body {
    margin: 0;
    height: 100vh;
    background-color: black;

    display: flex;
    justify-content: center;
    align-items: center;
    position: relative;
    overflow: hidden;
}

#particle-canvas {
    position: fixed;
    inset: 0;
    width: 100%;
    height: 100%;
    z-index: 0;
    pointer-events: none;
    display: block;
} 

.center-button {
    position: relative;
    z-index: 1;
    padding: 15px 30px;
    font-size: 18px;
    color: white;
    background-color: #222;
    border: 2px solid white;
    cursor: pointer;

    transition: opacity 0.6s ease;
}

.center-button.fade-out{
    opacity: 0;
    pointer-events: none;
}

.center-button:hover {
    background-color: white;
    color: black;
}

/* Hidden/visible helpers for the centered start button */
.center-button.hidden {
    opacity: 0;
    pointer-events: none;
}
.center-button.visible {
    opacity: 1;
    pointer-events: auto;
}

#heart-message {
    position: fixed;
    left: 50%;
    top: 25%;
    transform: translate(-50%, -50%) scale(0.96);
    z-index: 2;
    color: #ff32ff;
    font-size: 2rem;
    font-weight: 600;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.8s ease, transform 0.8s cubic-bezier(.2,.8,.2,1);
    text-shadow: 0 6px 18px rgba(248, 28, 248, 0.18);
    white-space: nowrap;
}

#heart-message.show {
    opacity: 1;
    transform: translate(-50%, -50%) scale(1);
}

@media (max-width: 480px) {
    #heart-message { font-size: 1.2rem; top: 64%; }
}

.heart-button {
    position: fixed;
    left: 50%;
    bottom: 8%;
    transform: translateX(-50%);
    z-index: 3;
    font-size: 48px;
    line-height: 1;
    padding: 0.2rem;
    background: transparent;
    border: none;
    color: #ff2d6f;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    -webkit-tap-highlight-color: transparent;
    transition: transform 1400ms ease;
    animation: heartbeat 1.2s ease-in-out infinite;
}

.heart-button:focus {
    outline: 2px solid rgba(255,45,111,0.25);
    outline-offset: 6px;
}

#more_message {
    position: fixed;
    left: 50%;
    bottom: 4.5%;
    transform: translateX(-50%);
    z-index: 3;
    color: #ffd1dc;
    font-size: 1rem;
    text-align: center;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.6s ease;
    white-space: nowrap;
}

#more_message.visible {
    opacity: 1;
    pointer-events: auto;
}

#more_message.hidden {
    opacity: 0;
    pointer-events: none;
}

@keyframes heartbeat {
    0%   { transform: translateX(-50%) scale(1); }
    8%   { transform: translateX(-50%) scale(1.28); }
    18%  { transform: translateX(-50%) scale(0.96); }
    30%  { transform: translateX(-50%) scale(1.14); }
    40%  { transform: translateX(-50%) scale(1); }
    100% { transform: translateX(-50%) scale(1); }
}

@media (max-width: 480px) {
    .heart-button { font-size: 40px; bottom: 10%; }
    #more_message { bottom: 3%; font-size: 0.95rem; }
}

/* Hidden/visible states for the bottom heart */
.heart-button.hidden {
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.6s ease;
    animation-play-state: paused;
}
.heart-button.visible {
    opacity: 1;
    pointer-events: auto;
    transition: opacity 0.6s ease;
    animation-play-state: running;
}