/* ============================================================
   GRAYSCALE PDF CONVERTER — style.css
   Dark-mode premium design, mobile-first responsive
   ============================================================ */

/* ---- CSS Variables ---- */
:root {
    --bg-base: #0f1117;
    --bg-card: #16191f;
    --bg-panel: #1c2030;
    --bg-elevated: #232736;
    --bg-input: #1a1d27;

    --accent: #6366f1;
    --accent-hover: #818cf8;
    --accent-glow: rgba(99, 102, 241, 0.3);
    --green: #10b981;
    --green-hover: #059669;

    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --text-dim: #64748b;
    --text-muted: #475569;

    --border: rgba(255, 255, 255, 0.07);
    --border-focus: rgba(99, 102, 241, 0.6);

    --radius-sm: 6px;
    --radius-md: 12px;
    --radius-lg: 18px;
    --radius-xl: 24px;

    --shadow-card: 0 4px 24px rgba(0, 0, 0, 0.4);
    --shadow-glow: 0 0 20px rgba(99, 102, 241, 0.2);

    --trans: all 0.22s ease;
}

/* ---- Reset / Base ---- */
*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

/* Global hidden utility — JS toggles this */
.hidden {
    display: none !important;
}


html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Inter', 'Outfit', system-ui, sans-serif;
    background: var(--bg-base);
    color: var(--text-primary);
    line-height: 1.65;
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
}

/* ---- Layout ---- */
.app-wrapper {
    max-width: 960px;
    margin: 0 auto;
    padding: 24px 16px 64px;
}

/* ---- HEADER ---- */
.main-header {
    text-align: center;
    padding: 40px 16px 28px;
}

.brand-area {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 14px;
    margin-bottom: 12px;
}

.brand-icon {
    width: 52px;
    height: 52px;
    flex-shrink: 0;
    filter: drop-shadow(0 4px 12px rgba(99, 102, 241, 0.4));
}

.brand-icon svg {
    width: 100%;
    height: 100%;
}

.brand-text h1 {
    font-family: 'Outfit', sans-serif;
    font-size: clamp(1.6rem, 5vw, 2.4rem);
    font-weight: 800;
    background: linear-gradient(135deg, #c7d2fe, #818cf8, #6366f1);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    letter-spacing: -0.5px;
    line-height: 1.2;
}

.badge-free {
    display: inline-block;
    background: linear-gradient(135deg, #10b981, #059669);
    color: #fff;
    font-size: 11px;
    font-weight: 700;
    letter-spacing: 0.5px;
    padding: 2px 10px;
    border-radius: 99px;
    text-transform: uppercase;
}

.header-subtitle {
    color: var(--text-secondary);
    font-size: clamp(0.9rem, 2.5vw, 1.05rem);
    max-width: 520px;
    margin: 0 auto;
}

/* ---- STAGES ---- */
.stage {
    transition: var(--trans);
}

.stage.hidden {
    display: none;
}

.stage.active {
    display: block;
}

/* ---- UPLOAD CARD ---- */
.upload-card {
    background: var(--bg-card);
    border: 2px dashed rgba(99, 102, 241, 0.35);
    border-radius: var(--radius-xl);
    padding: 56px 32px;
    text-align: center;
    cursor: pointer;
    transition: var(--trans);
    box-shadow: var(--shadow-card);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 12px;
}

.upload-card:hover,
.upload-card.drag-over {
    border-color: var(--accent);
    background: var(--bg-panel);
    box-shadow: var(--shadow-glow), var(--shadow-card);
    transform: translateY(-2px);
}

.upload-icon-wrap {
    width: 80px;
    height: 80px;
    margin-bottom: 8px;
}

.upload-icon-wrap svg {
    width: 100%;
    height: 100%;
}

.upload-title {
    font-family: 'Outfit', sans-serif;
    font-size: 1.6rem;
    font-weight: 700;
    color: var(--text-primary);
}

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

.link-style {
    color: var(--accent-hover);
    text-decoration: underline;
    cursor: pointer;
}

