:root {
    --primary-color: #4a90e2;
    --dark-bg: #02040a;
    --card-bg: rgba(10, 17, 40, 0.35);
    --border-color: rgba(255, 255, 255, 0.1);
    --glow-color: rgba(40, 60, 150, 0.3);
}

body {
    font-family: 'Poppins', sans-serif;
    margin: 0;
    color: #eaf0ff;
    background-color: var(--dark-bg);
    overflow-x: hidden;
    position: relative;
}

body::before {
    content: '';
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 80vw;
    height: 80vh;
    max-width: 900px;
    max-height: 900px;
    background: radial-gradient(circle, var(--glow-color) 0%, rgba(12, 26, 62, 0) 65%);
    filter: blur(120px);
    z-index: -1;
    pointer-events: none;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* --- Header --- */
.main-header {
    padding: 20px 0;
    text-align: center;
    background: rgba(2, 4, 10, 0.3);
    backdrop-filter: blur(5px);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 10;
}

.main-header h1 {
    margin: 0;
    font-size: 2rem;
    font-weight: 700;
    color: #fff;
}

/* --- Hero Section --- */
.hero {
    text-align: center;
    padding: 100px 0;
}

.hero h2 {
    font-size: 3.2rem;
    margin-top: 0;
    margin-bottom: 15px;
    color: #fff;
    text-shadow: 0 0 15px rgba(74, 144, 226, 0.4);
}

.hero .subtitle {
    font-size: 1.3rem;
    font-weight: 300;
    max-width: 650px;
    margin: 0 auto 20px auto;
    opacity: 0.8;
    line-height: 1.6;
}

/* --- StudySmarter Info --- */
.info-studysmarter {
    background-color: var(--card-bg);
    text-align: center;
    padding: 20px;
    margin: 40px auto;
    border-radius: 12px;
    border: 1px solid var(--border-color);
    max-width: 800px;
    backdrop-filter: blur(5px);
}

/* --- Decks Section --- */
.decks-section {
    padding: 50px 0;
}

.decks-section h3 {
    text-align: center;
    font-size: 2.8rem;
    margin-bottom: 50px;
    color: #fff;
}

.deck-item {
    background: var(--card-bg);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 30px;
    margin-bottom: 25px;
    transition: transform 0.3s ease, box-shadow 0.3s ease, border-color 0.3s ease;
    position: relative;
    overflow: hidden;
}

.deck-item:hover {
    transform: translateY(-8px) scale(1.01);
    box-shadow: 0 15px 30px rgba(0, 0, 0, 0.3);
    border-color: rgba(74, 144, 226, 0.4);
}

.deck-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 15px;
}

.deck-title {
    font-size: 1.8rem;
    font-weight: 600;
    margin: 0;
    color: #fff;
}

.deck-card-count {
    font-size: 1rem;
    font-weight: 300;
    opacity: 0.7;
}

.deck-actions {
    display: flex;
    gap: 15px;
}

.deck-features {
    list-style: none;
    padding: 10px 0 0 0;
    margin: 15px 0 0 0;
    border-top: 1px solid var(--border-color);
}

.deck-features li {
    font-size: 0.9rem;
    opacity: 0.8;
    padding: 4px 0;
    display: flex;
    align-items: center;
}

.deck-features li::before {
    content: '✓';
    color: var(--primary-color);
    font-weight: bold;
    margin-right: 10px;
}

.quality-note,
.note-construction {
    font-size: 0.85rem;
    font-style: italic;
    text-align: center;
    padding: 10px;
    margin-top: 15px;
    background-color: rgba(255, 165, 0, 0.05);
    border-top: 1px solid rgba(255, 165, 0, 0.2);
    border-bottom: 1px solid rgba(255, 165, 0, 0.2);
    color: #ffae42;
    opacity: 0.9;
}

.note-construction {
    position: absolute;
    top: 25px;
    right: -45px;
    background-color: #ff8c00;
    color: white;
    padding: 8px 40px;
    font-size: 0.9rem;
    font-weight: bold;
    text-transform: uppercase;
    transform: rotate(45deg);
    box-shadow: 0 0 15px rgba(255, 140, 0, 0.7);
    z-index: 2;
}

.btn {
    padding: 12px 24px;
    border: 1px solid transparent;
    border-radius: 10px;
    cursor: pointer;
    font-weight: 600;
    font-size: 0.95rem;
    transition: all 0.3s ease;
    text-align: center;
    box-sizing: border-box;
}

