body, html {
    margin: 0;
    padding: 0;
    width: 100%;
    height: 100%;
    overflow: hidden;
    background-color: #f0f0f0; 
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

/* 加载层 */
#loader-layer {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background-color: #f0f0f0;
    z-index: 9999;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    transition: opacity 0.8s cubic-bezier(0.8, 0, 0.2, 1);
}

.loader-text { 
    color: #222; 
    font-size: 1rem; 
    letter-spacing: 6px; 
    margin-bottom: 20px; 
    font-weight: 500; 
}

.blink { 
    animation: blinker 1s linear infinite; 
}

@keyframes blinker { 
    50% { opacity: 0; } 
}

.progress-box { 
    width: 200px; 
    height: 2px; 
    background: rgba(0,0,0,0.1); 
    position: relative; 
    overflow: hidden; 
}

.progress-bar { 
    position: absolute; 
    top: 0; 
    left: 0; 
    height: 100%; 
    width: 0%; 
    background: #222; 
}

/* 画布层 */
#fluid-canvas {
    width: 100vw; 
    height: 100vh; 
    position: absolute; 
    top: 0; 
    left: 0;
    z-index: 1; 
    filter: invert(1) sepia(0.05) contrast(1.1); 
    display: block; 
}

/* 主 UI 层 */
.ui-layer {
    position: absolute; 
    top: 50%; 
    left: 50%; 
    transform: translate(-50%, -50%);
    z-index: 10; 
    display: flex; 
    flex-direction: column; 
    align-items: center;
    color: #222; 
    text-shadow: 0 2px 10px rgba(255,255,255,0.5); 
    pointer-events: none; 
    opacity: 0; 
    transition: opacity 1.5s ease; 
}

.interactive-button {
    margin-top: 30px; 
    padding: 12px 36px; 
    background: rgba(255,255,255,0.1);
    border: 1px solid #222; 
    /* 移除 border-radius 保持纯粹的系统风格 */
    color: #222; 
    font-size: 1.1rem;
    cursor: pointer; 
    backdrop-filter: blur(4px); 
    transition: all 0.4s ease; 
    pointer-events: auto; 
}

.interactive-button:hover { 
    background: #222; 
    color: #fff; 
    transform: scale(1.02); 
    box-shadow: 0 4px 15px rgba(0,0,0,0.1); 
}

h1 { 
    font-size: 4rem; 
    font-weight: 300; 
    letter-spacing: 10px; 
    margin: 0; 
    text-align: center; 
}

p { 
    font-size: 1.2rem; 
    font-weight: 400; 
    letter-spacing: 4px; 
    opacity: 0.8; 
    margin-top: 10px; 
    text-align: center; 
}