:root {
  --navy-950: #081b1e;
  --navy-900: #0d2427;
  --teal-600: #0f8b8d;
  --teal-500: #14a3a6;
  --teal-glow: #5fd9d4;
  --paper: #f2f7f7;
  --card: #ffffff;
  --ink: #0b1e20;
  --ink-soft: #4a6265;
  --ink-faint: #8aa0a2;
  --line: rgba(11, 30, 32, 0.12);
  font-variant-numeric: tabular-nums;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: 'IBM Plex Sans', -apple-system, 'Segoe UI', sans-serif;
  font-size: 16px;
  line-height: 1.6;
}

h1, h2, h3 {
  font-family: 'Sora', 'IBM Plex Sans', sans-serif;
  font-weight: 700;
  line-height: 1.15;
  margin: 0 0 14px;
  text-wrap: balance;
}

.mono { font-family: 'JetBrains Mono', ui-monospace, monospace; }
a { color: var(--teal-600); text-decoration: none; }
a:hover { text-decoration: underline; }
.container { max-width: 1120px; margin: 0 auto; padding: 0 24px; }

/* ---- header ---- */
header.site-header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(8, 27, 30, 0.92);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid rgba(255,255,255,0.08);
}
.header-inner { display: flex; align-items: center; gap: 24px; padding: 16px 24px; }
.brand { display: flex; align-items: center; gap: 8px; color: #fff; font-family: 'Sora', sans-serif; font-weight: 700; font-size: 1.1rem; }
.brand .dot { width: 8px; height: 8px; border-radius: 50%; background: var(--teal-glow); box-shadow: 0 0 10px var(--teal-glow); }
.brand span { color: var(--teal-500); }
nav.site-nav { display: flex; gap: 28px; margin-left: auto; }
nav.site-nav a { color: rgba(255,255,255,0.78); font-size: .92rem; font-weight: 500; }
nav.site-nav a:hover { color: #fff; text-decoration: none; }
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: .5em;
  font-weight: 600; font-size: .92rem; padding: .68em 1.4em; border-radius: 8px;
  border: 1.5px solid transparent; cursor: pointer; font-family: inherit;
}
.btn.primary { background: var(--teal-600); color: #fff; }
.btn.primary:hover { background: var(--teal-500); }
.btn.on-dark { background: transparent; border-color: rgba(255,255,255,0.3); color: #fff; }
.btn.on-dark:hover { border-color: var(--teal-glow); color: var(--teal-glow); }
.btn.ghost { background: transparent; border-color: var(--line); color: var(--ink); }
.btn.ghost:hover { border-color: var(--teal-600); color: var(--teal-600); }
.btn:disabled { opacity: .55; cursor: not-allowed; }

/* ---- hero ---- */
section.hero {
  background: radial-gradient(ellipse 900px 500px at 15% -10%, rgba(20,163,166,0.35), transparent 60%), var(--navy-950);
  color: #fff; padding: 46px 0 80px; position: relative; overflow: hidden;
}
.hero-grid { display: grid; grid-template-columns: 1.1fr 0.9fr; gap: 48px; align-items: center; }
.eyebrow {
  display: inline-flex; align-items: center; gap: 8px; font-size: .78rem; font-weight: 700;
  text-transform: uppercase; letter-spacing: .08em; color: var(--teal-glow);
  background: rgba(20,163,166,0.12); border: 1px solid rgba(20,163,166,0.35);
  padding: 6px 14px; border-radius: 99px; margin-bottom: 20px;
}
.hero h1 { font-size: clamp(2.1rem, 4vw, 3.1rem); color: #fff; }
.hero h1 em { font-style: normal; color: var(--teal-glow); }
.hero p.lead { font-size: 1.1rem; color: rgba(255,255,255,0.75); max-width: 46ch; margin-bottom: 32px; }
.hero-ctas { display: flex; gap: 14px; flex-wrap: wrap; margin-bottom: 40px; }
.hero-stats { display: flex; gap: 32px; flex-wrap: wrap; }
.hero-stats div b { display: block; font-family: 'Sora', sans-serif; font-size: 1.5rem; color: #fff; }
.hero-stats div span { font-size: .82rem; color: rgba(255,255,255,0.6); }

