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

body {
    font-family: 'Inter', sans-serif;
    line-height: 1.6;
    color: #334155; /* Slate 700 */
    background-color: #f8fafc; /* Slate 50 */
}

a {
    text-decoration: none;
    color: inherit;
}

ul {
    list-style: none;
}

/* Typography */
h1, h2, h3 {
    color: #0f172a; /* Slate 900 */
    font-weight: 700;
}

p {
    margin-bottom: 1rem;
}

/* Layout Utilities */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
}

.flex {
    display: flex;
}

.grid {
    display: grid;
}

.items-center {
    align-items: center;
}

.justify-between {
    justify-content: space-between;
}

.gap-4 { gap: 1rem; }
.gap-8 { gap: 2rem; }

/* Colors */
:root {
    --primary: #0091DA; /* VMware Blue */
    --primary-dark: #0073ad;
    --dark: #1e293b; /* Slate 800 */
    --light: #ffffff;
    --border: #e2e8f0;
}

/* Header */
header {
    background-color: #ffffff;
    border-bottom: 1px solid var(--border);
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 100;
}

.logo {
    font-size: 1.25rem;
    font-weight: 800;
    color: var(--primary);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.nav-links a {
    margin-left: 2rem;
    font-weight: 500;
    color: #64748b;
    transition: color 0.2s;
}

.nav-links a:hover, .nav-links a.active {
    color: var(--primary);
}

.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    background-color: var(--primary);
    color: white;
    border-radius: 0.5rem;
    font-weight: 600;
    transition: background-color 0.2s;
    border: none;
    cursor: pointer;
}

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

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

.btn-outline {
    background-color: transparent;
    border: 1px solid var(--border);
    color: #334155;
}

.btn-outline:hover {
    border-color: var(--primary);
    color: var(--primary);
}

/* Homepage Hero */
.hero {
    background-color: #f8fafc;
    padding: 4rem 0;
    border-bottom: 1px solid var(--border);
}

.hero-layout {
    display: flex;
    gap: 3rem;
    align-items: center;
}

@media (max-width: 768px) {
    .hero-layout {
        flex-direction: column;
    }
}

.hero-left {
    flex: 2;
}

.hero-image {
    width: 100%;
    height: 350px;
    object-fit: cover;
    border-radius: 0.75rem;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
}

.hero-quote {
    margin-top: 1.5rem;
    font-size: 1.5rem;
    font-style: italic;
    color: #334155;
    border-left: 6px solid var(--primary);
    padding-left: 1.5rem;
    background: white;
    padding: 1rem 1.5rem;
    border-radius: 0 0.5rem 0.5rem 0;
    box-shadow: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
}

.hero-right {
    flex: 1;
    display: flex;
    justify-content: center;
    background-color: #0f172a;
    padding: 3rem;
    border-radius: 1rem;
    box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);
}

.hero-right .btn {
    font-size: 1.25rem;
    padding: 1.5rem 2rem;
    width: 100%;
    text-align: center;
}

/* Sections */
.section {
    padding: 4rem 0;
    background: white;
    border-bottom: 1px solid var(--border);
}

.section-title {
    font-size: 1.875rem;
    margin-bottom: 2rem;
    padding-bottom: 0.5rem;
    border-bottom: 3px solid var(--primary);
    display: inline-block;
}

/* Image Grid */
.img-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
}

.img-card {
    background: white;
    border: 1px solid var(--border);
    border-radius: 0.5rem;
    overflow: hidden;
    transition: transform 0.2s;
}

.img-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
}

.img-card img {
    width: 100%;
    height: 180px;
    object-fit: cover;
}

.img-card span {
    display: block;
    text-align: center;
    padding: 1rem;
    font-weight: 600;
    color: #475569;
}

/* Course Preview Grid */
.topic-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
}

.topic-card {
    background: white;
    border: 1px solid var(--border);
    border-radius: 0.75rem;
    padding: 1.5rem;
    transition: all 0.2s;
    cursor: pointer;
}

.topic-card:hover {
    border-color: var(--primary);
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
}

.topic-card h3 {
    color: var(--primary);
    margin-bottom: 0.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.topic-card p {
    color: #64748b;
    font-size: 0.95rem;
    margin: 0;
}

/* Footer */
footer {
    background-color: #0f172a;
    color: #cbd5e1;
    padding: 3rem 0;
    margin-top: auto;
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 2rem;
}

.footer-links {
    display: flex;
    gap: 1.5rem;
}

.footer-links a:hover {
    color: white;
}

/* Sidebar Layout (Course Page) */
.course-layout {
    display: flex;
    gap: 2rem;
    padding: 2rem 0;
}

.sidebar {
    width: 280px;
    flex-shrink: 0;
    background: white;
    border: 1px solid var(--border);
    border-radius: 0.5rem;
    padding: 1.5rem;
    height: fit-content;
}

.sidebar h3 {
    margin-bottom: 1rem;
    padding-bottom: 0.5rem;
    border-bottom: 1px solid var(--border);
}

.sidebar nav a {
    display: block;
    padding: 0.75rem;
    border-radius: 0.375rem;
    color: #64748b;
    margin-bottom: 0.25rem;
}

.sidebar nav a:hover {
    background-color: #f1f5f9;
    color: #0f172a;
}

.sidebar nav a.active {
    background-color: var(--primary);
    color: white;
}

.content-area {
    flex: 1;
    background: white;
    border: 1px solid var(--border);
    border-radius: 0.5rem;
    padding: 2.5rem;
    min-height: 600px;
}

.content-header {
    margin-bottom: 2rem;
    padding-bottom: 2rem;
    border-bottom: 1px solid var(--border);
}

.content-header h1 {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
}

.content-header p {
    font-size: 1.25rem;
    color: #64748b;
    font-weight: 300;
}

.prose {
    max-width: 65ch;
}

.prose h3 {
    margin-top: 2rem;
    margin-bottom: 1rem;
    font-size: 1.5rem;
}

.prose ul, .prose ol {
    margin-bottom: 1.5rem;
    padding-left: 1.5rem;
}

.prose li {
    margin-bottom: 0.5rem;
}

.diagram-placeholder {
    background-color: #f8fafc;
    border: 2px dashed #cbd5e1;
    border-radius: 0.5rem;
    padding: 3rem;
    text-align: center;
    margin: 2rem 0;
    color: #94a3b8;
}

.nav-buttons {
    margin-top: 4rem;
    padding-top: 2rem;
    border-top: 1px solid var(--border);
    display: flex;
    justify-content: space-between;
}