deg,var(--brand-forest-2),var(--brand-forest));color:var(--on-forest)}
.band h2,.band h3{color:#fff}
.band .eyebrow{color:#9ED9B4}
.band .eyebrow::before{background:rgba(255,255,255,.28)}
.band p{color:rgba(234,243,236,.85)}

/* ---- Metric tiles (proof) ---- */
.metrics{display:grid;grid-template-columns:repeat(3,1fr);gap:1rem;margin-top:1.6rem}
@media(max-width:800px){.metrics{grid-template-columns:1fr}}
.metric{padding:1.3rem;border-radius:var(--radius);background:rgba(255,255,255,.06);border:1px solid rgba(255,255,255,.14)}
.metric .v{font-family:var(--font-mono);font-size:1.35rem;color:#fff;font-weight:500}
.metric .v.pending{font-size:.82rem;color:var(--accent);letter-spacing:.04em;line-height:1.4}
.metric .k{font-size:.9rem;color:rgba(234,243,236,.8);margin-top:.5rem}

/* ---- Solution ladder / cards ---- */
.ladder{display:grid;gap:.75rem}
.rung{
  display:grid;grid-template-columns:auto 1fr auto;gap:1.1rem;align-items:center;
  padding:1.15rem 1.25rem;border:1px solid var(--line);border-radius:var(--radius);background:var(--surface);
}
.rung:hover{border-color:var(--line-strong)}
.rung .lv{font-family:var(--font-mono);font-size:.78rem;color:var(--brand);letter-spacing:.08em;white-space:nowrap}
.rung h3{font-size:1.1rem}
.rung .who{color:var(--ink-soft);font-size:.92rem;margin-top:.15rem}
.rung .go{color:var(--brand-deep);font-family:var(--font-mono);font-size:.8rem;white-space:nowrap}
@media(max-width:640px){.rung{grid-template-columns:1fr;gap:.4rem}.rung .go{justify-self:start}}

.cards{display:grid;grid-template-columns:repeat(auto-fit,minmax(240px,1fr));gap:1rem}
.card{padding:1.4rem;border:1px solid var(--line);border-radius:var(--radius);background:var(--surface)}
.card h3{font-size:1.15rem;margin-bottom:.4rem}
.card p{color:var(--ink-soft);font-size:.95rem}
.card .lv{font-family:var(--font-mono);font-size:.75rem;color:var(--brand);letter-spacing:.08em}

/* ---- CTA band ---- */
.cta-band{text-align:center}
.cta-band .wrap{display:flex;flex-direction:column;align-items:center;gap:1.1rem}
.cta-band h2{max-width:20ch}

/* ---- Form ---- */
.form{display:grid;gap:1rem;max-width:560px}
.field{display:grid;gap:.4rem}
.field label{font-size:.9rem;font-weight:600}
.field .hint{font-size:.82rem;color:var(--ink-faint)}
.field input,.field select,.field textarea{
  font:inherit;padding:.7rem .85rem;border:1px solid var(--line-strong);border-radius:var(--radius-sm);
  background:var(--surface);color:var(--ink);
}
.field input:focus,.field select:focus,.field textarea:focus{border-color:var(--brand);outline:none}
fieldset{border:1px solid var(--line);border-radius:var(--radius);padding:1.1rem 1.2rem;margin:0}
legend{font-family:var(--font-mono);font-size:.78rem;text-transform:uppercase;letter-spacing:.1em;color:var(--brand-deep);padding-inline:.4rem}
.choices{display:grid;gap:.55rem;margin-top:.4rem}
.choice{display:flex;gap:.6rem;align-items:flex-start;padding:.6rem .8rem;border:1px solid var(--line);border-radius:var(--radius-sm);cursor:pointer}
.choice:hover{background:var(--surface-2)}

/* ---- Notice / staging banner ---- */
.staging-note{
  background:var(--surface-2);border:1px dashed var(--line-strong);border-radius:var(--radius-sm);
  padding:.7rem 1rem;font-family:var(--font-mono);font-size:.8rem;color:var(--ink-soft);
  display:flex;gap:.6rem;align-items:center;flex-wrap:wrap
}
.staging-note b{color:var(--accent);font-weight:600}
.pending-tag{font-family:var(--font-mono);font-size:.78rem;color:var(--accent);border:1px solid var(--accent);border-radius:4px;padding:.1rem .45rem;letter-spacing:.03em;white-space:nowrap}

/* ---- Breadcrumb ---- */
.crumb{font-family:var(--font-mono);font-size:.78rem;color:var(--ink-faint);letter-spacing:.04em;padding-top:1.4rem}
.crumb a{color:var(--ink-faint)}

/* ---- Definition rows / spec tables ---- */
.deflist{display:grid;gap:0;border:1px solid var(--line);border-radius:var(--radius);overflow:hidden}
.deflist .row{display:grid;grid-template-columns:220px 1fr;gap:1rem;padding:.9rem 1.1rem;border-top:1px solid var(--line)}
.deflist .row:first-child{border-top:0}
.deflist dt{font-weight:600;font-size:.92rem}
.deflist dd{margin:0;color:var(--ink-soft);font-size:.95rem}
@media(max-width:640px){.deflist .row{grid-template-columns:1fr;gap:.2rem}}

/* ---- Footer ---- */
.site-footer{background:var(--surface);border-top:1px solid var(--line);padding-block:2.5rem;margin-top:1rem}
.footer-grid{display:grid;grid-template-columns:1.4fr 1fr 1fr;gap:2rem}
@media(max-width:760px){.footer-grid{grid-template-columns:1fr}}
.site-footer h4{font-family:var(--font-mono);font-size:.75rem;text-transform:uppercase;letter-spacing:.12em;color:var(--ink-faint);margin-bottom:.8rem;font-weight:500}
.site-footer a{display:block;color:var(--ink-soft);font-size:.92rem;padding:.2rem 0}
.footer-legal{margin-top:2rem;padding-top:1.3rem;border-top:1px solid var(--line);font-size:.85rem;color:var(--ink-faint);display:flex;justify-content:space-between;gap:1rem;flex-wrap:wrap}
.footer-sep{font-size:.82rem;color:var(--ink-faint);max-width:52ch;margin-top:.4rem}

.two-col{display:grid;grid-template-columns:1.2fr 1fr;gap:2.5rem}
@media(max-width:760px){.two-col{grid-template-columns:1fr;gap:1.6rem}}

.list-check{list-style:none;padding:0;margin:0;display:grid;gap:.6rem}
.list-check li{display:flex;gap:.6rem;align-items:flex-start;color:var(--ink-soft)}
.list-check li::before{content:"→";color:var(--brand);font-family:var(--font-mono);flex:none}

@media(prefers-reduced-motion:reduce){*{transition:none!important}}