/* RIA AI shared site styles. Brand kit v1.0 (2026-10-26): black / white / neutral grey.
   HEX and body font are still "to confirm" in the kit; Manrope + Noto Sans TC are the listed candidates. */
:root {
  --ink: #181818;
  --white: #ffffff;
  --mist: #f5f5f5;
  --gray: #737373;
  --line: #e4e4e4;
  --soft: #fafafa;
  --radius: 22px;
  --wrap: 1120px;
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body {
  margin: 0; background: var(--white); color: var(--ink);
  font: 400 17px/1.6 "Manrope", "Noto Sans TC", "PingFang HK", Arial, sans-serif;
}
img { max-width: 100%; display: block; }
a { color: inherit; }
.wrap { max-width: var(--wrap); margin: 0 auto; padding: 0 24px; }

/* language toggle: every bilingual string is a .en / .zh pair */
html[lang="zh-HK"] .en, html[lang="en"] .zh { display: none !important; }

/* header */
.top { position: sticky; top: 0; z-index: 20; background: rgba(255,255,255,.88); backdrop-filter: blur(14px); border-bottom: 1px solid var(--line); }
.top .wrap { display: flex; align-items: center; gap: 20px; height: 68px; }
.top .logo img { height: 30px; width: auto; }
.top .tag { font-size: 12px; letter-spacing: .14em; color: var(--gray); text-transform: uppercase; }
.top nav { margin-left: auto; display: flex; align-items: center; gap: 22px; font-size: 15px; }
.top nav a { text-decoration: none; color: var(--gray); }
.top nav a:hover { color: var(--ink); }
.lang { border: 1px solid var(--line); background: var(--white); border-radius: 99px; padding: 6px 12px; font: inherit; font-size: 13px; cursor: pointer; }

/* type */
.eyebrow { font-size: 12px; font-weight: 700; letter-spacing: .16em; text-transform: uppercase; color: var(--gray); margin: 0 0 16px; }
h1 { font-size: clamp(40px, 6.4vw, 76px); line-height: 1.04; letter-spacing: -.035em; font-weight: 800; margin: 0 0 24px; }
h2 { font-size: clamp(30px, 4.2vw, 50px); line-height: 1.1; letter-spacing: -.03em; font-weight: 800; margin: 0 0 18px; }
h3 { font-size: 20px; line-height: 1.3; letter-spacing: -.01em; margin: 0 0 8px; }
.lead { font-size: clamp(18px, 2vw, 21px); color: #404040; max-width: 620px; margin: 0 0 32px; }
.muted { color: var(--gray); }
.small { font-size: 14px; }

/* buttons */
.btns { display: flex; flex-wrap: wrap; gap: 12px; }
.btn { display: inline-flex; align-items: center; gap: 10px; padding: 15px 24px; border-radius: 99px; font-weight: 700; font-size: 16px; text-decoration: none; border: 1px solid var(--ink); }
.btn.dark { background: var(--ink); color: var(--white); }
.btn.light { background: var(--white); color: var(--ink); }
.btn:hover { transform: translateY(-1px); }

/* sections */
section { padding: 104px 0; }
section.mist { background: var(--mist); }
section.ink { background: var(--ink); color: var(--white); }
section.ink .muted, section.ink .lead { color: #a3a3a3; }
section.ink .eyebrow { color: #8a8a8a; }
.head { max-width: 720px; margin-bottom: 52px; }

/* hero */
.hero { padding: 84px 0 0; overflow: hidden; }
.hero .grid { display: grid; grid-template-columns: 1.1fr .9fr; gap: 40px; align-items: end; }
.hero .copy { padding-bottom: 96px; }
.hero .art { position: relative; align-self: end; }
.hero .art img.character { width: 100%; max-width: 460px; margin-left: auto; }
.bubble { position: absolute; background: var(--white); border: 1px solid var(--line); border-radius: 18px; padding: 14px 16px; font-size: 14px; line-height: 1.45; box-shadow: 0 10px 30px rgba(0,0,0,.07); max-width: 260px; }
.bubble b { display: block; font-size: 11px; letter-spacing: .12em; text-transform: uppercase; color: var(--gray); margin-bottom: 4px; }

/* cards */
.cards { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.cards.two { grid-template-columns: repeat(2, 1fr); }
.cards.four { grid-template-columns: repeat(4, 1fr); }
.card { background: var(--white); border: 1px solid var(--line); border-radius: var(--radius); padding: 28px; }
section.mist .card { border-color: transparent; }
section.ink .card { background: #222; border-color: #2e2e2e; }
.card .num { font-size: 13px; font-weight: 800; color: var(--gray); margin-bottom: 18px; display: block; }
.card p { margin: 0; color: #4a4a4a; font-size: 16px; }
section.ink .card p { color: #b5b5b5; }
.card .big { font-size: 44px; font-weight: 800; letter-spacing: -.03em; line-height: 1; margin-bottom: 12px; display: block; }

/* RIA letters */
.ria { display: grid; grid-template-columns: repeat(3, 1fr); gap: 0; border-top: 1px solid var(--line); }
.ria > div { padding: 34px 28px 0 0; }
.ria .L { font-size: 64px; font-weight: 800; line-height: 1; margin-bottom: 18px; }
.ria .w { font-weight: 800; font-size: 13px; letter-spacing: .16em; text-transform: uppercase; color: var(--gray); margin-bottom: 8px; }