.upload-note {
    font-size: 0.81rem;
    color: var(--text-dim);
    background: var(--bg-elevated);
    padding: 6px 16px;
    border-radius: 99px;
}

.btn-upload {
    background: linear-gradient(135deg, var(--accent), #8b5cf6);
    color: #fff;
    border: none;
    padding: 14px 36px;
    border-radius: 99px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--trans);
    box-shadow: 0 4px 16px rgba(99, 102, 241, 0.4);
    margin-top: 8px;
}

.btn-upload:hover {
    transform: translateY(-2px) scale(1.02);
    box-shadow: 0 8px 24px rgba(99, 102, 241, 0.5);
}

/* ---- LOADING ---- */
.loading-card {
    background: var(--bg-card);
    border-radius: var(--radius-xl);
    padding: 64px 32px;
    text-align: center;
    box-shadow: var(--shadow-card);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 20px;
}

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

.spinner {
    width: 52px;
    height: 52px;
    border: 4px solid var(--bg-elevated);
    border-top-color: var(--accent);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

.processing-text {
    color: var(--text-secondary);
    font-size: 1.05rem;
}

.progress-bar-wrap {
    width: 100%;
    max-width: 320px;
    height: 8px;
    background: var(--bg-elevated);
    border-radius: 99px;
    overflow: hidden;
}

.progress-bar {
    height: 100%;
    background: linear-gradient(90deg, var(--accent), #8b5cf6);
    border-radius: 99px;
    transition: width 0.3s ease;
}

/* ---- FILE INFO BAR ---- */
.file-info-bar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    padding: 12px 20px;
    margin-bottom: 20px;
    flex-wrap: wrap;
}

.file-meta {
    display: flex;
    align-items: center;
    gap: 8px;
    flex-wrap: wrap;
}

.file-icon {
    font-size: 1.2rem;
}

.file-name {
    font-weight: 600;
    color: var(--text-primary);
    max-width: 300px;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    font-size: 0.95rem;
}

.sep {
    color: var(--text-dim);
}

.meta-chip {
    background: var(--bg-elevated);
    border: 1px solid var(--border);
    border-radius: 99px;
    padding: 2px 10px;
    font-size: 0.8rem;
    color: var(--text-secondary);
}

/* ---- SETTINGS PANEL ---- */
.settings-panel {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-xl);
    padding: 28px;
    margin-bottom: 24px;
    box-shadow: var(--shadow-card);
}

.panel-title {
    font-family: 'Outfit', sans-serif;
    font-size: 1.15rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 24px;
    padding-bottom: 16px;
    border-bottom: 1px solid var(--border);
}

.settings-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
    gap: 24px;
    margin-bottom: 28px;
}

.setting-group {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

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

.setting-label {
    font-size: 0.88rem;
    font-weight: 600;
    color: var(--text-secondary);
    display: flex;
    align-items: center;
    justify-content: space-between;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.setting-value {
    color: var(--accent-hover);
    font-weight: 700;
    font-size: 0.9rem;
    text-transform: none;
    letter-spacing: 0;
}

/* Mode Buttons */
.mode-btns {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}

.mode-btn {
    background: var(--bg-elevated);
    border: 1.5px solid var(--border);
    color: var(--text-secondary);
    padding: 10px 18px;
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--trans);
    white-space: nowrap;
}

.mode-btn:hover {
    border-color: var(--accent);
    color: var(--text-primary);
    background: var(--bg-panel);
}

.mode-btn.active {
    background: linear-gradient(135deg, rgba(99, 102, 241, 0.2), rgba(139, 92, 246, 0.15));
    border-color: var(--accent);
    color: var(--accent-hover);
    box-shadow: 0 0 12px rgba(99, 102, 241, 0.2);
}

/* Range Slider */
.range-slider {
    -webkit-appearance: none;
    appearance: none;
    width: 100%;
    height: 6px;
    border-radius: 99px;
    background: var(--bg-elevated);
    outline: none;
    cursor: pointer;
    accent-color: var(--accent);
}

