:root {
    --blue: #176b87;
    --blue-dark: #0d4356;
    --blue-light: #eaf5f8;
    --text: #23313a;
    --muted: #60717c;
    --white: #ffffff;
    --border: #dce6ea;
    --shadow: 0 12px 32px rgba(20, 55, 70, 0.12);
}

* {
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
}

body {
    margin: 0;
    color: var(--text);
    background: var(--white);
    font-family: Arial, Helvetica, sans-serif;
    line-height: 1.65;
}

img {
    max-width: 100%;
}

a {
    color: var(--blue);
}

.container {
    width: min(1160px, calc(100% - 40px));
    margin: 0 auto;
}

.narrow {
    max-width: 780px;
}

.site-header {
    background: #e4eef1;
    border-bottom: 1px solid #c5d6dc;
}

.header-inner {
    min-height: 78px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 28px;
}

.brand {
    display: flex;
    flex-direction: column;
    color: var(--text);
    text-decoration: none;
}

.brand-title {
    color: var(--blue-dark);
    font-size: 1.22rem;
    font-weight: 800;
}

.brand-subtitle {
    color: var(--muted);
    font-size: 0.84rem;
}

.main-nav,
.footer-nav {
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
}

.main-nav a,
.footer-nav a {
    color: var(--text);
    text-decoration: none;
}

.main-nav a:hover,
.main-nav a.active,
.footer-nav a:hover {
    color: var(--blue);
}

.hero {
    padding: 90px 0;
    background: linear-gradient(135deg, #eef8fa, #ffffff);
}

.hero-grid,
.feature-grid {
    display: grid;
    grid-template-columns: 1.25fr 0.75fr;
    gap: 70px;
    align-items: center;
}

.eyebrow {
    margin: 0 0 10px;
    color: var(--blue);
    font-size: 0.85rem;
    font-weight: 700;
    letter-spacing: 0.1em;
    text-transform: uppercase;
}

h1,
h2,
h3 {
    color: var(--blue-dark);
    line-height: 1.2;
}

h1 {
    margin: 0 0 22px;
    font-size: clamp(2.4rem, 6vw, 4.5rem);
}

h2 {
    font-size: clamp(1.8rem, 4vw, 2.7rem);
}

.lead {
    max-width: 720px;
    color: var(--muted);
    font-size: 1.2rem;
}

.hero-actions {
    display: flex;
    flex-wrap: wrap;
    gap: 14px;
    margin: 30px 0;
}

.button {
    display: inline-block;
    padding: 13px 22px;
    border: 2px solid var(--blue);
    border-radius: 8px;
    font-weight: 700;
    text-decoration: none;
}

.button-primary {
    color: var(--white);
    background: var(--blue);
}

.button-secondary {
    color: var(--blue);
    background: transparent;
}

.hero-note {
    color: var(--muted);
    font-size: 0.95rem;
}

.book-image-frame {
    min-height: 360px;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 25px;
    background: var(--white);
    border-radius: 18px;
    box-shadow: var(--shadow);
}

.book-image-frame img {
    max-height: 420px;
    object-fit: contain;
}

.image-placeholder {
    display: none;
    min-height: 260px;
    align-items: center;
    justify-content: center;
    flex-direction: column;
    color: var(--muted);
    text-align: center;
}

.section {
    padding: 80px 0;
}

.section-alt {
    background: #f5f8f9;
}

.section-heading {
    max-width: 760px;
    margin-bottom: 38px;
}

.book-grid {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 18px;
}

.book-card,
.feature-item {
    padding: 24px;
    background: var(--white);
    border: 1px solid var(--border);
    border-radius: 12px;
}

.book-number {
    color: var(--blue);
    font-weight: 700;
}

.feature-list {
    display: grid;
    gap: 15px;
}

.feature-item {
    display: flex;
    flex-direction: column;
}

.center {
    margin-top: 32px;
    text-align: center;
}

.text-link {
    font-weight: 700;
    text-decoration: none;
}

.download-box {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 40px;
    padding: 38px;
    color: var(--white);
    background: var(--blue-dark);
    border-radius: 16px;
}

.download-box h2,
.download-box .eyebrow {
    color: var(--white);
}

.site-footer {
    padding: 42px 0;
    color: var(--white);
    background: #092f3d;
}

.footer-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 30px;
}

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

@media (max-width: 900px) {
    .header-inner,
    .footer-inner,
    .download-box {
        align-items: flex-start;
        flex-direction: column;
    }

    .hero-grid,
    .feature-grid {
        grid-template-columns: 1fr;
    }

    .book-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 560px) {
    .container {
        width: min(100% - 24px, 1120px);
    }

    .hero,
    .section {
        padding: 55px 0;
    }

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