/* Variables CSS pour système de design */
:root {
    --primary-h: 200;
    --primary-s: 50%;
    --primary-l: 50%;
    --secondary-h: 120;
    --secondary-s: 40%;
    --secondary-l: 40%;
    --bg-light: hsl(0, 0%, 98%);
    --bg-dark: hsl(0, 0%, 10%);
    --text-light: hsl(0, 0%, 10%);
    --text-dark: hsl(0, 0%, 95%);
    --border-radius: 16px;
    --shadow: 0 4px 12px hsla(0, 0%, 0%, 0.1);
    --font-family: system-ui, -apple-system, sans-serif;
    --transition: all 0.3s ease;
}

[data-theme="dark"] {
    --bg-light: hsl(0, 0%, 10%);
    --bg-dark: hsl(0, 0%, 5%);
    --text-light: hsl(0, 0%, 95%);
    --text-dark: hsl(0, 0%, 80%);
}

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

body {
    font-family: var(--font-family);
    background: var(--bg-light);
    color: var(--text-light);
    line-height: 1.6;
    transition: var(--transition);
}

header {
    background: var(--bg-dark);
    color: var(--text-dark);
    padding: 1rem;
    position: sticky;
    top: 0;
    z-index: 100;
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: 1200px;
    margin: 0 auto;
}

nav ul {
    list-style: none;
    display: flex;
    gap: 1rem;
}

nav a {
    color: var(--text-dark);
    text-decoration: none;
    padding: 0.5rem;
    border-radius: var(--border-radius);
    transition: var(--transition);
}

nav a:hover, nav a:focus {
    background: hsla(var(--primary-h), var(--primary-s), var(--primary-l), 0.2);
}

#theme-toggle {
    background: none;
    border: none;
    color: var(--text-dark);
    font-size: 1.5rem;
    cursor: pointer;
    padding: 0.5rem;
    border-radius: var(--border-radius);
    transition: var(--transition);
}

#theme-toggle:hover, #theme-toggle:focus {
    background: hsla(var(--primary-h), var(--primary-s), var(--primary-l), 0.2);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem 1rem;
}

.hero-bg {
    color: var(--text-dark);
    text-align: center;
    padding: 4rem 1rem;
    position: relative;
}

.hero-bg h2 {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.hero-bg p {
    font-size: 1.2rem;
    margin-bottom: 2rem;
}

.cta {
    display: inline-block;
    background: hsl(var(--primary-h), var(--primary-s), var(--primary-l));
    color: var(--text-dark);
    padding: 1rem 2rem;
    text-decoration: none;
    border-radius: var(--border-radius);
    transition: var(--transition);
}

.cta:hover, .cta:focus {
    background: hsl(var(--primary-h), var(--primary-s), calc(var(--primary-l) - 10%));
}

.hero-svg {
    width: 200px;
    height: 100px;
    margin: 2rem auto;
}

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

.card {
    background: var(--bg-dark);
    color: var(--text-dark);
    padding: 1.5rem;
    border-radius: var(--border-radius);
    box-shadow: var(--shadow);
    transition: var(--transition);
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 24px hsla(0, 0%, 0%, 0.15);
}

.filters {
    display: flex;
    gap: 1rem;
    flex-wrap: wrap;
    margin-bottom: 1rem;
}

.filters input, .filters select {
    padding: 0.5rem;
    border: 1px solid hsl(0, 0%, 80%);
    border-radius: var(--border-radius);
    background: var(--bg-light);
    color: var(--text-light);
}

#timeline-container {
    height: 200px;
    background: var(--bg-dark);
    border-radius: var(--border-radius);
    position: relative;
}

footer {
    background: var(--bg-dark);
    color: var(--text-dark);
    text-align: center;
    padding: 1rem;
}

button {
    background: hsl(var(--primary-h), var(--primary-s), var(--primary-l));
    color: var(--text-dark);
    border: none;
    padding: 0.75rem 1.5rem;
    border-radius: var(--border-radius);
    cursor: pointer;
    transition: var(--transition);
}

button:hover, button:focus {
    background: hsl(var(--primary-h), var(--primary-s), calc(var(--primary-l) - 10%));
}

@media (max-width: 768px) {
    nav ul {
        flex-direction: column;
        gap: 0.5rem;
    }
    .filters {
        flex-direction: column;
    }
    .hero-bg h2 {
        font-size: 2rem;
    }
}