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

:root {
    --bg: #f9fafb;
    --surface: #ffffff;
    --surface-raised: #ffffff;
    --border: rgba(0,0,0,0.08);
    --border-strong: rgba(0,0,0,0.14);
    --text-primary: #0d1117;
    --text-secondary: #586069;
    --text-muted: #8b949e;
    --accent: #2563eb;
    --accent-hover: #1d4ed8;
    --accent-light: #eff6ff;
    --accent-light-border: #bfdbfe;
    --green: #059669;
    --green-light: #ecfdf5;
    --red: #dc2626;
    --red-light: #fef2f2;
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
    --shadow-md: 0 4px 12px rgba(0,0,0,0.08), 0 1px 3px rgba(0,0,0,0.04);
    --shadow-lg: 0 10px 32px rgba(0,0,0,0.1), 0 2px 8px rgba(0,0,0,0.04);
    --radius-sm: 6px;
    --radius: 10px;
    --radius-lg: 14px;
    --radius-xl: 20px;
}

html.dark {
    --bg: #0d1117;
    --surface: #161b22;
    --surface-raised: #1c2128;
    --border: rgba(255,255,255,0.06);
    --border-strong: rgba(255,255,255,0.12);
    --text-primary: #e6edf3;
    --text-secondary: #8b949e;
    --text-muted: #6e7681;
    --accent: #3b82f6;
    --accent-hover: #60a5fa;
    --accent-light: rgba(59,130,246,0.08);
    --accent-light-border: rgba(59,130,246,0.2);
    --green: #10b981;
    --green-light: rgba(16,185,129,0.08);
    --red: #f87171;
    --red-light: rgba(248,113,113,0.08);
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.3);
    --shadow-md: 0 4px 12px rgba(0,0,0,0.4), 0 1px 3px rgba(0,0,0,0.2);
    --shadow-lg: 0 10px 32px rgba(0,0,0,0.5), 0 2px 8px rgba(0,0,0,0.2);
}

html { scroll-behavior: smooth; }

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
    background: var(--bg);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    transition: background 0.2s, color 0.2s;
    -webkit-font-smoothing: antialiased;
    width: 100%;
    overflow-x: hidden;
}

/* ── Header ── */
header {
    position: sticky;
    top: 0;
    z-index: 100;
    background: rgba(249,250,251,0.85);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    transition: background 0.2s;
}
html.dark header { background: rgba(13,17,23,0.88); }

.header-inner {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 24px;
    height: 65px;
    padding-top: 8px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 20px;
}

.logo { display: flex; align-items: center; gap: 5px; text-decoration: none; }
.logo-mark { width: 30px; height: 34px; flex-shrink: 0; position: relative; display: flex; align-items: center; justify-content: center; }
.logo-mark::before {
    content: ""; position: absolute; inset: 0; background: var(--accent);
    clip-path: polygon(0% 0%, calc(100% - 8px) 0%, 100% 8px, 100% 100%, 0% 100%); z-index: 1;
}
.logo-mark::after {
    content: ""; position: absolute; top: 0; right: 0; width: 8px; height: 8px;
    background: rgba(255,255,255,0.4); border-bottom-left-radius: 3px;
    clip-path: polygon(0 0, 100% 100%, 0 100%); z-index: 2;
}
.logo-mark svg { display: block; z-index: 3;}
.logo-dot {
    position: absolute; bottom: -2px; right: -2px; width: 10px; height: 10px;
    background-color: #3fb950; border-radius: 50%; border: 2px solid var(--surface); z-index: 4; 
    transition: background-color 0.3s ease;
}
.logo-dot.is-offline { background-color: #f85149; }
.logo-text { line-height: 1.2; }
.logo-name { font-size: 30px; font-weight: 700; color: var(--text-primary); letter-spacing: -0.02em; }
.logo-name span { color: var(--accent); font-weight: 700; }
.logo-sub { font-size: 10px; font-weight: 600; letter-spacing: 0.1em; text-transform: uppercase; color: var(--text-muted); font-family: 'SF Mono', 'Fira Code', monospace; }

nav { display: flex; align-items: center; gap: 4px; }

.hamburger-btn { display: none; width: 34px; height: 34px; border-radius: var(--radius-sm); border: none; background: transparent; color: var(--text-primary); cursor: pointer; align-items: center; justify-content: center; transition: background 0.15s, color 0.15s; margin-left: auto; }
.hamburger-btn:hover { background: var(--border); }
.hamburger-btn svg { transition: transform 0.2s; }

