:root {
    --sand: #f7f3ed;
    --sand-dark: #ede8e0;
    --sand-mid: #e2dbd0;
    --ink: #1c1917;
    --ink-mid: #44403c;
    --ink-light: #78716c;
    --ink-faint: #a8a29e;
    --orange: #c2410c;
    --orange-bg: #fff7ed;
    --orange-bdr: #fed7aa;
    --green: #15803d;
    --green-bg: #f0fdf4;
    --green-bdr: #bbf7d0;
    --blue: #1d4ed8;
    --blue-bg: #eff6ff;
    --blue-bdr: #bfdbfe;
    --yellow: #92400e;
    --yellow-bg: #fffbeb;
    --yellow-bdr: #fde68a;
    --red: #991b1b;
    --red-bg: #fef2f2;
    --red-bdr: #fecaca;
    --border: #d6d3ce;
    --white: #ffffff;
    --radius: 8px;
    /* 42 accent */
    --c42: #00babc;
    --c42-bg: #f0fffe;
    --c42-bdr: #99f6e4
}

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

html {
    scroll-behavior: smooth
}

body {
    background: var(--sand);
    color: var(--ink-mid);
    font-family: 'Lora', Georgia, serif;
    font-size: 15px;
    line-height: 1.7
}

h1,
h2,
h3,
h4 {
    font-family: 'Syne', sans-serif;
    color: var(--ink);
    line-height: 1.15
}

.display-title {
    font-size: clamp(2.2rem, 5vw, 3.8rem);
    font-weight: 800;
    letter-spacing: -.03em;
    color: var(--ink)
}

.display-title .hl {
    color: var(--orange)
}

.display-title .hl42 {
    color: var(--c42)
}

.section-title {
    font-size: 1.35rem;
    font-weight: 700;
    color: var(--ink);
    margin-bottom: .5rem
}

.section-label {
    font-family: 'DM Mono', monospace;
    font-size: .65rem;
    letter-spacing: .18em;
    text-transform: uppercase;
    color: var(--orange);
    margin-bottom: .5rem;
    display: flex;
    align-items: center;
    gap: .5rem
}

.section-label::before {
    content: '';
    display: inline-block;
    width: 1.2rem;
    height: 1px;
    background: var(--orange)
}

.prose {
    font-size: .93rem;
    line-height: 1.85;
    color: var(--ink-mid)
}

.mono {
    font-family: 'DM Mono', monospace;
    font-size: .78rem;
    background: var(--sand-dark);
    border: 1px solid var(--border);
    padding: .1em .4em;
    border-radius: 3px;
    color: var(--orange)
}

.badge-oam {
    display: inline-flex;
    align-items: center;
    font-family: 'DM Mono', monospace;
    font-size: .62rem;
    font-weight: 400;
    letter-spacing: .05em;
    padding: .2rem .55rem;
    border-radius: 4px;
    border: 1px solid;
    white-space: nowrap
}

.badge-green {
    background: var(--green-bg);
    color: var(--green);
    border-color: var(--green-bdr)
}

.badge-blue {
    background: var(--blue-bg);
    color: var(--blue);
    border-color: var(--blue-bdr)
}

.badge-yellow {
    background: var(--yellow-bg);
    color: var(--yellow);
    border-color: var(--yellow-bdr)
}

.badge-orange {
    background: var(--orange-bg);
    color: var(--orange);
    border-color: var(--orange-bdr)
}

.badge-red {
    background: var(--red-bg);
    color: var(--red);
    border-color: var(--red-bdr)
}

.badge-sand {
    background: var(--sand-dark);
    color: var(--ink-mid);
    border-color: var(--border)
}

.badge-42 {
    background: var(--c42-bg);
    color: var(--c42);
    border-color: var(--c42-bdr)
}

.notice {
    border-radius: var(--radius);
    padding: 1rem 1.2rem;
    margin-bottom: 1rem;
    border-left: 3px solid
}

.notice-label {
    font-family: 'DM Mono', monospace;
    font-size: .62rem;
    letter-spacing: .12em;
    text-transform: uppercase;
    font-weight: 400;
    margin-bottom: .4rem
}

.notice-text {
    font-size: .85rem;
    line-height: 1.75
}

.notice-orange {
    background: var(--orange-bg);
    border-color: var(--orange)
}

.notice-orange .notice-label {
    color: var(--orange)
}

.notice-orange .notice-text {
    color: #78350f
}

.notice-blue {
    background: var(--blue-bg);
    border-color: var(--blue)
}

.notice-blue .notice-label {
    color: var(--blue)
}

.notice-blue .notice-text {
    color: #1e3a8a
}

.notice-green {
    background: var(--green-bg);
    border-color: var(--green)
}

