/* ============================================================
   AIRIL — AI Reasoning Integrity Layer
   Design System: Trust & Precision
   ============================================================ */

/* --- Reset & Base --- */
*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

:root {
    --navy: #0A2540;
    --teal: #00B4A6;
    --teal-glow: rgba(0, 180, 166, 0.15);
    --teal-dim: rgba(0, 180, 166, 0.6);
    --gray: #64748B;
    --bg: #0F172A;
    --bg-card: #1E293B;
    --bg-card-h: #253347;
    --text: #F1F5F9;
    --text-dim: #94A3B8;
    --risk: #F59E0B;
    --risk-dim: rgba(245, 158, 11, 0.12);
    --white: #FFFFFF;
    --font: 'Inter', system-ui, -apple-system, sans-serif;
    --maxw: 1140px;
    --section-py: 100px;
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font);
    background: var(--bg);
    color: var(--text);
    line-height: 1.7;
    -webkit-font-smoothing: antialiased;
    overflow-x: hidden;
}

a {
    color: var(--teal);
    text-decoration: none;
    transition: color .2s;
}

a:hover {
    color: var(--white);
}

img {
    max-width: 100%;
    display: block;
}

.container {
    max-width: var(--maxw);
    margin: 0 auto;
    padding: 0 24px;
}

/* --- Typography --- */
h1,
h2,
h3,
h4 {
    font-weight: 700;
    letter-spacing: -0.02em;
    line-height: 1.2;
}

h1 {
    font-size: clamp(2.4rem, 5vw, 3.6rem);
}

h2 {
    font-size: clamp(1.8rem, 3.5vw, 2.6rem);
    margin-bottom: 20px;
}

h3 {
    font-size: 1.25rem;
    margin-bottom: 10px;
}

p {
    color: var(--text-dim);
    font-size: 1.05rem;
}

.accent {
    color: var(--teal);
}

.highlight {
    color: var(--white);
}

/* --- Buttons --- */
.btn {
    display: inline-block;
    padding: 14px 32px;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all .25s ease;
    border: none;
    text-align: center;
}

.btn-primary {
    background: var(--teal);
    color: var(--navy);
    box-shadow: 0 0 20px var(--teal-glow);
}

.btn-primary:hover {
    background: var(--white);
    color: var(--navy);
    box-shadow: 0 0 30px rgba(0, 180, 166, 0.3);
    transform: translateY(-1px);
}

.btn-secondary {
    background: transparent;
    color: var(--teal);
    border: 1.5px solid var(--teal-dim);
}

.btn-secondary:hover {
    background: var(--teal-glow);
    color: var(--white);
    border-color: var(--teal);
}

/* --- Navigation --- */
.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 100;
    background: rgba(15, 23, 42, 0.85);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid rgba(100, 116, 139, 0.15);
    padding: 0 24px;
}

.nav-inner {
    max-width: var(--maxw);
    margin: 0 auto;
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 68px;
}

.nav-logo {
    font-size: 1.35rem;
    font-weight: 800;
    color: var(--white);
    letter-spacing: 0.06em;
}

.nav-logo .logo-dot {
    color: var(--teal);
}

.nav-links {
    display: flex;
    gap: 32px;
    align-items: center;
}

.nav-links a {
    color: var(--text-dim);
    font-size: 0.92rem;
    font-weight: 500;
    transition: color .2s;
}

.nav-links a:hover {
    color: var(--white);
}

.nav-links .btn {
    padding: 10px 22px;
    font-size: 0.9rem;
}

/* Mobile hamburger */
.nav-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
}

.nav-toggle span {
    display: block;
    width: 24px;
    height: 2px;
    background: var(--text);
    margin: 5px 0;
    transition: all .3s;
}

/* --- Hero --- */
.hero {
    padding: 180px 0 var(--section-py);
    text-align: center;
    position: relative;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 600px;
    height: 600px;
    background: radial-gradient(circle, var(--teal-glow) 0%, transparent 70%);
    pointer-events: none;
}

.hero h1 {
    margin-bottom: 16px;
}

.hero h1 span.accent {
    display: block;
    margin-top: 4px;
}

.hero-tagline {
    font-size: 1.15rem;
    color: var(--gray);
    margin-bottom: 40px;
    font-weight: 400;
}

