* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    background: #f5f5f5;
    color: #333;
    min-height: 100vh;
    display: flex;
    justify-content: center;
    padding: 2rem 1rem;
}

.container {
    width: 100%;
    max-width: 560px;
}

h1 {
    font-size: 1.8rem;
    margin-bottom: 0.25rem;
}

.subtitle {
    color: #666;
    margin-bottom: 1.5rem;
}

.upload-area {
    border: 2px dashed #ccc;
    border-radius: 12px;
    padding: 2.5rem 1rem;
    text-align: center;
    cursor: pointer;
    transition: border-color 0.2s, background 0.2s;
    background: #fff;
}

.upload-area:hover,
.upload-area.dragover {
    border-color: #4a90d9;
    background: #f0f7ff;
}

.upload-icon {
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
}

.upload-area .link {
    color: #4a90d9;
    text-decoration: underline;
}

.upload-area .hint {
    font-size: 0.85rem;
    color: #999;
    margin-top: 0.5rem;
}

.file-info {
    display: flex;
    align-items: center;
    justify-content: space-between;
    background: #fff;
    border: 1px solid #ddd;
    border-radius: 8px;
    padding: 0.75rem 1rem;
    font-size: 0.95rem;
}

.btn-remove {
    background: none;
    border: none;
    font-size: 1.1rem;
    cursor: pointer;
    color: #999;
    padding: 0 0.25rem;
}

.btn-remove:hover {
    color: #e74c3c;
}

.params {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1rem;
    margin: 1.5rem 0;
}

.param-group label {
    display: block;
    font-size: 0.85rem;
    font-weight: 500;
    margin-bottom: 0.3rem;
    color: #555;
}

.param-group input {
    width: 100%;
    padding: 0.6rem 0.75rem;
    border: 1px solid #ddd;
    border-radius: 8px;
    font-size: 1rem;
    background: #fff;
}

.param-group input:focus {
    outline: none;
    border-color: #4a90d9;
    box-shadow: 0 0 0 2px rgba(74, 144, 217, 0.15);
}

.btn-convert {
    width: 100%;
    padding: 0.85rem;
    background: #4a90d9;
    color: #fff;
    border: none;
    border-radius: 8px;
    font-size: 1.05rem;
    font-weight: 600;
    cursor: pointer;
    transition: background 0.2s;
}

.btn-convert:hover:not(:disabled) {
    background: #3a7bc8;
}

.btn-convert:disabled {
    background: #b0c4de;
    cursor: not-allowed;
}

.loading {
    text-align: center;
    margin-top: 1.5rem;
}

.progress-bar {
    width: 100%;
    height: 12px;
    background: #e9ecef;
    border-radius: 6px;
    overflow: hidden;
    margin-bottom: 0.75rem;
}

.progress-fill {
    height: 100%;
    width: 0%;
    background: linear-gradient(90deg, #4a90d9, #357abd);
    border-radius: 6px;
    transition: width 0.3s ease;
}

.loading p {
    color: #666;
    font-size: 0.95rem;
}

.error {
    margin-top: 1rem;
    padding: 0.75rem 1rem;
    background: #fef2f2;
    color: #c0392b;
    border-radius: 8px;
    font-size: 0.95rem;
}