.range-slider::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 18px;
    height: 18px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--accent), #8b5cf6);
    cursor: pointer;
    box-shadow: 0 0 6px rgba(99, 102, 241, 0.5);
    transition: var(--trans);
}

.range-slider::-webkit-slider-thumb:hover {
    transform: scale(1.2);
}

.range-slider::-moz-range-thumb {
    width: 18px;
    height: 18px;
    border: none;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--accent), #8b5cf6);
    cursor: pointer;
}

/* Select */
.select-input {
    background: var(--bg-input);
    color: var(--text-primary);
    border: 1.5px solid var(--border);
    border-radius: var(--radius-sm);
    padding: 10px 14px;
    font-size: 0.9rem;
    width: 100%;
    cursor: pointer;
    transition: var(--trans);
    outline: none;
}

.select-input:focus {
    border-color: var(--border-focus);
    box-shadow: 0 0 0 3px var(--accent-glow);
}

/* Text input */
.text-input {
    background: var(--bg-input);
    color: var(--text-primary);
    border: 1.5px solid var(--border);
    border-radius: var(--radius-sm);
    padding: 10px 14px;
    font-size: 0.9rem;
    width: 100%;
    outline: none;
    transition: var(--trans);
}

.text-input:focus {
    border-color: var(--border-focus);
    box-shadow: 0 0 0 3px var(--accent-glow);
}

.text-input.hidden {
    display: none;
}

/* Page Range radio */
.page-range-row {
    display: flex;
    gap: 20px;
    flex-wrap: wrap;
}

.radio-label {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 0.9rem;
    color: var(--text-secondary);
    cursor: pointer;
}

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

/* ---- ACTION ROW ---- */
.action-row {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
    justify-content: flex-end;
}

.btn-primary {
    background: linear-gradient(135deg, var(--accent), #8b5cf6);
    color: #fff;
    border: none;
    padding: 13px 30px;
    border-radius: var(--radius-md);
    font-size: 0.98rem;
    font-weight: 700;
    cursor: pointer;
    transition: var(--trans);
    box-shadow: 0 4px 14px rgba(99, 102, 241, 0.35);
    white-space: nowrap;
}

.btn-primary:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: 0 8px 22px rgba(99, 102, 241, 0.45);
}

.btn-primary:disabled {
    opacity: 0.45;
    cursor: not-allowed;
}

.btn-secondary {
    background: var(--bg-elevated);
    color: var(--text-primary);
    border: 1.5px solid var(--border);
    padding: 13px 30px;
    border-radius: var(--radius-md);
    font-size: 0.98rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--trans);
    white-space: nowrap;
}

.btn-secondary:hover {
    border-color: var(--accent);
    color: var(--accent-hover);
    background: var(--bg-panel);
}

.btn-ghost {
    background: transparent;
    color: var(--text-secondary);
    border: 1px solid var(--border);
    padding: 8px 16px;
    border-radius: var(--radius-sm);
    font-size: 0.85rem;
    cursor: pointer;
    transition: var(--trans);
}

.btn-ghost:hover {
    color: var(--text-primary);
    border-color: var(--text-dim);
}

.btn-ghost.small {
    padding: 5px 12px;
    font-size: 0.82rem;
}

/* ---- PREVIEW SECTION ---- */
.preview-section {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-xl);
    padding: 24px;
    margin-bottom: 24px;
    box-shadow: var(--shadow-card);
}

.preview-section.hidden {
    display: none;
}

.preview-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 12px;
    margin-bottom: 20px;
}

.preview-header .panel-title {
    margin-bottom: 0;
    padding-bottom: 0;
    border-bottom: none;
}

.preview-meta {
    display: flex;
    align-items: center;
    gap: 10px;
}

.preview-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
    gap: 14px;
    max-height: 600px;
    overflow-y: auto;
    padding-right: 4px;
}

/* Scrollbar */
.preview-grid::-webkit-scrollbar {
    width: 6px;
}

.preview-grid::-webkit-scrollbar-track {
    background: var(--bg-base);
    border-radius: 99px;
}

.preview-grid::-webkit-scrollbar-thumb {
    background: var(--bg-elevated);
    border-radius: 99px;
}

