* {
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Verdana, sans-serif;
    background-color: #0B3861;
    margin: 0;
    padding: 0;
    position: relative;
    min-height: 100vh;
}

.header {
    position: sticky;
    display: flex;
    height: 60px;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 2rem;
    top: 0;
    z-index: 10;
    background-color: rgba(11, 56, 97, 0.9);
    backdrop-filter: blur(4px);
}

.logo {
    font-size: 1.5rem;
    font-weight: 600;
    color: #f0f0f0;
}

.nav ul {
    display: flex;
    list-style-type: none;
    color: #f0f0f0;
    font-size: 1em;
    gap: 1rem;
}

.nav ul li a {
    text-align: center;
    text-decoration: none;
    color: #f0f0f0;
    border-radius: 5px;
    padding: 0.5rem 1rem;   
}

.nav ul li a:hover { /* tous liens lors du survol dans la balise nav */
    color: #ffde7d; /* couleur de fond */
}

.background-animation {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
    overflow: hidden;
}

.circle {
    position: absolute;
    border-radius: 50%;
    animation: move 8s infinite ease-in-out;
    filter: blur(6px);
    mix-blend-mode: soft-light;
    pointer-events: none;
    z-index: 0;
}

@keyframes move {
    0%, 100% {
        transform: translate(0, 0);
    }
    50% {
        transform: translate(20px, 20px);
    }
}

.container {
    max-width: 1000px;
    padding: 2rem;
    background-color: #f6edf4;
    margin: 2rem auto;
    border: 1px solid rgba(255, 255, 255, 0.4);
    box-shadow: 0 4px 18px rgba(0, 0, 0, 0.12);
    border-radius: 22px;
    color: #004466;
}

.title h1 {
    font-family: Arial, Helvetica, sans-serif;
    text-align: center;
    font-size: 2rem;
    line-height: 1.3;
    font-weight: 700;
    color: #004466;
    margin-bottom: 1rem;
}

.title h1 .content h2 {
    opacity: 0;
    transform: translateY(20px);
    animation: fadeInUp 1s ease-out forwards;
}

@keyframes fadeInUp {
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.content {
    padding-left: 50px;
    padding-right: 50px;
    line-height: 1.6rem;
    padding-bottom: 4rem;
}

.content h2 {
    margin-top: 3rem;
    margin-bottom: 1rem;
    border-left: 5px solid #0088aa;
    padding-left: 12px;
    font-size: 1.75rem;
    font-weight: 600;
    font-style: italic;
    position: relative;
    line-height: 1.6;
}

.content h2::after {
    content: "";
    display: block;
    margin-top: 6px;
    width: 50px;
    height: 3px;
    background-color: #0088aa;
    border-radius: 2px;
}

.content h3 {
    font-weight: 600;
}

.content h4 {
    font-size: 1.2rem;
    color: #004466;
}

.content h5 {
    font-size: 1rem;
    font-style: italic;
    color: #505053;
}

.content strong {
    font-weight: 600;
}

.content p {
    font-size: 1.05rem;
    line-height: 1.7;
    margin-bottom: 1rem;
    text-align: justify;
    color: #030202;
}

pre {
    background: #f4f4f6;
    color: #002b36;
    padding: 1.2rem 1.5rem;
    border-radius: 10px;
    font-size: 0.95em;
    line-height: 1.5;
    overflow-x: auto;
    box-shadow: 0 3px 10px rgba(0, 0, 0, 0.1);
    border-left: 4px solid #0088aa;
    margin: 1.5rem 0;
    white-space: pre-wrap;  
    max-width: 90%;  
}

pre code {
    font-size: 0.9em;
    color: inherit;
}

pre::selection, pre code::selection {
    background: #004466;
    color: white;
}

ul, ol {
    padding-left: 1.5rem;
    margin-bottom: 1.5rem;
    list-style-position: outside;
    text-align: left;
}

ul li {
    position: relative;
    padding-left: 0.8rem;
}

li {
    line-height: 1.6;
    margin-bottom: 0.5rem;
    color: #004466;
}

li strong {
    font-weight: 900;
}

.graph {
    text-align: center;
    margin-top: 1rem;
    opacity: 0;
    transform: translateY(20px);
    animation: fadeInUp 1s ease forwards;
    animation-delay: 0.2s;
    margin: 2rem 0;
}

.graph p {
    text-align: center;
}

.graph img {
    max-width: 70%;
    height: auto;
    border-radius: 14px;
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.1);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.graph img:hover {
    transform: scale(1.02);
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.15);
}

.fig-caption {
    font-size: 0.9rem;
    font-style: italic;
    text-align: center;
    color: #555;
    margin-top: 0.5rem; 
}

.button {
    border: none;
    border-radius: 5px;
    color: white;
    text-align: center;
    text-decoration: none;
    font-size: 1rem;
    cursor: pointer;
    transition: background-color 0.3s ease;
}

.button-retour {
    text-align: center;
    margin-top: 2rem;
}

.button-retour a {
    display: inline-block;
    background-color: transparent;
    color: #004466;
    border: 1px solid #004466;
    border-radius: 5px;
    text-decoration: none;
    font-size: 1rem;
    font-weight: 600;
    padding: 0.5rem 1.25rem;
    transition: all 0.3s ease;
}

.button-retour a:hover {
    background-color: #004466;
    color: white;
}

.footer {
    height: 100%;
    margin: 0;
    display: flex;
    background-color: #0B3861;
    color: white;
    padding: 2rem 1rem;
    margin-top: 4rem;
}

.footer-container {
    margin: 0 auto;
    text-align: center;
}

.footer a {
    color: white;
}

.footer a:hover {
    color: #ffcc70;
}

.footer-links {
    margin-top: 1rem;
}

.footer-links a {
    margin: 0 10px;
    color: white;
    text-decoration: none;
}

.footer-links a:hover{
    text-decoration: underline;
}

@media screen and (max-width: 768px) {
    .container {
        padding: 1rem;
    }
    .content {
        padding: 0 0.5rem;
    }
    .graph img {
        max-width: 90%;
        max-height: 300px;
    }
    .title h1 {
        font-size: 1.8rem;  /* 28-30px */
    }
    .content h2 {
        font-size: 1.4rem; /* 22-24px */
    }
}