:root {
    --bg: #0f0f11;
    --surface: #1a1a1f;
    --surface-hover: #22222a;
    --border: #2a2a35;
    --text: #e8e8ed;
    --text-muted: #8888a0;
    --accent: #6c5ce7;
    --accent-hover: #7d6ff0;
    --accent-glow: rgba(108, 92, 231, 0.25);
    --danger: #e74c3c;
    --radius: 12px;
    --radius-sm: 8px;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    background: var(--bg);
    color: var(--text);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    padding: 5rem 1rem 2rem;
}

.container {
    width: 100%;
    max-width: 640px;
}

header {
    text-align: center;
    margin-bottom: 1.5rem;
}

/* Top Navigation Bar */
.top-nav {
    position: sticky;
    top: 0;
    z-index: 50;
    background: var(--surface);
    border-bottom: 1px solid var(--border);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
}

.nav-inner {
    max-width: 960px;
    margin: 0 auto;
    padding: 0 1.5rem;
    height: 3.5rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-brand {
    font-size: 1.15rem;
    font-weight: 700;
    letter-spacing: -0.02em;
    background: linear-gradient(135deg, var(--accent), #a29bfe);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    text-decoration: none;
}

.nav-links {
    display: flex;
    gap: 0.25rem;
    background: var(--bg);
    padding: 0.25rem;
    border-radius: var(--radius-sm);
    border: 1px solid var(--border);
}

.nav-link {
    padding: 0.4rem 1rem;
    color: var(--text-muted);
    font-size: 0.85rem;
    font-weight: 500;
    font-family: inherit;
    text-decoration: none;
    border-radius: 6px;
    transition: color 0.2s, background 0.2s;
}

.nav-link:hover {
    color: var(--text);
    background: var(--surface-hover);
}

.nav-link.active {
    background: var(--accent);
    color: #fff;
}

.subtitle {
    color: var(--text-muted);
    margin-top: 0.5rem;
    font-size: 0.95rem;
}

.upload-zone {
    border: 2px dashed var(--border);
    border-radius: var(--radius);
    padding: 3rem 2rem;
    text-align: center;
    cursor: pointer;
    transition: border-color 0.2s, background 0.2s;
    background: var(--surface);
}

.upload-zone:hover,
.upload-zone.drag-over {
    border-color: var(--accent);
    background: var(--surface-hover);
}

.upload-icon {
    color: var(--text-muted);
    margin-bottom: 1rem;
    transition: color 0.2s;
}

.upload-zone:hover .upload-icon {
    color: var(--accent);
}

.upload-text {
    font-size: 1rem;
    color: var(--text-muted);
}

.browse-link {
    color: var(--accent);
    cursor: pointer;
    text-decoration: underline;
    font-weight: 500;
}

.upload-hint {
    font-size: 0.8rem;
    color: var(--text-muted);
    opacity: 0.6;
    margin-top: 0.5rem;
}

.preview-section {
    margin-top: 1.5rem;
}

.preview-card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1rem;
    display: flex;
    align-items: center;
    gap: 1rem;
}

.preview-card img {
    width: 64px;
    height: 64px;
    object-fit: cover;
    border-radius: var(--radius-sm);
    flex-shrink: 0;
}

.preview-info {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
    min-width: 0;
}

.file-name {
    font-size: 0.9rem;
    font-weight: 500;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.file-dims {
    font-size: 0.8rem;
    color: var(--text-muted);
}

.btn-icon {
    background: none;
    border: none;
    color: var(--text-muted);
    cursor: pointer;
    padding: 0.5rem;
    border-radius: var(--radius-sm);
    transition: color 0.2s, background 0.2s;
    flex-shrink: 0;
}

.btn-icon:hover {
    color: var(--danger);
    background: rgba(231, 76, 60, 0.1);
}

.settings {
    margin-top: 1.5rem;
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1.5rem;
}

.settings h2 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

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

.input-group {
    display: flex;
    flex-direction: column;
    gap: 0.4rem;
}

.input-group label {
    font-size: 0.8rem;
    color: var(--text-muted);
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.input-group input[type="number"],
.input-group input[type="password"],
.input-group select,
.input-group textarea {
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    padding: 0.65rem 0.75rem;
    color: var(--text);
    font-size: 0.9rem;
    transition: border-color 0.2s;
    outline: none;
    width: 100%;
    font-family: inherit;
    resize: vertical;
}

.input-group textarea {
    min-height: 100px;
    line-height: 1.5;
}

.input-group input[type="number"]:focus,
.input-group input[type="password"]:focus,
.input-group select:focus,
.input-group textarea:focus {
    border-color: var(--accent);
}

.input-hint {
    font-size: 0.75rem;
    color: var(--text-muted);
    margin-top: 0.25rem;
}

/* Generate Section */
.generate-section {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1.5rem;
}

.generate-section h2 {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.generate-intro {
    color: var(--text-muted);
    font-size: 0.9rem;
    margin-bottom: 1.5rem;
}

.generate-section .input-group {
    margin-bottom: 1.25rem;
}

.generate-section .input-group:last-of-type {
    margin-bottom: 0;
}

.input-group select {
    cursor: pointer;
    -webkit-appearance: none;
    appearance: none;
}

.checkbox-group {
    grid-column: 1 / -1;
}

.input-group-full {
    grid-column: 1 / -1;
}

.checkbox-label {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    cursor: pointer;
    font-size: 0.9rem;
}

.checkbox-label input[type="checkbox"] {
    accent-color: var(--accent);
    width: 16px;
    height: 16px;
}

.btn-primary {
    margin-top: 1.25rem;
    width: 100%;
    padding: 0.75rem 1.5rem;
    background: var(--accent);
    color: #fff;
    border: none;
    border-radius: var(--radius-sm);
    font-size: 0.95rem;
    font-weight: 600;
    cursor: pointer;
    transition: background 0.2s, box-shadow 0.2s;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
}

.btn-primary:hover:not(:disabled) {
    background: var(--accent-hover);
    box-shadow: 0 0 20px var(--accent-glow);
}

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

.spin {
    animation: spin 1s linear infinite;
}

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

.result-section {
    margin-top: 1.5rem;
}

.result-section h2 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 1rem;
}

.result-card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1rem;
    text-align: center;
}

.result-card img {
    max-width: 100%;
    max-height: 400px;
    object-fit: contain;
    border-radius: var(--radius-sm);
}

.result-info {
    margin-top: 0.75rem;
}

.result-actions {
    margin-top: 1rem;
    display: flex;
    gap: 0.75rem;
}

.btn-download {
    flex: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    background: var(--accent);
    color: #fff;
    border: none;
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    text-decoration: none;
    transition: background 0.2s, box-shadow 0.2s;
}

.btn-download:hover {
    background: var(--accent-hover);
    box-shadow: 0 0 20px var(--accent-glow);
}

.btn-secondary {
    padding: 0.75rem 1.5rem;
    background: var(--surface);
    color: var(--text);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    font-weight: 500;
    cursor: pointer;
    transition: background 0.2s;
}

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

.error-toast {
    position: fixed;
    bottom: 2rem;
    left: 50%;
    transform: translateX(-50%);
    background: var(--danger);
    color: #fff;
    padding: 0.75rem 1.5rem;
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    font-weight: 500;
    box-shadow: 0 4px 20px rgba(0,0,0,0.4);
    z-index: 100;
    animation: fadeInUp 0.3s ease;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateX(-50%) translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateX(-50%) translateY(0);
    }
}