.preview-grid::-webkit-scrollbar-thumb:hover {
    background: var(--text-dim);
}

.preview-page-card {
    background: var(--bg-elevated);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    overflow: hidden;
    transition: var(--trans);
    display: flex;
    flex-direction: column;
}

.preview-page-card:hover {
    border-color: var(--accent);
    box-shadow: 0 0 14px rgba(99, 102, 241, 0.2);
    transform: translateY(-2px);
}

.preview-page-card canvas {
    width: 100%;
    display: block;
}

.preview-page-label {
    text-align: center;
    padding: 6px 8px;
    font-size: 0.78rem;
    color: var(--text-dim);
    border-top: 1px solid var(--border);
}

.preview-footer {
    display: flex;
    justify-content: center;
    padding-top: 20px;
    border-top: 1px solid var(--border);
    margin-top: 16px;
}

/* ---- SUCCESS CARD ---- */
.success-card {
    background: var(--bg-card);
    border: 1px solid rgba(16, 185, 129, 0.25);
    border-radius: var(--radius-xl);
    padding: 64px 32px;
    text-align: center;
    box-shadow: var(--shadow-card), 0 0 30px rgba(16, 185, 129, 0.05);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 16px;
}

@keyframes pop {
    0% {
        transform: scale(0.5);
        opacity: 0;
    }

    70% {
        transform: scale(1.15);
    }

    100% {
        transform: scale(1);
        opacity: 1;
    }
}

.success-icon {
    font-size: 3.5rem;
    animation: pop 0.5s ease forwards;
}

.success-title {
    font-family: 'Outfit', sans-serif;
    font-size: 1.8rem;
    font-weight: 800;
    color: var(--text-primary);
}

.success-sub {
    color: var(--text-secondary);
}

.success-actions {
    display: flex;
    gap: 12px;
    flex-wrap: wrap;
    justify-content: center;
    margin-top: 8px;
}

/* ---- TOAST ---- */
.toast {
    position: fixed;
    bottom: 28px;
    left: 50%;
    transform: translateX(-50%) translateY(80px);
    background: var(--bg-elevated);
    color: var(--text-primary);
    border: 1px solid var(--border);
    padding: 12px 28px;
    border-radius: 99px;
    font-size: 0.92rem;
    font-weight: 500;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.4);
    opacity: 0;
    transition: all 0.35s cubic-bezier(0.34, 1.56, 0.64, 1);
    z-index: 9999;
    pointer-events: none;
    white-space: nowrap;
}

.toast.show {
    opacity: 1;
    transform: translateX(-50%) translateY(0);
}

/* ---- SEO SECTION ---- */
.seo-section {
    margin-top: 56px;
    border-top: 1px solid var(--border);
    padding-top: 48px;
}

.seo-inner {
    display: flex;
    flex-direction: column;
    gap: 36px;
}

.seo-article {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-xl);
    padding: 28px 32px;
}

.seo-article h2 {
    font-family: 'Outfit', sans-serif;
    font-size: clamp(1.1rem, 3vw, 1.35rem);
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 14px;
}

.seo-article p {
    color: var(--text-secondary);
    font-size: 0.97rem;
    line-height: 1.75;
}

.seo-article strong {
    color: var(--text-primary);
}

.seo-article code {
    background: var(--bg-elevated);
    border-radius: 4px;
    padding: 1px 6px;
    font-size: 0.9em;
    color: var(--accent-hover);
}

/* Feature list */
.feature-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 16px;
    margin-top: 8px;
}

.feature-list li {
    display: flex;
    align-items: flex-start;
    gap: 14px;
}

.feature-icon {
    font-size: 1.4rem;
    flex-shrink: 0;
    margin-top: 2px;
}

.feature-list strong {
    display: block;
    margin-bottom: 3px;
    font-size: 0.97rem;
}

.feature-list p {
    font-size: 0.89rem;
    margin: 0;
    color: var(--text-dim);
}

/* Steps list */
.steps-list {
    padding-left: 24px;
    display: flex;
    flex-direction: column;
    gap: 12px;
    color: var(--text-secondary);
    font-size: 0.97rem;
    margin-top: 8px;
}