.hero-panel {
  background: var(--navy-900); border: 1px solid rgba(255,255,255,0.1); border-radius: 14px;
  padding: 22px; box-shadow: 0 30px 60px rgba(0,0,0,0.4);
}
.hero-panel .panel-head { display: flex; align-items: center; gap: 8px; margin-bottom: 16px; }
.hero-panel .panel-head .pip { width: 9px; height: 9px; border-radius: 50%; }
.hero-panel .panel-head .pip:nth-child(1) { background: #e5534b; }
.hero-panel .panel-head .pip:nth-child(2) { background: #e5b93f; }
.hero-panel .panel-head .pip:nth-child(3) { background: #3fb950; }
.hero-panel pre {
  margin: 0; font-family: 'JetBrains Mono', monospace; font-size: .8rem; line-height: 1.7;
  color: #9fe7e4; white-space: pre-wrap; word-break: break-word;
}
.hero-panel .k { color: #6fd6d1; } .hero-panel .s { color: #f2c078; } .hero-panel .c { color: #6b8a8c; }

/* ---- sections ---- */
section { padding: 88px 0; }
.section-head { max-width: 640px; margin: 0 auto 52px; text-align: center; }
.section-head .eyebrow { background: rgba(15,139,141,0.08); border-color: rgba(15,139,141,0.25); color: var(--teal-600); }
.section-head h2 { font-size: clamp(1.6rem, 3vw, 2.1rem); }
.section-head p { color: var(--ink-soft); font-size: 1.05rem; }

section.problem { background: var(--card); border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.problem-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 40px; }
.problem-col h3 { font-size: 1rem; text-transform: uppercase; letter-spacing: .04em; color: var(--ink-faint); margin-bottom: 18px; }
.problem-col.solution h3 { color: var(--teal-600); }
.problem-item { display: flex; gap: 12px; padding: 14px 0; border-bottom: 1px solid var(--line); }
.problem-item:last-child { border-bottom: none; }
.problem-item .mark { flex: none; width: 22px; height: 22px; border-radius: 50%; display: flex; align-items: center; justify-content: center; font-size: .75rem; font-weight: 700; }
.problem-col:not(.solution) .mark { background: #fbeae7; color: #b3402f; }
.problem-col.solution .mark { background: #e2f4f0; color: var(--teal-600); }

.feature-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.feature-card { background: var(--card); border: 1px solid var(--line); border-radius: 14px; padding: 26px; }
.feature-card .icon {
  width: 40px; height: 40px; border-radius: 10px; background: linear-gradient(135deg, var(--teal-600), var(--teal-500));
  display: flex; align-items: center; justify-content: center; margin-bottom: 16px; color: #fff;
}
.feature-card .icon svg { width: 21px; height: 21px; }
.feature-card h3 { font-size: 1.02rem; margin-bottom: 8px; }
.feature-card p { color: var(--ink-soft); font-size: .92rem; margin: 0; }

section.flow { background: var(--navy-950); color: #fff; }
section.flow .section-head p { color: rgba(255,255,255,0.65); }
section.flow .section-head .eyebrow { background: rgba(20,163,166,0.12); border-color: rgba(20,163,166,0.35); color: var(--teal-glow); }
.flow-steps { display: grid; grid-template-columns: repeat(4, 1fr); gap: 0; position: relative; }
.flow-step { padding: 0 16px; text-align: center; position: relative; }
.flow-step .num {
  width: 44px; height: 44px; border-radius: 50%; background: rgba(20,163,166,0.15); border: 1.5px solid var(--teal-500);
  color: var(--teal-glow); display: flex; align-items: center; justify-content: center; font-family: 'Sora', sans-serif;
  font-weight: 700; margin: 0 auto 16px;
}
.flow-step h3 { font-size: .95rem; color: #fff; }
.flow-step p { font-size: .84rem; color: rgba(255,255,255,0.6); margin: 0; }
.flow-arrow { position: absolute; top: 22px; right: -6%; color: rgba(255,255,255,0.25); font-size: 1.3rem; }
.flow-step:last-child .flow-arrow { display: none; }

