:root {
    --color-primary: #0052CC;
    --color-primary-hover: #0747A6;
    --color-secondary: #6B778C;
    --color-success: #00875A;
    --color-danger: #DE350B;
    --color-warning: #FF991F;
    --color-text: #172B4D;
    --color-text-subtle: #5E6C84;
    --color-background: #FAFBFC;
    --color-surface: #FFFFFF;
    --color-border: #DFE1E6;
    --radius-sm: 3px;
    --radius-md: 6px;
    --radius-lg: 12px;
    --shadow-sm: 0 1px 1px rgba(9, 30, 66, 0.08);
    --shadow-md: 0 2px 4px rgba(9, 30, 66, 0.12);
    --shadow-lg: 0 8px 16px rgba(9, 30, 66, 0.15);
    --transition: all 0.2s ease-in-out;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Fira Sans', 'Droid Sans', 'Helvetica Neue', sans-serif;
    font-size: 14px;
    line-height: 1.5;
    color: var(--color-text);
    background-color: var(--color-background);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
    flex: 1;
    display: flex;
    flex-direction: column;
}

/* Header */
header {
    text-align: center;
    padding: 48px 0 32px;
}

h1 {
    font-size: 32px;
    font-weight: 700;
    color: var(--color-text);
    margin-bottom: 8px;
}

.subtitle {
    font-size: 16px;
    color: var(--color-text-subtle);
    margin-bottom: 24px;
}

.lang-switcher {
    display: flex;
    gap: 8px;
    justify-content: center;
}

.lang-btn {
    padding: 6px 12px;
    border: 1px solid var(--color-border);
    background: var(--color-surface);
    border-radius: var(--radius-sm);
    font-size: 12px;
    color: var(--color-text-subtle);
    cursor: pointer;
    transition: var(--transition);
}

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

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

/* Main */
main {
    flex: 1;
    display: flex;
    justify-content: center;
    align-items: flex-start;
    padding-bottom: 48px;
}

/* Upload Area */
.upload-area {
    background: var(--color-surface);
    border: 2px dashed var(--color-border);
    border-radius: var(--radius-lg);
    padding: 64px;
    text-align: center;
    transition: var(--transition);
    cursor: pointer;
    box-shadow: var(--shadow-sm);
}

.upload-area:hover {
    border-color: var(--color-primary);
    box-shadow: var(--shadow-md);
}

.upload-area.dragover {
    border-color: var(--color-primary);
    background: #F4F8FF;
}

.upload-icon {
    width: 64px;
    height: 64px;
    color: var(--color-text-subtle);
    margin-bottom: 16px;
}

.upload-text {
    font-size: 18px;
    font-weight: 600;
    color: var(--color-text);
    margin-bottom: 8px;
}

.upload-subtext {
    color: var(--color-text-subtle);
    margin-bottom: 16px;
}

.upload-hint {
    font-size: 12px;
    color: var(--color-text-subtle);
    margin-top: 16px;
}

/* Editor Area */
.editor-area {
    width: 100%;
    max-width: 900px;
}

.video-container {
    background: var(--color-surface);
    border-radius: var(--radius-lg);
    padding: 24px;
    margin-bottom: 24px;
    box-shadow: var(--shadow-md);
}

#videoPlayer {
    width: 100%;
    max-height: 500px;
    border-radius: var(--radius-md);
}

/* Controls */
.controls {
    background: var(--color-surface);
    border-radius: var(--radius-lg);
    padding: 24px;
    box-shadow: var(--shadow-md);
}

.time-controls {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 16px;
    margin-bottom: 24px;
}

.control-group {
    display: flex;
    align-items: center;
    gap: 8px;
}

.control-group label {
    font-weight: 600;
    color: var(--color-text);
    min-width: 80px;
}

.control-group input[type="number"],
.control-group select {
    padding: 8px 12px;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    font-size: 14px;
    width: 100px;
    transition: var(--transition);
}

.control-group input[type="number"]:focus,
.control-group select:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 3px rgba(0, 82, 204, 0.1);
}

/* Timeline */
.timeline {
    margin: 24px 0;
    padding: 12px 0;
}

.timeline-bar {
    position: relative;
    height: 8px;
    background: var(--color-border);
    border-radius: 4px;
    cursor: pointer;
}

.timeline-selection {
    position: absolute;
    top: 0;
    height: 100%;
    background: var(--color-primary);
    border-radius: 4px;
    pointer-events: none;
}

.timeline-handle {
    position: absolute;
    top: 50%;
    transform: translate(-50%, -50%);
    width: 16px;
    height: 16px;
    background: var(--color-primary);
    border: 2px solid white;
    border-radius: 50%;
    cursor: ew-resize;
    box-shadow: var(--shadow-sm);
}

.timeline-handle:hover {
    transform: translate(-50%, -50%) scale(1.2);
}

/* Format Options */
.format-options,
.quality-options {
    margin: 24px 0;
}

.format-options h3,
.quality-options h3 {
    font-size: 16px;
    font-weight: 600;
    margin-bottom: 12px;
}

.radio-label {
    display: inline-flex;
    align-items: center;
    margin-right: 24px;
    cursor: pointer;
}

.radio-label input[type="radio"] {
    margin-right: 8px;
}

/* Buttons */
.btn {
    padding: 10px 20px;
    border: none;
    border-radius: var(--radius-sm);
    font-size: 14px;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
}

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

.btn-primary:hover {
    background: var(--color-primary-hover);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background: var(--color-secondary);
    color: white;
}

.btn-secondary:hover {
    background: #5E6C84;
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-ghost {
    background: transparent;
    color: var(--color-text-subtle);
    border: 1px solid var(--color-border);
}

.btn-ghost:hover {
    border-color: var(--color-primary);
    color: var(--color-primary);
}

.action-buttons {
    display: flex;
    gap: 12px;
    margin-top: 24px;
}

/* Progress */
.progress-container {
    margin-top: 24px;
    padding: 24px;
    background: var(--color-surface);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
}

.progress-bar {
    height: 8px;
    background: var(--color-border);
    border-radius: 4px;
    overflow: hidden;
    margin-bottom: 12px;
}

.progress-fill {
    height: 100%;
    background: var(--color-primary);
    transition: width 0.3s ease;
}

.progress-text {
    text-align: center;
    color: var(--color-text-subtle);
}

/* Result Area */
.result-area {
    margin-top: 24px;
    padding: 24px;
    background: var(--color-surface);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
    text-align: center;
}

.result-area h3 {
    font-size: 20px;
    font-weight: 600;
    margin-bottom: 16px;
    color: var(--color-success);
}

.result-preview {
    margin: 16px 0;
    max-height: 400px;
    overflow: hidden;
    border-radius: var(--radius-md);
}

.result-preview img,
.result-preview video {
    max-width: 100%;
    max-height: 400px;
    border-radius: var(--radius-md);
}

/* Footer */
footer {
    text-align: center;
    padding: 24px;
    color: var(--color-text-subtle);
    font-size: 12px;
    border-top: 1px solid var(--color-border);
}

/* Responsive */
@media (max-width: 768px) {
    .container {
        padding: 0 16px;
    }
    
    header {
        padding: 32px 0 24px;
    }
    
    h1 {
        font-size: 24px;
    }
    
    .upload-area {
        padding: 32px 16px;
    }
    
    .time-controls {
        grid-template-columns: 1fr;
    }
    
    .action-buttons {
        flex-direction: column;
    }
    
    .btn {
        width: 100%;
    }
}