:root {
    --bg-primary: #fff;
    --bg-secondary: #f5f5f5;
    --text-primary: #1a1a1a;
    --text-secondary: #666;
    --card-bg: #fff;
    --border-color: #e5e5e5;
    --shadow: rgba(0, 0, 0, 0.1);
}

[data-theme="dark"] {
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --text-primary: #94a3b8;
    --text-secondary: #94a3b8;
    --card-bg: #1e293b;
    --border-color: #334155;
    --shadow: rgba(0, 0, 0, 0.3);
}

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

body {
    font-family: "Poppins", sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    transition: all 0.3s ease;
    min-height: 100vh;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1.25rem 2.5rem;
}
header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 3.75rem;
    padding-bottom: 1.25rem;
    border-bottom: 2px solid var(--border-color);
}
header h1 {
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-primary);
    transition: color 0.3s ease;
}
.theme-toggle {
    display: flex;
    gap: 12px;
    align-items: center;
}
.theme-label {
    font-size: 0.9rem;
    color: var(--text-secondary);
    font-weight: 500;
    transition: color 0.3s ease;
}
.toggle-switch {
    width: 60px;
    height: 32px;
    background-color: var(--border-color);
    border-radius: 1rem;
    border: none;
    cursor: pointer;
    padding: 3px;
    transition: background 0.3s ease;
}
[data-theme="dark"] .toggle-switch {
    background-color: #3b82f6;
}
.toggle-slider {
    display: block;
    width: 26px;
    height: 26px;
    background-color: #fff;
    border-radius: 50%;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.8);
    transition: transform 0.3s ease;
}
[data-theme="dark"] .toggle-slider {
    transform: translateX(28px);
}
.hero {
    text-align: center;
    margin-bottom: 60px;
    padding: 60px 20px;
    background: var(--bg-secondary);
    border-radius: 20px;
    transition: background 0.3s ease;
}
.hero h2 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 16px;
    color: var(--text-secondary);
    transition: color 0.3s ease;
}
.hero p {
    font-size: 1.1rem;
    color: var(--text-secondary);
    transition: color 0.3s ease;
}
.content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
}
.card {
    background-color: var(--card-bg);
    padding: 2rem;
    border-radius: 1rem;
    border: 1px solid var(--border-color);
    box-shadow: 0 4px 20px var(--shadow);
    transition: all 0.3s ease;
}
.card:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 30px var(--shadow);
}
.card h3 {
    font-size: 1.3rem;
    font-weight: 600;
    margin-bottom: 12px;
    color: var(--text-primary);
    transition: color 0.3s ease;
}
.card p {
    color: var(--text-secondary);
    line-height: 1.7;
    transition: color 0.3s ease;
}
@media (max-width: 600px) {
    header {
        flex-direction: column;
        gap: 20px;
        align-items: center;
    }
    .hero h2 {
        font-size: 2rem;
    }
    .content {
        grid-template-columns: 1fr;
    }
}