:root {
    --bg: #f4f5f7;
    --card: #ffffff;
    --ink: #1f2430;
    --muted: #6b7280;
    --brand: #2563eb;
    --brand-dark: #1d4ed8;
    --line: #e5e7eb;
    --code-bg: #111827;
    --code-ink: #e5e7eb;
    --ok: #059669;
    --err: #dc2626;
}

* { box-sizing: border-box; }

body {
    margin: 0;
    font-family: -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background: var(--bg);
    color: var(--ink);
    line-height: 1.55;
}

.topbar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    background: var(--ink);
    color: #fff;
    padding: 10px 24px;
}

.brand { color: #fff; font-weight: 700; font-size: 18px; text-decoration: none; }

.topbar nav { display: flex; align-items: center; gap: 12px; }
.who { color: #cbd5e1; font-size: 14px; }
.inline-form { display: inline; }

.container { max-width: 1100px; margin: 24px auto; padding: 0 16px; }

.btn {
    border: 1px solid transparent;
    border-radius: 8px;
    cursor: pointer;
    font-size: 14px;
    padding: 8px 14px;
}
.btn-primary { background: var(--brand); color: #fff; }
.btn-primary:hover { background: var(--brand-dark); }
.btn-primary:disabled { opacity: .6; cursor: wait; }
.btn-ghost { background: transparent; color: inherit; border-color: var(--line); }

.crumbs { font-size: 13px; color: var(--muted); margin: 0 0 14px 2px; }
.crumbs a { color: var(--brand); text-decoration: none; }

.card {
    background: var(--card);
    border: 1px solid var(--line);
    border-radius: 12px;
    padding: 20px 24px;
    margin-bottom: 18px;
}

h1 { font-size: 24px; margin: 0 0 14px; }
h2 { font-size: 19px; margin: 22px 0 8px; }
h3 { font-size: 16px; margin: 16px 0 6px; }
.muted { color: var(--muted); }
.alert {
    background: #fef3c7;
    border: 1px solid #fcd34d;
    color: #92400e;
    border-radius: 8px;
    padding: 10px 14px;
    margin: 12px 0;
    font-size: 14px;
}

.layout { display: grid; grid-template-columns: 260px 1fr; gap: 20px; align-items: start; }
@media (max-width: 820px) { .layout { grid-template-columns: 1fr; } }

.side {
    background: var(--card);
    border: 1px solid var(--line);
    border-radius: 12px;
    padding: 14px;
    position: sticky;
    top: 12px;
}
.side-title { font-size: 13px; text-transform: uppercase; letter-spacing: .04em; color: var(--muted); margin-bottom: 8px; }
.side-nav { display: flex; flex-direction: column; }
.side-link {
    display: block;
    padding: 8px 10px;
    border-radius: 8px;
    color: var(--ink);
    text-decoration: none;
    font-size: 14px;
}
.side-link:hover { background: #eff6ff; }
.side-link.active { background: var(--brand); color: #fff; }

.login-card { max-width: 380px; margin: 60px auto; background: var(--card); border: 1px solid var(--line); border-radius: 14px; padding: 28px; text-align: center; }
.stack { display: flex; flex-direction: column; gap: 14px; text-align: left; margin-top: 16px; }
.stack label { display: flex; flex-direction: column; gap: 6px; font-size: 14px; }
.stack input { padding: 10px; border: 1px solid var(--line); border-radius: 8px; font-size: 15px; }

.week-list { list-style: none; margin: 0; padding: 0; }
.week-list li { margin-bottom: 12px; }
.card-link {
    display: flex;
    flex-direction: column;
    gap: 4px;
    background: var(--card);
    border: 1px solid var(--line);
    border-radius: 12px;
    padding: 16px 20px;
    text-decoration: none;
    color: var(--ink);
}
.card-link:hover { border-color: var(--brand); }
.card-title { font-size: 17px; font-weight: 600; }

/* markdown */
.md { font-size: 15px; }
.md table { border-collapse: collapse; margin: 12px 0; font-size: 14px; }
.md th, .md td { border: 1px solid var(--line); padding: 6px 10px; text-align: left; }
.md th { background: #f9fafb; }
.md code { background: #f1f5f9; padding: 1px 5px; border-radius: 5px; font-size: 13px; }
.md blockquote { border-left: 4px solid var(--brand); margin: 10px 0; padding: 2px 14px; color: #374151; background: #f8fafc; }

/* code cards */
.code-card { padding: 0; overflow: hidden; }
.code-head {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    padding: 10px 16px;
    border-bottom: 1px solid var(--line);
    background: #f9fafb;
}
.file-name { font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; font-size: 13px; font-weight: 600; }
.code { background: var(--code-bg); color: var(--code-ink); margin: 0; padding: 16px; overflow-x: auto; font-size: 13px; line-height: 1.5; }
.code code { font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; }

.run-console { padding: 0; overflow: hidden; }
.console {
    background: #0b1220;
    color: #d1fae5;
    margin: 0;
    padding: 14px 16px;
    max-height: 460px;
    overflow: auto;
    font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
    font-size: 13px;
    line-height: 1.5;
    white-space: pre-wrap;
    word-break: break-word;
}
.run-block + .run-block { margin-top: 10px; border-top: 1px dashed #334155; padding-top: 10px; }