:root {
    --bg-color: #0f0f13;
    --panel-bg: rgba(25, 25, 30, 0.7);
    --accent-color: #8b5cf6;
    --accent-hover: #a78bfa;
    --text-main: #e2e8f0;
    --text-muted: #94a3b8;
    --border-color: rgba(139, 92, 246, 0.3);
    --glass-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.37);
}

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

body {
    background-color: var(--bg-color);
    color: var(--text-main);
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    background-image: radial-gradient(circle at top right, rgba(139, 92, 246, 0.15), transparent 400px);
}

.app-container {
    width: 100%;
    max-width: 680px;
    padding: 2rem;
    background: var(--panel-bg);
    backdrop-filter: blur(12px);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    box-shadow: var(--glass-shadow);
}

.app-header h1 {
    font-size: 2rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    letter-spacing: -0.02em;
}

.app-header span { color: var(--accent-color); }
.app-header p { color: var(--text-muted); font-size: 0.9rem; margin-bottom: 2rem; }

/* Controls */
.control-panel {
    display: flex;
    flex-direction: column;
    gap: 1.2rem;
    margin-bottom: 2rem;
    padding: 1.2rem;
    background: rgba(0, 0, 0, 0.2);
    border-radius: 12px;
}

.mode-selector { display: flex; gap: 2rem; }

.radio-label, .checkbox-label {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    cursor: pointer;
    font-size: 0.95rem;
    user-select: none;
    transition: color 0.3s ease;
}

.radio-label:hover, .checkbox-label:hover { color: var(--accent-hover); }
input[type="radio"], input[type="checkbox"] { display: none; }

.radio-custom, .checkbox-custom {
    width: 18px;
    height: 18px;
    border: 2px solid var(--text-muted);
    border-radius: 50%;
    position: relative;
    transition: all 0.3s ease;
}
.checkbox-custom { border-radius: 4px; }

input[type="radio"]:checked + .radio-custom,
input[type="checkbox"]:checked + .checkbox-custom {
    border-color: var(--accent-color);
}
input[type="radio"]:checked + .radio-custom::after {
    content: ''; position: absolute; top: 3px; left: 3px; right: 3px; bottom: 3px;
    background: var(--accent-color); border-radius: 50%;
}
input[type="checkbox"]:checked + .checkbox-custom::after {
    content: '✓'; position: absolute; top: -3px; left: 2px;
    color: var(--accent-color); font-size: 14px; font-weight: bold;
}

/* Drop Zone */
.drop-zone {
    border: 2px dashed var(--border-color);
    border-radius: 12px;
    padding: 3rem 2rem;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    position: relative;
}

.drop-zone:hover, .drop-zone.dragover {
    background: rgba(139, 92, 246, 0.05);
    border-color: var(--accent-hover);
}

.upload-icon {
    width: 48px; height: 48px; fill: var(--text-muted);
    margin-bottom: 1rem; transition: fill 0.3s ease;
}
.drop-zone:hover .upload-icon { fill: var(--accent-color); }
.drop-zone p { font-size: 1.1rem; margin-bottom: 0.5rem; }
.drop-zone strong { color: var(--accent-color); }
.sub-text { font-size: 0.85rem; color: var(--text-muted); }
#fileInput { display: none; }

/* Progress Bar */
.progress-section { margin-top: 2rem; }
.progress-info {
    display: flex; justify-content: space-between;
    font-size: 0.85rem; color: var(--text-muted); margin-bottom: 0.5rem;
}
.progress-bar {
    width: 100%; height: 6px; background: rgba(255,255,255,0.1);
    border-radius: 3px; overflow: hidden;
}
.progress-fill {
    height: 100%; width: 0%; background: var(--accent-color);
    transition: width 0.15s ease-out; box-shadow: 0 0 8px var(--accent-color);
}