:root {
    /* Color Palette */
    --color-bg: #fdfdfd;       /* Off-white */
    --color-bg-alt: #f3f4f6;   /* Slightly darker off-white for sections */
    --color-text: #1a1a1a;     /* Charcoal / Near Black */
    --color-text-muted: #525252;
    --color-accent: #4338ca;   /* Deep Indigo */
    --color-accent-hover: #3730a3;
    --color-border: #e5e7eb;

    /* Typography */
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 2rem;
    --spacing-lg: 4rem;
    --spacing-xl: 6rem;

    /* Layout */
    --container-width: 1100px;
    --border-radius: 8px;
    
    /* Effects */
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --transition: 0.2s ease-in-out;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    background-color: var(--color-bg);
    color: var(--color-text);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4, h5, h6 {
    line-height: 1.2;
    font-weight: 600;
    color: var(--color-text);
    margin-bottom: var(--spacing-sm);
}

p {
    margin-bottom: var(--spacing-sm);
    color: var(--color-text-muted);
}

a {
    color: var(--color-text);
    text-decoration: none;
    transition: color var(--transition);
}

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

ul {
    list-style: none;
}

img {
    max-width: 100%;
    display: block;
}

/* Utility Classes */
.container {
    max-width: var(--container-width);
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border-radius: var(--border-radius);
    font-weight: 500;
    text-align: center;
    cursor: pointer;
    transition: all var(--transition);
    font-size: 0.95rem;
}

.btn-primary {
    background-color: var(--color-text);
    color: #fff;
}

.btn-primary:hover {
    background-color: var(--color-accent);
    transform: translateY(-1px);
}

.btn-sm {
    padding: 0.5rem 1rem;
    font-size: 0.875rem;
}

.section {
    padding: var(--spacing-xl) 0;
}

.section-title {
    font-size: 1.5rem;
    margin-bottom: var(--spacing-lg);
    font-weight: 500;
    letter-spacing: -0.02em;
}

.bg-subtle {
    background-color: var(--color-bg-alt);
}

/* Header */
.site-header {
    padding: var(--spacing-md) 0;
    position: sticky;
    top: 0;
    background-color: rgba(253, 253, 253, 0.9);
    backdrop-filter: blur(8px);
    z-index: 100;
    border-bottom: 1px solid transparent;
    transition: border-color var(--transition);
}

.site-header.scrolled {
    border-color: var(--color-border);
}

.site-header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-weight: 600;
    font-size: 1.1rem;
    letter-spacing: -0.02em;
}

.site-nav ul {
    display: flex;
    gap: var(--spacing-md);
    align-items: center;
}

.site-nav a {
    font-size: 0.9rem;
    color: var(--color-text-muted);
}

.site-nav a:hover,
.site-nav a.active {
    color: var(--color-text);
}

/* Hero Section */
.hero-section {
    padding: var(--spacing-xl) 0;
    min-height: 80vh;
    display: flex;
    align-items: center;
}

.hero-title {
    font-size: 4rem;
    letter-spacing: -0.03em;
    font-weight: 600;
    margin-bottom: var(--spacing-md);
    max-width: 800px;
}

.hero-subtitle {
    font-size: 1.25rem;
    max-width: 600px;
    margin-bottom: var(--spacing-lg);
    color: var(--color-text-muted);
}

/* Grid Layouts */
.grid-3 {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--spacing-md);
}

.grid-2 {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
    gap: var(--spacing-md);
}

/* Cards */
.card {
    background: #fff;
    padding: var(--spacing-md);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    transition: transform var(--transition), box-shadow var(--transition);
}

.card:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
    border-color: var(--color-accent);
}

.card h3 {
    font-size: 1.1rem;
    margin-bottom: var(--spacing-sm);
}

.card p {
    font-size: 0.95rem;
    margin-bottom: 0;
}

/* Project Cards */
.project-card {
    position: relative;
    padding-top: var(--spacing-lg);
}

.project-status {
    position: absolute;
    top: var(--spacing-sm);
    right: var(--spacing-sm);
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    background: var(--color-bg-alt);
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    color: var(--color-text-muted);
}

/* Principles */
.principles-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: var(--spacing-lg);
}

.principle h3 {
    font-size: 1.1rem;
    margin-bottom: 0.5rem;
    color: var(--color-accent);
}

/* Contact */
.contact-section {
    background-color: #fff;
}

.contact-content {
    max-width: 600px;
}

.email-link {
    font-size: 1.5rem;
    font-weight: 500;
    display: inline-block;
    margin-bottom: var(--spacing-lg);
    border-bottom: 2px solid var(--color-accent);
}

.email-link:hover {
    color: var(--color-accent);
}

.contact-form {
    margin-top: var(--spacing-md);
}

.form-group {
    margin-bottom: var(--spacing-sm);
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-size: 0.9rem;
    font-weight: 500;
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    font-family: inherit;
    font-size: 1rem;
    transition: border-color var(--transition);
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--color-accent);
}

/* Footer */
.site-footer {
    padding: var(--spacing-lg) 0;
    border-top: 1px solid var(--color-border);
    font-size: 0.875rem;
    color: var(--color-text-muted);
}

/* Mobile Responsive */
@media (max-width: 768px) {
    .site-nav {
        display: none; /* simple mobile hide for now, could add hamburger later */
    }
    
    .hero-title {
        font-size: 2.5rem;
    }
    
    .section {
        padding: var(--spacing-lg) 0;
    }
    
    .grid-2, .grid-3 {
        grid-template-columns: 1fr;
    }
}