.nav-scrim { display: none; position: fixed; inset: 0; background: rgba(0,0,0,0.4); z-index: 199; opacity: 0; transition: opacity 0.25s ease; }
.nav-scrim.open { opacity: 1; }

.nav-drawer { display: none; }
body.drawer-open { overflow: hidden; }

.nav-link { font-size: 13px; font-weight: 500; color: var(--text-secondary); text-decoration: none; padding: 6px 12px; border-radius: var(--radius-sm); transition: color 0.15s, background 0.15s; }
.nav-link:hover { color: var(--text-primary); background: var(--border); }

/* Dropdown */
.nav-dropdown { position: relative; }
.nav-dropdown-btn { font-size: 13px; font-weight: 600; color: var(--text-secondary); padding: 8px 14px; border-radius: var(--radius-sm); border: none; background: none; cursor: pointer; display: flex; align-items: center; gap: 6px; transition: color 0.15s, background 0.15s; }
.nav-dropdown-btn:hover { color: var(--text-primary); background: var(--border); }
.nav-dropdown-btn svg { transition: transform 0.2s; }
.nav-dropdown-btn.open svg { transform: rotate(180deg); }

.dropdown-menu {
    position: absolute; top: calc(100% + 10px); left: 50%; min-width: 460px; max-width: min(460px, 92vw);
    display: grid; grid-template-columns: 1fr 1fr; gap: 4px; background: var(--surface-raised);
    border: 1px solid var(--border-strong); border-radius: var(--radius-lg); box-shadow: var(--shadow-lg);
    padding: 10px; overflow: hidden; opacity: 0; visibility: hidden; pointer-events: none;
    transform: translate(-50%, -8px); transition: opacity 0.22s ease, transform 0.22s ease, visibility 0.22s;
    z-index: 50;
}
.dropdown-menu.open { opacity: 1; visibility: visible; pointer-events: auto; transform: translate(-50%, 0); }

.dropdown-column { display: flex; flex-direction: column; gap: 2px; }
.dropdown-column-title { font-size: 11px; font-weight: 700; letter-spacing: 0.04em; text-transform: uppercase; color: var(--text-muted); padding: 6px 10px 8px; }
.dropdown-item { display: flex; align-items: center; gap: 10px; padding: 9px 10px; text-decoration: none; font-size: 13px; font-weight: 500; color: var(--text-primary); border-radius: var(--radius-sm); transition: background 0.12s; }
.dropdown-item:hover { background: var(--bg); }
.dropdown-icon { width: 28px; height: 28px; border-radius: var(--radius-sm); background: var(--accent-light); display: flex; align-items: center; justify-content: center; font-size: 14px; flex-shrink: 0; }

.theme-btn { width: 34px; height: 34px; border-radius: var(--radius-sm); border: none; background: transparent; cursor: pointer; display: flex; align-items: center; justify-content: center; font-size: 16px; transition: background 0.15s, border-color 0.15s; }
.theme-btn:hover { background: var(--bg); }

.nav-divider { width: 1px; height: 20px; background: var(--border-strong); margin: 0 4px; }

@media (max-width: 600px) {
    .header-inner { padding: 0 12px; gap: 8px; }
    .logo-name { font-size: 20px; }
    nav { display: none; }
    .hamburger-btn { display: flex; }
    .nav-scrim { display: block; pointer-events: none; }
    .nav-scrim.open { pointer-events: auto; }
    
    .nav-drawer {
        position: fixed; top: 0; right: 0; bottom: 0; width: min(82vw, 320px); max-width: 100vw;
        box-sizing: border-box; background: var(--surface); border-left: 1px solid var(--border);
        box-shadow: var(--shadow-lg); z-index: 200; display: flex; flex-direction: column; gap: 4px;
        padding: 20px 16px; transform: translateX(100%); transition: transform 0.3s ease;
        overflow-y: auto; overflow-x: hidden;
    }
    .nav-drawer.open { transform: translateX(0); }
    
