:root {
    --bg-dark-radial: radial-gradient(circle at center, #1b0a0e 0%, #060405 100%);
    --primary-red: #ff003c;
    --primary-red-glow: rgba(255, 0, 60, 0.85);
    --gold-glow: rgba(255, 183, 3, 0.4);
    --text-white: #ffffff;
    --text-muted: #a6989b;
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    -webkit-tap-highlight-color: transparent;
}

body {
    font-family: var(--font-sans);
    background: #060405;
    background: var(--bg-dark-radial);
    min-height: 100vh;
    width: 100vw;
    overflow: hidden;
    display: flex;
    justify-content: center;
    align-items: center;
    position: relative;
    color: var(--text-white);
}


#heartCanvas {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 1;
}


.landing-screen {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(6, 4, 5, 0.85);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 10;
    transition: opacity 1.2s cubic-bezier(0.25, 1, 0.5, 1);
    padding: 20px;
}

.landing-screen.fade-out {
    opacity: 0;
    pointer-events: none;
}


.landing-card {
    background: rgba(20, 12, 14, 0.65);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid rgba(255, 255, 255, 0.08);
    box-shadow: 0 20px 50px rgba(0, 0, 0, 0.8),
                0 0 30px rgba(255, 0, 60, 0.1);
    border-radius: 24px;
    padding: 40px 30px;
    width: 100%;
    max-width: 420px;
    text-align: center;
    animation: cardZoomIn 1s cubic-bezier(0.16, 1, 0.3, 1);
}

.card-title {
    font-size: 1.8rem;
    font-weight: 700;
    color: var(--text-white);
    margin-bottom: 1rem;
    letter-spacing: -0.5px;
    text-shadow: 0 0 10px rgba(255, 255, 255, 0.1);
}

.card-message {
    font-size: 0.95rem;
    color: var(--text-muted);
    line-height: 1.6;
    margin-bottom: 2rem;
}


.start-btn {
    font-family: var(--font-sans);
    background: linear-gradient(135deg, #ff3366 0%, #ff003c 100%);
    color: var(--text-white);
    border: none;
    padding: 14px 36px;
    font-size: 1rem;
    font-weight: 600;
    border-radius: 30px;
    cursor: pointer;
    box-shadow: 0 4px 20px rgba(255, 0, 60, 0.45);
    transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1.4);
    border: 1px solid rgba(255, 255, 255, 0.15);
    animation: btnPulse 2s infinite ease-in-out;
}

.start-btn:hover {
    transform: translateY(-3px) scale(1.04);
    box-shadow: 0 8px 30px rgba(255, 0, 60, 0.7);
    background: linear-gradient(135deg, #ff003c 0%, #ff3366 100%);
}

.start-btn:active {
    transform: translateY(1px) scale(0.98);
}


.center-container {
    position: absolute;
    z-index: 5;
    pointer-events: none;
    display: flex;
    flex-direction: column; /* Susun vertikal agar tombol berada di bawah teks */
    justify-content: center;
    align-items: center;
    text-align: center;
    gap: 1.8rem; /* Jarak antara teks Love you. dan tombol Kembali */
}

.center-text {
    font-size: clamp(2.6rem, 10vw, 5rem); /* Skala responsif otomatis agar teks tidak meluap/turun baris di HP kecil */
    white-space: nowrap; /* Mencegah teks patah menjadi 2 baris */
    font-weight: 800;
    color: #ffffff;
    letter-spacing: -2px;
    opacity: 0;
    transform: scale(0.85);
    /* Desain bayangan cahaya merah persis gambar referensi */
    text-shadow: 0 0 12px var(--primary-red-glow),
                 0 0 25px var(--primary-red-glow),
                 0 0 50px rgba(255, 0, 60, 0.3);
    transition: all 2s cubic-bezier(0.25, 1, 0.5, 1) 1.5s; /* Fades in elegantly after heart forms */
}

.center-container.active .center-text {
    opacity: 1;
    transform: scale(1);
    animation: textFloat 3s infinite ease-in-out 3.5s;
}

/* Back Button (Tombol Kembali Glassmorphic) */
.back-btn {
    pointer-events: all; /* Aktifkan klik kembali meskipun pembungkusnya pointer-events: none */
    font-family: var(--font-sans);
    background: rgba(255, 255, 255, 0.05);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    color: rgba(255, 255, 255, 0.65);
    border: 1px solid rgba(255, 255, 255, 0.12);
    padding: 10px 24px;
    font-size: 0.85rem;
    font-weight: 500;
    border-radius: 30px;
    cursor: pointer;
    opacity: 0;
    transform: translateY(15px);
    transition: all 1.5s cubic-bezier(0.25, 1, 0.5, 1) 2.5s; /* Muncul paling terakhir setelah teks muncul */
    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.4);
}

.center-container.active .back-btn {
    opacity: 1;
    transform: translateY(0);
}

.back-btn:hover {
    background: rgba(255, 255, 255, 0.15);
    color: #ffffff;
    border-color: var(--primary-red);
    box-shadow: 0 0 15px rgba(255, 0, 60, 0.45);
}

.sound-toggle {
    position: fixed;
    bottom: 20px;
    right: 20px;
    background: rgba(20, 12, 14, 0.55);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid rgba(255, 255, 255, 0.08);
    color: rgba(255, 255, 255, 0.7);
    padding: 10px 18px;
    border-radius: 30px;
    font-family: var(--font-sans);
    font-weight: 500;
    font-size: 0.85rem;
    cursor: pointer;
    box-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.3);
    z-index: 12;
    transition: all 0.3s ease;
}

.sound-toggle:hover {
    transform: scale(1.05);
    background: rgba(255, 255, 255, 0.1);
    color: #ffffff;
}

.sound-toggle.muted {
    background: rgba(0, 0, 0, 0.4);
    color: rgba(255, 255, 255, 0.35);
    border-color: transparent;
}


@keyframes cardZoomIn {
    0% {
        opacity: 0;
        transform: scale(0.9) translateY(15px);
        filter: blur(10px);
    }
    100% {
        opacity: 1;
        transform: scale(1) translateY(0);
        filter: blur(0);
    }
}

@keyframes btnPulse {
    0%, 100% {
        box-shadow: 0 4px 20px rgba(255, 0, 60, 0.45);
    }
    50% {
        box-shadow: 0 4px 30px rgba(255, 0, 60, 0.75), 0 0 10px rgba(255, 0, 60, 0.3);
    }
}

@keyframes textFloat {
    0%, 100% {
        transform: translateY(0) scale(1);
    }
    50% {
        transform: translateY(-8px) scale(1.02);
    }
}


@media (max-width: 600px) {
    .center-text {
        letter-spacing: -1px;
    }
    .landing-card {
        padding: 32px 20px;
        margin: 15px; /* Jarak dari sisi HP */
        max-width: 90%; /* Membatasi lebar agar pas di semua ukuran HP */
        box-shadow: 0 15px 35px rgba(0, 0, 0, 0.8),
                    0 0 20px rgba(255, 0, 60, 0.08);
    }
    .card-title {
        font-size: 1.4rem;
        line-height: 1.35;
    }
    .card-message {
        font-size: 0.85rem;
        line-height: 1.5;
        margin-bottom: 1.6rem;
    }
    .start-btn {
        padding: 12px 28px;
        font-size: 0.95rem;
    }
}