body {
            background-color: #0c0a09;
            color: #ffffff;
            margin: 0;
            overflow: hidden;
            font-family: 'Satoshi', sans-serif;
            -webkit-font-smoothing: antialiased;
        }

        /* Layer Latar Belakang & 3D (Dinaikkan z-index agar render di depan kartu saat burst) */
        #webgl-container {
            position: fixed;
            top: 0;
            left: 0;
            width: 100vw;
            height: 100vh;
            z-index: 45; /* Di atas kartu untuk efek kedalaman 3D maksimal */
            pointer-events: none; /* Klik tetap menembus ke tombol di bawahnya */
        }

        /* Animasi Gradien Aurora */
        .aurora-bg {
            position: fixed;
            top: 0;
            left: 0;
            width: 100vw;
            height: 100vh;
            z-index: 0;
            overflow: hidden;
            background: #0c0a09;
        }
        .orb {
            position: absolute;
            border-radius: 50%;
            filter: blur(80px);
            opacity: 0.6;
            animation: float 20s infinite alternate ease-in-out;
        }
        .orb-1 { width: 60vw; height: 60vw; background: hsla(333,70%,55%,.4); top: -10%; left: -10%; animation-duration: 25s; }
        .orb-2 { width: 50vw; height: 50vw; background: hsla(282,82%,54%,.3); bottom: -20%; right: -10%; animation-duration: 22s; animation-direction: alternate-reverse; }
        .orb-3 { width: 40vw; height: 40vw; background: hsla(210,89%,60%,.3); top: 40%; left: 30%; animation-duration: 28s; }
        .orb-4 { width: 35vw; height: 35vw; background: hsla(35,90%,60%,.2); top: 10%; right: 20%; animation-duration: 30s; }

        @keyframes float {
            0% { transform: translate(0, 0) scale(1); }
            33% { transform: translate(30px, -50px) scale(1.1); }
            66% { transform: translate(-20px, 20px) scale(0.9); }
            100% { transform: translate(0, 0) scale(1); }
        }

        /* Elemen Antarmuka Pengguna */
        #ui-layer {
            position: relative;
            z-index: 10;
            width: 100%;
            height: 100vh;
            display: flex;
            flex-direction: column;
        }

        /* Progress Bar */
        #progress-container {
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 4px;
            background: rgba(255, 255, 255, 0.1);
            z-index: 50;
        }
        #progress-bar {
            height: 100%;
            width: 0%;
            background: linear-gradient(90deg, #ec4899, #e11d48);
            transition: width 0.6s cubic-bezier(0.4, 0, 0.2, 1);
        }

        /* Glassmorphism Card */
        .glass-card {
            background: rgba(20, 16, 18, 0.4);
            backdrop-filter: blur(16px);
            -webkit-backdrop-filter: blur(16px);
            border: 1px solid rgba(255, 255, 255, 0.1);
            box-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.37);
        }

        /* Gradien Teks */
        .text-gradient {
            background: linear-gradient(to right, #fbcfe8, #ffffff);
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            background-clip: text;
        }

        /* Gaya Tombol Modern */
        .btn-modern {
            background: linear-gradient(135deg, #ec4899, #e11d48);
            box-shadow: 0 4px 15px rgba(236, 72, 153, 0.4);
            transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
            cursor: pointer;
        }
        .btn-modern:hover {
            transform: translateY(-4px) scale(1.05);
            box-shadow: 0 8px 25px rgba(236, 72, 153, 0.6);
        }
        .btn-modern:active { transform: translateY(2px) scale(0.98); }
        .btn-modern:disabled { opacity: 0; pointer-events: none; }

        /* Animasi Denyut Emoji */
        .pulse-emoji { animation: pulse-glow 2s infinite ease-in-out; }
        @keyframes pulse-glow {
            0% { transform: scale(1); filter: drop-shadow(0 0 10px rgba(236,72,153,0.5)); }
            50% { transform: scale(1.15); filter: drop-shadow(0 0 25px rgba(236,72,153,0.8)); }
            100% { transform: scale(1); filter: drop-shadow(0 0 10px rgba(236,72,153,0.5)); }
        }