    .nav-drawer-close { align-self: flex-end; width: 32px; height: 32px; border: none; background: transparent; border-radius: 50%; cursor: pointer; display: flex; align-items: center; justify-content: center; margin-bottom: 8px; transition: background 0.15s; }
    .nav-drawer-close:hover { background: var(--border); }
    
    .nav-drawer .nav-link, .nav-drawer .theme-btn-mobile { width: 100%; justify-content: flex-start; padding: 12px 10px; border-radius: var(--radius-sm); font-size: 14px; }
    .theme-btn-mobile { display: flex; align-items: center; gap: 10px; background: none; border: none; color: var(--text-secondary); cursor: pointer; width: 100%; text-align: left; transition: background 0.15s; }
    .theme-btn-mobile:hover { background: var(--border); }
    
    .nav-drawer .nav-dropdown-btn { width: 100%; justify-content: space-between; padding: 12px 10px; }
    .nav-drawer .dropdown-menu {
        position: static; left: auto; display: none; grid-template-columns: 1fr; min-width: 0; width: 100%;
        border: none; box-shadow: none; background: var(--bg); border-radius: var(--radius);
        opacity: 1; visibility: visible; pointer-events: auto; transform: none; padding: 8px; margin-top: 4px;
    }
    .nav-drawer .dropdown-menu.open { display: grid; }
    .nav-drawer .dropdown-column + .dropdown-column { margin-top: 6px; }
}

/* ── Main Layout ── */
main { max-width: 1100px; margin: 0 auto; padding: 80px 24px 80px; }

.hero { display: grid; grid-template-columns: 1fr 1fr; gap: 80px; align-items: start; margin-bottom: 40px; }
@media (max-width: 800px) { .hero { grid-template-columns: 1fr; gap: 48px; } }

.hero-eyebrow { display: inline-flex; align-items: center; gap: 6px; background: var(--accent-light); border: 1px solid var(--accent-light-border); border-radius: 20px; padding: 4px 12px; font-size: 11.5px; font-weight: 600; color: var(--accent); letter-spacing: 0.06em; text-transform: uppercase; margin-bottom: 20px; }
.hero-eyebrow::before { content: ''; width: 6px; height: 6px; background: var(--accent); border-radius: 50%; }

.hero-title { font-size: clamp(32px, 5vw, 52px); font-weight: 800; letter-spacing: -0.035em; line-height: 1.1; color: var(--text-primary); margin-bottom: 16px; }
.hero-title em { font-style: normal; color: var(--accent); }
.hero-desc { font-size: 15.5px; color: var(--text-secondary); line-height: 1.65; max-width: 420px; }

/* ── Upload card ── */
.upload-card { background: var(--surface); border: 1px solid var(--border-strong); border-radius: var(--radius-xl); padding: 24px; box-shadow: var(--shadow-md); position: relative; }

.upload-card::before {
    content: ''; position: absolute; inset: -1px; border-radius: calc(var(--radius-xl) + 1px);
    background: linear-gradient(135deg, rgba(37,99,235,0.15) 0%, transparent 50%);
    pointer-events: none; opacity: 0; transition: opacity 0.3s;
}
.upload-card.drag-active::before { opacity: 1; }

.drop-zone { border: 1.5px dashed var(--border-strong); border-radius: var(--radius-lg); padding: 30px 20px; display: flex; flex-direction: column; align-items: center; text-align: center; transition: border-color 0.2s, background 0.2s; cursor: pointer; }
.drop-zone:hover, .upload-card.drag-active .drop-zone { border-color: var(--accent); background: var(--accent-light); }

.drop-icon { width: 44px; height: 56px; margin-bottom: 14px; position: relative; }
.drop-icon-file { width: 44px; height: 56px; background: var(--surface-raised); border: 1.5px solid var(--border-strong); border-radius: var(--radius-sm); position: relative; display: flex; align-items: flex-end; padding: 5px; box-shadow: var(--shadow-sm); }
.drop-icon-file::after { content: ''; position: absolute; top: 0; right: 0; width: 14px; height: 14px; background: var(--bg); border-left: 1.5px solid var(--border-strong); border-bottom: 1.5px solid var(--border-strong); border-radius: 0 var(--radius-sm) 0 var(--radius-sm); }
.pdf-badge { background: #ef4444; color: white; font-size: 9px; font-weight: 800; letter-spacing: 0.08em; padding: 2px 5px; border-radius: 3px; width: 100%; text-align: center; font-family: 'SF Mono', monospace; }

