body { 
    margin: 0; 
    overflow: hidden; 
    background: #000; 
    font-family: 'Segoe UI', Roboto, Helvetica, Arial, sans-serif; 
    color: white;
}

canvas { 
    display: block; 
    width: 100vw; 
    height: 100vh; 
}

video { 
    display: none; 
}

.hidden {
    display: none !important;
}

/* --- 开始界面样式 --- */
#intro {
    position: fixed; 
    top: 0; 
    left: 0; 
    width: 100%; 
    height: 100%;
    background: rgba(0, 5, 15, 0.85);
    backdrop-filter: blur(12px);
    z-index: 100;
    display: flex; 
    justify-content: center; 
    align-items: center;
    transition: opacity 0.8s ease;
}

.intro-content {
    max-width: 700px;
    text-align: center;
    padding: 40px;
    border: 1px solid rgba(255, 255, 255, 0.15);
    border-radius: 24px;
    background: rgba(255, 255, 255, 0.03);
    box-shadow: 0 0 50px rgba(0, 255, 255, 0.1);
}

h1 {
    font-size: 42px;
    letter-spacing: 6px;
    margin-bottom: 5px;
    background: linear-gradient(90deg, #00f2fe, #4facfe, #f093fb);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

h1 span {
    display: block;
    font-size: 18px;
    letter-spacing: 12px;
    color: rgba(255,255,255,0.6);
    -webkit-text-fill-color: rgba(255,255,255,0.6);
    margin-top: 10px;
}

.subtitle {
    color: rgba(255,255,255,0.5);
    letter-spacing: 2px;
    margin-bottom: 35px;
}

.gesture-list {
    display: flex;
    flex-direction: column;
    gap: 15px;
    margin-bottom: 40px;
}

.gesture-item {
    display: flex;
    align-items: center;
    gap: 20px;
    background: rgba(255, 255, 255, 0.05);
    padding: 15px 20px;
    border-radius: 16px;
    border: 1px solid rgba(255, 255, 255, 0.08);
    text-align: left;
    transition: transform 0.3s, background 0.3s;
}

.gesture-item:hover {
    background: rgba(0, 242, 254, 0.1);
    transform: translateY(-3px);
    border-color: rgba(0, 242, 254, 0.3);
}

.icon {
    font-size: 36px;
    filter: drop-shadow(0 0 10px rgba(255,255,255,0.3));
}

.text strong {
    display: block;
    font-size: 18px;
    color: #4facfe;
    margin-bottom: 6px;
}

.text p {
    margin: 2px 0;
    font-size: 13px;
    color: rgba(255,255,255,0.7);
}

#startBtn {
    background: linear-gradient(45deg, #00f2fe, #4facfe);
    border: none;
    color: white;
    font-size: 18px;
    font-weight: bold;
    letter-spacing: 2px;
    padding: 16px 48px;
    border-radius: 50px;
    cursor: pointer;
    box-shadow: 0 0 20px rgba(79, 172, 254, 0.4);
    transition: all 0.3s;
}

#startBtn:hover {
    transform: scale(1.05);
    box-shadow: 0 0 40px rgba(79, 172, 254, 0.8);
}

.hint {
    margin-top: 20px;
    font-size: 12px;
    color: rgba(255,255,255,0.4);
}

/* --- 状态提示样式 --- */
#loading {
    position: fixed; 
    top: 50%; 
    left: 50%; 
    transform: translate(-50%, -50%);
    color: white; 
    font-size: 18px;
    background: rgba(0,0,0,0.8);
    padding: 20px 40px;
    border-radius: 12px;
    z-index: 101;
    border: 1px solid #4facfe;
}

.hud {
    position: fixed; 
    bottom: 20px; 
    left: 50%; 
    transform: translateX(-50%);
    z-index: 50;
    pointer-events: none;
}

#status-text {
    background: rgba(0, 0, 0, 0.6);
    padding: 8px 24px;
    border-radius: 20px;
    font-size: 14px;
    letter-spacing: 1px;
    border: 1px solid rgba(255,255,255,0.2);
    backdrop-filter: blur(5px);
    color: #00f2fe;
}