:root {
    --bg: #f7f7f8;
    --bg-white: #ffffff;
    --text: #1a1a1a;
    --text-secondary: #666666;
    --text-muted: #999999;
    --primary: #2563eb;
    --primary-hover: #1d4ed8;
    --primary-light: rgba(37, 99, 235, 0.1);
    --border: #e5e5e5;
    --font: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    --radius: 8px;
    --radius-lg: 12px;
    --shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
    --container: 1100px;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
body {
    font-family: var(--font);
    font-size: 15px;
    line-height: 1.5;
    color: var(--text);
    background: var(--bg);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

a { color: inherit; text-decoration: none; }
button { font: inherit; border: none; background: none; cursor: pointer; }
input { font: inherit; }
svg { display: block; }
.container { width: 100%; max-width: var(--container); margin: 0 auto; padding: 0 20px; }

.header { background: var(--bg-white); border-bottom: 1px solid var(--border); padding: 14px 0; }
.header__inner { display: flex; align-items: center; justify-content: space-between; }
.back-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    background: #f5f5f5;
    border-radius: 10px;
    color: #333;
    margin-right: 12px;
    transition: all 0.2s;
}
.back-btn:hover { background: #333; color: #fff; }
.back-btn svg { width: 20px; height: 20px; }
.logo { display: flex; align-items: center; gap: 10px; font-size: 20px; font-weight: 700; }
.logo__icon { width: 28px; height: 28px; }
.nav { display: flex; gap: 4px; }
.nav__link {
    padding: 10px 16px;
    font-size: 14px;
    font-weight: 500;
    color: var(--text-secondary);
    border-radius: 6px;
}
.nav__link:hover { color: var(--text); background: var(--bg); }

.page { display: none; flex: 1; }
.page.active { display: flex; align-items: center; justify-content: center; }

.upload-box { text-align: center; padding: 60px 20px; max-width: 760px; margin: 0 auto; }
.upload-title { font-size: 40px; font-weight: 700; margin-bottom: 14px; }
.upload-desc { font-size: 18px; color: var(--text-secondary); margin-bottom: 30px; }

.dropzone {
    border: 2px dashed #cbd5e1;
    border-radius: var(--radius-lg);
    padding: 38px 20px;
    background: #fff;
    transition: all 0.2s;
}
.dropzone--active { border-color: var(--primary); background: #eff6ff; }
.upload-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 18px 48px;
    font-size: 18px;
    font-weight: 600;
    color: #fff;
    background: var(--primary);
    border-radius: var(--radius-lg);
    cursor: pointer;
    box-shadow: var(--shadow);
}
.upload-btn:hover { background: var(--primary-hover); }
.upload-hint { margin-top: 12px; font-size: 14px; color: var(--text-muted); }
.privacy-badge {
    margin-top: 16px;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    color: #2563eb;
    font-size: 13px;
    font-weight: 500;
}
.privacy-badge svg { width: 15px; height: 15px; }

#page-editor.active { display: flex; align-items: stretch; }
.editor { display: flex; width: 100%; min-height: calc(100vh - 120px); }
.editor__preview { flex: 1; padding: 24px; overflow: hidden; display: flex; flex-direction: column; }
.editor__header { display: flex; align-items: center; justify-content: space-between; margin-bottom: 18px; gap: 14px; }
.editor__stats { font-size: 13px; color: var(--text-muted); }
.add-btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 10px 16px;
    font-size: 14px;
    font-weight: 500;
    background: #fff;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    cursor: pointer;
}

.pages-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
    gap: 12px;
    overflow-y: auto;
    align-content: flex-start;
}

.page-card {
    background: #fff;
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 8px;
    cursor: pointer;
    transition: all 0.2s;
}
.page-card img {
    width: 100%;
    aspect-ratio: 1 / 1.35;
    object-fit: cover;
    border-radius: 6px;
    background: #f8fafc;
}
.page-card__num {
    margin-top: 8px;
    text-align: center;
    font-size: 12px;
    color: var(--text-secondary);
}
.page-card.selected {
    border-color: var(--primary);
    box-shadow: 0 0 0 2px var(--primary-light);
}

