:root {
    /* DARK MODE (Default) */
    --bg-color: #1e1e1e;
    --card-bg: #252526;
    --text-color: #d4d4d4;
    --text-muted: #a0a0a0;
    --accent-color: #007acc;
    --border-color: #3e3e42;
    --input-bg: #1e1e1e;
    --font-mono: 'Consolas', 'Monaco', 'Courier New', monospace;
}

/* LIGHT MODE OVERRIDES */
[data-theme="light"] {
    --bg-color: #f0f2f5;
    --card-bg: #ffffff;
    --text-color: #333333;
    --text-muted: #666666;
    --accent-color: #0066cc;
    --border-color: #cccccc;
    --input-bg: #f9f9f9;
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    margin: 0;
    padding: 20px;
    display: flex;
    justify-content: center;
    transition: background-color 0.3s, color 0.3s;
}

.theme-btn {
    position: absolute;
    top: 20px;
    right: 20px;
    background: transparent;
    border: 1px solid var(--border-color);
    font-size: 1.2rem;
    padding: 5px 10px;
    margin: 0;
}

.container {
    width: 100%;
    max-width: 900px;
    margin-top: 20px;
}

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

h1 {
    font-weight: 300;
    margin-bottom: 5px;
}

p {
    color: var(--text-muted);
    font-size: 0.9rem;
}

.controls {
    background-color: var(--card-bg);
    padding: 15px;
    border-radius: 6px;
    display: flex;
    align-items: center;
    gap: 20px;
    margin-bottom: 20px;
    border: 1px solid var(--border-color);
    flex-wrap: wrap;
    transition: background-color 0.3s, border-color 0.3s;
}

.control-group {
    display: flex;
    align-items: center;
    gap: 10px;
}

.checkbox-group {
    cursor: pointer;
    user-select: none;
}

.checkbox-group input {
    cursor: pointer;
    width: 16px;
    height: 16px;
}

input[type="number"] {
    background: var(--input-bg);
    border: 1px solid var(--border-color);
    color: var(--text-color);
    padding: 8px;
    border-radius: 4px;
    width: 70px;
}

button {
    border-radius: 4px;
    cursor: pointer;
    font-weight: bold;
    transition: all 0.2s;
}

.action-btn {
    background-color: var(--accent-color);
    color: white;
    border: none;
    padding: 10px 20px;
    margin-left: auto;
}

.action-btn:hover {
    filter: brightness(1.1);
}

.secondary-btn {
    background-color: var(--input-bg);
    color: var(--text-color);
    border: 1px solid var(--border-color);
    padding: 5px 10px;
    font-size: 0.8rem;
}

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

.editor-area {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 20px;
}

@media (max-width: 700px) {
    .editor-area {
        grid-template-columns: 1fr;
    }
    .action-btn {
        margin-left: 0;
        width: 100%;
    }
}

.input-group {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.output-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

textarea {
    background-color: var(--card-bg);
    color: var(--text-color);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    padding: 15px;
    font-family: var(--font-mono);
    font-size: 14px;
    line-height: 1.5;
    min-height: 400px;
    resize: vertical;
    transition: background-color 0.3s, border-color 0.3s, color 0.3s;
}

textarea:focus {
    outline: 1px solid var(--accent-color);
}