/* aitcore.net — VoIP bandwidth optimization */
:root {
  --ink: #13263B;
  --slate: #5B6B7C;
  --paper: #EEF2F5;
  --white: #FFFFFF;
  --signal: #1747D6;
  --signal-dark: #0F35A6;
  --amber: #F2A33A;
  --line: #D3DCE4;
  --radius-s: 6px;
  --radius-l: 14px;
  --font-head: "Sora", "Segoe UI", Arial, sans-serif;
  --font-body: "IBM Plex Sans", "Segoe UI", Arial, sans-serif;
}
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; font-family: var(--font-body); font-size: 1.0625rem; line-height: 1.6; color: var(--ink); background: var(--white); }
img { max-width: 100%; height: auto; display: block; }
a { color: var(--signal); }
a:hover { color: var(--signal-dark); }
:focus-visible { outline: 3px solid var(--amber); outline-offset: 2px; }
h1, h2, h3 { font-family: var(--font-head); line-height: 1.15; margin: 0 0 .5em; letter-spacing: -0.02em; }
h1 { font-size: clamp(2.2rem, 5vw, 3.6rem); font-weight: 700; }
h2 { font-size: clamp(1.5rem, 3vw, 2rem); font-weight: 600; }
h3 { font-size: 1.15rem; font-weight: 600; }
p { margin: 0 0 1em; }
.wrap { width: min(1120px, 100% - 2.5rem); margin-inline: auto; }
.narrow { max-width: 68ch; }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }
.skip { position: absolute; left: -999px; top: 0; background: var(--ink); color: #fff; padding: .5rem 1rem; z-index: 10; }
.skip:focus { left: 1rem; }

/* Buttons */
.btn { display: inline-block; font: 600 1rem/1 var(--font-body); padding: .85rem 1.3rem; border-radius: var(--radius-s); background: var(--signal); color: #fff; text-decoration: none; border: 2px solid var(--signal); cursor: pointer; }
.btn:hover { background: var(--signal-dark); border-color: var(--signal-dark); color: #fff; }
.btn-ghost { background: transparent; color: var(--signal); }
.btn-ghost:hover { background: var(--signal); color: #fff; }
.btn-amber { background: var(--amber); border-color: var(--amber); color: var(--ink); }
.btn-amber:hover { background: #E08E1F; border-color: #E08E1F; color: var(--ink); }
.btn-small { padding: .6rem 1rem; font-size: .95rem; }

/* Header */
.site-header { border-bottom: 1px solid var(--line); background: var(--white); position: sticky; top: 0; z-index: 5; }
.header-inner { display: flex; align-items: center; justify-content: space-between; gap: 1rem; min-height: 72px; }
.site-nav { display: flex; align-items: center; gap: 1.5rem; }
.site-nav a:not(.btn) { color: var(--ink); text-decoration: none; font-weight: 500; padding: .25rem 0; border-bottom: 2px solid transparent; }
.site-nav a:not(.btn):hover, .site-nav a[aria-current="page"] { border-bottom-color: var(--signal); }
.nav-toggle { display: none; font: 600 1rem var(--font-body); background: none; border: 1px solid var(--line); border-radius: var(--radius-s); padding: .5rem .9rem; color: var(--ink); cursor: pointer; }

/* Hero */
.hero { background: var(--paper); padding: clamp(3rem, 8vw, 6rem) 0; }
.hero-grid { display: grid; grid-template-columns: 1.05fr 1fr; gap: 3.5rem; align-items: center; }
.hero h1 { max-width: 14ch; }
.lead { font-size: 1.2rem; color: var(--slate); max-width: 52ch; }
.actions { display: flex; flex-wrap: wrap; gap: .75rem; margin-top: 1.75rem; }

