:root {
    --teal-dark: #0d2833;
    --teal: #1e5a6b;
    --teal-bright: #2a7a8f;
    --orange: #e85d24;
    --gold: #f5a623;
    --cyan: #38bdf8;
    --bg: #0a1628;
    --surface: #112236;
    --surface-elevated: #1a3048;
    --text: #e8f4f8;
    --text-muted: #94b8c8;
    --header-h: 72px;
    --radius: 10px;
    --shadow-glow: 0 0 40px rgba(56, 189, 248, 0.12);
}

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

html {
    scroll-behavior: smooth;
}

body {
    margin: 0;
    font-family: "Exo 2", "Segoe UI", system-ui, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
    min-height: 100vh;
}

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

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

/* —— Header —— */
.site-header {
    position: sticky;
    top: 0;
    z-index: 100;
    background: linear-gradient(180deg, rgba(13, 40, 51, 0.98) 0%, rgba(10, 22, 40, 0.95) 100%);
    border-bottom: 1px solid rgba(56, 189, 248, 0.2);
    backdrop-filter: blur(12px);
    box-shadow: 0 4px 24px rgba(0, 0, 0, 0.35);
}

.header-inner {
    display: flex;
    align-items: center;
    gap: 1rem;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0.5rem 1.25rem;
    min-height: var(--header-h);
}

.brand {
    display: flex;
    align-items: center;
    gap: 0.65rem;
    flex: 1 1 auto;
    min-width: 0;
    text-decoration: none;
    color: var(--text);
}

.brand-logo {
    flex-shrink: 0;
    width: auto;
    height: auto;
    max-height: 52px;
    max-width: 62px;
    object-fit: contain;
    filter: drop-shadow(0 2px 8px rgba(0, 0, 0, 0.4));
}

.brand-text {
    min-width: 0;
}

.brand-title {
    display: block;
    font-size: 1.05rem;
    font-weight: 700;
    letter-spacing: 0.04em;
    text-transform: uppercase;
    line-height: 1.2;
    background: linear-gradient(90deg, var(--text) 0%, var(--cyan) 100%);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

.brand-sub {
    display: block;
    font-size: 0.7rem;
    font-weight: 500;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--orange);
    margin-top: 2px;
}

.site-nav {
    display: flex;
    align-items: center;
    gap: 0.25rem;
}

.site-nav a {
    color: var(--text-muted);
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 600;
    letter-spacing: 0.03em;
    text-transform: uppercase;
    padding: 0.5rem 0.85rem;
    border-radius: 6px;
    transition: color 0.2s, background 0.2s;
}

.site-nav a:hover,
.site-nav a[aria-current="page"] {
    color: var(--text);
    background: rgba(56, 189, 248, 0.12);
}

.nav-toggle {
    display: none;
    flex: 0 0 auto;
    width: 44px;
    height: 44px;
    margin: 0;
    padding: 0;
    border: 1px solid rgba(56, 189, 248, 0.35);
    border-radius: 8px;
    background: var(--surface);
    cursor: pointer;
    position: relative;
}

.nav-toggle span {
    position: absolute;
    left: 50%;
    width: 20px;
    height: 2px;
    background: var(--cyan);
    border-radius: 1px;
    transform: translateX(-50%);
    transition: transform 0.25s, opacity 0.25s;
}

.nav-toggle span:nth-child(1) { top: 14px; }
.nav-toggle span:nth-child(2) { top: 21px; }
.nav-toggle span:nth-child(3) { top: 28px; }

.site-header.nav-open .nav-toggle span:nth-child(1) {
    top: 21px;
    transform: translateX(-50%) rotate(45deg);
}
.site-header.nav-open .nav-toggle span:nth-child(2) { opacity: 0; }
.site-header.nav-open .nav-toggle span:nth-child(3) {
    top: 21px;
    transform: translateX(-50%) rotate(-45deg);
}

/* —— Hero —— */
.hero {
    position: relative;
    overflow: hidden;
    padding: 4.5rem 1.5rem 5rem;
    text-align: center;
    background:
        linear-gradient(135deg, rgba(10, 22, 40, 0.88) 0%, rgba(30, 90, 107, 0.55) 50%, rgba(10, 22, 40, 0.92) 100%),
        url("../images/hero-grid.svg") center / cover no-repeat;
}

.hero::before {
    content: "";
    position: absolute;
    inset: 0;
    background: radial-gradient(ellipse 80% 60% at 50% 0%, rgba(245, 166, 35, 0.15), transparent 70%);
    pointer-events: none;
}

.hero-inner {
    position: relative;
    max-width: 820px;
    margin: 0 auto;
}

.hero-badge {
    display: inline-block;
    font-size: 0.75rem;
    font-weight: 700;
    letter-spacing: 0.2em;
    text-transform: uppercase;
    color: var(--gold);
    border: 1px solid rgba(245, 166, 35, 0.4);
    padding: 0.35rem 1rem;
    border-radius: 999px;
    margin-bottom: 1.25rem;
    background: rgba(232, 93, 36, 0.1);
}

.hero h1,
.hero h2 {
    margin: 0 0 1rem;
    font-size: clamp(1.75rem, 5vw, 2.75rem);
    font-weight: 800;
    line-height: 1.15;
    letter-spacing: 0.02em;
}

