body {
            background: 
                radial-gradient(circle at 85% 15%, rgba(209, 109, 129, 0.2) 0%, transparent 40%),
                linear-gradient(135deg, #fff0f3 0%, #ffccd5 100%),
                url("https://www.transparenttextures.com/patterns/shippo.png");
            background-attachment: fixed;
            font-family: 'Inter', sans-serif;
            min-height: 100vh;
            overflow-x: hidden;
            color: #4a3b3b;
            transition: background 0.5s ease, color 0.5s ease;
        }

        /* Mode Nuit */
        body.night-mode {
            background: 
                radial-gradient(circle at 15% 15%, rgba(129, 140, 248, 0.2) 0%, transparent 40%),
                linear-gradient(135deg, #020617 0%, #1e1b4b 100%),
                url("https://www.transparenttextures.com/patterns/shippo.png");
            color: #cbd5e1;
        }

        h1, h2 {
            font-family: 'Noto Serif JP', serif;
        }

        #conteneur {
            max-width: 900px;
            margin: 0 auto;
            position: relative;
            z-index: 10;
        }

        .btn-sakura {
            background: white;
            color: #d16d81;
            border: 2px solid #ffb7c5;
            padding: 10px 25px;
            border-radius: 50px;
            transition: all 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);
            display: inline-block;
            font-weight: bold;
            text-decoration: none;
            margin: 5px;
            box-shadow: 0 4px 6px rgba(209, 109, 129, 0.1);
            position: relative;
            overflow: hidden;
        }

        .btn-sakura::after {
            content: '';
            position: absolute;
            top: 0;
            left: -100%;
            width: 100%;
            height: 100%;
            background: linear-gradient(
                120deg,
                transparent,
                rgba(255, 255, 255, 0.4),
                transparent
            );
            transition: all 0.6s;
        }

        .btn-sakura:hover {
            background: #ffb7c5;
            color: white;
            transform: translateY(-5px) scale(1.05);
            box-shadow: 0 10px 20px rgba(209, 109, 129, 0.3);
        }

        .btn-sakura:hover::after {
            left: 100%;
        }

        body.night-mode .btn-sakura {
            background: #0f172a;
            color: #a5b4fc;
            border-color: #4338ca;
        }

        body.night-mode .btn-sakura:hover {
            background: #4338ca;
            color: white;
            box-shadow: 0 10px 25px rgba(67, 56, 202, 0.5);
        }

        /* Animation des pétales */
        .sakura {
            position: fixed;
            top: -10%;
            background: #ffb7c5;
            border-radius: 100% 0 100% 0;
            opacity: 0.7;
            pointer-events: none;
            animation: fall linear infinite;
            z-index: 1;
        }

        body.night-mode .sakura {
            background: #818cf8; /* Pétales bleus la nuit */
            box-shadow: 0 0 8px rgba(129, 140, 248, 0.5);
        }

        @keyframes fall {
            0% { top: -10%; transform: translateX(0) rotate(0deg); }
            100% { top: 110%; transform: translateX(100px) rotate(360deg); }
        }

        .tetrismarge {
            background: rgba(255, 255, 255, 0.6);
            backdrop-filter: blur(5px);
            border: 2px solid #ffb7c5;
            border-radius: 20px;
            padding: 20px;
        }

        body.night-mode .tetrismarge {
            background: rgba(15, 23, 42, 0.6);
            border-color: #4338ca;
        }

        footer {
            border-top: 1px solid #ffb7c5;
            margin-top: 50px;
            padding-top: 20px;
            color: #d16d81;
            font-style: italic;
        }

        body.night-mode footer, 
        body.night-mode h1, 
        body.night-mode h2, 
        body.night-mode .vertical-text, 
        body.night-mode .hanko {
            color: #a5b4fc;
            border-color: #4338ca;
        }

        /* Texte vertical décoratif */
        .vertical-text {
            writing-mode: vertical-rl;
            text-orientation: upright;
            position: absolute;
            left: -50px;
            top: 0;
            color: #d16d81;
            opacity: 0.3;
            font-family: 'Noto Serif JP', serif;
            font-size: 1.5rem;
            letter-spacing: 0.5rem;
        }

        /* Sceau Hanko */
        .hanko {
            display: inline-block;
            border: 2px solid #d16d81;
            color: #d16d81;
            padding: 5px;
            font-family: 'Noto Serif JP', serif;
            font-weight: bold;
            margin-top: 10px;
            line-height: 1;
            transform: rotate(-5deg);
            border-radius: 2px;
        }

        /* Bouton Switch */
        #mode-toggle {
            position: fixed;
            top: 20px;
            right: 20px;
            z-index: 100;
            width: 50px;
            height: 50px;
            border-radius: 50%;
            background: white;
            border: 2px solid #ffb7c5;
            cursor: pointer;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 1.5rem;
            box-shadow: 0 4px 6px rgba(0,0,0,0.1);
            transition: all 0.3s ease;
        }
        #mode-toggle:hover {
            transform: scale(1.1) rotate(15deg);
            box-shadow: 0 6px 12px rgba(0,0,0,0.2);
        }
        body.night-mode #mode-toggle {
            background: #1e1b4b;
            border-color: #4338ca;
        }