.steps-list li strong {
    color: var(--text-primary);
}

/* Plain list */
.plain-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 10px;
    font-size: 0.97rem;
    color: var(--text-secondary);
    margin-top: 8px;
}

.plain-list strong {
    color: var(--text-primary);
}

/* FAQ */
.faq-list {
    display: flex;
    flex-direction: column;
    gap: 10px;
    margin-top: 8px;
}

.faq-item {
    background: var(--bg-elevated);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    overflow: hidden;
    transition: var(--trans);
}

.faq-item[open] {
    border-color: rgba(99, 102, 241, 0.3);
}

.faq-item summary {
    padding: 16px 20px;
    font-weight: 600;
    color: var(--text-primary);
    cursor: pointer;
    font-size: 0.95rem;
    list-style: none;
    display: flex;
    align-items: center;
    justify-content: space-between;
    transition: var(--trans);
}

.faq-item summary::-webkit-details-marker {
    display: none;
}

.faq-item summary::after {
    content: '+';
    width: 22px;
    height: 22px;
    background: var(--bg-panel);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.1rem;
    color: var(--accent-hover);
    flex-shrink: 0;
    transition: var(--trans);
}

.faq-item[open] summary::after {
    content: '−';
}

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

.faq-item p {
    padding: 0 20px 16px;
    color: var(--text-secondary);
    font-size: 0.92rem;
    line-height: 1.7;
}

/* Related tools */
.related-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
    gap: 12px;
    margin-top: 12px;
}

.related-card {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    background: var(--bg-elevated);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    padding: 18px 12px;
    text-decoration: none;
    color: var(--text-secondary);
    font-size: 0.88rem;
    font-weight: 600;
    transition: var(--trans);
    text-align: center;
}

.related-card:hover {
    border-color: var(--accent);
    color: var(--text-primary);
    background: var(--bg-panel);
    transform: translateY(-3px);
    box-shadow: 0 6px 18px rgba(99, 102, 241, 0.15);
}

.r-icon {
    font-size: 1.8rem;
}

/* ---- FOOTER ---- */
.site-footer {
    text-align: center;
    margin-top: 56px;
    padding: 24px 16px;
    border-top: 1px solid var(--border);
    color: var(--text-dim);
    font-size: 0.85rem;
    display: flex;
    flex-direction: column;
    gap: 6px;
}

.footer-link {
    color: var(--accent-hover);
    text-decoration: none;
}

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

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

/* ---- RESPONSIVE ---- */
@media (max-width: 640px) {
    .app-wrapper {
        padding: 12px 10px 48px;
    }

    .main-header {
        padding: 28px 12px 20px;
    }

    .brand-area {
        gap: 10px;
    }

    .brand-icon {
        width: 42px;
        height: 42px;
    }

    .upload-card {
        padding: 40px 16px;
    }

    .upload-title {
        font-size: 1.3rem;
    }

    .settings-panel {
        padding: 20px 16px;
    }

    .settings-grid {
        grid-template-columns: 1fr;
        gap: 18px;
    }

    .mode-btns {
        flex-direction: column;
    }

    .mode-btn {
        text-align: left;
    }

    .action-row {
        flex-direction: column;
    }

    .btn-primary,
    .btn-secondary {
        width: 100%;
        text-align: center;
    }

    .file-info-bar {
        flex-direction: column;
        align-items: flex-start;
        gap: 8px;
    }

    .file-name {
        max-width: 220px;
    }

    .preview-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    .success-card {
        padding: 40px 20px;
    }

    .success-actions {
        flex-direction: column;
        width: 100%;
    }

    .seo-article {
        padding: 20px 16px;
    }

    .related-grid {
        grid-template-columns: repeat(3, 1fr);
    }

    .toast {
        bottom: 16px;
        white-space: normal;
        max-width: calc(100vw - 32px);
        text-align: center;
    }
}

@media (max-width: 360px) {
    .related-grid {
        grid-template-columns: repeat(2, 1fr);
    }

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