:root{
  --bg-deep:#0F1115;
  --bg-panel:#171A21;
  --bg-panel-2:#1E222B;
  --border:#2A2F3A;
  --text-primary:#E9E8E3;
  --text-muted:#9498A3;
  --accent:#F2C14E;
  --accent-ink:#3A2E05;
  --accent-2:#6C8EF5;
  --guest:#6FCF97;
  --danger:#E5735E;
  --radius-s:8px;
  --radius-m:14px;
}

*{box-sizing:border-box;}
html,body{margin:0;padding:0;overflow-x:hidden;}
body{
  background:var(--bg-deep);
  color:var(--text-primary);
  font-family:'Inter',sans-serif;
  line-height:1.55;
  -webkit-font-smoothing:antialiased;
}
h1,h2,h3,.logo,.btn,.pill,.nav a{font-family:'Space Grotesk',sans-serif;}
code,.mono,.code-block,.chat-bubble .code{font-family:'JetBrains Mono',monospace;}

a{color:var(--accent-2);}
::selection{background:var(--accent);color:var(--accent-ink);}
:focus-visible{outline:2px solid var(--accent-2);outline-offset:2px;}

/* ---------- layout shells ---------- */
.wrap{max-width:1120px;margin:0 auto;padding:0 28px;}

header{
  position:sticky;top:0;z-index:40;
  background:rgba(15,17,21,.9);
  backdrop-filter:blur(8px);
  border-bottom:1px solid var(--border);
}
.topbar{display:flex;align-items:center;justify-content:space-between;padding:16px 0;}
.logo{font-size:22px;font-weight:700;letter-spacing:.2px;display:flex;align-items:center;gap:8px;color:var(--text-primary);text-decoration:none;}
.logo .dot{width:9px;height:9px;border-radius:50%;background:var(--accent);}

.nav{display:flex;gap:26px;}
.nav a{color:var(--text-muted);text-decoration:none;font-size:15px;font-weight:500;}
.nav a:hover{color:var(--text-primary);}

.auth-area{display:flex;align-items:center;gap:12px;}

.btn{
  border:none;cursor:pointer;font-weight:600;font-size:14.5px;
  border-radius:var(--radius-s);padding:10px 18px;
  display:inline-flex;align-items:center;gap:8px;
  transition:transform .12s ease, background .15s ease, opacity .15s ease;
}
.btn:active{transform:scale(.97);}
.btn-primary{background:var(--accent);color:var(--accent-ink);}
.btn-primary:hover{background:#f5cd6c;}
.btn-ghost{background:transparent;color:var(--text-primary);border:1px solid var(--border);}
.btn-ghost:hover{border-color:var(--text-muted);}
.btn-danger{background:transparent;color:var(--danger);border:1px solid var(--border);}
.btn-danger:hover{border-color:var(--danger);}
.btn-block{width:100%;justify-content:center;}
.btn-sm{padding:7px 12px;font-size:13px;}

/* avatar + dropdown */
.account{position:relative;}
.avatar-btn{
  display:flex;align-items:center;gap:9px;background:var(--bg-panel-2);
  border:1px solid var(--border);border-radius:999px;padding:6px 12px 6px 6px;
  cursor:pointer;color:var(--text-primary);font-family:'Inter',sans-serif;font-weight:500;font-size:14px;
}
.avatar-circle{
  width:26px;height:26px;border-radius:50%;background:var(--accent-2);
  display:flex;align-items:center;justify-content:center;color:#0F1115;font-weight:700;font-size:12px;flex-shrink:0;
}
.badge-guest{
  font-size:11px;font-weight:600;color:var(--guest);background:rgba(111,207,151,.12);
  border:1px solid rgba(111,207,151,.35);padding:1px 7px;border-radius:999px;margin-left:2px;
}
.dropdown{
  position:absolute;right:0;top:calc(100% + 10px);width:230px;
  background:var(--bg-panel-2);border:1px solid var(--border);border-radius:var(--radius-m);
  box-shadow:0 12px 30px rgba(0,0,0,.4);overflow:hidden;display:none;
}
.dropdown.open{display:block;}
.dropdown-item{
  display:flex;align-items:center;gap:10px;width:100%;background:none;border:none;text-align:left;
  color:var(--text-primary);font-family:'Inter',sans-serif;font-size:14px;font-weight:500;
  padding:12px 14px;cursor:pointer;border-bottom:1px solid var(--border);
}
.dropdown-item:last-child{border-bottom:none;}
.dropdown-item:hover{background:rgba(255,255,255,.03);}
.dropdown-item.danger{color:var(--danger);}

