:root {
    --bg-color: #ffffff;
    --surface-color: #f4f7f9;
    --text-main: #001f3f;
    --text-muted: #546e7a;
    --primary: #00d1ff;
    --border: #e1e8ed;
    --header-large: 220px;
    --header-small: 70px;
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg-color: #001f3f;
        --surface-color: #002b56;
        --text-main: #ffffff;
        --text-muted: #94a3b8;
        --border: #003a70;
    }
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
body { font-family: system-ui, -apple-system, sans-serif; background: var(--bg-color); color: var(--text-main); scroll-behavior: smooth; line-height: 1.6; }

/* --- HEADER & NAVIGATION --- */
.header-wrapper { height: var(--header-large); width: 100%; }

.site-header {
    background: var(--surface-color);
    border-bottom: 1px solid var(--border);
    position: fixed;
    top: 0; width: 100%;
    height: var(--header-large);
    z-index: 1000;
    display: flex;
    align-items: center;
}

.header-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    width: 100%;
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

.main-logo { width: 240px; height: auto; }

.site-nav ul {
    list-style: none;
    display: flex;
    gap: 1.5rem;
    margin-top: 1rem;
}

.site-nav a { color: var(--text-main); text-decoration: none; font-weight: 600; }

/* --- HAMBURGER ANIMATION --- */
.menu-toggle {
    display: none;
    flex-direction: column;
    gap: 6px;
    background: none;
    border: none;
    cursor: pointer;
    z-index: 1001;
}

.menu-toggle span {
    display: block;
    width: 28px;
    height: 3px;
    background: var(--text-main);
    border-radius: 3px;
    transition: 0.3s ease-in-out;
}

.menu-toggle.active span:nth-child(1) { transform: translateY(9px) rotate(45deg); }
.menu-toggle.active span:nth-child(2) { opacity: 0; }
.menu-toggle.active span:nth-child(3) { transform: translateY(-9px) rotate(-45deg); }

/* --- SCROLLED STATE --- */
.site-header.scrolled {
    height: var(--header-small);
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.15);
}

.site-header.scrolled .header-content { flex-direction: row; justify-content: space-between; }
.site-header.scrolled .main-logo { width: 130px; }
.site-header.scrolled .site-nav ul { margin-top: 0; }

.site-header.scrolled .menu-toggle { display: flex; }

.site-header.scrolled .site-nav {
    display: none;
    position: absolute;
    top: var(--header-small);
    left: 0; width: 100%;
    background: var(--surface-color);
    padding: 2rem;
    border-bottom: 1px solid var(--border);
}

.site-header.scrolled .site-nav.active { display: block; }
.site-header.scrolled .site-nav ul { flex-direction: column; align-items: center; gap: 2rem; }

/* --- CONTENT BLOCKS --- */
.container { max-width: 1100px; margin: 0 auto; padding: 0 1.5rem; }
.hero { text-align: center; padding: 100px 0; }
.btn { display: inline-block; background: var(--primary); color: #001f3f; padding: 0.8rem 2rem; border-radius: 4px; font-weight: bold; text-decoration: none; }

.split-layout { display: flex; flex-wrap: wrap; align-items: center; gap: 3rem; margin: 4rem 0; }
.split-image, .split-text { flex: 1 1 350px; }
.split-image img { width: 100%; border-radius: 12px; display: block; }

.grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 1.5rem; margin: 4rem 0; }
.card { background: var(--surface-color); padding: 2.5rem; border-radius: 12px; border: 1px solid var(--border); }
.site-footer { text-align: center; padding: 4rem 0; border-top: 1px solid var(--border); color: var(--text-muted); }