/* Pipe visual: the one moving element on the site */
.pipe { margin: 0; background: var(--ink); color: #fff; border-radius: var(--radius-l); padding: 2rem 1.75rem 1.5rem; }
.pipe-row { margin-bottom: 1.75rem; }
.pipe-label { display: flex; justify-content: space-between; align-items: baseline; margin-bottom: .6rem; }
.pipe-label span { color: #A9B8C8; }
.pipe-label strong { font-family: var(--font-head); font-size: 1.4rem; }
.pipe-track { position: relative; height: 56px; background: #22385A; border-radius: 28px; overflow: hidden; }
.pipe-thin { height: 14px; width: var(--w, 12%); min-width: 60px; background: var(--signal); border-radius: 7px; }
.flow { position: absolute; inset: 0; background-image: radial-gradient(circle, rgba(255,255,255,.55) 2px, transparent 2.5px); background-size: 18px 18px; animation: flow 1.6s linear infinite; }
.pipe-wide .flow { background-image: radial-gradient(circle, #F2A33A 3px, transparent 3.5px); background-size: 14px 14px; }
.pipe-thin .flow { background-size: 14px 14px; background-position: 0 50%; }
@keyframes flow { to { background-position-x: 18px; } }
.pipe figcaption { color: #A9B8C8; font-size: .95rem; border-top: 1px solid #2C4468; padding-top: 1rem; }

/* Sections */
.section { padding: clamp(3rem, 7vw, 5rem) 0; }
.section-alt { background: var(--paper); }
.section-title { margin-bottom: .4em; }
.section-intro { color: var(--slate); max-width: 60ch; margin-bottom: 2rem; }
.page-head { background: var(--paper); padding: 3.5rem 0 2.5rem; }
.note { color: var(--slate); font-size: .95rem; }
.split { display: grid; grid-template-columns: 1fr 1fr; gap: 3rem; align-items: start; }

/* Savings ladder (a real sequence, so it is numbered) */
.ladder { list-style: none; counter-reset: rung; padding: 0; margin: 0; border-top: 1px solid var(--line); }
.rung { counter-increment: rung; display: grid; grid-template-columns: 2.5rem 1.4fr 1fr 9rem; gap: 1.25rem; align-items: center; padding: 1.5rem 0; border-bottom: 1px solid var(--line); }
.rung::before { content: counter(rung); font: 700 1.5rem var(--font-head); color: var(--signal); }
.rung-text h3 { margin-bottom: .25rem; }
.rung-text p { margin: 0; color: var(--slate); font-size: 1rem; }
.rung-bar { height: 12px; background: var(--paper); border-radius: 6px; overflow: hidden; }
.rung-bar span { display: block; height: 100%; background: var(--signal); border-radius: 6px; }
.rung-num { text-align: right; }
.rung-num strong { display: block; font: 600 1.25rem var(--font-head); }
.rung-num span { color: var(--slate); font-size: .9rem; }

.checks { list-style: none; padding: 0; margin: 0; }
.checks li { padding: 0 0 1rem 1.75rem; position: relative; }
.checks li::before { content: ""; position: absolute; left: 0; top: .45em; width: 10px; height: 10px; border-radius: 50%; background: var(--amber); }

.cta-band { background: var(--signal); color: #fff; padding: 2.5rem 0; }
.cta-inner { display: flex; justify-content: space-between; align-items: center; gap: 1.5rem; flex-wrap: wrap; }
.cta-inner p { margin: 0; font: 600 1.3rem/1.35 var(--font-head); max-width: 40ch; }

/* Packet anatomy */
.packet { display: flex; height: 64px; border-radius: var(--radius-s); overflow: hidden; margin: 1rem 0 .75rem; font-size: .9rem; font-weight: 600; }
.packet-small { width: 23%; min-width: 220px; }
.seg { display: flex; align-items: center; justify-content: center; padding: 0 .4rem; white-space: nowrap; overflow: hidden; }
.seg-l2 { background: #A9B8C8; color: var(--ink); }
.seg-hdr { background: var(--amber); color: var(--ink); }
.seg-voice { background: var(--signal); color: #fff; }
.packet + .note { margin-bottom: 2.5rem; }
.feature-list { display: grid; grid-template-columns: repeat(3, 1fr); gap: 2.5rem 3rem; }
.feature-list article { border-top: 3px solid var(--ink); padding-top: 1rem; }
.feature-list p { color: var(--slate); margin: 0; }

