*,
*::before,
*::after {
    box-sizing: border-box;
}

:root {
    --sl-blue: #223a75;
    --sl-blue-deep: #1b3b6c;
    --sl-blue-dark: #1e293d;
    --sl-orange: #f28c23;
    --sl-text: #1b1b1d;
    --sl-muted: rgba(29, 29, 31, 0.6);
    --sl-bg: #ffffff;
    --sl-bg-soft: #f5f8f8;
    --sl-border: #e3e8ef;
    --sl-shadow: 0 8px 28px rgba(30, 41, 61, 0.08);
}

html {
    scroll-behavior: smooth;
}

body {
    margin: 0;
    font-family: "Exo 2", "Segoe UI", sans-serif;
    font-size: 16px;
    color: var(--sl-text);
    background:
        radial-gradient(1200px 480px at 10% -10%, rgba(34, 58, 117, 0.12), transparent 60%),
        radial-gradient(900px 420px at 100% 0%, rgba(242, 140, 35, 0.12), transparent 55%),
        linear-gradient(180deg, #eef2f7 0%, var(--sl-bg-soft) 40%, #ffffff 100%);
    line-height: 1.55;
    min-height: 100vh;
}

a {
    color: var(--sl-blue);
    text-decoration: none;
}

a:hover {
    color: var(--sl-orange);
}

.site-header {
    background: linear-gradient(135deg, var(--sl-blue-dark) 0%, var(--sl-blue) 55%, #2a4a8f 100%);
    color: #fff;
    border-bottom: 4px solid var(--sl-orange);
}

.site-header__inner {
    max-width: 980px;
    margin: 0 auto;
    padding: 22px 24px 28px;
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 20px 28px;
}

.brand {
    display: flex;
    align-items: center;
    gap: 14px;
    color: #fff;
}

.brand:hover {
    color: #fff;
}

.brand__logo {
    width: 64px;
    height: 40px;
    display: block;
    object-fit: contain;
    background: #fff;
    padding: 4px 8px;
    border-radius: 2px;
}

.brand__text {
    display: flex;
    flex-direction: column;
    gap: 2px;
}

.brand__name {
    font-size: 1.35rem;
    font-weight: 700;
    letter-spacing: 0.02em;
    line-height: 1.1;
}

.brand__tag {
    font-size: 0.78rem;
    font-weight: 400;
    opacity: 0.8;
}

.header-meta {
    margin-left: auto;
    text-align: right;
    font-size: 0.85rem;
    opacity: 0.85;
}

.header-meta strong {
    display: block;
    font-weight: 600;
    opacity: 1;
    margin-bottom: 2px;
}

.page {
    max-width: 980px;
    margin: 0 auto;
    padding: 36px 24px 56px;
}

.intro {
    margin-bottom: 36px;
}

.eyebrow {
    display: inline-block;
    margin: 0 0 10px;
    font-size: 0.78rem;
    font-weight: 700;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--sl-orange);
}

.intro h1 {
    margin: 0 0 12px;
    font-size: clamp(1.75rem, 3vw, 2.35rem);
    font-weight: 700;
    color: var(--sl-blue);
    line-height: 1.2;
}

.intro__lead {
    margin: 0 0 18px;
    max-width: 62ch;
    color: var(--sl-muted);
    font-size: 1.05rem;
}

.disclaimer {
    margin: 0;
    padding: 14px 16px;
    background: #fff8ef;
    border-left: 4px solid var(--sl-orange);
    color: #4a4034;
    font-size: 0.92rem;
}

.calculator-block {
    margin-bottom: 28px;
    padding: 28px 28px 24px;
    background: var(--sl-bg);
    border: 1px solid var(--sl-border);
    box-shadow: var(--sl-shadow);
    border-radius: 2px;
}

.calculator-block__head {
    display: flex;
    align-items: flex-start;
    gap: 14px;
    margin-bottom: 18px;
}

.calc-badge {
    flex: 0 0 auto;
    min-width: 42px;
    height: 42px;
    display: grid;
    place-items: center;
    background: var(--sl-blue);
    color: #fff;
    font-weight: 700;
    font-size: 0.95rem;
    border-radius: 2px;
}

.calculator-block h2 {
    margin: 0;
    font-size: 1.2rem;
    font-weight: 700;
    color: var(--sl-blue-deep);
    line-height: 1.35;
}

.calculator-block__subtitle {
    margin: 4px 0 0;
    font-size: 0.9rem;
    color: var(--sl-muted);
}

.formula-box {
    margin-bottom: 20px;
    padding: 18px 20px;
    background: var(--sl-bg-soft);
    border-top: 3px solid var(--sl-blue);
}

.formula-box > p {
    margin: 0 0 10px;
}

.formula {
    font-weight: 700;
    font-size: 1.05rem;
    color: var(--sl-blue);
    letter-spacing: 0.01em;
}

.formula-legend {
    margin: 12px 0 0;
    padding-left: 1.2rem;
}

.formula-legend li {
    margin-bottom: 6px;
}

.formula-note {
    margin: 14px 0 0;
    font-size: 0.92rem;
    color: var(--sl-muted);
}

.calc-frame {
    display: block;
    width: 100%;
    height: 360px;
    border: 1px solid var(--sl-border);
    background: #fff;
    border-radius: 2px;
}

.calc-frame--light {
    height: 460px;
}

.site-footer {
    background: var(--sl-blue-dark);
    color: rgba(255, 255, 255, 0.75);
    margin-top: 20px;
}

.site-footer__inner {
    max-width: 980px;
    margin: 0 auto;
    padding: 28px 24px;
    display: flex;
    flex-wrap: wrap;
    gap: 16px 32px;
    justify-content: space-between;
    align-items: center;
    font-size: 0.88rem;
}

.site-footer a {
    color: #fff;
}

.site-footer a:hover {
    color: var(--sl-orange);
}

.site-footer__brand {
    font-weight: 600;
    color: #fff;
}

@media (max-width: 640px) {
    .site-header__inner {
        padding: 18px 16px 22px;
    }

    .header-meta {
        margin-left: 0;
        text-align: left;
        width: 100%;
    }

    .page {
        padding: 24px 16px 40px;
    }

    .calculator-block {
        padding: 20px 16px 16px;
    }

    .calc-frame {
        height: 400px;
    }

    .calc-frame--light {
        height: 520px;
    }
}