* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background: linear-gradient(135deg, #1a2a6c, #b21f1f, #fdbb2d);
    color: white;
    min-height: 100vh;
    padding: 20px;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
}

header {
    text-align: center;
    padding: 30px 0;
    margin-bottom: 30px;
}

h1 {
    font-size: 2.5rem;
    margin-bottom: 10px;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.3);
}

.subtitle {
    font-size: 1.2rem;
    opacity: 0.9;
    max-width: 800px;
    margin: 0 auto;
}

.cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 25px;
    margin-bottom: 40px;
}

.card {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    border-radius: 15px;
    padding: 25px;
    box-shadow: 0 10px 20px rgba(0, 0, 0, 0.2);
    transition: transform 0.3s ease;
}

.card:hover {
    transform: translateY(-5px);
}

.card h2 {
    font-size: 1.5rem;
    margin-bottom: 15px;
    color: #ffcc00;
}

.demo-container {
    position: relative;
    width: 100%;
    height: 250px;
    border-radius: 10px;
    overflow: hidden;
    margin: 15px 0;
    border: 2px solid rgba(255, 255, 255, 0.2);
}

.video-demo {
    width: 100%;
    height: 100%;
    object-fit: contain;
}

.background-selector {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    margin-top: 15px;
}

.bg-option {
    padding: 8px 15px;
    background: rgba(255, 255, 255, 0.2);
    border-radius: 20px;
    cursor: pointer;
    transition: all 0.3s ease;
}

.bg-option:hover {
    background: rgba(255, 255, 255, 0.3);
}

.bg-option.active {
    background: #ffcc00;
    color: #333;
}

.controls {
    display: flex;
    justify-content: center;
    gap: 15px;
    margin-top: 15px;
}

button {
    padding: 10px 20px;
    border: none;
    border-radius: 30px;
    background: #ffcc00;
    color: #333;
    font-weight: bold;
    cursor: pointer;
    transition: all 0.3s ease;
}

button:hover {
    background: #ffd633;
    transform: scale(1.05);
}

.info-box {
    background: rgba(0, 0, 0, 0.3);
    border-radius: 10px;
    padding: 20px;
    margin-top: 30px;
}

.info-box h3 {
    margin-bottom: 15px;
    color: #ffcc00;
}

.info-box ul {
    padding-left: 20px;
}

.info-box li {
    margin-bottom: 10px;
    line-height: 1.5;
}

.note {
    margin-top: 30px;
    text-align: center;
    font-style: italic;
    opacity: 0.8;
}

footer {
    text-align: center;
    margin-top: 50px;
    padding: 20px;
    border-top: 1px solid rgba(255, 255, 255, 0.2);
}

@media (max-width: 768px) {
    .cards {
        grid-template-columns: 1fr;
    }

    h1 {
        font-size: 2rem;
    }
}

/* 上传区域样式 */
.upload-section {
    margin: 20px 0;
    text-align: center;
    padding: 15px;
    /* background: #f8f9fa; */
    border-radius: 8px;
    border: 2px dashed #dee2e6;
    color: white;
}

.file-input {
    display: none;
}

.upload-btn {
    display: inline-block;
    padding: 12px 24px;
    background: #28a745;
    color: white;
    border-radius: 5px;
    cursor: pointer;
    transition: background 0.3s;
    font-weight: bold;
}

.upload-btn:hover {
    background: #218838;
}

.file-info {
    margin-top: 10px;
    font-size: 14px;
    color: white;
}

.controls {
    display: flex;
    gap: 10px;
    justify-content: center;
    margin-top: 15px;
    flex-wrap: wrap;
}

.controls button {
    padding: 8px 16px;
    border: none;
    border-radius: 4px;
    background: #007bff;
    color: white;
    cursor: pointer;
    transition: background 0.3s;
    font-size: 14px;
}

.controls button:hover {
    background: #0056b3;
}

.controls .use-uploaded {
    background: #28a745;
}

.controls .use-uploaded:hover {
    background: #218838;
}

.controls button:disabled {
    background: #6c757d;
    cursor: not-allowed;
}