.hero-ctas {
    display: flex;
    gap: 16px;
    justify-content: center;
    flex-wrap: wrap;
}

/* --- Section base --- */
section {
    padding: var(--section-py) 0;
}

.section-label {
    font-size: 0.8rem;
    font-weight: 700;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--teal);
    margin-bottom: 12px;
}

.section-lead {
    font-size: 1.15rem;
    color: var(--text-dim);
    max-width: 680px;
    margin-bottom: 48px;
}

.section-lead.centered {
    margin-left: auto;
    margin-right: auto;
    text-align: center;
}

/* --- Problem Section --- */
.problem {
    background: linear-gradient(180deg, var(--bg) 0%, rgba(30, 41, 59, 0.4) 100%);
}

.problem-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 24px;
    margin-top: 48px;
}

.problem-card {
    background: var(--bg-card);
    border: 1px solid rgba(100, 116, 139, 0.12);
    border-radius: 12px;
    padding: 28px;
    transition: border-color .25s, transform .25s;
}

.problem-card:hover {
    border-color: rgba(245, 158, 11, 0.3);
    transform: translateY(-2px);
}

.problem-card .card-icon {
    width: 40px;
    height: 40px;
    background: var(--risk-dim);
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin-bottom: 16px;
    font-size: 1.2rem;
}

.problem-card h3 {
    font-size: 1.05rem;
    color: var(--white);
}

.problem-card p {
    font-size: 0.93rem;
    margin-top: 8px;
}

/* --- Solution Section --- */
.solution {
    position: relative;
}

.solution-content {
    max-width: 720px;
}

.solution-content p {
    margin-bottom: 20px;
}

.solution-checks {
    list-style: none;
    margin: 28px 0 36px;
}

.solution-checks li {
    position: relative;
    padding-left: 32px;
    margin-bottom: 14px;
    color: var(--text);
    font-size: 1rem;
}

.solution-checks li::before {
    content: '✓';
    position: absolute;
    left: 0;
    top: 0;
    color: var(--teal);
    font-weight: 700;
    font-size: 1.1rem;
}

.solution-callout {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--white);
    margin-top: 40px;
    line-height: 1.4;
}

.solution-callout span {
    color: var(--teal);
}

/* --- Flow diagram --- */
.flow {
    background: rgba(30, 41, 59, 0.3);
}

.flow-steps {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 0;
    margin-top: 56px;
    position: relative;
}

.flow-step {
    text-align: center;
    padding: 32px 20px;
    position: relative;
}

.flow-step::after {
    content: '';
    position: absolute;
    top: 48px;
    right: -1px;
    width: 2px;
    height: 0;
    background: var(--teal-dim);
    display: none;
}

.step-number {
    width: 52px;
    height: 52px;
    border-radius: 50%;
    background: var(--teal-glow);
    border: 2px solid var(--teal-dim);
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 18px;
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--teal);
}

.flow-step h3 {
    color: var(--white);
    font-size: 1rem;
}

.flow-step p {
    font-size: 0.9rem;
    margin-top: 8px;
}

/* Arrow connectors */
.flow-connector {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0;
}

.flow-grid {
    display: grid;
    grid-template-columns: 1fr auto 1fr auto 1fr auto 1fr;
    align-items: start;
    margin-top: 56px;
}

.flow-arrow {
    display: flex;
    align-items: center;
    justify-content: center;
    padding-top: 40px;
    color: var(--teal-dim);
    font-size: 1.5rem;
}

/* --- Audiences Section --- */
.audiences {}

.audience-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin-top: 48px;
}

.audience-card {
    background: var(--bg-card);
    border: 1px solid rgba(100, 116, 139, 0.1);
    border-radius: 12px;
    padding: 28px 24px;
    text-align: center;
    transition: border-color .25s, transform .25s;
}

.audience-card:hover {
    border-color: var(--teal-dim);
    transform: translateY(-2px);
}

.audience-card .card-icon {
    width: 48px;
    height: 48px;
    background: var(--teal-glow);
    border-radius: 12px;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 16px;
    font-size: 1.4rem;
}

