body { 
    margin: 0; 
    padding: 0; 
    background-color: #000; 
    overflow: hidden; 
    font-family: sans-serif; 
    height: 100vh; 
    display: block; /* 取消 flex，改用绝对定位布局 */
}

/* 1. 容器占满全屏 */
#camera-container {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%; 
    z-index: 1;
    overflow: hidden;
}

/* 2. 视频：保持比例填满屏幕 (可能会有裁切，但为了全屏体验必须这样) */
video {
    width: 100%;
    height: 100%;
    object-fit: cover; 
    transform: scaleX(-1); /* 镜像 */
}

/* 3. 结果图：全屏显示 */
#photo-result {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: fill; /* 让结果图完整铺满 */
    display: none;
    z-index: 10;
}

/* 4. 拍照框：强制拉伸填满 (解决框显示不全的问题) */
.frame-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    /* 关键：使用 fill 强制拉伸，确保上下左右都显示出来，不被裁切 */
    object-fit: fill; 
    pointer-events: none; /* 点击穿透 */
    z-index: 5;
}

/* 倒计时 */
#countdown-display {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 100px;
    color: white;
    font-weight: bold;
    text-shadow: 2px 2px 10px rgba(0,0,0,0.5);
    display: none;
    z-index: 20;
}

/* 5. 底部控制区：改为透明浮层，不占用高度 */
.controls {
    position: absolute; /* 绝对定位，浮在视频上面 */
    bottom: 0;
    left: 0;
    width: 100%;
    height: 140px; 
    /* 底部黑色渐变，防止按钮看不清 */
    background: linear-gradient(to top, rgba(0,0,0,0.8), rgba(0,0,0,0));
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 30; 
}

#start-btn {
    width: 70px;
    height: 70px;
    border-radius: 50%;
    background-color: #fff;
    border: 5px solid #ccc;
    outline: none;
    cursor: pointer;
    box-shadow: 0 4px 10px rgba(0,0,0,0.3);
}
#start-btn:active { background-color: #ddd; transform: scale(0.95); }

#result-controls {
    display: none; 
    width: 100%;
    justify-content: space-around;
    align-items: center;
}

.action-btn {
    padding: 10px 25px;
    border-radius: 25px;
    border: none;
    font-size: 16px;
    color: white;
    cursor: pointer;
    user-select: none;
    box-shadow: 0 2px 5px rgba(0,0,0,0.5);
}

.btn-retake { background-color: #555; }
.btn-save { background-color: #28a745; position: relative;}

.save-tip {
    font-size: 12px;
    position: absolute;
    bottom: -25px;
    left: 50%;
    transform: translateX(-50%);
    color: #fff;
    text-shadow: 0 1px 2px rgba(0,0,0,0.8);
    white-space: nowrap;
}