:root {
    --bg: #ffffff;
    --text: #111;
    --primary: #0066ff;
    --card: #f4f4f4;
	
    --dark: #111827;
    --light-bg: #f9fafc;
    --card-light: #ffffff;
    --text-light: #333;
}

body.dark {
    --bg: #0f172a;
    --text: #f1f5f9;
    --card: #1e293b;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: Arial, sans-serif;
}

body {
    background: var(--bg);
    color: var(--text);
    transition: 0.3s;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 40px;
    background: var(--card);
    position: sticky;
    top: 0;
    z-index: 1000;
}

.logo {
    font-weight: bold;
    font-size: 20px;
}

nav ul {
    display: flex;
    list-style: none;
    gap: 20px;
}

nav a {
    text-decoration: none;
    color: var(--text);
    font-weight: 500;
}

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

#darkToggle {
    padding: 6px 10px;
    cursor: pointer;
    border: none;
    background: var(--primary);
    color: white;
    border-radius: 5px;
}

main {
    padding: 60px 40px;
    min-height: 80vh;
}

<!-- -->
.toggle-btn {
    position: absolute;
    right: 20px;
    top: 20px;
    cursor: pointer;
    background: var(--primary);
    color: white;
    padding: 8px 12px;
    border-radius: 6px;
}

.hero {
    background: linear-gradient(135deg, #2563eb, #1e3a8a);
    color: white;
    padding: 120px 20px;
    text-align: center;
}

.section {
    padding: 80px 20px;
    max-width: 1100px;
    margin: auto;
}

.grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 30px;
}

.card {
    background: var(--card-light);
    padding: 30px;
    border-radius: 16px;
    box-shadow: 0 8px 25px rgba(0,0,0,0.05);
    text-align: center;
    transition: 0.3s;
}

body.dark .card {
    background: #1e293b;
}

.card:hover {
    transform: translateY(-8px);
}

.card img {
    width: 90px;
    margin-bottom: 20px;
    border-radius: 20px;
}

.btn-primary {
    display: inline-block;
    margin-top: 20px;
    padding: 12px 25px;
    background: var(--primary);
    color: white;
    border-radius: 8px;
    text-decoration: none;
}
<!-- -->
.section {
    margin-bottom: 50px;
}

.card {
    background: var(--card);
    padding: 20px;
    border-radius: 12px;
    margin-bottom: 20px;
    transition: 0.3s;
}

footer {
    text-align: center;
    padding: 20px;
    background: var(--card);
}

h1 {
    margin-bottom: 20px;
    font-size: 32px;
}

p {
    line-height: 1.6;
}