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

:root {
    --primary-color: #3b82f6;
    --primary-hover: #2563eb;
    --secondary-color: #64748b;
    --success-color: #10b981;
    --error-color: #ef4444;
    --bg-color: #f8fafc;
    --card-bg: #ffffff;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --border-color: #e2e8f0;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.1);
}

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

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Header */
header {
    background: linear-gradient(135deg, var(--primary-color) 0%, #6366f1 100%);
    color: white;
    padding: 3rem 0;
    text-align: center;
    box-shadow: var(--shadow-lg);
}

header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
}

.subtitle {
    font-size: 1.1rem;
    opacity: 0.95;
}

/* Main Content */
main {
    padding: 3rem 0;
}

section {
    margin-bottom: 4rem;
}

h2 {
    font-size: 2rem;
    color: var(--text-primary);
    margin-bottom: 1.5rem;
    font-weight: 600;
}

h3 {
    font-size: 1.3rem;
    color: var(--text-primary);
    margin-bottom: 1rem;
    font-weight: 600;
}

/* Introduction Section */
.intro-section {
    background: var(--card-bg);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow);
}

.intro-section p {
    font-size: 1.05rem;
    line-height: 1.8;
    color: var(--text-secondary);
}

/* Converter Section */
.converter-section {
    background: var(--card-bg);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow-lg);
}

.tool-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
}

.input-panel,
.output-panel {
    display: flex;
    flex-direction: column;
}

.panel-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
}

.panel-header h3 {
    margin: 0;
}

/* Textarea */
#dotInput {
    width: 100%;
    min-height: 300px;
    padding: 1rem;
    border: 2px solid var(--border-color);
    border-radius: 8px;
    font-family: 'Courier New', monospace;
    font-size: 0.95rem;
    resize: vertical;
    transition: border-color 0.3s;
}

#dotInput:focus {
    outline: none;
    border-color: var(--primary-color);
}

/* Options */
.options {
    display: flex;
    gap: 1.5rem;
    margin: 1.5rem 0;
    flex-wrap: wrap;
}

.option-group {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.option-group label {
    font-weight: 500;
    color: var(--text-secondary);
}

.option-group select,
.option-group input {
    padding: 0.5rem;
    border: 2px solid var(--border-color);
    border-radius: 6px;
    font-size: 0.95rem;
    transition: border-color 0.3s;
}

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

/* Buttons */
.btn-primary,
.btn-secondary {
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s;
}

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

.btn-primary:hover:not(:disabled) {
    background: var(--primary-hover);
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.btn-primary:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

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

.btn-secondary:hover {
    background: #475569;
    transform: translateY(-2px);
}

/* Output Area */
.output-area {
    flex: 1;
    border: 2px dashed var(--border-color);
    border-radius: 8px;
    padding: 2rem;
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 300px;
    background: #fafafa;
}

.output-area img {
    max-width: 100%;
    height: auto;
    border-radius: 8px;
    box-shadow: var(--shadow);
}

.placeholder {
    text-align: center;
    color: var(--text-secondary);
}

.placeholder svg {
    margin-bottom: 1rem;
    opacity: 0.5;
}

.placeholder p {
    font-size: 1rem;
}

/* Error Message */
.error-message {
    background: #fee;
    border: 1px solid var(--error-color);
    color: var(--error-color);
    padding: 1rem;
    border-radius: 8px;
    margin-top: 1rem;
}

/* Features Section */
.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
}

.feature-card {
    background: var(--card-bg);
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow);
    text-align: center;
    transition: transform 0.3s, box-shadow 0.3s;
}

.feature-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.feature-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.feature-card h3 {
    margin-bottom: 0.5rem;
}

.feature-card p {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

/* Examples Section */
.example-list {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.example-item {
    background: var(--card-bg);
    padding: 1.5rem;
    border-radius: 12px;
    box-shadow: var(--shadow);
}

.example-item h3 {
    font-size: 1.1rem;
    margin-bottom: 1rem;
    color: var(--primary-color);
}

.example-item pre {
    background: #f1f5f9;
    padding: 1rem;
    border-radius: 6px;
    overflow-x: auto;
}

.example-item code {
    font-family: 'Courier New', monospace;
    font-size: 0.9rem;
    color: var(--text-primary);
}

/* FAQ Section */
.faq-list {
    background: var(--card-bg);
    border-radius: 12px;
    box-shadow: var(--shadow);
    overflow: hidden;
}

.faq-item {
    border-bottom: 1px solid var(--border-color);
}

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

.faq-item summary {
    padding: 1.5rem;
    font-weight: 600;
    cursor: pointer;
    user-select: none;
    transition: background 0.3s;
}

.faq-item summary:hover {
    background: var(--bg-color);
}

.faq-item p {
    padding: 0 1.5rem 1.5rem;
    color: var(--text-secondary);
    line-height: 1.8;
}

/* Footer */
footer {
    background: var(--text-primary);
    color: white;
    padding: 2rem 0;
    text-align: center;
    margin-top: 4rem;
}

footer p {
    margin-bottom: 0.5rem;
}

.footer-links a {
    color: white;
    text-decoration: none;
    opacity: 0.8;
    transition: opacity 0.3s;
}

.footer-links a:hover {
    opacity: 1;
    text-decoration: underline;
}

/* Responsive Design */
@media (max-width: 768px) {
    header h1 {
        font-size: 2rem;
    }

    .tool-grid {
        grid-template-columns: 1fr;
    }

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

    .option-group {
        flex-direction: column;
        align-items: flex-start;
    }

    h2 {
        font-size: 1.5rem;
    }

    .features-grid,
    .example-list {
        grid-template-columns: 1fr;
    }
}

/* Loading Animation */
@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

.btn-loading::before {
    content: '';
    display: inline-block;
    width: 1rem;
    height: 1rem;
    border: 2px solid white;
    border-top-color: transparent;
    border-radius: 50%;
    margin-right: 0.5rem;
    animation: spin 0.6s linear infinite;
}