:root {
    --bg-color: #f5f7fa;
    --text-color: #333;
    --text-muted: #666;
    --card-bg: #ffffff;
    --border-color: #e4e7ed;
    --primary-color: #409eff;
    --primary-hover: #66b1ff;
    --radius: 12px;
    --shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg-color: #1a1a1a;
        --text-color: #f0f0f0;
        --text-muted: #a0a0a0;
        --card-bg: #2d2d2d;
        --border-color: #444;
        --primary-color: #3a8ee6;
        --primary-hover: #5ea4f0;
        --shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
    }
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    transition: background-color 0.3s, color 0.3s;
}

.container { max-width: 800px; margin: 0 auto; padding: 20px; }
header { text-align: center; margin-bottom: 30px; }
header p { color: var(--text-muted); font-size: 0.9em; }

.card {
    background: var(--card-bg);
    border-radius: var(--radius);
    padding: 20px;
    margin-bottom: 20px;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
}

h2 {
    font-size: 1.2rem;
    margin-bottom: 15px;
    border-bottom: 2px solid var(--border-color);
    padding-bottom: 10px;
}

.file-upload-wrapper { display: flex; align-items: center; gap: 15px; flex-wrap: wrap; }
input[type="file"] { display: none; }

.upload-btn, .secondary-btn {
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-color);
    padding: 8px 16px;
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.2s;
    font-size: 0.95em;
}

.upload-btn:hover, .secondary-btn:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
}

.mode-selector { display: flex; gap: 20px; margin-bottom: 20px; }
.settings-panel { display: none; animation: fadeIn 0.3s ease; }
.settings-panel.active { display: block; }
.form-group { margin-bottom: 15px; display: flex; flex-direction: column; gap: 5px; }

input[type="range"] { width: 100%; }
select, input[type="number"], input[type="color"] {
    padding: 8px;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    background: var(--bg-color);
    color: var(--text-color);
    font-family: inherit;
}

.primary-btn {
    width: 100%;
    background: var(--primary-color);
    color: white;
    border: none;
    padding: 12px;
    font-size: 1.1rem;
    border-radius: var(--radius);
    cursor: pointer;
    transition: background 0.2s;
    margin-bottom: 20px;
}

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

.result-header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 15px; }
.hint-text { font-size: 0.85em; color: var(--text-muted); margin-bottom: 15px; }

.preview-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
    gap: 15px;
}

.preview-item {
    display: flex;
    flex-direction: column;
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    overflow: hidden;
    background: var(--bg-color);
}

.preview-item img {
    width: 100%;
    height: auto;
    display: block;
    border-bottom: 1px solid var(--border-color);
}

.action-bar {
    padding: 10px;
    text-align: center;
    background: var(--card-bg);
}

.action-bar .secondary-btn { width: 100%; }

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(-5px); }
    to { opacity: 1; transform: translateY(0); }
}

@media (max-width: 500px) {
    .result-header { flex-direction: column; align-items: flex-start; gap: 10px; }
}