.notice-green .notice-label {
    color: var(--green)
}

.notice-green .notice-text {
    color: #14532d
}

.notice-42 {
    background: var(--c42-bg);
    border-color: var(--c42)
}

.notice-42 .notice-label {
    color: var(--c42)
}

.notice-42 .notice-text {
    color: #134e4a
}

.sidebar-nav {
    position: sticky;
    top: 1.5rem
}

.sidebar-heading {
    font-family: 'DM Mono', monospace;
    font-size: .58rem;
    letter-spacing: .2em;
    text-transform: uppercase;
    color: var(--ink-faint);
    padding-bottom: .4rem;
    margin-bottom: .3rem;
    border-bottom: 1px solid var(--border)
}

.sidebar-link {
    display: flex;
    align-items: center;
    gap: .5rem;
    padding: .3rem .5rem;
    font-family: 'DM Mono', monospace;
    font-size: .72rem;
    color: var(--ink-light);
    text-decoration: none;
    border-radius: 4px;
    border-left: 2px solid transparent;
    transition: all .15s;
    line-height: 1.4
}

.sidebar-link:hover {
    color: var(--orange);
    background: var(--orange-bg);
    border-left-color: var(--orange-bdr)
}

.sidebar-link.active {
    color: var(--orange);
    background: var(--orange-bg);
    border-left-color: var(--orange)
}

.sidebar-dot {
    width: 6px;
    height: 6px;
    border-radius: 50%;
    flex-shrink: 0
}

.hero-sub {
    font-size: .95rem;
    color: var(--ink-light);
    line-height: 1.8;
    max-width: 64ch;
    font-style: italic
}

.metric-card {
    background: var(--sand);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1.1rem 1.3rem;
    border-top: 3px solid var(--orange);
    height: 100%
}

.metric-val {
    font-family: 'Syne', sans-serif;
    font-weight: 800;
    font-size: 1.8rem;
    color: var(--ink);
    line-height: 1;
    margin-bottom: .2rem
}

.metric-val .unit {
    font-size: 1rem;
    color: var(--orange)
}

.metric-label {
    font-family: 'DM Mono', monospace;
    font-size: .62rem;
    letter-spacing: .1em;
    text-transform: uppercase;
    color: var(--ink-faint)
}

.feat-table {
    width: 100%;
    border-collapse: collapse;
    font-size: .82rem
}

.feat-table th {
    font-family: 'DM Mono', monospace;
    font-size: .62rem;
    letter-spacing: .1em;
    text-transform: uppercase;
    color: var(--ink-faint);
    font-weight: 400;
    padding: .6rem .9rem;
    border-bottom: 2px solid var(--border);
    text-align: left;
    background: var(--sand)
}

.feat-table td {
    padding: .75rem .9rem;
    border-bottom: 1px solid var(--sand-dark);
    color: var(--ink-mid);
    vertical-align: top
}

.feat-table tr:last-child td {
    border-bottom: none
}

.feat-table tr:hover td {
    background: var(--sand)
}

.feat-table td:first-child {
    font-family: 'DM Mono', monospace;
    color: var(--ink);
    font-size: .78rem
}

.table-wrap {
    background: var(--white);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    overflow: hidden;
    overflow-x: auto
}

.flow-list {
    background: var(--white);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    overflow: hidden
}

.flow-step {
    display: grid;
    grid-template-columns: 2.2rem 1fr auto;
    align-items: start;
    gap: 1rem;
    padding: 1rem 1.2rem;
    border-bottom: 1px solid var(--sand-dark);
    transition: background .15s
}

.flow-step:last-child {
    border-bottom: none
}

.flow-step:hover {
    background: var(--sand)
}

.flow-num {
    font-family: 'DM Mono', monospace;
    font-size: .65rem;
    color: var(--ink-faint);
    padding-top: .1rem;
    text-align: right
}

.flow-title {
    font-family: 'Syne', sans-serif;
    font-weight: 600;
    font-size: .82rem;
    color: var(--ink);
    margin-bottom: .2rem
}

.flow-desc {
    font-size: .78rem;
    color: var(--ink-light);
    line-height: 1.6
}

.flow-badge {
    padding-top: .05rem
}

.feat-card {
    background: var(--white);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1.2rem;
    height: 100%;
    transition: box-shadow .2s, border-color .2s
}

.feat-card:hover {
    border-color: var(--orange);
    box-shadow: 0 4px 16px rgba(194, 65, 12, .07)
}

