:root {
    --primary-color: #003366;
    /* Navy Blue */
    --secondary-color: #f4f6f8;
    /* Light Grey */
    --text-color: #333333;
    --accent-color: #0056b3;
    --success-color: #28a745;
    --error-color: #dc3545;
    --border-radius: 8px;
    --font-family: 'Inter', sans-serif;
}

body {
    font-family: var(--font-family);
    background-color: var(--secondary-color);
    margin: 0;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    color: var(--text-color);
}

.app-header {
    background-color: white;
    padding: 1rem 2rem;
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.05);
}

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

.app-container {
    flex: 1;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 2rem;
}

.card {
    background-color: white;
    padding: 2.5rem;
    border-radius: var(--border-radius);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
    width: 100%;
    max-width: 400px;
    text-align: center;
}

h2 {
    margin-top: 0;
    color: var(--primary-color);
    font-weight: 600;
}

.description {
    color: #666;
    margin-bottom: 2rem;
    font-size: 0.95rem;
}

.status-container {
    margin-bottom: 2rem;
}

.status-indicator {
    display: inline-block;
    padding: 0.5rem 1rem;
    border-radius: 20px;
    background-color: #e9ecef;
    color: #666;
    font-size: 0.9rem;
    font-weight: 500;
    transition: all 0.3s ease;
}

.status-indicator.connected {
    background-color: #d4edda;
    color: var(--success-color);
}

.controls {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.control-group {
    text-align: left;
}

.control-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-size: 0.85rem;
    font-weight: 500;
    color: #555;
}

select {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid #ddd;
    border-radius: var(--border-radius);
    font-family: inherit;
    font-size: 1rem;
    background-color: white;
    appearance: none;
    /* Remove default arrow on some browsers */
    background-image: url("data:image/svg+xml;charset=US-ASCII,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%22292.4%22%20height%3D%22292.4%22%3E%3Cpath%20fill%3D%22%23007CB2%22%20d%3D%22M287%2069.4a17.6%2017.6%200%200%200-13-5.4H18.4c-5%200-9.3%201.8-12.9%205.4A17.6%2017.6%200%200%200%200%2082.2c0%205%201.8%209.3%205.4%2012.9l128%20127.9c3.6%203.6%207.8%205.4%2012.8%205.4s9.2-1.8%2012.8-5.4L287%2095c3.5-3.5%205.4-7.8%205.4-12.8%200-5-1.9-9.2-5.5-12.8z%22%2F%3E%3C%2Fsvg%3E");
    background-repeat: no-repeat;
    background-position: right 0.7rem top 50%;
    background-size: 0.65rem auto;
}

select:disabled {
    background-color: #f8f9fa;
    color: #999;
    cursor: not-allowed;
}

button {
    width: 100%;
    padding: 0.85rem;
    border: none;
    border-radius: var(--border-radius);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: background-color 0.2s;
}

.btn-start {
    background-color: var(--primary-color);
    color: white;
}

.btn-start:hover {
    background-color: #002244;
}

.btn-stop {
    background-color: var(--error-color);
    color: white;
}

.btn-stop:hover {
    background-color: #bd2130;
}

button:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

.app-footer {
    text-align: center;
    padding: 1.5rem;
    color: #888;
    font-size: 0.85rem;
}