/* CSS Reset */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

/* CSS Variables */
:root {
    --color-bg: #fafafa;
    --color-text: #1a1a1a;
    --color-accent: #0d7377;
    --color-accent-hover: #095b5e;
    --color-border: #e0e0e0;
    --color-card-bg: #ffffff;
    --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    --max-width: 800px;
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 2rem;
    --spacing-lg: 3rem;
    --spacing-xl: 4rem;
}

/* Base Styles */
body {
    font-family: var(--font-sans);
    font-size: 16px;
    line-height: 1.5;
    color: var(--color-text);
    background-color: var(--color-bg);
}

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 var(--spacing-sm);
}

/* Typography */
h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: var(--spacing-xs);
}

h2 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: var(--spacing-md);
}

h3 {
    font-size: 1.125rem;
    font-weight: 600;
    margin-bottom: var(--spacing-sm);
}

/* Hero Section */
.hero {
    padding: var(--spacing-xl) 0 var(--spacing-lg);
    text-align: center;
}

.hero h1 {
    color: var(--color-text);
}

.hero h2 {
    font-size: 1.25rem;
    font-weight: 500;
    margin-bottom: var(--spacing-sm);
    color: var(--color-accent);
}

.tagline {
    font-size: 1.125rem;
    line-height: 1.6;
    margin-bottom: var(--spacing-md);
    color: #555;
}

/* Buttons */
.actions {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
    align-items: center;
    margin-bottom: var(--spacing-md);
}

.btn-primary,
.btn-linkedin {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.75rem 1.5rem;
    border-radius: 2rem;
    text-decoration: none;
    font-weight: 600;
    transition: background-color 0.2s ease;
}

.btn-primary {
    background-color: var(--color-accent);
    color: white;
    min-width: 200px;
}

.btn-primary:hover {
    background-color: var(--color-accent-hover);
}

.btn-linkedin {
    background-color: #0077b5;
    color: white;
    width: 48px;
    height: 48px;
    padding: 0;
}

.btn-linkedin:hover {
    background-color: #006399;
}

.contact {
    margin-top: var(--spacing-md);
    font-size: 0.9375rem;
}

.contact p {
    margin: var(--spacing-xs) 0;
}

/* Systems Expertise Section */
.expertise {
    padding: var(--spacing-lg) 0;
    background-color: white;
}

.expertise h2 {
    text-align: center;
}

.expertise-grid {
    display: grid;
    gap: var(--spacing-md);
}

.expertise-category h3 {
    color: var(--color-accent);
}

.expertise-category ul {
    list-style: none;
    padding-left: 0;
}

.expertise-category li {
    padding: var(--spacing-xs) 0;
    padding-left: 1.25rem;
    position: relative;
}

.expertise-category li::before {
    content: "▸";
    position: absolute;
    left: 0;
    color: var(--color-accent);
}

/* Case Studies Section */
.case-studies {
    padding: var(--spacing-lg) 0;
}

.case-studies h2 {
    text-align: center;
}

.case-study {
    background-color: var(--color-card-bg);
    border: 1px solid var(--color-border);
    border-radius: 0.5rem;
    padding: var(--spacing-md);
    margin-bottom: var(--spacing-md);
    cursor: pointer;
    transition: box-shadow 0.2s ease;
}

.case-study:hover {
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

.case-study-header h3 {
    margin-bottom: 0;
    color: var(--color-accent);
}

.case-study-header h3::after {
    content: " ▼";
    font-size: 0.75rem;
    color: var(--color-text);
    opacity: 0.5;
}

.case-study.expanded .case-study-header h3::after {
    content: " ▲";
}

.case-study-details {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease;
}

.case-study.expanded .case-study-details {
    max-height: 500px;
    margin-top: var(--spacing-md);
}

.case-study-details p {
    margin-bottom: var(--spacing-sm);
}

.case-study-details p:last-child {
    margin-bottom: 0;
}

/* Background Section */
.background {
    padding: var(--spacing-lg) 0;
    background-color: white;
}

.background h2 {
    text-align: center;
}

.background ul {
    list-style: none;
    padding-left: 0;
    max-width: 600px;
    margin: 0 auto;
}

.background li {
    padding: var(--spacing-xs) 0;
    padding-left: 1.25rem;
    position: relative;
}

.background li::before {
    content: "•";
    position: absolute;
    left: 0;
    color: var(--color-accent);
    font-weight: bold;
}

/* Footer */
footer {
    padding: var(--spacing-lg) 0 var(--spacing-md);
    text-align: center;
    border-top: 1px solid var(--color-border);
}

footer p {
    margin-bottom: var(--spacing-sm);
    color: #666;
    font-size: 0.9375rem;
}

.footer-links {
    display: flex;
    gap: var(--spacing-md);
    align-items: center;
    justify-content: center;
}

.footer-links a {
    color: var(--color-accent);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.2s ease;
}

.footer-links a:hover {
    color: var(--color-accent-hover);
}

.footer-links svg {
    fill: var(--color-accent);
    transition: fill 0.2s ease;
}

.footer-links a:hover svg {
    fill: var(--color-accent-hover);
}

/* Tablet Breakpoint: 768px+ */
@media (min-width: 768px) {
    h1 {
        font-size: 3rem;
    }
    
    h2 {
        font-size: 2rem;
    }
    
    .actions {
        flex-direction: row;
        justify-content: center;
    }
    
    .expertise-grid {
        grid-template-columns: repeat(3, 1fr);
    }
}

/* Desktop Breakpoint: 1024px+ */
@media (min-width: 1024px) {
    h1 {
        font-size: 3.5rem;
    }
    
    .tagline {
        font-size: 1.25rem;
    }
    
    .container {
        padding: 0 var(--spacing-md);
    }
}