:root {
    --bg-body: #13131a;
    --bg-card: #1e1e2e;
    --text-primary: #e0e0e6;
    --text-heading: #f0f0f5;
    --text-secondary: #a0a0b0;
    --text-tertiary: #8888a0;
    --text-label: #b0b0c0;
    --text-muted: #707080;
    --text-faint: #606070;
    --accent: #5a9fe6;
    --accent-hover: #4a8fd6;
    --accent-disabled: #2a4a6a;
    --border: #333345;
    --border-light: #2a2a3a;
    --border-subtle: #252535;
    --accent-bg: #1a2a3e;
    --success-bg: #1a2e1a;
    --success-text: #5cb85c;
    --stat-bg: #252535;
    --row-hover: #252535;
    --shadow-card: rgba(0, 0, 0, 0.4);
    --shadow-accent: rgba(90, 159, 230, 0.3);
    --shadow-toggle: rgba(0, 0, 0, 0.4);
    --toggle-knob: #ccc;
}

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

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

.container {
    max-width: 720px;
    margin: 0 auto;
    padding: 20px;
}

/* Header */
header {
    text-align: center;
    padding: 30px 0 20px;
}

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

.subtitle {
    color: var(--text-secondary);
    font-size: 14px;
    margin-top: 4px;
}

/* Cards */
.card {
    background: var(--bg-card);
    border-radius: 12px;
    padding: 20px;
    box-shadow: 0 2px 8px var(--shadow-card);
    margin-bottom: 16px;
}

.card-title {
    font-size: 16px;
    color: var(--text-heading);
    margin-bottom: 16px;
}

/* Drop zone */
.drop-zone {
    border: 2px dashed var(--border-light);
    border-radius: 10px;
    padding: 40px 20px;
    text-align: center;
    transition: all 0.2s;
    cursor: pointer;
}

.drop-zone:hover,
.drop-zone.dragover {
    border-color: var(--accent);
    background: var(--accent-bg);
}

.drop-zone-icon {
    font-size: 40px;
    margin-bottom: 8px;
}

.drop-zone-text {
    color: var(--text-secondary);
    font-size: 14px;
}

.file-label {
    cursor: pointer;
}

.file-btn {
    color: var(--accent);
    font-weight: 600;
    text-decoration: underline;
    cursor: pointer;
}

.file-btn:hover {
    color: var(--accent-hover);
}

.file-info {
    margin-top: 12px;
    padding: 10px 16px;
    background: var(--success-bg);
    border-radius: 8px;
    color: var(--success-text);
    font-size: 14px;
    font-weight: 500;
}

/* Settings */
.settings-panel {
    animation: slideDown 0.3s ease;
}

@keyframes slideDown {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.setting-group {
    margin-bottom: 20px;
}

.setting-label {
    display: block;
    font-size: 14px;
    color: var(--text-tertiary);
    margin-bottom: 8px;
}

.setting-label strong {
    color: var(--text-heading);
    font-size: 16px;
}

/* Slider */
.slider {
    -webkit-appearance: none;
    width: 100%;
    height: 6px;
    background: var(--border);
    border-radius: 3px;
    outline: none;
    margin: 8px 0;
}

.slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 22px;
    height: 22px;
    background: var(--accent);
    border-radius: 50%;
    cursor: pointer;
    box-shadow: 0 2px 4px var(--shadow-accent);
    transition: transform 0.15s;
}

.slider::-webkit-slider-thumb:hover {
    transform: scale(1.15);
}

.slider::-moz-range-thumb {
    width: 22px;
    height: 22px;
    background: var(--accent);
    border-radius: 50%;
    border: none;
    cursor: pointer;
    box-shadow: 0 2px 4px var(--shadow-accent);
}

.slider-labels {
    display: flex;
    justify-content: space-between;
    font-size: 11px;
    color: var(--text-faint);
    padding: 0 2px;
}

/* Toggle switches */
.toggles-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 12px;
    margin-bottom: 20px;
}

.toggle {
    display: flex;
    align-items: center;
    gap: 10px;
    cursor: pointer;
    user-select: none;
}

.toggle input {
    display: none;
}

.toggle-slider {
    width: 40px;
    height: 22px;
    background: var(--border-light);
    border-radius: 11px;
    position: relative;
    transition: background 0.2s;
    flex-shrink: 0;
}

.toggle-slider::after {
    content: "";
    position: absolute;
    top: 3px;
    left: 3px;
    width: 16px;
    height: 16px;
    background: var(--toggle-knob);
    border-radius: 50%;
    transition: transform 0.2s;
    box-shadow: 0 1px 3px var(--shadow-toggle);
}

.toggle input:checked + .toggle-slider {
    background: var(--accent);
}

.toggle input:checked + .toggle-slider::after {
    transform: translateX(18px);
}

.toggle-label {
    font-size: 14px;
    color: var(--text-label);
}

/* Convert button */
.convert-btn {
    width: 100%;
    padding: 12px;
    background: var(--accent);
    color: #fff;
    border: none;
    border-radius: 8px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: background 0.2s;
}

.convert-btn:hover {
    background: var(--accent-hover);
}

.convert-btn:disabled {
    background: var(--accent-disabled);
    cursor: not-allowed;
}

/* Processing */
.processing {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
    padding: 30px;
    color: var(--text-secondary);
    font-size: 16px;
}

.spinner {
    width: 24px;
    height: 24px;
    border: 3px solid var(--border);
    border-top-color: var(--accent);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* Stats grid */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
    gap: 12px;
    margin-bottom: 20px;
}

.stat-card {
    background: var(--stat-bg);
    border-radius: 8px;
    padding: 14px;
    text-align: center;
}

.stat-value {
    font-size: 22px;
    font-weight: 700;
    color: var(--text-heading);
}

.stat-label {
    font-size: 12px;
    color: var(--text-muted);
    margin-top: 2px;
}

/* File list */
.file-list {
    margin-bottom: 16px;
}

.file-row {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 10px 14px;
    border-bottom: 1px solid var(--border-subtle);
    transition: background 0.15s;
}

.file-row:last-child {
    border-bottom: none;
}

.file-row:hover {
    background: var(--row-hover);
}

.file-name {
    font-size: 14px;
    color: var(--text-primary);
    font-weight: 500;
    flex: 1;
    min-width: 0;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.file-meta {
    font-size: 12px;
    color: var(--text-faint);
    margin: 0 12px;
    white-space: nowrap;
}

.file-download-btn {
    padding: 5px 14px;
    background: var(--bg-card);
    border: 1px solid var(--border-light);
    border-radius: 6px;
    font-size: 13px;
    color: var(--accent);
    cursor: pointer;
    transition: all 0.2s;
    white-space: nowrap;
}

.file-download-btn:hover {
    border-color: var(--accent);
    background: var(--accent-bg);
}

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

    header {
        padding: 16px 0 12px;
    }

    .toggles-grid {
        grid-template-columns: 1fr;
    }

    .stats-grid {
        grid-template-columns: 1fr 1fr;
    }

    .file-meta {
        display: none;
    }

    .drop-zone {
        padding: 24px 16px;
    }
}