:root {
    --primary-color: #007AFF;
    --primary-dark: #0056CC;
    --text-color: #1D1D1F;
    --background-color: #FFFFFF;
    --light-gray: #F5F5F7;
    --border-color: #E5E5EA;
    --placeholder-color: #8E8E93;
    --shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
    --radius: 12px;
    --transition: all 0.3s ease;
}

@media (prefers-color-scheme: dark) {
    :root {
        --text-color: #F5F5F7;
        --background-color: #1C1C1E;
        --light-gray: #2C2C2E;
        --border-color: #3A3A3C;
        --placeholder-color: #8E8E93;
        --shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
    }
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
}

body {
    background-color: var(--background-color);
    color: var(--text-color);
    line-height: 1.6;
    padding: 20px;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.container {
    width: 100%;
    max-width: 1000px;
    margin: 0 auto;
}

header {
    text-align: center;
    margin-bottom: 40px;
    padding-top: 20px;
}

h1 {
    font-size: 2.5rem;
    font-weight: 600;
    margin-bottom: 8px;
    letter-spacing: -0.5px;
}

.subtitle {
    font-size: 1.1rem;
    color: var(--placeholder-color);
    margin-bottom: 30px;
}

.controls {
    background-color: var(--light-gray);
    border-radius: var(--radius);
    padding: 24px;
    margin-bottom: 30px;
    box-shadow: var(--shadow);
}

.control-row {
    display: flex;
    gap: 20px;
    margin-bottom: 20px;
}

.control-group {
    flex: 1;
    margin-bottom: 0;
}

.control-group:last-child {
    margin-bottom: 0;
}

label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
    font-size: 1rem;
}

select, input, button {
    width: 100%;
    padding: 14px 16px;
    border-radius: var(--radius);
    border: 1px solid var(--border-color);
    background-color: var(--background-color);
    color: var(--text-color);
    font-size: 1rem;
    transition: var(--transition);
}

select:focus, input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 2px rgba(0, 122, 255, 0.2);
}

input[type="number"] {
    -moz-appearance: textfield;
}

input::-webkit-outer-spin-button,
input::-webkit-inner-spin-button {
    -webkit-appearance: none;
    margin: 0;
}

.button-group {
    display: flex;
    gap: 12px;
    margin-top: 10px;
}

button {
    flex: 1;
    background-color: var(--primary-color);
    color: white;
    border: none;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
}

button:hover {
    background-color: var(--primary-dark);
    transform: translateY(-1px);
}

button:active {
    transform: translateY(0);
}

button.secondary {
    background-color: transparent;
    color: var(--primary-color);
    border: 1px solid var(--border-color);
}

button.secondary:hover {
    background-color: rgba(0, 122, 255, 0.1);
}

.preview {
    background-color: var(--background-color);
    border-radius: var(--radius);
    padding: 32px;
    margin-bottom: 30px;
    box-shadow: var(--shadow);
    border: 1px solid var(--border-color);
    min-height: 300px;
    max-height: 60vh;
    overflow-y: auto;
}

.preview-content {
    font-size: 1.05rem;
    line-height: 1.7;
}

.preview-content h2, .preview-content h3 {
    margin-top: 1.5em;
    margin-bottom: 0.5em;
    font-weight: 600;
}

.preview-content p {
    margin-bottom: 1.2em;
}

.preview-content ul, .preview-content ol {
    margin-bottom: 1.2em;
    padding-left: 1.5em;
}

.preview-content li {
    margin-bottom: 0.5em;
}

.stats {
    display: flex;
    justify-content: space-between;
    background-color: var(--light-gray);
    border-radius: var(--radius);
    padding: 16px 24px;
    margin-bottom: 30px;
    box-shadow: var(--shadow);
}

.stat-item {
    text-align: center;
}

.stat-value {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--primary-color);
}

.stat-label {
    font-size: 0.9rem;
    color: var(--placeholder-color);
}

footer {
    text-align: center;
    margin-top: auto;
    padding: 20px 0;
    color: var(--placeholder-color);
    font-size: 0.9rem;
}

@media (max-width: 768px) {
    h1 {
        font-size: 2rem;
    }
    
    .control-row {
        flex-direction: column;
        gap: 15px;
    }
    
    .controls {
        padding: 20px;
    }
    
    .button-group {
        flex-direction: column;
    }
    
    .stats {
        flex-direction: column;
        gap: 15px;
    }
}