/* ---------- hero ---------- */
.hero{padding:76px 0 64px;display:grid;grid-template-columns:1.05fr .95fr;gap:56px;align-items:center;}
.hero > div{min-width:0;} /* chặn grid item bị "blowout" theo nội dung bên trong (khối code) */
.eyebrow-tag{
  display:inline-flex;align-items:center;gap:8px;color:var(--text-muted);
  font-size:13.5px;font-weight:500;margin-bottom:18px;
}
.eyebrow-tag .icon-spark{width:12px;height:12px;background:var(--accent);
  clip-path:polygon(50% 0%,61% 39%,100% 50%,61% 61%,50% 100%,39% 61%,0% 50%,39% 39%);}
.hero h1{font-size:44px;line-height:1.12;font-weight:700;margin:0 0 20px;max-width:520px;}
.hero p.lead{color:var(--text-muted);font-size:17px;max-width:460px;margin:0 0 30px;}
.hero-ctas{display:flex;gap:12px;}

.mock-window{
  background:var(--bg-panel);border:1px solid var(--border);border-radius:var(--radius-m);
  overflow:hidden;box-shadow:0 30px 60px rgba(0,0,0,.35);min-width:0;max-width:100%;
}
.mock-titlebar{display:flex;align-items:center;gap:7px;padding:12px 14px;border-bottom:1px solid var(--border);}
.mock-dot{width:9px;height:9px;border-radius:50%;background:#3A3F4B;}
.mock-titlebar span{margin-left:8px;color:var(--text-muted);font-size:12.5px;font-family:'JetBrains Mono',monospace;}
.mock-body{padding:18px;display:flex;flex-direction:column;gap:14px;max-height:420px;overflow-y:auto;}

.chat-bubble{max-width:88%;padding:11px 14px;border-radius:12px;font-size:13.5px;position:relative;}
.chat-bubble.user{align-self:flex-end;background:var(--accent-2);color:#101323;border-bottom-right-radius:3px;}
.chat-bubble.moi{align-self:flex-start;background:var(--bg-panel-2);border:1px solid var(--border);border-bottom-left-radius:3px;}
.code-block{
  background:#0B0D11;border:1px solid var(--border);border-radius:8px;padding:12px 14px;
  font-size:12.5px;color:#B8E986;overflow-x:auto;margin-top:8px;white-space:pre;
}
.code-block .kw{color:var(--accent-2);}
.code-block .fn{color:var(--accent);}

.mock-inputbar{display:flex;gap:8px;padding:12px 14px;border-top:1px solid var(--border);}
.mock-inputbar input{
  flex:1;background:var(--bg-panel-2);border:1px solid var(--border);border-radius:999px;
  padding:9px 14px;color:var(--text-primary);font-size:13px;font-family:'Inter',sans-serif;
}
.mock-inputbar input::placeholder{color:var(--text-muted);}
.send-btn{
  width:36px;height:36px;border-radius:50%;background:var(--accent);border:none;
  display:flex;align-items:center;justify-content:center;cursor:pointer;flex-shrink:0;
}

