:root { color-scheme: light; --ink: #142e2c; --muted: #4b6360; --green: #17634e; --line: #cddbd3; --paper: #f7f8f2; }
* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 1.5rem; }
body { margin: 0; background: var(--paper); color: var(--ink); font: 16px/1.65 system-ui, -apple-system, sans-serif; }
a { color: var(--green); text-underline-offset: 4px; }
button, input, select, textarea { font: inherit; }
button, .button { cursor: pointer; border: 1px solid var(--green); border-radius: 7px; background: var(--green); color: white; padding: .7rem 1.2rem; font-weight: 650; text-decoration: none; display: inline-block; }
button:hover, .button:hover { background: #104c3b; }
button.secondary { background: transparent; color: var(--green); }
button:disabled { cursor: not-allowed; opacity: .5; }
:focus-visible { outline: 3px solid #ba6619; outline-offset: 4px; }
.skip { position: absolute; top: -100px; padding: .5rem; background: white; z-index: 5; }
.skip:focus { top: 0; }
.site-header { max-width: 1280px; margin: auto; padding: 1.4rem 2.5rem; display: flex; justify-content: space-between; align-items: center; border-bottom: 1px solid var(--line); gap: 1rem; }
.brand { font-weight: 800; font-size: 1.2rem; color: var(--ink); text-decoration: none; letter-spacing: -.04em; }
nav { display: flex; gap: 1.6rem; font-size: .9rem; }
nav a { text-decoration: none; }
main { max-width: 1280px; margin: auto; padding: 0 2.5rem; }
.hero { padding: 4.5rem 0 4rem; max-width: 820px; }
.eyebrow { font-size: .72rem; letter-spacing: .16em; font-weight: 750; color: var(--green); }
h1 { font-size: clamp(2.5rem, 5.3vw, 4.7rem); line-height: 1.1; letter-spacing: -.055em; margin: 1rem 0 1.5rem; }
h1 span { color: var(--green); }
.hero > p:not(.eyebrow) { max-width: 640px; color: var(--muted); font-size: 1.1rem; margin-bottom: 1.8rem; }
.hero-note { color: var(--muted); font-size: .8rem; margin-left: 1rem; display: inline-block; }
.section-heading { display: flex; justify-content: space-between; align-items: end; gap: 1rem; margin: 1.5rem 0; }
h2 { font-size: clamp(1.5rem, 3vw, 2rem); line-height: 1.3; letter-spacing: -.035em; margin: .25rem 0; }
.section-heading > p { font-size: .85rem; color: var(--muted); }
.workbench { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1.1fr); gap: 1.5rem; align-items: start; }
form { min-width: 0; }
fieldset { margin: 0 0 1.25rem; padding: 1.3rem 1.5rem; border: 1px solid var(--line); border-radius: 10px; background: white; min-width: 0; }
legend { font-weight: 750; padding: 0 .4rem; font-size: .95rem; }
label { display: block; font-weight: 600; font-size: .9rem; margin: .75rem 0 .3rem; }
input:not([type=checkbox]), select, textarea { display: block; width: 100%; background: #fbfcf8; color: var(--ink); border: 1px solid #a5b9b0; padding: .65rem .75rem; border-radius: 5px; min-height: 44px; }
textarea { resize: vertical; }
#commands, pre, code { font-family: ui-monospace, Consolas, monospace; font-size: .85rem; }
.check { display: flex; align-items: center; gap: .65rem; min-height: 36px; font-weight: 500; }
input[type=checkbox] { accent-color: var(--green); width: 19px; height: 19px; flex-shrink: 0; }
.help { color: var(--muted); font-size: .8rem; margin: .45rem 0 .9rem; }
.preview-panel { border: 1px solid var(--line); border-radius: 10px; overflow: hidden; background: white; position: sticky; top: 1rem; min-width: 0; }
.preview-bar { background: #e7eee7; display: flex; justify-content: space-between; align-items: center; padding: .9rem 1.2rem; font-size: .7rem; letter-spacing: .06em; }
.preview-bar > div { display: flex; align-items: center; gap: .6rem; }
.preview-bar h3 { margin: 0; font-size: .85rem; letter-spacing: 0; }
.status-dot { width: 8px; height: 8px; border-radius: 50%; background: var(--green); }
.file-path { color: var(--muted); font: .8rem ui-monospace, monospace; overflow-wrap: anywhere; padding: 0 1.2rem; }
.preview-panel > .help, #feedback { padding: 0 1.2rem; }
.preview-panel pre { margin: 0; background: #122c2b; color: #e1efe5; padding: 1.3rem; max-height: 570px; overflow: auto; font-size: .8rem; tab-size: 2; }
.actions { display: flex; flex-wrap: wrap; gap: .65rem; }
.preview-panel .actions { padding: 1rem 1.2rem 0; }
#feedback { font-size: .85rem; }
.safety { border-top: 1px solid var(--line); padding-top: .8rem !important; }
.errors { color: #872616; background: #fff0ea; margin: 1rem; padding: .5rem 1rem; font-size: .85rem; border-left: 3px solid #a03620; }
#learn { padding-top: 2.5rem; }
.lessons { display: grid; grid-template-columns: 1fr 1fr; gap: 1rem; align-items: start; }
details { border: 1px solid var(--line); border-radius: 8px; background: white; padding: 1.1rem 1.3rem; min-width: 0; }
summary { cursor: pointer; font-weight: 650; }
details p { font-size: .9rem; }
details pre { background: #edf2eb; padding: 1rem; overflow: auto; }
.quiz { margin: 1.5rem 0; background: #e7eee1; border-radius: 10px; padding: 1.5rem; }
.quiz h3 { margin: 0; }
.next { max-width: 850px; padding: 2.5rem 0; }
.next li { padding: .5rem 0 .5rem .3rem; }
.next > p:last-child { color: var(--muted); font-size: .9rem; }
footer { border-top: 1px solid var(--line); padding: 1.5rem 0 2.5rem; color: var(--muted); font-size: .8rem; }
footer div { display: flex; flex-wrap: wrap; gap: 1.2rem; }
@media (max-width: 800px) { .workbench, .lessons { grid-template-columns: 1fr; } .preview-panel { position: static; } .section-heading { display: block; } .hero { padding-top: 3rem; } }
@media (max-width: 480px) { main { padding: 0 1rem; } .site-header { padding: 1rem; flex-wrap: wrap; } nav { gap: 1.2rem; } .hero-note { margin: 1rem 0 0; display: block; } fieldset { padding: 1rem; } h1 { font-size: 2.5rem; } }
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }