/* --- 0. Variable & Reset Definitions --- */
:root {
    /* Primary Colors (Cybersecurity/Professional Theme) */
    --color-primary-dark: #001f3f; /* Deep Navy Blue */
    --color-secondary-dark: #121212; /* Near Black for sections */
    --color-accent: #00ffff;       /* Electric Cyan/Blue for highlights */
    --color-text-light: #f4f4f4;   /* Off-white for body text */
    --color-text-dark: #333333;    /* Dark gray for light backgrounds (not used much) */

    /* Typography */
    --font-heading: 'Roboto', sans-serif;
    --font-body: 'Open Sans', sans-serif;
}

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

/* Base Body Styling */
body {
    font-family: var(--font-body);
    color: var(--color-text-light);
    #background-color: var(--color-secondary-dark); /* Dark mode base */
    background-color: #1f3b55; /* Deep Blue base */
    line-height: 1.6;
    scroll-behavior: smooth; /* Smooth scrolling for navigation clicks */
}

/* Global Typography */
h1, h2, h3, h4 {
    font-family: var(--font-heading);
    margin-bottom: 0.5em;
    color: var(--color-text-light);
}

h1 { font-size: 3em; }
h2 { font-size: 2em; color: var(--color-accent); }
h3 { font-size: 1.5em; border-bottom: 2px solid var(--color-primary-dark); padding-bottom: 0.25em; }

p {
    margin-bottom: 1em;
}

/* Links */
a {
    color: var(--color-accent);
    text-decoration: none;
    transition: color 0.3s ease;
}

a:hover {
    color: #fff; /* White on hover for accent links */
}

/* --- 1. Header & Navigation --- */
header {
    background-color: rgba(0, 0, 0, 0.9); /* Slightly transparent dark background */
    color: var(--color-text-light);
    padding: 1rem 5%;
    display: flex;
    justify-content: space-between;
    align-items: center;
    position: fixed;
    width: 100%;
    top: 0;
    z-index: 1000;
    box-shadow: 0 2px 5px rgba(0, 0, 0, 0.5);
}

.logo {
    font-size: 1.5em;
    font-weight: bold;
    letter-spacing: 2px;
}

nav a {
    margin-left: 1.5rem;
    font-weight: 500;
    text-transform: uppercase;
}

/* Call-to-Action Button in Nav */
.cta-button {
    background-color: var(--color-accent);
    color: var(--color-secondary-dark) !important;
    padding: 0.5rem 1rem;
    border-radius: 5px;
    font-weight: bold;
    transition: background-color 0.3s ease;
}

.cta-button:hover {
    background-color: #fff;
    color: var(--color-secondary-dark) !important;
}

/* --- 2. General Section Styling --- */
section {
    padding: 6rem 5%;
    max-width: 1200px;
    margin: 0 auto;
}

/* Alternating Section Backgrounds for visual interest */
#about, #experience {
    background-color: var(--color-primary-dark);
}

/* --- 3. Hero Section --- */
#hero {
    /* Full height of the viewport minus the header height */
    min-height: calc(100vh - 70px); 
    display: flex;
    align-items: center;
    text-align: left;
    background-color: var(--color-secondary-dark);
    /* Placeholder for a strong, dark background image */
    background-image: url('placeholder-hero.jpg'); /* REPLACE with actual image */
    background-size: cover;
    background-position: center;
    position: relative;
    padding-top: 100px; /* Account for fixed header */
}

.hero-content {
    /* Ensure content is readable over the image */
    background: rgba(0, 0, 0, 0.5); 
    padding: 2rem;
    border-radius: 8px;
}

#hero h1 {
    font-size: 4em;
    color: var(--color-accent);
    margin-bottom: 0.1em;
}

#hero h2 {
    font-size: 2em;
    color: var(--color-text-light);
    margin-bottom: 1em;
}

.cta-primary {
    display: inline-block;
    background-color: var(--color-accent);
    color: var(--color-secondary-dark);
    padding: 1rem 2rem;
    border-radius: 5px;
    font-size: 1.1em;
    font-weight: bold;
    margin-top: 1.5rem;
    transition: transform 0.2s, background-color 0.3s;
}

.cta-primary:hover {
    background-color: #fff;
    transform: translateY(-2px);
}

/* --- 4. Expertise Section --- */
.expertise-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
}

.expertise-item {
    background-color: var(--color-primary-dark);
    padding: 1.5rem;
    border-radius: 5px;
    border-left: 5px solid var(--color-accent);
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.3);
}

.expertise-item h4 {
    color: var(--color-accent);
    margin-top: 0;
}

/* --- 5. Experience Section (Timeline Look) --- */
.timeline-item {
    border-left: 3px solid var(--color-accent);
    padding: 0 0 2rem 2rem;
    position: relative;
    margin-left: 1rem;
}

.timeline-item:last-child {
    padding-bottom: 0; /* Remove padding from last item */
}

.timeline-item::before {
    content: '';
    position: absolute;
    width: 12px;
    height: 12px;
    background: var(--color-accent);
    border-radius: 50%;
    left: -7.5px; /* Adjust to align with the left border */
    top: 5px;
    border: 2px solid var(--color-secondary-dark);
}

.timeline-date {
    color: #aaa;
    font-style: italic;
    font-size: 0.9em;
    margin-bottom: 0.25rem;
}

/* --- 6. Contact & Footer --- */
#contact {
    text-align: center;
    padding-bottom: 4rem;
}

address a {
    font-size: 1.2em;
    font-weight: bold;
}

.social-links {
    margin-top: 1.5rem;
}

.social-links a {
    font-size: 2em;
    margin: 0 0.75rem;
    /* You'd replace the text with actual SVG or Font Awesome icons */
}

footer {
    background-color: var(--color-secondary-dark);
    text-align: center;
    padding: 1rem;
    font-size: 0.8em;
    color: #666;
    border-top: 1px solid var(--color-primary-dark);
}

/* --- 7. Responsive Adjustments (Mobile First) --- */
@media (max-width: 768px) {
    header {
        flex-direction: column;
        text-align: center;
        padding: 0.5rem 5%;
    }

    .logo {
        margin-bottom: 0.5rem;
    }

    nav {
        display: flex;
        justify-content: center;
        width: 100%;
        padding-bottom: 0.5rem;
    }

    nav a {
        margin: 0 0.5rem;
        font-size: 0.9em;
    }

    #hero {
        text-align: center;
        min-height: 80vh;
    }

    #hero h1 {
        font-size: 2.5em;
    }

    #hero h2 {
        font-size: 1.5em;
    }

    .cta-button {
        display: none; /* Hide the CTA button in the nav on small screens */
    }
}