:root {
    --primary-bg: #0c0a1f; /* Deep indigo/purple */
    --text-light: #ffffff;
    --text-muted: #c0c0d0;
    --button-bg: #3b3081; /* Darker blue/purple for button */
    --button-hover-bg: #4a409c;
    --horizon-glow-center: rgba(66, 117, 209, 0.4);
    --horizon-glow-mid: rgba(40, 80, 160, 0.15);
    --horizon-line: rgba(100, 150, 255, 0.6);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Poppins', sans-serif;
    background-color: var(--primary-bg);
    color: var(--text-light);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    overflow-x: hidden; /* Important for planet horizon */
    position: relative; /* For absolute positioning of stars and horizon */
}

.stars-bg {
    position: fixed; /* Fixed so it doesn't scroll */
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-image:
        radial-gradient(1px 1px at 20px 30px, white, transparent),
        radial-gradient(1px 1px at 40px 80px, white, transparent),
        radial-gradient(1.5px 1.5px at 90px 40px, white, transparent),
        radial-gradient(1px 1px at 120px 120px, white, transparent),
        radial-gradient(1.5px 1.5px at 160px 80px, white, transparent),
        radial-gradient(1px 1px at 50% 30%, white, transparent),
        radial-gradient(1.5px 1.5px at 25% 70%, white, transparent),
        radial-gradient(1px 1px at 80% 90%, white, transparent);
    background-size: 200px 200px; /* Adjust for density */
    z-index: -2; /* Behind everything */
    opacity: 0.7;
}


header {
    width: 100%;
    padding: 20px 5%;
    position: fixed; /* Or absolute if you prefer */
    top: 0;
    left: 0;
    z-index: 100;
    background: linear-gradient(to bottom, rgba(12, 10, 31, 0.7), transparent); /* Slight fade for readability */
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: 1200px;
    margin: 0 auto;
}

.logo {
    display: flex;
    align-items: center;
    font-size: 1.8rem;
    font-weight: 600;
}

.logo-icon {
    width: 36px;
    height: 36px;
    border: 2.5px solid var(--text-light);
    border-radius: 50%;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    margin-right: 10px;
    font-weight: 700;
    font-size: 1.5rem;
}

.nav-links {
    list-style: none;
    display: flex;
}

.nav-links li {
    margin-left: 30px;
}

.nav-links a {
    text-decoration: none;
    color: var(--text-muted);
    font-weight: 500;
    transition: color 0.3s ease;
}

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

.login-btn {
    text-decoration: none;
    color: var(--text-light);
    font-weight: 500;
    padding: 8px 16px;
}

.mobile-menu-toggle {
    display: none; /* Hidden by default */
    background: none;
    border: none;
    color: var(--text-light);
    font-size: 1.8rem;
    cursor: pointer;
}

main {
    flex-grow: 1;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    text-align: center;
    padding: 120px 20px 50px; /* Top padding for fixed header */
    width: 100%;
    max-width: 800px; /* Max width for hero content */
    z-index: 1; /* Above background elements */
}

.hero h1 {
    font-size: 3.5rem;
    font-weight: 700;
    margin-bottom: 25px;
    line-height: 1.2;
}

.hero p {
    font-size: 1.1rem;
    color: var(--text-muted);
    line-height: 1.7;
    margin-bottom: 40px;
    max-width: 700px; /* More constrained width for paragraph */
    margin-left: auto;
    margin-right: auto;
}

.cta-button {
    display: inline-block;
    background-color: var(--button-bg);
    color: var(--text-light);
    padding: 16px 35px;
    border-radius: 50px;
    text-decoration: none;
    font-weight: 500;
    font-size: 1rem;
    transition: background-color 0.3s ease, transform 0.2s ease;
}

.cta-button:hover {
    background-color: var(--button-hover-bg);
    transform: translateY(-2px);
}

.planet-horizon-container {
    position: fixed; /* Fixed so it's always at the bottom */
    bottom: 0;
    left: 0;
    width: 100%;
    height: 35vh; /* Adjust height of the visible glow area */
    overflow: hidden; /* Crucial to clip the oversized horizon */
    pointer-events: none; /* So it doesn't block interactions */
    z-index: 0; /* Behind main content, above stars */
}

.planet-horizon {
    position: absolute;
    bottom: -20vh; /* Pull down to make the curve less sharp, adjust this and height */
    left: 50%;
    transform: translateX(-50%);
    width: 180vw; /* Must be wider than viewport for gentle curve */
    height: 50vh; /* Height of the gradient element itself */
    border-top-left-radius: 50%; /* Creates the arc */
    border-top-right-radius: 50%;
    background: radial-gradient(ellipse at 50% 100%, /* Gradient origin at bottom center of element */
        var(--horizon-glow-center) 0%,
        var(--horizon-glow-mid) 35%,
        transparent 65%
    );
}

.planet-horizon::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 2px; /* Thickness of the bright line */
    background-color: var(--horizon-line);
    border-top-left-radius: inherit; /* Follows parent's curve */
    border-top-right-radius: inherit;
    box-shadow: 0 0 15px 3px var(--horizon-line); /* Glow for the line */
}

/* Responsive adjustments */
@media (max-width: 768px) {
    .nav-links {
        display: none; /* Hide for mobile */
        position: absolute;
        top: 70px; /* Below header */
        left: 0;
        width: 100%;
        background-color: rgba(12, 10, 31, 0.95); /* Solid background for dropdown */
        flex-direction: column;
        align-items: center;
        padding: 20px 0;
    }

    .nav-links.active {
        display: flex; /* Show when active */
    }

    .nav-links li {
        margin: 10px 0;
        margin-left: 0; /* Reset margin */
    }

    .mobile-menu-toggle {
        display: block; /* Show hamburger icon */
    }

    .login-btn {
        display: none; /* Optionally hide or move into mobile menu */
    }
    /* If you want login in mobile menu: */
    /* .nav-links.active .login-btn-mobile { display: block; } */
    /* And add <li class="login-btn-mobile"><a href="#">Log in</a></li> to nav-links ul */


    .hero h1 {
        font-size: 2.5rem;
    }

    .hero p {
        font-size: 1rem;
    }

    .cta-button {
        padding: 14px 30px;
        font-size: 0.9rem;
    }

    .planet-horizon-container {
        height: 25vh;
    }
    .planet-horizon {
        bottom: -15vh;
        height: 40vh;
    }
}

@media (max-width: 480px) {
    .hero h1 {
        font-size: 2rem;
    }
    .logo {
        font-size: 1.5rem;
    }
    .logo-icon {
        width: 30px;
        height: 30px;
        font-size: 1.2rem;
    }
}