.btn-secondary {
    background-color: rgba(255, 255, 255, 0.05);
    border-color: rgba(255, 255, 255, 0.2);
    color: #fff;
}

.btn-secondary:hover {
    background-color: rgba(255, 255, 255, 0.1);
    border-color: rgba(255, 255, 255, 0.5);
}

.btn-primary {
    background-color: var(--primary-color);
    color: #ffffff;
    box-shadow: 0 0 20px rgba(74, 144, 226, 0.4);
}

.btn-primary:hover {
    background-color: #357abd;
    transform: translateY(-2px);
    box-shadow: 0 5px 25px rgba(74, 144, 226, 0.6);
}

.chapters-list {
    list-style: none;
    padding-left: 0;
    margin-top: 25px;
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.6s ease-in-out, padding-top 0.6s ease-in-out;
}

.chapters-list.open {
    max-height: 10000px;
    padding-top: 15px;
}

.chapters-list li {
    padding: 8px 0;
    border-bottom: 1px solid var(--border-color-light);
}

/* --- Styles du Modal --- */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.7);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s ease, visibility 0.3s ease;
}

.modal-overlay.active {
    opacity: 1;
    visibility: visible;
}

.modal-content {
    background: rgba(10, 25, 47, 0.8);
    border: 1px solid var(--border-color);
    border-radius: 15px;
    padding: 40px;
    width: 90%;
    max-width: 500px;
    box-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.37), 0 0 20px var(--glow-color);
    position: relative;
    transform: scale(0.95);
    transition: transform 0.3s ease;
}

.modal-overlay.active .modal-content {
    transform: scale(1);
}

.modal-close-btn {
    position: absolute;
    top: 15px;
    right: 20px;
    background: none;
    border: none;
    color: #fff;
    font-size: 2rem;
    cursor: pointer;
    opacity: 0.7;
    transition: opacity 0.2s ease, transform 0.2s ease;
}

.modal-close-btn:hover {
    opacity: 1;
    transform: rotate(90deg);
}

.modal-content h3 {
    margin-top: 0;
    color: var(--primary-color);
    text-align: center;
}

.modal-content p {
    text-align: center;
    opacity: 0.8;
    margin-bottom: 30px;
}

.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    opacity: 0.9;
}

.form-group input {
    width: 95%;
    padding: 12px;
    background-color: rgba(255, 255, 255, 0.05);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    color: #fff;
    font-size: 1rem;
    transition: border-color 0.2s, box-shadow 0.2s;
}

.form-group input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 10px var(--primary-color-glow);
}

.paypal-info {
    background-color: rgba(255, 255, 255, 0.1);
    border: 1px solid var(--border-color);
    padding: 15px;
    border-radius: 8px;
    text-align: center;
    margin: 20px 0;
    font-size: 1.1rem;
    letter-spacing: 1px;
}

.btn-paypal {
    display: inline-block;
    margin: 20px 0;
    background-color: #0070ba; /* Couleur officielle PayPal */
    border-color: #0070ba;
    color: #fff;
    width: 100%;
}

.btn-paypal:hover {
    background-color: #005ea6;
    border-color: #005ea6;
    box-shadow: 0 0 15px #0070ba;
}

/* --- Séparateur et Disclaimer --- */
.section-separator {
    border: 0;
    height: 1px;
    background-image: linear-gradient(to right, rgba(255, 255, 255, 0), rgba(255, 255, 255, 0.15), rgba(255, 255, 255, 0));
    margin: 60px 0;
}

.disclaimer {
    background: rgba(150, 100, 40, 0.1);
    border: 1px solid rgba(255, 200, 100, 0.2);
    border-radius: 12px;
    padding: 10px 25px;
    margin: -20px auto 40px auto;
    max-width: 90%;
    text-align: center;
    backdrop-filter: blur(5px);
}

/* --- Footer --- */
.main-footer {
    text-align: center;
    padding: 40px 0;
    margin-top: 40px;
    border-top: 1px solid var(--border-color);
    font-size: 0.9rem;
    opacity: 0.6;
}

/* --- Responsive --- */
@media (max-width: 768px) {
    .main-header h1 { font-size: 4vw; }
    .hero h2 { font-size: 2.5rem; }
    .hero .subtitle { font-size: 1.1rem; }
    .deck-header { flex-direction: column; align-items: flex-start; }
    .deck-actions { width: 100%; margin-top: 20px; }
    .btn { width: 100%; text-align: center; box-sizing: border-box; }
}