:root {
    --bg: #f4f4f9;
    --text: #333;
    --primary: #2c3e50;
    --accent: #3498db;
    --card: #ffffff;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--bg);
    color: var(--text);
    margin: 0;
    padding: 20px;
    text-align: center;
}

.container {
    max-width: 800px;
    margin: 0 auto;
}

.hidden { display: none; }

/* Cards & Layout */
.card {
    background: var(--card);
    padding: 20px;
    margin: 15px 0;
    border-radius: 8px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}

.dual-columns {
    display: flex;
    gap: 15px;
    flex-wrap: wrap;
}

.dual-columns .card {
    flex: 1;
    min-width: 250px;
}

/* Controls */
select {
    padding: 10px;
    font-size: 16px;
    margin: 10px;
    border-radius: 5px;
}

.btn {
    padding: 12px 24px;
    font-size: 16px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    background-color: var(--primary);
    color: white;
    transition: 0.2s;
    margin: 5px;
}

.btn:hover { opacity: 0.9; }
.btn:disabled { background-color: #ccc; cursor: not-allowed; }
.btn.warning { background-color: #e67e22; }
.btn-small { float: left; background: none; border: 1px solid #ccc; color: #555; padding: 5px 10px; }

/* Status Boxes */
.status-box {
    margin-top: 20px;
    font-weight: bold;
    color: var(--accent);
}

.result-box {
    margin-top: 10px;
    font-family: monospace;
    background: #eee;
    padding: 10px;
    border-radius: 5px;
    text-align: left;
}

.highlight { border-left: 5px solid var(--accent); }