:root {
    /* Color Palette - Deep Blue & Sophisticated Slate */
    --primary: #2563eb;
    --primary-hover: #1d4ed8;
    --bg-main: #f8fafc;
    --bg-card: #ffffff;
    --text-main: #1e293b;
    --text-muted: #64748b;
    --border: #e2e8f0;
    --accent: #8b5cf6;

    /* Layout */
    --max-width: 1000px;
    --radius: 12px;
    --shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg-main: #0f172a;
        --bg-card: #1e293b;
        --text-main: #f1f5f9;
        --text-muted: #94a3b8;
        --border: #334155;
    }
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
}

body {
    background-color: var(--bg-main);
    color: var(--text-main);
    line-height: 1.6;
    transition: background-color 0.3s, color 0.3s;
}

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 2rem 1rem;
}

header {
    text-align: center;
    margin-bottom: 3rem;
}

h1 {
    font-size: 2.5rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--primary), var(--accent));
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    margin-bottom: 0.5rem;
}

.subtitle {
    color: var(--text-muted);
}

.main-grid {
    display: grid;
    grid-template-columns: 1fr 1.5fr;
    gap: 2rem;
}

@media (max-width: 768px) {
    .main-grid {
        grid-template-columns: 1fr;
    }
}

.card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1.5rem;
    box-shadow: var(--shadow);
}

.input-section h2,
.output-section h2 {
    font-size: 1.25rem;
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.form-group {
    margin-bottom: 1.5rem;
}

.usage-display {
    margin-top: 1rem;
    font-size: 0.875rem;
    color: var(--text-muted);
}

label {
    display: block;
    font-size: 0.875rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-muted);
}

textarea,
input[type="text"],
select {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border);
    border-radius: 8px;
    background: var(--bg-main);
    color: var(--text-main);
    font-size: 1rem;
    transition: border-color 0.2s, ring 0.2s;
}

textarea:focus,
input[type="text"]:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.75rem 1.5rem;
    border-radius: 8px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    border: none;
    gap: 0.5rem;
}

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

#generate-btn {
    font-size: 1.2rem;
}

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

.btn-secondary {
    background: transparent;
    border: 1px solid var(--border);
    color: var(--text-main);
}

.btn-secondary:hover {
    background: var(--bg-main);
}

.output-actions .btn {
    font-size: 1.05rem;
}

.output-char-count {
    font-size: 0.9rem;
    color: var(--text-muted);
    margin: 0 0 0.75rem 0;
}

.output-area {
    min-height: 400px;
    border: 1px dashed var(--border);
    border-radius: var(--radius);
    padding: 1.5rem;
    background: var(--bg-main);
    position: relative;
}

.output-content {
    position: relative;
    min-height: 320px;
    white-space: pre-wrap;
    padding-bottom: 2.5rem;
}

.output-content[contenteditable="true"] {
    cursor: text;
}

.output-content[contenteditable="true"]:focus {
    outline: none;
}

.output-toolbar {
    position: absolute;
    bottom: 0.75rem;
    right: 0.75rem;
}

.output-toolbar .btn-inner {
    padding: 0.4rem 0.75rem;
    font-size: 0.9rem;
}

.placeholder-content {
    color: var(--text-muted);
    text-align: center;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
}

.info-section {
    margin-top: 2rem;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
}

@media (max-width: 768px) {
    .info-section {
        grid-template-columns: 1fr;
    }
}

.info-section h3 {
    font-size: 1.1rem;
    margin-bottom: 0.75rem;
    color: var(--primary);
}

.info-section ul {
    list-style: none;
    font-size: 0.9rem;
}

.info-section li {
    margin-bottom: 0.5rem;
    color: var(--text-muted);
}

.footer {
    margin-top: 4rem;
    text-align: center;
    color: var(--text-muted);
    font-size: 0.875rem;
}

/* Animations */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.card {
    animation: fadeIn 0.5s ease-out forwards;
}

/* Spinner */
.spinner {
    width: 40px;
    height: 40px;
    border: 3px solid var(--border);
    border-top-color: var(--primary);
    border-radius: 50%;
    margin: 0 auto 1rem;
    animation: spin 1s linear infinite;
}

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