/* Global Digital Systems & Node Management - Core Styles */
:root {
    --deep-slate: #1E293B;
    --tech-blue: #3B82F6;
    --text-main: #334155;
    --text-light: #64748B;
    --bg-light: #F8FAFC;
    --border: #E2E8F0;
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-main);
    background-color: var(--bg-light);
}

header {
    background-color: white;
    border-bottom: 1px solid var(--border);
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    position: sticky;
    top: 0;
    z-index: 100;
}

.logo {
    font-weight: 700;
    color: var(--deep-slate);
    font-size: 1.25rem;
    text-decoration: none;
}

nav ul {
    list-style: none;
    display: flex;
    gap: 1.5rem;
}

nav a {
    text-decoration: none;
    color: var(--text-light);
    font-size: 0.9rem;
    font-weight: 500;
    transition: color 0.2s;
}

nav a:hover {
    color: var(--tech-blue);
}

.btn-primary {
    background-color: var(--tech-blue);
    color: white;
    padding: 0.5rem 1rem;
    border-radius: 6px;
    text-decoration: none;
    font-size: 0.9rem;
    font-weight: 600;
    transition: opacity 0.2s;
}

.btn-primary:hover {
    opacity: 0.9;
}

main {
    max-width: 1000px;
    margin: 3rem auto;
    padding: 0 2rem;
}

h1 {
    color: var(--deep-slate);
    font-size: 2.5rem;
    margin-bottom: 1.5rem;
    letter-spacing: -0.025em;
}

h2 {
    color: var(--deep-slate);
    font-size: 1.5rem;
    margin: 2rem 0 1rem;
}

p {
    margin-bottom: 1.25rem;
}

.card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
    margin-top: 2rem;
}

.card {
    background: white;
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 1.5rem;
}

.card h3 {
    margin-bottom: 0.75rem;
    color: var(--deep-slate);
}

footer {
    border-top: 1px solid var(--border);
    padding: 2rem;
    text-align: center;
    color: var(--text-light);
    font-size: 0.875rem;
    margin-top: 4rem;
}

.code-block {
    background: #1e293b;
    color: #e2e8f0;
    padding: 1rem;
    border-radius: 6px;
    font-family: monospace;
    margin: 1rem 0;
    overflow-x: auto;
}