        /* Bingkai Polaroid */
        .polaroid-wrapper { perspective: 1000px; display: inline-block; }
        .polaroid {
            background: #ffffff;
            padding: 12px 12px 40px 12px;
            box-shadow: 0 20px 40px rgba(0,0,0,0.5);
            transform-style: preserve-3d;
            transition: transform 0.1s ease-out;
            cursor: pointer;
        }
        .polaroid img { width: 100%; height: auto; border-radius: 2px; pointer-events: none; }
        .polaroid-caption {
            color: #333; font-family: 'Playfair Display', serif; text-align: center;
            font-style: italic; margin-top: 15px; font-size: 1.1rem; pointer-events: none;
        }

        /* Wadah Halaman Langkah */
        .step-container { display: none; flex: 1; align-items: center; justify-content: center; padding: 20px; }
        .step-container.active { display: flex; }
        .stagger-el { opacity: 0; }

        /* =========================================
           DESAIN SURAT CINTA (Responsif & Serasi)
           ========================================= */
        .envlope-wrapper {
            height: 280px;
            display: flex;
            justify-content: center;
            align-items: flex-end;
            margin-top: 20px;
        }
        @media (max-width: 640px) {
            .envlope-wrapper {
                height: 210px;
                margin-top: 0;
            }
        }
        #envelope {
            position: relative;
            width: 280px;
            height: 180px;
            border-bottom-left-radius: 6px;
            border-bottom-right-radius: 6px;
            background-color: #e11d48; /* Merah Rose 600 */
            box-shadow: 0 4px 20px rgba(0, 0, 0, 0.2);
            cursor: pointer;
        }
        .front { position: absolute; width: 0; height: 0; z-index: 3; }
        .flap {
            border-left: 140px solid transparent;
            border-right: 140px solid transparent;
            border-bottom: 82px solid transparent;
            border-top: 98px solid #e11d48; /* Merah Rose 600 */
            transform-origin: top;
            pointer-events: none;
        }
        .pocket {
            border-left: 140px solid #f472b6; /* Pink 400 (Sisi kiri/kanan) */
            border-right: 140px solid #f472b6;
            border-bottom: 90px solid #ec4899; /* Pink 500 (Bagian bawah saku) */
            border-top: 90px solid transparent;
            border-bottom-left-radius: 6px;
            border-bottom-right-radius: 6px;
            pointer-events: none;
        }
        .letter {
            position: relative;
            background-color: #fff;
            width: 90%;
            margin-left: auto;
            margin-right: auto;
            height: 90%;
            top: 5%;
            border-radius: 6px;
            box-shadow: 0 2px 26px rgba(0, 0, 0, 0.12);
            font-family: "Dancing Script", cursive;
            color: #333;
        }
        .letter:after { content: ""; position: absolute; top: 0; bottom: 0; left: 0; right: 0; }
        .words { position: absolute; left: 10%; width: 80%; height: 14%; background-color: #fce7f3; color: #333; } /* Kertas Garis Pink 100 */
        .words.line1 { top: 10%; width: 20%; height: 7%; font-size: 0.7rem; }
        .words.line2 { top: 30%; text-align: center; font-size: 1.1rem; line-height: 1.1; }
        .words.line3 { top: 50%; text-align: center; font-size: 1.1rem; line-height: 1.1; }
        .words.line4 { top: 70%; text-align: center; font-size: 1.1rem; line-height: 1.1; }

        /* Logika Translasi Amplop Buka-Tutup */
        .open .flap { transform: rotateX(180deg); transition: transform 0.4s ease, z-index 0.6s; z-index: 1; }
        .close .flap { transform: rotateX(0deg); transition: transform 0.4s 0.6s ease, z-index 1s; z-index: 5; }
        .close .letter { transform: translateY(0px); transition: transform 0.4s ease, z-index 1s; z-index: 1; }
        .open .letter { transform: translateY(-100px); transition: transform 0.4s 0.6s ease, z-index 0.6s; z-index: 2; }