/* CSS Reset and Base Styles */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

:root {
    --primary-color: #4f46e5;
    --primary-hover: #4338ca;
    --secondary-color: #6b7280;
    --background-color: #f9fafb;
    --surface-color: #ffffff;
    --text-primary: #111827;
    --text-secondary: #6b7280;
    --border-color: #e5e7eb;
    --success-color: #10b981;
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
    --radius-sm: 6px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --transition: all 0.2s ease;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background-color: var(--background-color);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
}

.container {
    max-width: 900px;
    margin: 0 auto;
    padding: 2rem 1rem;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header Styles */
header {
    text-align: center;
    margin-bottom: 2rem;
}

.logo-container {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.75rem;
    margin-bottom: 0.5rem;
}

.logo {
    width: 48px;
    height: 48px;
    object-fit: contain;
}

h1 {
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-primary);
}

.tagline {
    color: var(--text-secondary);
    font-size: 1.1rem;
}

/* Main Content */
main {
    flex: 1;
}

.tool-section {
    background: var(--surface-color);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    box-shadow: var(--shadow-md);
    margin-bottom: 2rem;
}

/* Mode Toggle */
.mode-toggle {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
    background: var(--background-color);
    padding: 0.25rem;
    border-radius: var(--radius-md);
}

.mode-btn {
    flex: 1;
    padding: 0.75rem 1.5rem;
    border: none;
    background: transparent;
    color: var(--text-secondary);
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    border-radius: var(--radius-sm);
    transition: var(--transition);
}

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

.mode-btn.active {
    background: var(--primary-color);
    color: white;
    box-shadow: var(--shadow-sm);
}

/* Input/Output Sections */
.input-section,
.output-section,
.preview-section {
    margin-bottom: 1.5rem;
}

.input-section:last-child,
.output-section:last-child,
.preview-section:last-child {
    margin-bottom: 0;
}

label {
    display: block;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

textarea {
    width: 100%;
    min-height: 120px;
    padding: 1rem;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    font-family: 'Monaco', 'Menlo', 'Ubuntu Mono', monospace;
    font-size: 0.9rem;
    resize: vertical;
    transition: var(--transition);
    background: var(--surface-color);
}

textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
}

textarea::placeholder {
    color: var(--text-secondary);
}

textarea[readonly] {
    background: var(--background-color);
}

/* Action Buttons */
.input-actions,
.output-actions {
    display: flex;
    gap: 0.5rem;
    margin-top: 0.75rem;
    align-items: center;
}

.action-btn {
    padding: 0.5rem 1rem;
    border: 1px solid var(--border-color);
    background: var(--surface-color);
    color: var(--text-secondary);
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    border-radius: var(--radius-sm);
    transition: var(--transition);
}

.action-btn:hover {
    background: var(--background-color);
    color: var(--text-primary);
    border-color: var(--secondary-color);
}

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

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

.copy-feedback {
    color: var(--success-color);
    font-weight: 500;
    font-size: 0.875rem;
    opacity: 0;
    transition: opacity 0.3s ease;
}

.copy-feedback.show {
    opacity: 1;
}

/* Preview Section */
.preview-box {
    min-height: 80px;
    padding: 1rem;
    background: var(--background-color);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    word-wrap: break-word;
    overflow-wrap: break-word;
}

.preview-placeholder {
    color: var(--text-secondary);
    font-style: italic;
}

/* Reference Section */
.reference-section {
    background: var(--surface-color);
    border-radius: var(--radius-lg);
    padding: 1.5rem;
    box-shadow: var(--shadow-md);
}

.reference-section h2 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.reference-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
    gap: 0.75rem;
}

.reference-item {
    display: flex;
    flex-direction: column;
    padding: 0.75rem;
    background: var(--background-color);
    border-radius: var(--radius-sm);
    border: 1px solid var(--border-color);
    cursor: pointer;
    transition: var(--transition);
}

.reference-item:hover {
    border-color: var(--primary-color);
    box-shadow: var(--shadow-sm);
}

.reference-item .entity {
    font-family: 'Monaco', 'Menlo', 'Ubuntu Mono', monospace;
    font-size: 0.8rem;
    color: var(--primary-color);
    margin-bottom: 0.25rem;
}

.reference-item .character {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.25rem;
}

.reference-item .name {
    font-size: 0.75rem;
    color: var(--text-secondary);
}

/* Footer */
footer {
    margin-top: 2rem;
    padding-top: 1.5rem;
    border-top: 1px solid var(--border-color);
    text-align: center;
}

footer p {
    color: var(--text-secondary);
    font-size: 0.875rem;
}

footer a {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
}

footer a:hover {
    color: var(--primary-hover);
    text-decoration: underline;
}

/* Mobile Responsive */
@media (max-width: 768px) {
    .container {
        padding: 1rem;
    }

    h1 {
        font-size: 1.5rem;
    }

    .logo {
        width: 40px;
        height: 40px;
    }

    .tagline {
        font-size: 1rem;
    }

    .tool-section,
    .reference-section {
        padding: 1rem;
    }

    .mode-btn {
        padding: 0.625rem 1rem;
        font-size: 0.9rem;
    }

    textarea {
        min-height: 100px;
        padding: 0.75rem;
        font-size: 0.85rem;
    }

    .reference-grid {
        grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
        gap: 0.5rem;
    }

    .reference-item {
        padding: 0.5rem;
    }

    .reference-item .entity {
        font-size: 0.7rem;
    }

    .reference-item .character {
        font-size: 1rem;
    }

    .reference-item .name {
        font-size: 0.7rem;
    }
}

@media (max-width: 480px) {
    .logo-container {
        flex-direction: column;
        gap: 0.5rem;
    }

    .reference-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .input-actions,
    .output-actions {
        flex-wrap: wrap;
    }

    .action-btn {
        flex: 1;
        min-width: 80px;
        text-align: center;
    }
}

/* Dark Mode Support */
@media (prefers-color-scheme: dark) {
    :root {
        --background-color: #111827;
        --surface-color: #1f2937;
        --text-primary: #f9fafb;
        --text-secondary: #9ca3af;
        --border-color: #374151;
        --primary-color: #6366f1;
        --primary-hover: #4f46e5;
    }

    textarea {
        background: var(--surface-color);
        color: var(--text-primary);
    }

    textarea[readonly] {
        background: #111827;
    }

    .action-btn {
        background: var(--surface-color);
        color: var(--text-secondary);
    }

    .action-btn:hover {
        background: #374151;
    }
}