/* steps */
.steps { list-style: none; padding: 0; margin: 0; display: grid; gap: 12px; }
.steps li { display: grid; grid-template-columns: 56px 1fr auto; gap: 18px; align-items: center; background: var(--white); border-radius: 18px; padding: 20px 24px; }
.steps .n { width: 40px; height: 40px; border-radius: 50%; background: var(--ink); color: var(--white); display: grid; place-items: center; font-weight: 800; }
.steps .t { font-size: 13px; font-weight: 800; color: var(--gray); white-space: nowrap; }
.steps p { margin: 2px 0 0; color: var(--gray); font-size: 15px; }
.total { display: flex; justify-content: space-between; align-items: center; margin-top: 18px; padding: 22px 24px; border-radius: 18px; background: var(--ink); color: var(--white); font-weight: 800; }

/* chips + prompts */
.chips { display: flex; flex-wrap: wrap; gap: 10px; }
.chip { border: 1px solid var(--line); border-radius: 99px; padding: 9px 16px; font-size: 15px; background: var(--white); }
.prompts { display: grid; gap: 10px; }
.prompt { display: flex; justify-content: space-between; gap: 14px; background: var(--white); border: 1px solid var(--line); border-radius: 16px; padding: 16px 20px; font-weight: 700; }
.prompt span.arrow { color: var(--gray); }

/* compare */
.compare { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; }
.compare .card ol { margin: 14px 0 0; padding-left: 20px; color: var(--gray); }
.compare .card.now { background: var(--ink); color: var(--white); }
.compare .card.now p, .compare .card.now li { color: #c4c4c4; }

/* split */
.split { display: grid; grid-template-columns: 1fr 1fr; gap: 64px; align-items: center; }
.phone { max-width: 330px; margin: 0 auto; border-radius: 38px; border: 10px solid var(--ink); overflow: hidden; box-shadow: 0 30px 60px rgba(0,0,0,.15); }

/* list with ticks */
.ticks { list-style: none; padding: 0; margin: 0; display: grid; gap: 14px; }
.ticks li { padding-left: 34px; position: relative; }
.ticks li::before { content: ""; position: absolute; left: 0; top: 5px; width: 20px; height: 20px; border-radius: 50%; background: var(--ink); -webkit-mask: radial-gradient(circle, #000 99%, transparent); }
.ticks li::after { content: ""; position: absolute; left: 6px; top: 10px; width: 8px; height: 5px; border-left: 2px solid #fff; border-bottom: 2px solid #fff; transform: rotate(-45deg); }
section.ink .ticks li::before { background: var(--white); }
section.ink .ticks li::after { border-color: var(--ink); }

/* flow diagram (ria.com.ai) */
.flow { display: grid; grid-template-columns: 1fr auto 1fr auto 1fr; gap: 14px; align-items: stretch; }
.flow .node { background: var(--white); border: 1px solid var(--line); border-radius: var(--radius); padding: 28px; text-align: center; }
.flow .node.mid { background: var(--ink); color: var(--white); border-color: var(--ink); }
.flow .node img { height: 54px; width: auto; margin: 0 auto 14px; }
.flow .node p { margin: 6px 0 0; font-size: 15px; color: var(--gray); }
.flow .node.mid p { color: #a3a3a3; }
.flow .link { display: grid; place-items: center; color: var(--gray); font-size: 26px; }

/* timeline */
.timeline { counter-reset: s; display: grid; gap: 0; border-left: 2px solid var(--line); margin-left: 10px; }
.timeline > div { position: relative; padding: 0 0 34px 34px; }
.timeline > div::before { counter-increment: s; content: counter(s); position: absolute; left: -16px; top: -2px; width: 30px; height: 30px; border-radius: 50%; background: var(--ink); color: var(--white); font-size: 13px; font-weight: 800; display: grid; place-items: center; }
.timeline .who { font-size: 12px; font-weight: 800; letter-spacing: .14em; text-transform: uppercase; color: var(--gray); }
.timeline p { margin: 4px 0 0; color: #4a4a4a; }

/* cta + footer */
.cta { text-align: center; }
.cta h2 { max-width: 760px; margin-left: auto; margin-right: auto; }
.cta .lead { margin-left: auto; margin-right: auto; }
.cta .btns { justify-content: center; }
footer { padding: 40px 0; border-top: 1px solid var(--line); font-size: 14px; color: var(--gray); }
footer .wrap { display: flex; flex-wrap: wrap; gap: 18px; align-items: center; justify-content: space-between; }
footer img { height: 22px; width: auto; }
footer nav { display: flex; gap: 18px; }
footer a { text-decoration: none; }
.src { font-size: 12px; color: var(--gray); margin-top: 22px; }

@media (max-width: 900px) {
  .hero .grid, .split, .compare { grid-template-columns: 1fr; }
  .hero .copy { padding-bottom: 20px; }
  .hero .art img.character { margin: 0 auto; max-width: 340px; }
  .cards, .cards.four { grid-template-columns: 1fr 1fr; }
  .flow { grid-template-columns: 1fr; }
  .flow .link { transform: rotate(90deg); }
  section { padding: 76px 0; }
}
@media (max-width: 600px) {
  .wrap { padding: 0 16px; }
  .cards, .cards.two, .cards.four, .ria { grid-template-columns: 1fr; }
  .top nav a.hide-sm, .top .tag { display: none; }
  .steps li { grid-template-columns: 44px 1fr; }
  .steps .t { grid-column: 2; }
  .bubble { position: static; margin: 10px auto 0; max-width: none; }
}