.pricing-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; align-items: stretch; }
.price-card { background: var(--card); border: 1px solid var(--line); border-radius: 16px; padding: 30px 26px; display: flex; flex-direction: column; }
.price-card.featured { border-color: var(--teal-600); box-shadow: 0 16px 40px rgba(15,139,141,0.16); position: relative; }
.price-card.featured::before {
  content: 'Phổ biến nhất'; position: absolute; top: -12px; left: 26px; background: var(--teal-600); color: #fff;
  font-size: .72rem; font-weight: 700; padding: 4px 12px; border-radius: 99px; text-transform: uppercase; letter-spacing: .03em;
}
.price-card h3 { font-size: 1.1rem; margin-bottom: 4px; }
.price-card .price { font-family: 'Sora', sans-serif; font-size: 1.4rem; font-weight: 700; color: var(--teal-600); margin-bottom: 6px; }
.price-card .price-note { color: var(--ink-faint); font-size: .82rem; margin-bottom: 22px; }
.price-card ul { list-style: none; margin: 0 0 26px; padding: 0; flex: 1; }
.price-card li { display: flex; gap: 10px; padding: 7px 0; font-size: .9rem; color: var(--ink-soft); }
.price-card li::before { content: '✓'; color: var(--teal-600); font-weight: 700; flex: none; }

section.contact { background: var(--card); border-top: 1px solid var(--line); }
.contact-grid { display: grid; grid-template-columns: 0.85fr 1.15fr; gap: 56px; align-items: start; }
.contact-info h2 { font-size: 1.7rem; }
.contact-info p { color: var(--ink-soft); }
.contact-list { list-style: none; padding: 0; margin: 26px 0 0; }
.contact-list li { padding: 10px 0; border-top: 1px solid var(--line); font-size: .92rem; }
.contact-list li b { display: block; color: var(--ink-faint); font-size: .74rem; text-transform: uppercase; letter-spacing: .04em; margin-bottom: 2px; }

form#contactForm { display: grid; gap: 16px; }
.field-row { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.field label { display: block; font-size: .82rem; font-weight: 600; color: var(--ink-soft); margin-bottom: 6px; }
.field input, .field textarea {
  width: 100%; padding: 11px 13px; border: 1px solid var(--line); border-radius: 8px; font: inherit;
  background: var(--paper); color: var(--ink);
}
.field textarea { resize: vertical; min-height: 110px; }
.form-msg { font-size: .88rem; display: none; padding: 10px 14px; border-radius: 8px; }
.form-msg.show.ok { display: block; background: #e2f4f0; color: var(--teal-600); }
.form-msg.show.err { display: block; background: #fbeae7; color: #b3402f; }

footer.site-footer { background: var(--navy-950); color: rgba(255,255,255,0.55); padding: 40px 0; font-size: .86rem; }
.footer-inner { display: flex; justify-content: space-between; align-items: center; flex-wrap: wrap; gap: 12px; }
footer.site-footer a { color: rgba(255,255,255,0.75); }

@media (max-width: 860px) {
  nav.site-nav { display: none; }
  .hero-grid, .problem-grid, .contact-grid { grid-template-columns: 1fr; }
  .feature-grid, .pricing-grid { grid-template-columns: 1fr; }
  .flow-steps { grid-template-columns: 1fr; gap: 28px; }
  .flow-arrow { display: none; }
  .field-row { grid-template-columns: 1fr; }
}