:root {
    --ink: #17202b;
    --muted: #66717f;
    --blue: #1473e6;
    --blue-dark: #0758bb;
    --surface: #ffffff;
    --soft: #f3f5f7;
    --line: rgba(23, 32, 43, .1);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { margin: 0; background: var(--surface); color: var(--ink); font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif; -webkit-font-smoothing: antialiased; }
a { color: inherit; text-decoration: none; }

.site-header { position: absolute; inset: 0 0 auto; z-index: 3; height: 72px; padding: 0 5vw; display: flex; align-items: center; justify-content: space-between; border-bottom: 1px solid rgba(23, 32, 43, .08); }
.brand { font-size: 1rem; font-weight: 700; letter-spacing: -.02em; }
.brand span { color: var(--blue); }
.brand img { display: block; width: auto; height: 38px; }
nav { display: flex; align-items: center; gap: 30px; color: #4f5b68; font-size: .86rem; }
nav a { transition: color .2s ease; }
nav a:hover { color: var(--blue); }
.nav-link { padding: 0; border: 0; color: inherit; background: none; font: inherit; cursor: pointer; }
.nav-link:hover { color: var(--blue); }
.nav-cta { padding: 9px 16px; color: #fff; background: var(--blue); border-radius: 999px; }
.nav-cta:hover { color: #fff; background: var(--blue-dark); }

.hero { min-height: 100vh; position: relative; display: flex; align-items: center; padding: 120px 9vw 80px; overflow: hidden; background: linear-gradient(90deg, rgba(247,250,252,.98) 0%, rgba(247,250,252,.93) 31%, rgba(247,250,252,.28) 60%, rgba(247,250,252,.02) 78%), url('/static/images/atc-hero-v2-social.jpg') center / cover no-repeat; }
.hero-copy { position: relative; z-index: 1; width: min(590px, 50vw); }
.eyebrow { margin: 0 0 22px; color: var(--blue); font-size: .75rem; font-weight: 650; letter-spacing: .13em; text-transform: uppercase; }
h1, h2 { margin: 0; letter-spacing: -.055em; }
h1 { max-width: 760px; font-size: clamp(3.5rem, 6.2vw, 6.9rem); line-height: .98; font-weight: 680; }
.hero-text { max-width: 500px; margin: 28px 0 34px; color: #4e5b68; font-size: 1.15rem; line-height: 1.6; }
.button { display: inline-flex; align-items: center; justify-content: center; gap: 18px; min-height: 50px; padding: 0 22px; border-radius: 999px; font-size: .95rem; font-weight: 600; transition: transform .2s ease, background .2s ease; }
.button:hover { transform: translateY(-1px); }
.button-primary { color: #fff; background: var(--blue); box-shadow: 0 10px 30px rgba(20,115,230,.18); }
.button-primary:hover { background: var(--blue-dark); }
.scroll-cue { position: absolute; bottom: 28px; left: 9vw; color: #697582; font-size: .78rem; }
.scroll-cue span { margin-left: 9px; color: var(--blue); }

.section { padding: 140px 8vw; }
.section-copy { max-width: 780px; margin: 0 auto 70px; text-align: center; }
.section h2 { font-size: clamp(2.7rem, 5vw, 5.1rem); line-height: 1.02; font-weight: 650; }
.section-lead { max-width: 610px; margin: 26px auto 0; color: var(--muted); font-size: 1.15rem; line-height: 1.65; }
.experience { background: var(--surface); }
.experience-steps { max-width: 700px; margin: 40px auto 0; padding: 0; display: grid; grid-template-columns: repeat(3, 1fr); list-style: none; border-top: 1px solid var(--line); }
.experience-steps li { padding: 20px 12px 0; display: flex; flex-direction: column; gap: 7px; }
.experience-steps span, .capability-grid article > span { color: var(--blue); font: 600 .72rem "B612 Mono", "SFMono-Regular", monospace; letter-spacing: .08em; }
.experience-steps strong { font-size: .95rem; font-weight: 600; }
.product-frame { max-width: 1320px; margin: 0 auto; overflow: hidden; border: 1px solid rgba(23,32,43,.12); border-radius: 24px; background: #e8ebee; box-shadow: 0 35px 90px rgba(27,43,61,.16); }
.window-bar { height: 45px; display: flex; align-items: center; gap: 7px; padding: 0 16px; color: #808995; background: rgba(250,251,252,.9); font-size: .75rem; }
.window-bar i { width: 10px; height: 10px; border-radius: 50%; background: #cfd4da; }
.window-bar span { margin: auto; transform: translateX(-24px); }
.product-frame img { display: block; width: 100%; aspect-ratio: 16 / 9; object-fit: cover; object-position: center 44%; }

