:root{
    --paper:#fff;
    --ink:#000;
    --hair:rgba(0,0,0,.08);
    --hair2:rgba(0,0,0,.14);

    --mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono","Courier New", monospace;

    --border:2px solid var(--ink);
    --border-1:1px solid var(--ink);

    --pad:18px;
    --gap:16px;
    --max:1450px;
}

*{box-sizing:border-box}
html,body{height:100%}
body{
    margin:0;
    background:var(--paper);
    color:var(--ink);
    font-family:var(--mono);
    letter-spacing:.1px;
    overflow-x:hidden;
}
::selection{background:#000; color:#fff}
a{color:inherit; text-decoration:none}
a:focus-visible, button:focus-visible{
    outline:2px solid #000;
    outline-offset:2px;
}

/* background canvas */
.bg{
    position:fixed;
    inset:0;
    z-index:0;
    pointer-events:none;
}
body::before{
    content:"";
    position:fixed;
    inset:0;
    z-index:1;
    pointer-events:none;
    background:
            linear-gradient(to right, rgba(0,0,0,.04) 1px, transparent 1px),
            linear-gradient(to bottom, rgba(0,0,0,.03) 1px, transparent 1px);
    background-size: 120px 120px;
    opacity:.10;
    mix-blend-mode:multiply;
}

/* top nav */
.top-nav{
    position:fixed;
    left:0; top:0;
    width:100%;
    z-index:70;
    background:rgba(255,255,255,.90);
    border-bottom:1px solid var(--hair2);
    backdrop-filter: blur(3px);
}
.top-nav .row{
    max-width:var(--max);
    margin:0 auto;
    padding:10px var(--pad);
    display:flex;
    gap:10px;
    align-items:center;
}
.spacer{flex:1}

/* buttons */
.btn, .nav-btn{
    display:inline-flex;
    align-items:center;
    justify-content:center;
    padding:10px 14px;
    border:var(--border);
    background:rgba(255,255,255,.75);
    cursor:pointer;
    text-transform:uppercase;
    letter-spacing:.7px;
    font-size:12px;
    line-height:1;
    transition: transform .12s ease, background .12s ease;
    user-select:none;
}
.btn:hover{background:#fff; transform: translateY(-1px)}
.btn:active{transform: translateY(0)}
.btn.ghost{background:transparent}
button.btn{font-family:var(--mono); color:inherit}

/* pills */
.pill{
    display:inline-flex;
    align-items:center;
    padding:6px 10px;
    border:var(--border-1);
    border-radius:999px;
    font-size:11px;
    text-transform:uppercase;
    letter-spacing:1px;
    background:rgba(255,255,255,.65);
}
.pill.dim{
    border-color:rgba(0,0,0,.35);
    color:rgba(0,0,0,.65);
}

/* layout */
.page{
    position:relative;
    z-index:10;
    padding: calc(56px + var(--pad)) var(--pad) var(--pad);
}
.wrap{
    max-width:var(--max);
    margin:0 auto;
    display:grid;
    grid-template-columns: 1.65fr 1fr;
    gap: var(--gap);
}
@media (max-width: 1100px){
    .wrap{grid-template-columns:1fr}
}

/* panels */
.panel{
    border:var(--border);
    background:rgba(255,255,255,.92);
}
.panel-title{
    display:flex;
    gap:10px;
    align-items:center;
    padding:12px 14px;
    border-bottom:1px solid var(--hair2);
    text-transform:uppercase;
    letter-spacing:1px;
    font-size:12px;
}
.panel-title .title{font-weight:800}
.panel-body{padding:14px}

.hr{height:0; border-top:1px solid var(--hair2); margin:14px 0}
.hr.faint{border-top:1px solid var(--hair)}

.muted{color:rgba(0,0,0,.68)}
.strong{font-weight:800}
.micro{font-size:11px; letter-spacing:.2px; margin-top:10px}

.kicker{
    text-transform:uppercase;
    letter-spacing:1px;
    font-size:11px;
    color:rgba(0,0,0,.68);
}
.headline{margin:10px 0 6px; font-size:26px; line-height:1.15}
.subhead{margin:0; font-size:13px; line-height:1.65; color:rgba(0,0,0,.78)}
p{margin:0 0 10px; font-size:12.8px; line-height:1.78}

.mono{
    border-left:2px solid rgba(0,0,0,.45);
    padding:10px 12px;
    background:rgba(0,0,0,.03);
    line-height:1.85;
}
.mono.small{font-size:12px}

.metaRow{
    display:grid;
    grid-template-columns: 1.3fr 1fr;
    gap: var(--gap);
}
@media (max-width: 900px){
    .metaRow{grid-template-columns:1fr}
}
.console{
    border:1px solid rgba(0,0,0,.18);
    background:rgba(255,255,255,.78);
    padding:12px;
    display:grid;
    gap:10px;
}
.kv{
    border:1px solid rgba(0,0,0,.18);
    padding:10px;
    background:rgba(255,255,255,.86);
}
.kv .k{
    font-weight:800;
    letter-spacing:1px;
    text-transform:uppercase;
    font-size:11px;
}
.kv .v{
    margin-top:6px;
    font-size:11.5px;
    letter-spacing:.8px;
    text-transform:uppercase;
    color:rgba(0,0,0,.72);
}