/* Calculator */
.calc { display: grid; grid-template-columns: 1fr 1.15fr; gap: 3rem; align-items: start; }
.calc-form, .contact-form { display: grid; gap: 1.1rem; }
label { display: grid; gap: .35rem; font-weight: 600; font-size: .98rem; }
label.check { display: flex; align-items: center; gap: .6rem; font-weight: 500; }
input[type="text"], input[type="email"], input[type="number"], select, textarea {
  font: 400 1rem var(--font-body); color: var(--ink); background: #fff; border: 1px solid #B7C4D1; border-radius: var(--radius-s); padding: .7rem .8rem; width: 100%;
}
input:focus, select:focus, textarea:focus { border-color: var(--signal); }
input[type="checkbox"] { width: 1.15rem; height: 1.15rem; accent-color: var(--signal); }
.opt { font-weight: 400; color: var(--slate); }
.calc-result { background: var(--ink); color: #fff; border-radius: var(--radius-l); padding: 2rem; }
.big-saving { font: 700 clamp(4rem, 10vw, 6.5rem)/1 var(--font-head); letter-spacing: -0.04em; margin-bottom: 1.5rem; color: var(--amber); }
.big-saving small { display: block; font: 500 1.05rem var(--font-body); letter-spacing: 0; color: #A9B8C8; margin-top: .5rem; }
.result-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem 1.5rem; margin: 0 0 1.5rem; }
.result-grid dt { color: #A9B8C8; font-size: .9rem; }
.result-grid dd { margin: 0; font: 600 1.25rem var(--font-head); }
.result-extra { font-size: 1.1rem; }
.calc-result .note { color: #A9B8C8; }
.calc-result .btn-ghost { color: #fff; border-color: #fff; }
.calc-result .btn-ghost:hover { background: #fff; color: var(--ink); }

/* Pricing table */
.table-scroll { overflow-x: auto; }
.plans { width: 100%; border-collapse: collapse; min-width: 640px; }
.plans th, .plans td { padding: 1rem 1.25rem; text-align: left; border-bottom: 1px solid var(--line); vertical-align: top; }
.plans thead th { border-bottom: 2px solid var(--ink); }
.plans tbody th { font-weight: 600; color: var(--slate); }
.plans .featured { background: var(--paper); }
.plan-name { display: block; font: 600 1.1rem var(--font-head); }
.plan-price { display: block; font: 700 2rem var(--font-head); margin-top: .5rem; }
.plan-per { display: block; color: var(--slate); font-weight: 400; font-size: .9rem; }

/* Contact */
.hp { position: absolute; left: -9999px; }
.field-err { color: #B42318; font-weight: 500; font-size: .92rem; }
.alert { border-radius: var(--radius-s); padding: 1rem 1.25rem; margin-bottom: 1.25rem; }
.alert-ok { background: #E6F4EA; border-left: 4px solid #1E7B3A; }
.alert-err { background: #FDECEA; border-left: 4px solid #B42318; }
.contact-aside { background: var(--paper); padding: 1.75rem; border-radius: var(--radius-l); }

/* Footer */
.site-footer { background: var(--ink); color: #C9D4DF; padding-top: 3rem; }
.site-footer a { color: #fff; text-decoration: none; }
.site-footer a:hover { text-decoration: underline; }
.footer-grid { display: grid; grid-template-columns: 2fr 1fr 1fr; gap: 2rem; }
.footer-grid ul { list-style: none; padding: 0; margin: 0; display: grid; gap: .4rem; }
.footer-h { font: 600 1rem var(--font-head); color: #fff; }
.footer-note { margin-top: 1rem; max-width: 32ch; }
.footer-base { border-top: 1px solid #2C4468; margin-top: 2.5rem; padding: 1.25rem 0; font-size: .9rem; }
.footer-base p { margin: 0; }

/* Responsive */
@media (max-width: 900px) {
  .hero-grid, .split, .calc { grid-template-columns: 1fr; }
  .feature-list { grid-template-columns: 1fr 1fr; }
  .rung { grid-template-columns: 2rem 1fr; }
  .rung-bar, .rung-num { grid-column: 2; text-align: left; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 760px) {
  .nav-toggle { display: block; }
  .site-nav { display: none; position: absolute; top: 72px; left: 0; right: 0; background: #fff; flex-direction: column; align-items: stretch; padding: 1rem 1.25rem 1.5rem; gap: .75rem; border-bottom: 1px solid var(--line); }
  .site-nav.open { display: flex; }
  .site-nav .btn { text-align: center; }
  .feature-list, .footer-grid, .result-grid { grid-template-columns: 1fr; }
}
@media (prefers-reduced-motion: reduce) {
  .flow { animation: none; }
}