* {
    box-sizing: border-box;
}

body {
    font-family: system-ui, -apple-system, sans-serif;
    max-width: 800px;
    margin: 0 auto;
    padding: 1rem 1rem 3rem;
    color: #222;
    background: #fafafa;
}

h1 {
    margin-bottom: 1.5rem;
}

section {
    margin-bottom: 1.5rem;
}

label {
    display: inline-block;
    margin-right: 0.5rem;
    font-weight: 500;
}

input[type="number"],
select {
    padding: 0.3rem 0.5rem;
    border: 1px solid #aaa;
    border-radius: 4px;
    font-size: 0.95rem;
}

#preview {
    display: block;
    max-width: 300px;
    max-height: 200px;
    margin-top: 0.5rem;
}

#options {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    align-items: center;
}

#warning {
    display: none;
    padding: 0.75rem 1rem;
    background: #fff3cd;
    border: 1px solid #ffda6a;
    border-radius: 4px;
    color: #664d03;
    margin-bottom: 1.5rem;
}

button {
    padding: 0.5rem 1.25rem;
    border: 1px solid #555;
    border-radius: 4px;
    background: #fff;
    font-size: 0.95rem;
    cursor: pointer;
}

button:hover {
    background: #eee;
}

#generate-btn {
    font-size: 1.1rem;
    font-weight: 600;
    padding: 0.6rem 2rem;
    background: #2563eb;
    color: #fff;
    border: none;
    border-radius: 4px;
}

#generate-btn:hover:not(:disabled) {
    background: #1d4ed8;
}

#generate-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

#result {
    display: none;
    margin-top: 1.5rem;
}

#result canvas {
    display: block;
    max-width: 100%;
    margin-bottom: 1rem;
}

#result-actions {
    display: flex;
    gap: 0.75rem;
}

.tabs {
    display: flex;
    border-bottom: 2px solid #ddd;
    margin-bottom: 1.5rem;
}

.tab-btn {
    padding: 0.5rem 1.25rem;
    border: 1px solid #ddd;
    border-bottom: none;
    border-radius: 4px 4px 0 0;
    background: #eee;
    font-size: 0.95rem;
    cursor: pointer;
    margin-right: 2px;
}

.tab-btn:hover {
    background: #e0e0e0;
}

.tab-btn.active {
    background: #fafafa;
    border-bottom: 2px solid #fafafa;
    margin-bottom: -2px;
    font-weight: 600;
}

.tab-content {
    display: none;
}

.tab-content.active {
    display: block;
}

#puzzle-filter {
    width: 100%;
    padding: 0.3rem 0.5rem;
    border: 1px solid #aaa;
    border-radius: 4px;
    font-size: 0.95rem;
    margin-bottom: 0.75rem;
}

.show-titles-label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: normal;
    cursor: pointer;
}

#puzzle-list {
    max-height: 160px;
    overflow-y: auto;
    border: 1px solid #ddd;
    border-radius: 4px;
}

.puzzle-item {
    padding: 0.6rem 0.75rem;
    cursor: pointer;
    border-bottom: 1px solid #eee;
}

.puzzle-item:hover {
    background: #f0f4ff;
}

.puzzle-item:last-child {
    border-bottom: none;
}

.puzzle-item .puzzle-id {
    color: #888;
}

#puzzle-empty {
    padding: 1rem;
    color: #888;
}