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

:root {
    --primary: #4f46e5;
    --primary-hover: #4338ca;
    --bg: #f8fafc;
    --card-bg: #ffffff;
    --text: #1e293b;
    --text-muted: #64748b;
    --border: #e2e8f0;
    --success: #10b981;
    --error: #ef4444;
    --radius: 12px;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
    min-height: 100vh;
}

header {
    background: var(--card-bg);
    border-bottom: 1px solid var(--border);
    padding: 1rem 2rem;
}

nav {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text);
    text-decoration: none;
}

.tagline {
    color: var(--text-muted);
    font-size: 0.875rem;
}

main {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
}

.hero {
    text-align: center;
    padding: 3rem 0;
}

.hero h1 {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 1rem;
    color: var(--text);
}

.hero p {
    font-size: 1.125rem;
    color: var(--text-muted);
    max-width: 600px;
    margin: 0 auto;
}

.tools-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1.5rem;
    margin: 2rem 0;
}

.tool-card {
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 2rem;
    text-decoration: none;
    color: var(--text);
    transition: all 0.2s ease;
    display: block;
}

.tool-card:hover {
    border-color: var(--primary);
    box-shadow: 0 4px 12px rgba(79, 70, 229, 0.15);
    transform: translateY(-2px);
}

.tool-icon {
    font-size: 2.5rem;
    margin-bottom: 1rem;
}

.tool-card h3 {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
}

.tool-card p {
    color: var(--text-muted);
    font-size: 0.875rem;
}

.features {
    padding: 3rem 0;
}

.features h2 {
    text-align: center;
    font-size: 1.75rem;
    margin-bottom: 2rem;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
    gap: 1.5rem;
}

.feature {
    text-align: center;
    padding: 1.5rem;
}

.feature h3 {
    font-size: 1.125rem;
    margin-bottom: 0.5rem;
}

.feature p {
    color: var(--text-muted);
    font-size: 0.875rem;
}

footer {
    text-align: center;
    padding: 2rem;
    color: var(--text-muted);
    font-size: 0.875rem;
    border-top: 1px solid var(--border);
}

/* Tool page styles */
.tool-page {
    max-width: 800px;
    margin: 0 auto;
    padding: 2rem;
}

.tool-page h1 {
    font-size: 2rem;
    margin-bottom: 0.5rem;
}

.tool-page .subtitle {
    color: var(--text-muted);
    margin-bottom: 2rem;
}

.back-link {
    display: inline-block;
    color: var(--primary);
    text-decoration: none;
    margin-bottom: 1.5rem;
    font-size: 0.875rem;
}

.back-link:hover {
    text-decoration: underline;
}

/* Drop zone */
.drop-zone {
    border: 2px dashed var(--border);
    border-radius: var(--radius);
    padding: 3rem 2rem;
    text-align: center;
    cursor: pointer;
    transition: all 0.2s ease;
    background: var(--card-bg);
    margin-bottom: 1.5rem;
}

.drop-zone:hover,
.drop-zone.drag-over {
    border-color: var(--primary);
    background: rgba(79, 70, 229, 0.05);
}

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

.drop-zone h3 {
    font-size: 1.125rem;
    margin-bottom: 0.5rem;
}

.drop-zone p {
    color: var(--text-muted);
    font-size: 0.875rem;
}

/* File list */
.file-list {
    list-style: none;
    margin-bottom: 1.5rem;
}

.file-item {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.75rem 1rem;
    background: var(--card-bg);
    border: 1px solid var(--border);
    border-radius: 8px;
    margin-bottom: 0.5rem;
}

.file-item .file-name {
    font-weight: 500;
    flex: 1;
}

.file-item .file-size {
    color: var(--text-muted);
    font-size: 0.875rem;
    margin: 0 1rem;
}

.file-item .remove-btn {
    background: none;
    border: none;
    color: var(--error);
    cursor: pointer;
    font-size: 1.25rem;
    padding: 0 0.5rem;
}

.file-item .move-btn {
    background: none;
    border: none;
    color: var(--text-muted);
    cursor: pointer;
    font-size: 1rem;
    padding: 0 0.25rem;
}

.file-item .move-btn:hover {
    color: var(--primary);
}

/* Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.75rem 1.5rem;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    border: none;
    transition: all 0.2s ease;
}

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

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

.btn-primary:disabled {
    background: var(--border);
    color: var(--text-muted);
    cursor: not-allowed;
}

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

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

/* Progress */
.progress-bar {
    width: 100%;
    height: 8px;
    background: var(--border);
    border-radius: 4px;
    overflow: hidden;
    margin: 1rem 0;
    display: none;
}

.progress-bar.active {
    display: block;
}

.progress-bar .fill {
    height: 100%;
    background: var(--primary);
    border-radius: 4px;
    transition: width 0.3s ease;
    width: 0%;
}

.status {
    text-align: center;
    padding: 1rem;
    color: var(--text-muted);
    display: none;
}

.status.active {
    display: block;
}

.status.success {
    color: var(--success);
}

.status.error {
    color: var(--error);
}

/* Page range input */
.page-range-input {
    width: 100%;
    padding: 0.75rem 1rem;
    border: 1px solid var(--border);
    border-radius: 8px;
    font-size: 1rem;
    margin-bottom: 1rem;
    font-family: inherit;
}

.page-range-input:focus {
    outline: none;
    border-color: var(--primary);
}

/* Quality slider */
.slider-group {
    margin-bottom: 1.5rem;
}

.slider-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
}

.slider-group input[type="range"] {
    width: 100%;
}

.slider-value {
    text-align: center;
    color: var(--text-muted);
    font-size: 0.875rem;
    margin-top: 0.25rem;
}


/* Dark mode — auto-detect + manual toggle */
[data-theme="dark"],
.dark-mode {
    --primary: #818cf8;
    --primary-hover: #a5b4fc;
    --bg: #0f172a;
    --card-bg: #1e293b;
    --text: #f1f5f9;
    --text-muted: #94a3b8;
    --border: #334155;
}

@media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) {
        --primary: #818cf8;
        --primary-hover: #a5b4fc;
        --bg: #0f172a;
        --card-bg: #1e293b;
        --text: #f1f5f9;
        --text-muted: #94a3b8;
        --border: #334155;
    }
}

/* Theme toggle button */
.theme-toggle {
    background: none;
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 0.4rem 0.75rem;
    cursor: pointer;
    font-size: 1.1rem;
    color: var(--text);
    transition: all 0.2s;
    line-height: 1;
}
.theme-toggle:hover {
    border-color: var(--primary);
    background: var(--card-bg);
}

/* Responsive */
@media (max-width: 640px) {
    .hero h1 {
        font-size: 1.75rem;
    }

    main {
        padding: 1rem;
    }

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

    .drop-zone {
        padding: 2rem 1rem;
    }
}