:root {
    --bg-color: #fdf6e3; /* Warm Beige */
    --card-bg: #ffffff;
    --text-primary: #5c4033; /* Dark Brown */
    --text-secondary: #8d6e63;
    --accent: #e67e22; /* Orange */
    --accent-hover: #d35400;
    --lung-color: #ffffff; /* White organs */
    --particle-fresh: #2980b9; /* Blue particles */
    --particle-used: #8e44ad; /* Purple particles */
}

body {
    margin: 0;
    font-family: 'Noto Sans TC', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-primary);
    display: flex;
    justify-content: center;
    min-height: 100vh;
}

.container {
    width: 100%;
    max-width: 900px;
    padding: 20px;
    display: flex;
    flex-direction: column;
    gap: 20px;
}

header {
    text-align: center;
    margin-bottom: 10px;
}

h1 {
    margin: 0;
    font-size: 2rem;
    color: var(--accent);
}

.subtitle {
    color: var(--text-secondary);
    margin-top: 5px;
    font-size: 1rem;
}

.canvas-container {
    background-color: var(--bg-color); /* Transparent on beige usually, or white? Reference has beige bg everywhere */
    /* Let's keep card bg for structure, but canvas itself can match or be white */
    border-radius: 20px;
    padding: 30px;
    /* Box shadow removed for flatter look or kept subtler */
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05);
    display: flex;
    flex-direction: column;
    align-items: center;
    position: relative;
    border: none;
}

canvas {
    background-color: #fdf6e3; /* Match body beige */
    border-radius: 12px;
    max-width: 100%;
    height: auto;
    cursor: pointer;
}

.labels {
    display: flex;
    gap: 20px;
    margin-top: 15px;
    font-size: 0.9rem;
    color: var(--text-secondary);
    font-weight: 500;
}

.dot {
    display: inline-block;
    width: 12px;
    height: 12px;
    border-radius: 50%;
    margin-right: 6px;
    vertical-align: middle;
}

.dot.fresh { background-color: var(--particle-fresh); }
.dot.used { background-color: var(--particle-used); }

.controls {
    background-color: var(--card-bg);
    padding: 20px;
    border-radius: 16px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05);
}

.control-group {
    display: flex;
    align-items: center;
    gap: 15px;
}

.btn {
    padding: 10px 20px;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.2s;
    font-weight: 600;
}

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

.btn.primary:hover {
    background-color: var(--accent-hover);
    transform: translateY(-1px);
}

.btn.secondary {
    background-color: white;
    border: 2px solid #e0e0e0;
    color: var(--text-secondary);
}

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

.info-panel {
    display: grid;
    grid-template-columns: 1fr;
    gap: 20px;
}

.step-cards {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 15px;
}

.step-card {
    background: white;
    padding: 15px;
    border-radius: 12px;
    border: 2px solid #eee;
    opacity: 0.6;
    transition: all 0.3s;
}

.step-card.active {
    opacity: 1;
    border-color: var(--accent);
    background-color: #fff8e1; /* very light orange/yellow */
    transform: scale(1.02);
    box-shadow: 0 4px 10px rgba(230, 126, 34, 0.2);
}

.step-card h4 {
    margin: 0 0 8px 0;
    color: var(--accent);
    font-size: 1.1rem;
}

.step-card p {
    margin: 0;
    font-size: 0.9rem;
    line-height: 1.5;
    color: var(--text-primary);
}

.step-number {
    display: inline-block;
    width: 24px;
    height: 24px;
    background-color: var(--accent);
    color: white;
    border-radius: 50%;
    text-align: center;
    line-height: 24px;
    margin-right: 8px;
    font-size: 0.85rem;
}

input[type="range"] {
    accent-color: var(--accent);
}