.drop-title { font-size: 14px; font-weight: 600; color: var(--text-primary); margin-bottom: 4px; }
.drop-sub { font-size: 12.5px; color: var(--text-muted); margin-bottom: 16px; }

.btn-upload { display: inline-flex; align-items: center; gap: 6px; background: var(--accent); color: white; font-size: 12.5px; font-weight: 600; padding: 9px 18px; border-radius: var(--radius-sm); border: none; cursor: pointer; letter-spacing: 0.02em; transition: background 0.15s; }
.btn-upload:hover { background: var(--accent-hover); }

.file-list { margin-top: 16px; display: flex; flex-direction: column; gap: 8px; }
.file-item { display: flex; align-items: center; gap: 10px; padding: 9px 12px; background: var(--bg); border: 1px solid var(--border); border-radius: var(--radius-sm); font-size: 12.5px; }
.file-item-icon { width: 26px; height: 26px; background: rgba(239,68,68,0.1); border-radius: 5px; display: flex; align-items: center; justify-content: center; flex-shrink: 0; }
.file-item-name { flex: 1; font-weight: 500; color: var(--text-primary); white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.file-item-size { font-size: 11px; color: var(--text-muted); font-family: 'SF Mono', monospace; flex-shrink: 0; }
.file-item-remove { width: 22px; height: 22px; border-radius: 4px; border: 1px solid var(--border); background: transparent; color: var(--text-muted); font-size: 11px; cursor: pointer; display: flex; align-items: center; justify-content: center; flex-shrink: 0; transition: background 0.12s, color 0.12s; }
.file-item-remove:hover { background: var(--red-light); color: var(--red); border-color: rgba(220,38,38,0.2); }

/* Status */
.status-bar { border-radius: var(--radius-sm); padding: 10px 14px; font-size: 12.5px; font-weight: 500; margin-bottom: 14px; display: none; }
.status-bar.info { background: var(--accent-light); color: var(--accent); border: 1px solid var(--accent-light-border); display: block; }
.status-bar.success { background: var(--green-light); color: var(--green); border: 1px solid rgba(5,150,105,0.2); display: block; }
.status-bar.error { background: var(--red-light); color: var(--red); border: 1px solid rgba(220,38,38,0.15); display: block; }

/* ── Toolbar ── */
.toolbar { display: flex; flex-wrap: wrap; align-items: center; gap: 10px; margin-bottom: 18px; }
.btn { display: inline-flex; align-items: center; gap: 6px; font-size: 12.5px; font-weight: 600; padding: 9px 15px; border-radius: var(--radius-sm); border: 1px solid var(--border-strong); background: var(--surface); color: var(--text-primary); cursor: pointer; transition: background 0.15s, color 0.15s, border-color 0.15s, opacity 0.15s; }
.btn:hover { background: var(--bg); }
.btn:disabled { opacity: 0.45; cursor: not-allowed; }
.btn-primary { background: var(--accent); color: white; border-color: var(--accent); }
.btn-primary:hover { background: var(--accent-hover); }
.btn-danger-outline { color: var(--red); border-color: rgba(220,38,38,0.3); }
.btn-danger-outline:hover { background: var(--red-light); }
.toolbar-spacer { flex: 1; }
.page-count-pill { font-size: 12px; font-weight: 600; color: var(--text-secondary); background: var(--bg); border: 1px solid var(--border); padding: 6px 12px; border-radius: 20px; }

/* ── Board ── */
.board-wrap { background: var(--surface); border: 1px solid var(--border-strong); border-radius: var(--radius-xl); padding: 20px; box-shadow: var(--shadow-md); margin-bottom: 24px; }
.board { max-height: 500px; overflow-y: auto; display: grid; grid-template-columns: repeat(auto-fill, minmax(110px, 1fr)); gap: 14px; padding: 4px; }
.board::-webkit-scrollbar { width: 8px; }
.board::-webkit-scrollbar-track { background: transparent; }
.board::-webkit-scrollbar-thumb { background: var(--border-strong); border-radius: 10px; }

