:root {
    --primary-color: #3498db;
    --success-color: #2ecc71;
    --error-color: #e74c3c;
    --bg-color: #f8f9fa;
    --text-color: #2c3e50;
    --card-bg: #ffffff;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    margin: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
}

.container {
    background-color: var(--card-bg);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: 0 10px 25px rgba(0,0,0,0.1);
    width: 90%;
    max-width: 650px;
    text-align: center;
}

h1 {
    margin-top: 0;
    color: var(--primary-color);
}

.unit-toggle {
    display: flex;
    justify-content: center;
    gap: 1rem;
    font-weight: bold;
}

.footer-controls {
    margin-top: 2rem;
    padding-top: 1.5rem;
    border-top: 1px solid #eee;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1rem;
}

.footer-controls .btn-secondary {
    margin-top: 0;
}

.unit-toggle label {
    cursor: pointer;
}

.controls {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
    margin: 2rem 0;
}

.control-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    text-align: left;
}

input[type="range"] {
    width: 100%;
    cursor: pointer;
}

.stats {
    background-color: #eee;
    padding: 1rem;
    border-radius: 8px;
    margin-bottom: 2rem;
}

.stat-item {
    font-size: 1.2rem;
    font-weight: bold;
    margin-bottom: 0.5rem;
}

.status-msg {
    font-weight: bold;
    padding: 0.5rem;
    border-radius: 4px;
}

.status-msg.success {
    color: #fff;
    background-color: var(--success-color);
}

.status-msg.alert {
    color: #fff;
    background-color: var(--error-color);
}

.btn-secondary {
    margin-top: 1rem;
    padding: 0.5rem 1rem;
    background-color: #95a5a6;
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.9rem;
    transition: background-color 0.2s;
}

.btn-secondary:hover {
    background-color: #7f8c8d;
}

.btn-secondary.copied {
    background-color: var(--success-color);
}

.visualization {
    border: 1px solid #ddd;
    border-radius: 8px;
    background: #fff;
    overflow: hidden;
}

#visualizer {
    width: 100%;
    height: auto;
    max-height: 400px;
}

#diagonal-line.success {
    stroke: var(--success-color);
}

#diagonal-line.alert {
    stroke: var(--error-color);
}