:root {
    --bg-color: #f3f4f6;
    --text-primary: #111827;
    --text-secondary: #6b7280;
    --border-color: #e5e7eb;
    --card-bg: #ffffff;
    --primary-color: #2563eb;
    --primary-hover: #1d4ed8;
    --error-color: #ef4444;
    --error-bg: #fef2f2;
    --radius-md: 8px;
    --radius-lg: 12px;
    --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);
}

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

body {
    background-color: var(--bg-color);
    color: var(--text-primary);
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    line-height: 1.5;
    padding: 2rem 1rem;
}

.container {
    max-width: 800px;
    margin: 0 auto;
}

header {
    text-align: center;
    margin-bottom: 2.5rem;
}

h1 {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
}

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

.card {
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    padding: 2rem;
    margin-bottom: 1.5rem;
}

.card h2 {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 1.5rem;
    padding-bottom: 0.75rem;
    border-bottom: 1px solid var(--border-color);
}

.input-section form {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

label {
    font-weight: 500;
    font-size: 0.95rem;
    color: var(--text-primary);
}

.input-group {
    display: flex;
    gap: 0.5rem;
}

input[type="text"] {
    flex-grow: 1;
    background-color: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 0.75rem 1rem;
    font-size: 1rem;
    font-family: inherit;
    outline: none;
    transition: border-color 0.15s ease, box-shadow 0.15s ease;
}

input[type="text"]:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

button {
    background-color: var(--primary-color);
    color: #ffffff;
    border: none;
    border-radius: var(--radius-md);
    padding: 0.75rem 1.5rem;
    font-size: 1rem;
    font-weight: 500;
    font-family: inherit;
    cursor: pointer;
    transition: background-color 0.15s ease;
}

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

button:disabled {
    opacity: 0.7;
    cursor: not-allowed;
}

.hidden {
    display: none !important;
}

.loading-state {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 3rem 0;
    color: var(--text-secondary);
}

.spinner {
    width: 40px;
    height: 40px;
    border: 3px solid rgba(37, 99, 235, 0.2);
    border-radius: 50%;
    border-top-color: var(--primary-color);
    animation: spin 1s ease-in-out infinite;
    margin-bottom: 1rem;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

.video-thumbnail {
    width: 100%;
    max-height: 400px;
    object-fit: cover;
    border-radius: var(--radius-md);
    margin-bottom: 1.5rem;
    border: 1px solid var(--border-color);
}

.info-grid {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.info-item {
    display: flex;
    flex-direction: column;
}

.info-item .label {
    font-size: 0.875rem;
    color: var(--text-secondary);
    font-weight: 500;
}

.info-item .value {
    font-size: 1rem;
    font-weight: 500;
    color: var(--text-primary);
}

.btn-primary {
    display: inline-flex;
    justify-content: center;
    align-items: center;
    background-color: var(--primary-color);
    color: #ffffff;
    text-decoration: none;
    font-weight: 500;
    padding: 0.75rem 1.5rem;
    border-radius: var(--radius-md);
    transition: background-color 0.15s ease;
}

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

.btn-secondary {
    background-color: var(--card-bg);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
    padding: 0.75rem 1rem;
    border-radius: var(--radius-md);
    font-size: 0.95rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.15s ease;
}

.btn-secondary:hover {
    background-color: #f3f4f6;
}

.seo-block {
    margin-bottom: 1.5rem;
}

.seo-block:last-child {
    margin-bottom: 0;
}

.seo-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.5rem;
}

.seo-header h3 {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-primary);
}

.btn-copy {
    background-color: #f3f4f6;
    color: var(--text-primary);
    border: 1px solid var(--border-color);
    padding: 0.4rem 0.75rem;
    font-size: 0.875rem;
}

.btn-copy:hover {
    background-color: #e5e7eb;
}

.copy-box {
    background: #f9fafb;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: 1rem;
}

.copy-box span, .copy-box pre {
    font-family: inherit;
    font-size: 0.95rem;
    color: var(--text-primary);
    word-break: break-word;
    white-space: pre-wrap;
    margin: 0;
}

.error-card {
    border-color: var(--error-color);
    background-color: var(--error-bg);
}

.error-card h2 {
    color: var(--error-color);
    border-bottom-color: rgba(239, 68, 68, 0.2);
}

#errorText {
    color: var(--error-color);
}

footer {
    margin-top: 3rem;
    padding-top: 2rem;
    border-top: 1px solid var(--border-color);
    color: var(--text-secondary);
    font-size: 0.875rem;
}

.footer-content {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
}

.footer-logo {
    width: 24px;
    height: 24px;
    border-radius: 50%;
    object-fit: cover;
}

@media (max-width: 600px) {
    .input-group {
        flex-direction: column;
    }
    #submitBtn, .btn-primary {
        width: 100%;
    }
}