.board-empty-msg { grid-column: 1 / -1; text-align: center; padding: 40px 10px; color: var(--text-muted); font-size: 13px; }

.slot { aspect-ratio: 3 / 4; border-radius: var(--radius-sm); border: 1.5px solid var(--border-strong); background: var(--bg); position: relative; display: flex; flex-direction: column; cursor: grab; user-select: none; transition: transform 0.12s, border-color 0.12s, box-shadow 0.12s; overflow: hidden; }
.slot:active { cursor: grabbing; }
.slot.drag-over { border-color: var(--accent); transform: scale(1.04); box-shadow: var(--shadow-lg); }
.slot.dragging { opacity: 0.4; }

.slot-index { position: absolute; top: 4px; left: 5px; font-size: 9px; font-weight: 700; color: var(--text-muted); font-family: 'SF Mono', monospace; z-index: 2; }
.slot-checkbox { position: absolute; top: 4px; right: 4px; z-index: 2; width: 15px; height: 15px; cursor: pointer; }

.slot.empty { align-items: center; justify-content: center; border-style: dashed; }
.slot-empty-label { font-size: 10.5px; font-weight: 600; color: var(--text-muted); letter-spacing: 0.04em; text-transform: uppercase; }

.slot.filled { justify-content: center; align-items: center; padding-top: 14px; }
.slot-page-icon { width: 34px; height: 44px; background: var(--surface); border: 1.5px solid var(--border-strong); border-radius: 3px; display: flex; align-items: center; justify-content: center; margin-bottom: 6px; box-shadow: var(--shadow-sm); }
.slot-page-icon span { font-size: 13px; font-weight: 800; color: var(--accent); }
.slot-file-name { font-size: 9px; color: var(--text-secondary); max-width: 90%; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; text-align: center; padding: 0 4px; }
.slot-delete { position: absolute; bottom: 4px; right: 4px; z-index: 2; width: 20px; height: 20px; border-radius: 4px; border: 1px solid var(--border-strong); background: var(--surface); color: var(--red); display: flex; align-items: center; justify-content: center; cursor: pointer; transition: background 0.12s; }
.slot-delete:hover { background: var(--red-light); }

@media (max-width: 500px) {
    .board { grid-template-columns: repeat(auto-fill, minmax(84px, 1fr)); gap: 10px; }
    .slot-page-icon { width: 26px; height: 34px; }
    .slot-file-name { font-size: 8px; }
}

/* ── Footer ── */
footer { border-top: 1px solid var(--border); background: var(--surface); padding: 28px 24px; margin-top: 80px; }
.footer-inner { max-width: 1100px; margin: 0 auto; display: flex; align-items: center; justify-content: space-between; gap: 20px; flex-wrap: wrap; }
.footer-copy { font-size: 12.5px; color: var(--text-muted); }
.footer-links { display: flex; align-items: center; gap: 20px; }
.footer-link { font-size: 12.5px; font-weight: 500; color: var(--text-muted); text-decoration: none; transition: color 0.15s; }
.footer-link:hover { color: var(--text-primary); }

/* Language Control */
.lang-box { position: relative; display: inline-block; }
.lang-trigger { font-size: 12px; font-weight: 500; color: var(--text-muted); background: none; border: 1px solid var(--border-strong); padding: 5px 10px; border-radius: var(--radius-sm); cursor: pointer; display: flex; align-items: center; gap: 4px; }
.lang-trigger:hover { color: var(--text-primary); background: var(--bg); }
.lang-popover { position: absolute; bottom: calc(100% + 6px); right: 0; min-width: 130px; background: var(--surface-raised); border: 1px solid var(--border-strong); border-radius: var(--radius-sm); box-shadow: var(--shadow-lg); overflow: hidden; opacity: 0; visibility: hidden; transform: translateY(4px); transition: all 0.15s; z-index: 150; }
.lang-popover.open { opacity: 1; visibility: visible; transform: translateY(0); }
.lang-option { width: 100%; background: none; border: none; display: flex; align-items: center; justify-content: space-between; padding: 8px 12px; font-size: 12.5px; color: var(--text-primary); cursor: pointer; text-align: left; }
.lang-option:hover { background: var(--bg); }
.lang-option.selected { color: var(--accent); font-weight: 600; }

input[type="file"] { display: none; }