.hero p {
    margin: 0 auto 1.75rem;
    max-width: 640px;
    font-size: 1.1rem;
    color: var(--text-muted);
}

.hero-visual {
    margin: 2rem auto 0;
    max-width: 900px;
    border-radius: var(--radius);
    overflow: hidden;
    border: 1px solid rgba(56, 189, 248, 0.25);
    box-shadow: var(--shadow-glow), 0 20px 50px rgba(0, 0, 0, 0.45);
}

.hero-visual img {
    width: 100%;
    height: auto;
    aspect-ratio: 16 / 7;
    object-fit: cover;
}

.page-hero {
    padding: 3rem 1.5rem;
    text-align: center;
    background: linear-gradient(180deg, var(--surface) 0%, var(--bg) 100%);
    border-bottom: 1px solid rgba(56, 189, 248, 0.15);
}

.page-hero h1 {
    margin: 0;
    font-size: clamp(1.5rem, 4vw, 2.25rem);
    font-weight: 800;
    letter-spacing: 0.03em;
}

.page-hero p {
    margin: 0.75rem auto 0;
    max-width: 560px;
    color: var(--text-muted);
}

/* —— Content —— */
.content {
    padding: 3rem 1.5rem 4rem;
    max-width: 1100px;
    margin: 0 auto;
}

.content h2,
.content h3 {
    color: var(--text);
    letter-spacing: 0.02em;
}

.content h2 {
    font-size: 1.75rem;
    margin-top: 0;
}

.content p {
    color: var(--text-muted);
}

.lead {
    font-size: 1.15rem;
    color: var(--text);
}

/* Feature grid */
.features {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 1.5rem;
    margin: 2.5rem 0;
}

.feature-card {
    background: var(--surface);
    border: 1px solid rgba(56, 189, 248, 0.15);
    border-radius: var(--radius);
    padding: 1.5rem;
    transition: transform 0.2s, border-color 0.2s, box-shadow 0.2s;
}

.feature-card:hover {
    transform: translateY(-4px);
    border-color: rgba(245, 166, 35, 0.4);
    box-shadow: var(--shadow-glow);
}

.feature-card img {
    width: 64px;
    height: 64px;
    margin-bottom: 1rem;
}

.feature-card h3 {
    margin: 0 0 0.5rem;
    font-size: 1.1rem;
    color: var(--cyan);
}

.feature-card p {
    margin: 0;
    font-size: 0.95rem;
}

/* Split section with image */
.split-section {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
    align-items: center;
    margin: 3rem 0;
}

.split-section img {
    border-radius: var(--radius);
    border: 1px solid rgba(56, 189, 248, 0.2);
    box-shadow: 0 16px 40px rgba(0, 0, 0, 0.35);
    aspect-ratio: 4 / 3;
    object-fit: cover;
    width: 100%;
}

.button {
    display: inline-block;
    padding: 0.85rem 1.75rem;
    background: linear-gradient(135deg, var(--orange) 0%, var(--gold) 100%);
    color: var(--teal-dark);
    text-decoration: none;
    font-weight: 700;
    font-size: 0.95rem;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    border-radius: 8px;
    border: none;
    box-shadow: 0 4px 20px rgba(232, 93, 36, 0.35);
    transition: transform 0.2s, box-shadow 0.2s;
}

.button:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 28px rgba(245, 166, 35, 0.45);
}

/* Books */
.book-list {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1.25rem;
}

.book {
    background: var(--surface);
    padding: 1.5rem;
    border-radius: var(--radius);
    border-left: 4px solid var(--teal-bright);
    position: relative;
    overflow: hidden;
    transition: border-color 0.2s, transform 0.2s;
}

.book::after {
    content: "";
    position: absolute;
    top: 0;
    right: 0;
    width: 80px;
    height: 80px;
    background: radial-gradient(circle at top right, rgba(56, 189, 248, 0.12), transparent);
    pointer-events: none;
}

.book:hover {
    border-left-color: var(--gold);
    transform: translateY(-2px);
}

.book-num {
    display: inline-block;
    font-size: 0.7rem;
    font-weight: 800;
    letter-spacing: 0.15em;
    color: var(--orange);
    margin-bottom: 0.5rem;
}

.book h3 {
    margin: 0 0 0.5rem;
    font-size: 1.05rem;
    color: var(--text);
}

.book p {
    margin: 0;
    font-size: 0.9rem;
    color: var(--text-muted);
}

/* Contact */
.contact-grid {
    display: grid;
    gap: 1.5rem;
    max-width: 480px;
}

.contact-card {
    background: var(--surface);
    padding: 1.5rem;
    border-radius: var(--radius);
    border: 1px solid rgba(56, 189, 248, 0.2);
}

.contact-card strong {
    display: block;
    color: var(--cyan);
    font-size: 0.8rem;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    margin-bottom: 0.35rem;
}

/* Footer */
footer {
    background: var(--teal-dark);
    color: var(--text-muted);
    text-align: center;
    padding: 1.5rem;
    margin-top: auto;
    border-top: 1px solid rgba(56, 189, 248, 0.15);
    font-size: 0.9rem;
}

footer p {
    margin: 0;
}