:root {
    --bg-color: #f8fafc;
    --text-color: #1e293b;
    --primary-color: #2563eb;
    --primary-hover: #1d4ed8;
    --secondary-bg: #ffffff;
    --border-color: #e2e8f0;
    --accent-color: #64748b;
    --danger-color: #dc2626;
    --danger-hover: #b91c1c;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --radius: 0.75rem;
    --font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
}

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

body {
    font-family: var(--font-family);
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.5;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 2rem;
}

.app-container {
    width: 100%;
    max-width: 1000px;
    margin: 0 auto;
}

.app-header {
    text-align: center;
    margin-bottom: 2rem;
}

.app-header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--text-color);
    margin-bottom: 0.5rem;
    letter-spacing: -0.025em;
}

.app-header p {
    color: var(--accent-color);
    font-size: 1.1rem;
}

.converter-wrapper {
    background-color: var(--secondary-bg);
    border-radius: var(--radius);
    box-shadow: var(--shadow-md);
    padding: 1.5rem;
    border: 1px solid var(--border-color);
    margin-bottom: 3rem;
}

.toolbar {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
    justify-content: center;
}

.btn {
    padding: 0.75rem 1.25rem;
    border-radius: 0.5rem;
    font-weight: 500;
    font-size: 0.9rem;
    cursor: pointer;
    transition: all 0.2s ease;
    border: 1px solid transparent;
    font-family: var(--font-family);
    white-space: nowrap;
    flex-shrink: 0;
}

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

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

.btn-secondary {
    background-color: white;
    color: var(--text-color);
    border-color: var(--border-color);
}

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

.btn-danger {
    background-color: white;
    color: var(--danger-color);
    border-color: var(--border-color);
}

.btn-danger:hover {
    background-color: #fef2f2;
    border-color: var(--danger-color);
}

.input-area {
    margin-bottom: 1.5rem;
}

textarea {
    width: 100%;
    height: 400px;
    padding: 1.25rem;
    border: 1px solid var(--border-color);
    border-radius: var(--radius);
    font-family: var(--font-family);
    font-size: 1rem;
    resize: vertical;
    outline: none;
    transition: border-color 0.2s;
    background-color: #fafafa;
}

textarea:focus {
    border-color: var(--primary-color);
    background-color: white;
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

.action-bar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1.5rem;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
}

.stats {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    color: var(--accent-color);
    font-size: 0.9rem;
    font-weight: 500;
}

.stats span.separator {
    color: var(--border-color);
}

.actions {
    display: flex;
    gap: 0.75rem;
}

/* SEO Content Section */
.content-section {
    margin-top: 3rem;
    color: var(--text-color);
}

.content-section article {
    margin-bottom: 2rem;
}

.content-section h2 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    color: var(--text-color);
}

.content-section p {
    color: var(--accent-color);
    line-height: 1.7;
    margin-bottom: 1rem;
}

.app-footer {
    text-align: center;
    margin-top: 4rem;
    color: var(--accent-color);
    font-size: 0.875rem;
    padding-bottom: 3rem;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 2rem;
    border-top: 1px solid var(--border-color);
    padding-top: 3rem;
}

.tool-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
    gap: 1rem;
    width: 100%;
    max-width: 900px;
    margin: 0 auto;
}

.tool-grid a {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 0.75rem 1rem;
    background-color: white;
    border: 1px solid var(--border-color);
    border-radius: 0.5rem;
    color: var(--text-color);
    text-decoration: none;
    font-weight: 500;
    transition: all 0.2s ease;
    text-align: center;
    min-height: 3.5rem;
}

.tool-grid a:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
    transform: translateY(-2px);
    box-shadow: var(--shadow-sm);
}

.tool-grid a.active {
    background-color: var(--bg-color);
    border-color: var(--primary-color);
    color: var(--primary-color);
}

.language-switcher select {
    appearance: none;
    -webkit-appearance: none;
    -moz-appearance: none;
    padding: 0.5rem 2.5rem 0.5rem 1rem;
    border-radius: 0.5rem;
    border: 1px solid var(--border-color);
    background-color: white;
    color: var(--text-color);
    font-family: var(--font-family);
    font-size: 0.9rem;
    cursor: pointer;
    outline: none;
    transition: border-color 0.2s;
    background-image: url("data:image/svg+xml;charset=UTF-8,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='none' stroke='%2364748b' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3e%3cpolyline points='6 9 12 15 18 9'%3e%3c/polyline%3e%3c/svg%3e");
    background-repeat: no-repeat;
    background-position: right 0.7rem center;
    background-size: 1em;
}

.language-switcher select:hover {
    border-color: var(--accent-color);
}

.language-switcher select:focus {
    border-color: var(--primary-color);
}

@media (max-width: 768px) {
    body {
        padding: 1rem;
    }

    .action-bar {
        flex-direction: column;
        align-items: stretch;
    }

    .stats {
        justify-content: center;
        flex-wrap: wrap;
    }

    .actions {
        justify-content: center;
    }
}