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

:root {
    --primary: #4a90d9;
    --primary-hover: #357abd;
    --bg: #f5f7fa;
    --card: #ffffff;
    --text: #333333;
    --text-light: #666666;
    --border: #e0e0e0;
    --success: #52c41a;
    --error: #ff4d4f;
    --warning: #faad14;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
}

.container {
    max-width: 900px;
    margin: 0 auto;
    padding: 20px;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 24px;
}

header h1 {
    font-size: 28px;
    color: var(--primary);
}

.lang-btn {
    padding: 8px 16px;
    background: transparent;
    border: 1px solid var(--primary);
    color: var(--primary);
    border-radius: 6px;
    cursor: pointer;
    font-size: 14px;
    transition: all 0.2s;
}

.lang-btn:hover {
    background: var(--primary);
    color: white;
}

.tabs {
    display: flex;
    gap: 4px;
    margin-bottom: 24px;
    background: var(--card);
    padding: 8px;
    border-radius: 12px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.06);
    overflow-x: auto;
}

.tab {
    padding: 10px 20px;
    border: none;
    background: transparent;
    cursor: pointer;
    border-radius: 8px;
    font-size: 14px;
    font-weight: 500;
    color: var(--text-light);
    transition: all 0.2s;
    white-space: nowrap;
}

.tab:hover {
    background: var(--bg);
    color: var(--text);
}

.tab.active {
    background: var(--primary);
    color: white;
}

.panel {
    display: none;
    background: var(--card);
    padding: 32px;
    border-radius: 12px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.06);
}

.panel.active {
    display: block;
}

.panel h2 {
    margin-bottom: 24px;
    font-size: 20px;
    color: var(--text);
}

.upload-area {
    border: 2px dashed var(--border);
    border-radius: 12px;
    padding: 40px;
    text-align: center;
    background: var(--bg);
    transition: all 0.2s;
    cursor: pointer;
}

.upload-area:hover {
    border-color: var(--primary);
    background: #f0f7ff;
}

.upload-area.dragover {
    border-color: var(--primary);
    background: #e6f3ff;
}

.upload-area p {
    color: var(--text-light);
    font-size: 15px;
}

.link {
    color: var(--primary);
    cursor: pointer;
    text-decoration: underline;
}

.file-list {
    margin: 16px 0;
}

.file-item {
    display: flex;
    align-items: center;
    padding: 12px;
    background: var(--bg);
    border-radius: 8px;
    margin-bottom: 8px;
}

.file-item .file-name {
    flex: 1;
    font-size: 14px;
    color: var(--text);
}

.file-item .file-size {
    color: var(--text-light);
    font-size: 13px;
    margin-left: 12px;
}

.file-item .remove-btn {
    background: none;
    border: none;
    color: var(--error);
    cursor: pointer;
    font-size: 18px;
    margin-left: 12px;
    padding: 4px 8px;
}

.file-info {
    margin: 16px 0;
    padding: 12px;
    background: var(--bg);
    border-radius: 8px;
    font-size: 14px;
    color: var(--text);
    display: none;
}

.form-group {
    margin: 16px 0;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-size: 14px;
    font-weight: 500;
    color: var(--text);
}

.form-group input,
.form-group select {
    width: 100%;
    padding: 10px 14px;
    border: 1px solid var(--border);
    border-radius: 8px;
    font-size: 14px;
    transition: border-color 0.2s;
}

.form-group input:focus,
.form-group select:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(74, 144, 217, 0.1);
}

.btn {
    padding: 12px 24px;
    border: none;
    border-radius: 8px;
    font-size: 15px;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s;
    margin-top: 20px;
}

.btn.primary {
    background: var(--primary);
    color: white;
    width: 100%;
}

.btn.primary:hover:not(:disabled) {
    background: var(--primary-hover);
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.hidden {
    display: none !important;
}

.toast {
    position: fixed;
    bottom: 20px;
    left: 50%;
    transform: translateX(-50%);
    padding: 12px 24px;
    background: var(--text);
    color: white;
    border-radius: 8px;
    font-size: 14px;
    z-index: 1000;
    animation: fadeIn 0.3s ease;
}

.toast.success {
    background: var(--success);
}

.toast.error {
    background: var(--error);
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateX(-50%) translateY(20px); }
    to { opacity: 1; transform: translateX(-50%) translateY(0); }
}

.progress-bar {
    width: 100%;
    height: 4px;
    background: var(--border);
    border-radius: 2px;
    margin-top: 16px;
    overflow: hidden;
}

.progress-bar .progress {
    height: 100%;
    background: var(--primary);
    border-radius: 2px;
    transition: width 0.3s ease;
}

@media (max-width: 600px) {
    .container {
        padding: 12px;
    }

    header h1 {
        font-size: 22px;
    }

    .tabs {
        padding: 6px;
    }

    .tab {
        padding: 8px 14px;
        font-size: 13px;
    }

    .panel {
        padding: 20px;
    }

    .upload-area {
        padding: 30px 20px;
    }
}

.preview-container {
    margin-top: 16px;
    width: 100%;
}

.preview-container embed {
    width: 100%;
    border: 1px solid var(--border);
    border-radius: 8px;
}
    border-radius: 8px;
}