/* ---------- features ---------- */
.features{padding:50px 0 80px;border-top:1px solid var(--border);}
.features h2{font-size:26px;margin:0 0 34px;max-width:480px;}
.feature-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:20px;}
.feature-card{
  background:var(--bg-panel);border:1px solid var(--border);border-radius:var(--radius-m);
  padding:22px;
}
.feature-card h3{font-size:16.5px;margin:14px 0 8px;}
.feature-card p{color:var(--text-muted);font-size:14px;margin:0;}
.feature-icon{width:32px;height:32px;position:relative;}

.icon-layers::before,.icon-layers::after{content:"";position:absolute;left:0;width:32px;height:8px;
  background:var(--accent);clip-path:polygon(50% 0,100% 50%,50% 100%,0 50%);}
.icon-layers::before{top:0;opacity:.4;}
.icon-layers::after{top:12px;opacity:1;}

.icon-review{width:30px;height:24px;border:2.5px solid var(--accent-2);border-radius:6px;position:relative;}
.icon-review::before{content:"";position:absolute;top:6px;left:5px;width:14px;height:2.5px;background:var(--accent-2);box-shadow:0 6px 0 var(--accent-2);}

.icon-bolt{width:16px;height:26px;background:var(--guest);
  clip-path:polygon(55% 0,0 55%,40% 55%,20% 100%,100% 40%,55% 40%);}

/* ---------- footer ---------- */
footer{border-top:1px solid var(--border);padding:26px 0;color:var(--text-muted);font-size:13.5px;}
.footer-row{display:flex;justify-content:space-between;align-items:center;flex-wrap:wrap;gap:10px;}
.footer-links{display:flex;gap:18px;}
.footer-links button{background:none;border:none;color:var(--text-muted);font-size:13.5px;cursor:pointer;padding:0;font-family:'Inter',sans-serif;}
.footer-links button:hover{color:var(--text-primary);}

/* ---------- icons (vẽ bằng CSS thuần, không dùng emoji hệ thống) ---------- */
.icon-gear{width:18px;height:18px;border-radius:50%;flex-shrink:0;
  background:repeating-conic-gradient(currentColor 0deg 18deg, transparent 18deg 36deg);}
.icon-gear::after{content:"";display:block;width:8px;height:8px;margin:5px;border-radius:50%;background:var(--bg-panel-2);}
.dropdown-item .icon-gear{color:var(--text-muted);}

.icon-user{width:16px;height:16px;position:relative;flex-shrink:0;color:var(--text-muted);}
.icon-user::before{content:"";position:absolute;top:0;left:4px;width:8px;height:8px;border-radius:50%;background:currentColor;}
.icon-user::after{content:"";position:absolute;bottom:0;left:0;width:16px;height:8px;border-radius:8px 8px 0 0;background:currentColor;}

.icon-logout{width:16px;height:16px;position:relative;flex-shrink:0;color:var(--danger);}
.icon-logout::before{content:"";position:absolute;left:0;top:1px;width:10px;height:14px;border:2px solid currentColor;border-right:none;border-radius:3px 0 0 3px;}
.icon-logout::after{content:"";position:absolute;right:0;top:6px;width:8px;height:2px;background:currentColor;box-shadow:3px -3px 0 -2px currentColor, 3px 3px 0 -2px currentColor;}

.icon-link{width:16px;height:16px;position:relative;flex-shrink:0;color:var(--accent-2);}
.icon-link::before,.icon-link::after{content:"";position:absolute;width:9px;height:9px;border:2px solid currentColor;border-radius:5px;}
.icon-link::before{top:1px;left:0;transform:rotate(45deg);}
.icon-link::after{bottom:1px;right:0;transform:rotate(45deg);}

.icon-close{width:14px;height:14px;position:relative;cursor:pointer;flex-shrink:0;}
.icon-close::before,.icon-close::after{content:"";position:absolute;top:6px;left:0;width:14px;height:2px;background:currentColor;}
.icon-close::before{transform:rotate(45deg);}
.icon-close::after{transform:rotate(-45deg);}