.capabilities { background: var(--soft); }
.section-heading { max-width: 900px; margin-bottom: 80px; }
.capability-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.capability-grid article { min-height: 300px; padding: 32px; border: 1px solid rgba(23,32,43,.07); border-radius: 24px; background: rgba(255,255,255,.82); box-shadow: 0 12px 35px rgba(25,40,58,.05); }
.capability-grid h3 { margin: 80px 0 14px; font-size: 1.45rem; letter-spacing: -.025em; }
.capability-grid p { margin: 0; color: var(--muted); font-size: 1rem; line-height: 1.65; }
.closing-cta { margin-top: 130px; padding: 78px 7vw; display: flex; align-items: center; justify-content: space-between; gap: 30px; border-radius: 32px; color: #fff; background: #172536; }
.closing-cta h2 { max-width: 710px; font-size: clamp(2.5rem, 4vw, 4.5rem); }
footer { padding: 28px 8vw; display: flex; justify-content: space-between; color: #7a8490; background: var(--soft); border-top: 1px solid var(--line); font-size: .75rem; letter-spacing: .08em; text-transform: uppercase; }

.login-page { min-height: 100vh; display: grid; place-items: center; padding: 32px 20px; background: radial-gradient(circle at 75% 15%, rgba(20,115,230,.12), transparent 35%), var(--soft); }
.login-card { width: min(460px, 100%); padding: 38px; border: 1px solid rgba(255,255,255,.9); border-radius: 28px; background: rgba(255,255,255,.92); box-shadow: 0 30px 80px rgba(25,40,58,.13); backdrop-filter: blur(18px); }
.login-card .brand { display: inline-block; margin-bottom: 34px; }
.login-card .eyebrow { margin: 30px 0 12px; }
.login-card h1 { font-size: clamp(2.7rem, 9vw, 4.5rem); }
.login-card h1 em { color: var(--blue); font-style: normal; }
.login-card form { margin-top: 30px; }
.login-card label { display: grid; gap: 8px; margin-top: 18px; color: #4f5b68; font-size: .78rem; font-weight: 650; letter-spacing: .04em; }
.login-card input { width: 100%; height: 50px; padding: 0 15px; border: 1px solid rgba(23,32,43,.15); border-radius: 13px; outline: 0; background: #fff; color: var(--ink); font: inherit; transition: border-color .2s, box-shadow .2s; }
.login-card input:focus { border-color: var(--blue); box-shadow: 0 0 0 4px rgba(20,115,230,.1); }
.login-card form > .button { width: 100%; margin-top: 10px; border: 0; cursor: pointer; }
.login-card form > .button:disabled { opacity: .55; cursor: wait; }
.auth-tabs { display: grid; grid-template-columns: 1fr 1fr; padding: 4px; border-radius: 13px; background: var(--soft); }
.auth-tabs button { min-height: 40px; border: 0; border-radius: 10px; color: var(--muted); background: transparent; font: inherit; font-size: .83rem; font-weight: 600; cursor: pointer; }
.auth-tabs button.active { color: var(--ink); background: #fff; box-shadow: 0 3px 12px rgba(23,32,43,.08); }
.trial-message { display: grid; gap: 4px; margin: -10px 0 24px; padding: 14px 16px; border-radius: 14px; color: #315f96; background: #eef5ff; font-size: .85rem; line-height: 1.45; }
.trial-message span { color: #58718f; }
.auth-hint, #login-error { min-height: 18px; margin: 9px 2px 0; font-size: .78rem; line-height: 1.45; }
.auth-hint { color: var(--muted); }
#login-error { color: #c6232d; }

@media (max-width: 820px) {
    .site-header { position: absolute; padding: 0 6vw; }
    nav { gap: 14px; }
    nav > a:first-child { display: none; }
    .hero { min-height: 820px; align-items: flex-start; padding: 130px 7vw 70px; background: linear-gradient(180deg, rgba(247,250,252,.98) 0%, rgba(247,250,252,.9) 38%, rgba(247,250,252,.08) 72%), url('/static/images/atc-hero-v2-social.jpg') 64% center / cover no-repeat; }
    .hero-copy { width: 100%; }
    h1 { font-size: clamp(3.15rem, 13vw, 5rem); }
    .hero-text { font-size: 1rem; }
    .section { padding: 100px 6vw; }
    .experience-steps, .capability-grid { grid-template-columns: 1fr; }
    .experience-steps { gap: 18px; }
    .product-frame { border-radius: 16px; }
    .product-frame img { aspect-ratio: 4 / 3; }
    .capability-grid article { min-height: 230px; }
    .capability-grid h3 { margin-top: 50px; }
    .closing-cta { margin-top: 80px; padding: 52px 28px; align-items: flex-start; flex-direction: column; border-radius: 24px; }
    footer span:last-child { display: none; }
    .login-card { padding: 28px 24px; border-radius: 22px; }
}

@media (prefers-reduced-motion: reduce) {
    html { scroll-behavior: auto; }
    *, *::before, *::after { transition: none !important; }
}