:root {
    --dark-blue: #0a1929;
    --medium-blue: #1a3a5f;
    --light-blue: #4d94ff;
    --accent-blue: #007bff;
    --text-light: #e6f0ff;
    --text-dark: #000000;
    --card-bg: rgba(26, 58, 95, 0.7);
    --hover-bg: rgba(77, 148, 255, 0.2);
}

/* hide page scrollbar */
html { scrollbar-width: none; } /* Firefox */
body { -ms-overflow-style: none; } /* IE and Edge */
body::-webkit-scrollbar,
body::-webkit-scrollbar-button { display: none; } /* Chrome */

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background: linear-gradient(135deg, var(--dark-blue), #0d1b2a);
    color: var(--text-light);
    min-height: 100vh;
    overflow-x: hidden;
}

header {
    background: rgba(10, 25, 41, 0.95);
    backdrop-filter: blur(10px);
    padding: 1rem 2rem;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.5);
    border-bottom: 1px solid var(--light-blue);
}

.header-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: 1400px;
    margin: 0 auto;
    position: relative; /* anchor mobile dropdown */
}

.logo {
    display: flex;
    align-items: center;
    gap: 15px;
}

.logo h1 {
    font-size: 2.2rem;
    background: linear-gradient(to right, var(--light-blue), #80d0ff);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    text-shadow: 0 0 10px rgba(77, 148, 255, 0.3);
}

.logo i {
    color: var(--light-blue);
    font-size: 2.5rem;
}

/* Desktop nav */
nav ul {
    display: flex;
    list-style: none;
    gap: 2rem;
}

nav a {
    color: var(--text-light);
    text-decoration: none;
    font-weight: 500;
    font-size: 1.1rem;
    padding: 0.5rem 1rem;
    border-radius: 5px;
    transition: all 0.3s ease;
}

nav a:hover {
    background: var(--hover-bg);
    color: var(--light-blue);
}

/* --- Hamburger button --- */
.nav-toggle {
    display: none; /* desktop default */
    background: rgba(10, 25, 41, 0.6);
    border: 1px solid rgba(77, 148, 255, 0.35);
    color: var(--text-light);
    width: 48px;
    height: 48px;
    border-radius: 12px;
    cursor: pointer;
    transition: all 0.2s ease;
    align-items: center;
    justify-content: center;
    font-size: 1.3rem;
}

.nav-toggle:hover {
    background: rgba(77, 148, 255, 0.12);
    border-color: rgba(77, 148, 255, 0.65);
    transform: translateY(-1px);
}

/* Footer */
footer {
    background: var(--dark-blue);
    padding: 3rem 2rem;
    text-align: center;
    margin-top: 3rem;
    border-top: 1px solid var(--light-blue);
}

.footer-content {
    max-width: 1400px;
    margin: 0 auto;
}

.footer-logo {
    font-size: 2rem;
    margin-bottom: 1.5rem;
    color: var(--light-blue);
}

.social-icons {
    display: flex;
    justify-content: center;
    gap: 1.5rem;
    margin: 2rem 0;
}

.social-icons a {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background: var(--medium-blue);
    color: var(--light-blue);
    font-size: 1.5rem;
    transition: all 0.3s ease;
}

.social-icons a:hover {
    background: var(--light-blue);
    color: var(--dark-blue);
    transform: translateY(-5px);
}

.copyright {
    margin-top: 2rem;
    color: #6c8bb8;
    font-size: 0.9rem;
}

/* ===== Mobile hamburger behavior ===== */
@media (max-width: 768px) {
    /* Keep logo + hamburger on the same row */
    .header-container {
        flex-direction: row;
        gap: 0.75rem;
    }

    .nav-toggle {
        display: inline-flex;
        margin-left: auto;
    }

    /*
      IMPORTANT:
      This targets BOTH:
        <nav class="nav"> ... </nav>
      and:
        <nav> ... </nav>
      so it works on every page.
    */
    header nav {
        position: absolute;
        left: 0;
        right: 0;
        top: 100%;
        background: rgba(10, 25, 41, 0.98);
        border-bottom: 1px solid rgba(77, 148, 255, 0.35);
        box-shadow: 0 14px 30px rgba(0, 0, 0, 0.45);
        padding: 0.75rem 1rem;
        display: none; /* hidden until open */
        z-index: 200;
    }

    header nav.open {
        display: block;
        animation: navDrop 180ms ease-out;
    }

    nav ul {
        flex-direction: column;
        gap: 0.5rem;
    }

    nav a {
        display: block;
        padding: 0.8rem 1rem;
        border-radius: 10px;
        font-size: 1.05rem;
    }

    @keyframes navDrop {
        from { opacity: 0; transform: translateY(-8px); }
        to   { opacity: 1; transform: translateY(0); }
    }
}