.audience-card h3 {
    font-size: 1rem;
    color: var(--white);
}

.audience-card p {
    font-size: 0.88rem;
    margin-top: 6px;
}

.audience-card .learn-link {
    display: inline-block;
    margin-top: 14px;
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--teal);
}

.audience-card .learn-link:hover {
    color: var(--white);
}

/* --- Final CTA --- */
.final-cta {
    text-align: center;
    padding: 120px 0;
    position: relative;
}

.final-cta::before {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 500px;
    height: 500px;
    background: radial-gradient(circle, var(--teal-glow) 0%, transparent 70%);
    pointer-events: none;
}

.final-cta h2 {
    font-size: clamp(1.8rem, 4vw, 2.8rem);
    margin-bottom: 8px;
    color: var(--white);
}

.final-cta .sub {
    font-size: 1.3rem;
    color: var(--teal);
    font-weight: 600;
    margin-bottom: 36px;
}

/* --- Footer --- */
.footer {
    border-top: 1px solid rgba(100, 116, 139, 0.15);
    padding: 40px 0;
}

.footer-inner {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 16px;
}

.footer-logo {
    font-weight: 800;
    font-size: 1.1rem;
    color: var(--text-dim);
    letter-spacing: 0.06em;
}

.footer-links {
    display: flex;
    gap: 24px;
}

.footer-links a {
    color: var(--gray);
    font-size: 0.88rem;
}

.footer-links a:hover {
    color: var(--text);
}

.footer-copy {
    color: var(--gray);
    font-size: 0.82rem;
}

/* --- Divider --- */
.divider {
    width: 60px;
    height: 3px;
    background: var(--teal);
    border-radius: 2px;
    margin-bottom: 24px;
}

.divider.centered {
    margin-left: auto;
    margin-right: auto;
}

/* --- Subpage hero --- */
.subpage-hero {
    padding: 160px 0 80px;
    text-align: center;
}

.subpage-hero h1 {
    margin-bottom: 12px;
}

.subpage-hero .sub {
    font-size: 1.2rem;
    color: var(--teal);
    font-weight: 600;
}

.subpage-content {
    max-width: 720px;
    margin: 0 auto;
    padding: 0 24px 100px;
}

.subpage-content p {
    margin-bottom: 20px;
    font-size: 1.05rem;
}

.subpage-content .solution-checks {
    margin: 24px 0 32px;
}

.subpage-content .callout {
    font-size: 1.3rem;
    font-weight: 700;
    color: var(--teal);
    margin: 40px 0 20px;
    text-align: center;
}

/* ============================================================
   Responsive
   ============================================================ */

@media (max-width: 768px) {
    :root {
        --section-py: 64px;
    }

    .nav-links {
        display: none;
    }

    .nav-links.open {
        display: flex;
        flex-direction: column;
        position: absolute;
        top: 68px;
        left: 0;
        right: 0;
        background: rgba(15, 23, 42, 0.97);
        padding: 24px;
        gap: 20px;
        border-bottom: 1px solid rgba(100, 116, 139, 0.2);
    }

    .nav-toggle {
        display: block;
    }

    .hero {
        padding: 140px 0 64px;
    }

    .hero h1 {
        font-size: 2rem;
    }

    .flow-grid {
        grid-template-columns: 1fr;
        gap: 0;
    }

    .flow-arrow {
        display: none;
    }

    .flow-step {
        text-align: left;
        padding: 20px 0;
        display: flex;
        gap: 16px;
        align-items: flex-start;
    }

    .step-number {
        margin: 0;
        flex-shrink: 0;
        width: 44px;
        height: 44px;
        font-size: 1rem;
    }

    .problem-grid {
        grid-template-columns: 1fr;
    }

    .audience-grid {
        grid-template-columns: 1fr 1fr;
    }
}

@media (max-width: 480px) {
    .audience-grid {
        grid-template-columns: 1fr;
    }

    .hero-ctas {
        flex-direction: column;
        align-items: center;
    }

    .btn {
        width: 100%;
        max-width: 300px;
    }
}