.icon-google{width:18px;height:18px;border-radius:50%;flex-shrink:0;
  background:conic-gradient(#4285F4 0deg 90deg,#EA4335 90deg 180deg,#FBBC05 180deg 270deg,#34A853 270deg 360deg);
  position:relative;}
.icon-google::after{content:"";position:absolute;inset:4px;border-radius:50%;background:#fff;}

.icon-caret{width:0;height:0;border-left:4px solid transparent;border-right:4px solid transparent;border-top:5px solid currentColor;flex-shrink:0;}

.icon-send{width:0;height:0;border-top:6px solid transparent;border-bottom:6px solid transparent;border-left:10px solid #101323;margin-left:2px;}

/* ---------- modals ---------- */
.modal-overlay{
  position:fixed;inset:0;background:rgba(6,7,10,.72);display:none;
  align-items:center;justify-content:center;z-index:100;padding:20px;
}
.modal-overlay.open{display:flex;}
.modal{
  background:var(--bg-panel);border:1px solid var(--border);border-radius:var(--radius-m);
  width:100%;max-width:440px;max-height:86vh;display:flex;flex-direction:column;
  box-shadow:0 30px 70px rgba(0,0,0,.5);
}
.modal.modal-wide{max-width:620px;}
.modal-head{display:flex;align-items:center;justify-content:space-between;padding:18px 20px;border-bottom:1px solid var(--border);}
.modal-head h3{margin:0;font-size:17px;}
.modal-body{padding:20px;overflow-y:auto;}
.modal-foot{padding:16px 20px;border-top:1px solid var(--border);display:flex;justify-content:flex-end;gap:10px;}

.field{margin-bottom:16px;}
.field label{display:block;font-size:13.5px;color:var(--text-muted);margin-bottom:7px;font-weight:500;}
.field input,.field select,.field textarea{
  width:100%;background:var(--bg-panel-2);border:1px solid var(--border);border-radius:var(--radius-s);
  padding:10px 12px;color:var(--text-primary);font-family:'Inter',sans-serif;font-size:14px;
}
.field small{display:block;color:var(--text-muted);font-size:12px;margin-top:6px;}

.persona-grid{display:grid;grid-template-columns:1fr 1fr;gap:10px;margin-bottom:6px;}
.persona-card{
  border:1px solid var(--border);border-radius:var(--radius-s);padding:12px;cursor:pointer;
  background:var(--bg-panel-2);
}
.persona-card.active{border-color:var(--accent);background:rgba(242,193,78,.06);}
.persona-card h4{margin:0 0 4px;font-size:14px;}
.persona-card p{margin:0;font-size:12px;color:var(--text-muted);}

.divider-text{display:flex;align-items:center;gap:10px;color:var(--text-muted);font-size:12.5px;margin:16px 0;}
.divider-text::before,.divider-text::after{content:"";flex:1;height:1px;background:var(--border);}

.tos-body h4{font-size:14.5px;margin:20px 0 6px;color:var(--text-primary);}
.tos-body h4:first-child{margin-top:0;}
.tos-body p,.tos-body li{font-size:13.5px;color:var(--text-muted);margin:0 0 8px;}
.tos-body{font-size:13.5px;}
.tos-updated{color:var(--text-muted);font-size:12.5px;margin-bottom:14px;}

.toast{
  position:fixed;bottom:24px;left:50%;transform:translateX(-50%) translateY(20px);
  background:var(--bg-panel-2);border:1px solid var(--border);color:var(--text-primary);
  padding:12px 20px;border-radius:999px;font-size:13.5px;opacity:0;pointer-events:none;
  transition:opacity .2s ease, transform .2s ease;z-index:200;
}
.toast.show{opacity:1;transform:translateX(-50%) translateY(0);}

@media(max-width:860px){
  .hero{grid-template-columns:1fr;padding:40px 0;}
  .feature-grid{grid-template-columns:1fr;}
  .nav{display:none;}
  .hero h1{font-size:32px;}
}

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