:root {
    --primary-color: #3b82f6;
    --primary-hover: #2563eb;
    --danger-color: #ef4444;
    --bg-color: #f9fafb;
    --card-bg: #ffffff;
    --text-color: #111827;
    --text-secondary: #6b7280;
    --border-color: #e5e7eb;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
}

.container {
    max-width: 900px;
    margin: 0 auto;
    padding: 20px;
}

header {
    text-align: center;
    margin-bottom: 30px;
}

header h1 {
    font-size: 2.5rem;
    color: var(--primary-color);
    margin-bottom: 10px;
}

header p {
    color: var(--text-secondary);
}

.card {
    background: var(--card-bg);
    border-radius: 12px;
    padding: 30px;
    box-shadow: var(--shadow);
    margin-bottom: 20px;
}

.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 500;
}

.form-group input {
    width: 100%;
    padding: 12px;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
}

.form-group input:focus {
    outline: none;
    border-color: var(--primary-color);
}

.form-group small {
    color: var(--text-secondary);
    font-size: 0.85rem;
}

.btn {
    padding: 12px 24px;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.3s;
}

.btn-primary {
    background-color: var(--primary-color);
    color: white;
    width: 100%;
}

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

.btn-secondary {
    background-color: var(--text-secondary);
    color: white;
    margin-right: 10px;
    margin-top: 10px;
}

.btn-danger {
    background-color: var(--danger-color);
    color: white;
    margin-top: 10px;
}

.result-display {
    text-align: center;
}

.short-url {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
}

.short-url input {
    flex: 1;
    padding: 12px;
    border: 2px solid var(--primary-color);
    border-radius: 8px;
    font-size: 1.1rem;
    background-color: #eff6ff;
}

#qrcode {
    margin: 20px auto;
    display: inline-block;
}

.filter-bar {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
}

.filter-bar input,
.filter-bar select {
    flex: 1;
    padding: 10px;
    border: 2px solid var(--border-color);
    border-radius: 8px;
}

.url-item {
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 15px;
    margin-bottom: 10px;
}

.url-item h3 {
    margin-bottom: 8px;
    color: var(--primary-color);
    word-break: break-all;
}

.url-item p {
    color: var(--text-secondary);
    font-size: 0.9rem;
    margin: 5px 0;
}

.url-item .tags {
    display: flex;
    gap: 8px;
    margin: 10px 0;
}

.tag {
    background-color: var(--primary-color);
    color: white;
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 0.85rem;
}

.url-actions {
    display: flex;
    gap: 10px;
    margin-top: 10px;
}

@media (max-width: 768px) {
    .card {
        padding: 20px;
    }

    .filter-bar {
        flex-direction: column;
    }
}