.feat-card-icon {
    font-size: 1.3rem;
    margin-bottom: .6rem
}

.feat-card-title {
    font-family: 'Syne', sans-serif;
    font-weight: 700;
    font-size: .85rem;
    color: var(--ink);
    margin-bottom: .4rem
}

.feat-card-desc {
    font-size: .78rem;
    color: var(--ink-light);
    line-height: 1.65
}

/* subject card */
.subject-card {
    background: var(--white);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    overflow: hidden;
    height: 100%
}

.subject-header {
    padding: .7rem 1rem;
    background: var(--sand);
    border-bottom: 1px solid var(--border);
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: .5rem
}

.subject-name {
    font-family: 'DM Mono', monospace;
    font-size: .78rem;
    color: var(--orange);
    font-weight: 400
}

.subject-body {
    padding: 1rem;
    font-size: .78rem;
    color: var(--ink-light);
    line-height: 1.65
}

.subject-skills {
    display: flex;
    flex-wrap: wrap;
    gap: .3rem;
    margin-top: .7rem
}

/* latex box */
.latex-preview {
    background: #1c1917;
    border-radius: var(--radius);
    padding: 1.5rem;
    color: #e5e0d8;
    font-family: 'DM Mono', monospace;
    font-size: .72rem;
    line-height: 1.8;
    overflow-x: auto
}

.latex-preview .lk {
    color: #93c5fd
}

.latex-preview .ls {
    color: #86efac
}

.latex-preview .lc {
    color: #6b7280;
    font-style: italic
}

.latex-preview .lo {
    color: #fcd34d
}

.section-divider {
    height: 1px;
    background: var(--border);
    margin: 2.5rem 0
}

.doc-section {
    scroll-margin-top: 1.5rem
}

.reveal {
    opacity: 0;
    transform: translateY(18px);
    transition: opacity .5s ease, transform .5s ease
}

.reveal.visible {
    opacity: 1;
    transform: none
}

@media(max-width:991px) {
    .sidebar-nav {
        position: static;
        margin-bottom: 2rem
    }
}

@media(max-width:575px) {
    .display-title {
        font-size: 2rem
    }

    .flow-step {
        grid-template-columns: 1fr;
        gap: .3rem
    }

    .flow-num,
    .flow-badge {
        display: none
    }
}

/* arch diagram */
.arch-wrap { background: var(--white); border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden; }
.arch-caption { padding: 0.7rem 1.2rem; background: var(--sand); border-bottom: 1px solid var(--border); font-family: 'DM Mono', monospace; font-size: 0.62rem; letter-spacing: 0.12em; text-transform: uppercase; color: var(--ink-faint); display: flex; justify-content: space-between; align-items: center; flex-wrap: wrap; gap: 0.5rem; }
.arch-layers { padding: 1.2rem 1.5rem; }
.arch-layer-row { display: flex; align-items: stretch; margin-bottom: 0.8rem; gap: 0; }
.arch-layer-row:last-child { margin-bottom: 0; }
.arch-layer-tag { font-family: 'DM Mono', monospace; font-size: 0.58rem; letter-spacing: 0.15em; text-transform: uppercase; color: var(--ink-faint); writing-mode: vertical-rl; transform: rotate(180deg); padding: 0.2rem 0.3rem; border-right: 1px solid var(--border); margin-right: 1rem; flex-shrink: 0; text-align: center; width: 28px; }
.arch-nodes { display: flex; flex-wrap: wrap; gap: 0.5rem; flex: 1; align-items: center; }
.arch-node { border: 1px solid var(--border); border-radius: 5px; padding: 0.5rem 0.8rem; background: var(--sand); transition: border-color 0.2s, box-shadow 0.2s; cursor: default; }
.arch-node:hover { border-color: var(--orange); box-shadow: 0 2px 8px rgba(194,65,12,0.08); }
.arch-node-name { font-family: 'DM Mono', monospace; font-size: 0.72rem; color: var(--ink); margin-bottom: 0.1rem; }
.arch-node-sub  { font-family: 'DM Mono', monospace; font-size: 0.6rem; color: var(--ink-faint); line-height: 1.4; }
.n-orange { border-color: var(--orange-bdr); background: var(--orange-bg); }
.n-orange .arch-node-name { color: var(--orange); }
.n-green  { border-color: var(--green-bdr); background: var(--green-bg); }
.n-green  .arch-node-name { color: var(--green); }
.n-blue   { border-color: var(--blue-bdr); background: var(--blue-bg); }
.n-blue   .arch-node-name { color: var(--blue); }
.n-red    { border-color: var(--red-bdr); background: var(--red-bg); }
.n-red    .arch-node-name { color: var(--red); }
.arch-sep { height: 1px; background: var(--border); margin: 0.6rem 0; }