/* BOOK */
.bookShell{
    display:flex;
    justify-content:center;
    padding: 6px 0 14px;
}
.book{
    width:min(980px, 100%);
    height: min(520px, 62vh);
    position:relative;
    perspective: 1400px;
    border:2px solid #000;
    background:rgba(255,255,255,.84);
    overflow:hidden;
}

/* spine */
.book::before{
    content:"";
    position:absolute;
    left:50%;
    top:0;
    width:2px;
    height:100%;
    background:#000;
    opacity:.35;
    z-index:2;
}
.book::after{
    content:"";
    position:absolute;
    left:calc(50% - 14px);
    top:0;
    width:28px;
    height:100%;
    background:linear-gradient(to right, rgba(0,0,0,.05), rgba(0,0,0,.00), rgba(0,0,0,.05));
    z-index:1;
    opacity:.7;
}

.paper{
    position:absolute;
    top:0;
    width:50%;
    height:100%;
    padding:14px;
    display:grid;
    grid-template-rows: auto 1fr auto;
    gap:10px;
    z-index:3;
}
.paper.left{left:0}
.paper.right{right:0}

.paperHead{
    display:flex;
    gap:10px;
    align-items:center;
    justify-content:space-between;
}
.paperTitle{
    font-weight:900;
    text-transform:uppercase;
    letter-spacing:1px;
    font-size:13px;
}
.paperBody{
    border:1px solid rgba(0,0,0,.18);
    background:rgba(255,255,255,.92);
    padding:12px;
    overflow:auto;
}
.paperFoot{
    display:flex;
    align-items:center;
    justify-content:space-between;
    gap:10px;
}

.code{
    display:inline-flex;
    padding:6px 10px;
    border:1px solid rgba(0,0,0,.25);
    background:rgba(0,0,0,.03);
    letter-spacing:1px;
    text-transform:uppercase;
    font-size:11px;
}
.pageNo{
    font-weight:900;
    letter-spacing:1px;
    text-transform:uppercase;
    font-size:12px;
    opacity:.8;
}

/* FLIP layer */
.flipLayer{
    position:absolute;
    inset:0;
    z-index:9;
    pointer-events:auto;
}
.flipSheet{
    position:absolute;
    top:0;
    height:100%;
    width:50%;
    transform-style:preserve-3d;
    transform-origin: left center;
    left:50%;
    will-change:transform;
    display:none; /* shown during flip */
}
.flipSheet.flipFromLeft{
    left:0;
    transform-origin: right center;
}
.flipFront, .flipBack{
    position:absolute;
    inset:0;
    backface-visibility:hidden;
    background:rgba(255,255,255,.92);
    border-left:1px solid rgba(0,0,0,.12);
    border-right:1px solid rgba(0,0,0,.12);
    padding:14px;
    display:grid;
    grid-template-rows: auto 1fr auto;
    gap:10px;
}
.flipBack{
    transform: rotateY(180deg);
}

/* corners */
.corner{
    position:absolute;
    top:0;
    width:20%;
    height:100%;
    background:transparent;
    border:0;
    cursor:pointer;
}
.corner.c-left{left:0}
.corner.c-right{right:0}

/* hint corners */
.book .paper.left::after,
.book .paper.right::after{
    content:"";
    position:absolute;
    bottom:10px;
    width:16px;
    height:16px;
    border:2px solid rgba(0,0,0,.25);
    opacity:.35;
}
.book .paper.left::after{
    right:12px;
    border-left:0; border-top:0;
    transform: rotate(0deg);
}
.book .paper.right::after{
    left:12px;
    border-right:0; border-top:0;
    transform: rotate(0deg);
}

/* index */
.indexList{
    display:grid;
    gap:10px;
}
.indexItem{
    border:2px solid #000;
    background:rgba(255,255,255,.9);
    padding:10px;
    display:grid;
    gap:6px;
    cursor:pointer;
    transition: transform .12s ease, background .12s ease;
}
.indexItem:hover{transform: translateY(-1px); background:#fff}
.indexTop{
    display:flex;
    gap:10px;
    align-items:center;
    justify-content:space-between;
}
.indexDate{
    font-weight:900;
    letter-spacing:1px;
    text-transform:uppercase;
    font-size:11.5px;
}
.indexSig{
    color:rgba(0,0,0,.72);
    font-size:11.5px;
    text-transform:uppercase;
    letter-spacing:.8px;
}
.indexDesc{
    color:rgba(0,0,0,.65);
    font-size:12px;
    line-height:1.7;
}

/* side */
.side{display:grid; gap: var(--gap)}

/* actions */
.actions{
    display:flex;
    gap:10px;
    flex-wrap:wrap;
    margin-top:10px;
}

/* toast */
.toast{
    position:fixed;
    left:50%;
    bottom:18px;
    transform:translateX(-50%);
    z-index:110;
    border:2px solid #000;
    background:rgba(255,255,255,.92);
    padding:10px 12px;
    font-size:11px;
    letter-spacing:1px;
    text-transform:uppercase;
    opacity:0;
    pointer-events:none;
    transition: opacity .15s ease, transform .15s ease;
    max-width:min(980px, calc(100vw - 28px));
}
.toast.show{
    opacity:1;
    transform:translateX(-50%) translateY(-2px);
}

@media (prefers-reduced-motion: reduce){
    .btn,.indexItem{transition:none !important}
    .book{perspective:none}
}