.editor__panel {
    width: 360px;
    padding: 32px;
    background: #fff;
    border-left: 1px solid var(--border);
    display: flex;
    flex-direction: column;
    gap: 16px;
}
.panel-title { font-size: 18px; font-weight: 600; text-align: center; }
.setting-group {
    background: #f8fafc;
    border: 1px solid #e2e8f0;
    border-radius: 10px;
    padding: 14px;
}
.setting-label {
    display: block;
    font-size: 13px;
    font-weight: 600;
    color: var(--text-secondary);
    margin-bottom: 10px;
}
.mode-list { display: grid; gap: 8px; }
.mode-list label { display: flex; align-items: center; gap: 8px; font-size: 13px; color: var(--text-secondary); }
.mode-list input { accent-color: var(--primary); }
.range-input {
    width: 100%;
    border: 1px solid var(--border);
    border-radius: 8px;
    padding: 10px;
    font-size: 14px;
    background: #fff;
}
.hint {
    margin-top: 8px;
    font-size: 12px;
    color: var(--text-muted);
}

.split-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    width: 100%;
    margin-top: auto;
    padding: 16px;
    font-size: 16px;
    font-weight: 600;
    color: #fff;
    background: var(--primary);
    border-radius: var(--radius-lg);
}
.split-btn:hover:not(:disabled) { background: var(--primary-hover); }
.split-btn:disabled { opacity: 0.5; cursor: not-allowed; }
.split-btn svg { width: 20px; height: 20px; }

#page-download.active { display: flex; }
.download-box {
    text-align: center;
    padding: 40px 20px;
    max-width: 580px;
    margin: 0 auto;
    width: 100%;
}
.success-icon { width: 80px; height: 80px; margin: 0 auto 24px; color: #2563eb; }
.download-title { font-size: 28px; font-weight: 700; margin-bottom: 8px; }
.download-info { font-size: 16px; color: var(--text-secondary); margin-bottom: 24px; }

.pdf-preview {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 16px;
    padding: 20px;
    background: var(--bg);
    border-radius: var(--radius-lg);
    margin-bottom: 24px;
}
.pdf-icon { width: 48px; height: 48px; color: var(--primary); flex-shrink: 0; }
.pdf-name { font-size: 15px; font-weight: 600; }
.pdf-size { font-size: 13px; color: var(--text-muted); margin-left: auto; }

.download-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 10px;
    padding: 18px 40px;
    font-size: 16px;
    font-weight: 600;
    color: #fff;
    background: #2563eb;
    border-radius: var(--radius-lg);
    margin-bottom: 20px;
}
.download-btn:hover { background: #1d4ed8; }
.download-btn svg { width: 22px; height: 22px; }

.more-actions { display: flex; align-items: center; justify-content: center; gap: 16px; }
.link-btn { font-size: 14px; font-weight: 500; color: var(--primary); }
.link-btn:hover { text-decoration: underline; }
.divider { color: var(--text-muted); }

.processing {
    position: fixed;
    inset: 0;
    z-index: 200;
    display: flex;
    align-items: center;
    justify-content: center;
    background: rgba(255, 255, 255, 0.95);
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s;
}
.processing.active { opacity: 1; visibility: visible; }
.processing__modal { text-align: center; max-width: 420px; padding: 0 20px; }
.spinner {
    width: 48px;
    height: 48px;
    margin: 0 auto 20px;
    border: 3px solid var(--border);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }
.processing__modal p { font-size: 16px; color: var(--text-secondary); margin-bottom: 16px; }
.progress { width: 100%; height: 4px; background: var(--border); border-radius: 2px; overflow: hidden; }
.progress__bar { height: 100%; width: 0; background: var(--primary); transition: width 0.2s; }

.footer {
    padding: 20px;
    text-align: center;
    font-size: 13px;
    color: var(--text-muted);
    border-top: 1px solid var(--border);
    background: var(--bg-white);
    margin-top: auto;
}

@media (max-width: 960px) {
    .editor { flex-direction: column; }
    .editor__panel { width: 100%; border-left: none; border-top: 1px solid var(--border); }
}
@media (max-width: 680px) {
    .upload-title { font-size: 30px; }
    .upload-desc { font-size: 16px; }
    .nav { display: none; }
    .pdf-preview { flex-direction: column; text-align: center; }
    .pdf-size { margin-left: 0; }
    .more-actions { flex-wrap: wrap; }
    .pages-grid { grid-template-columns: repeat(auto-fill, minmax(120px, 1fr)); }
}