/* Material 3 Expressive tokens, light */
:root {
  --primary: #0b57d0;
  --on-primary: #ffffff;
  --primary-container: #d3e3fd;
  --on-primary-container: #041e49;
  --surface: #f8fafd;
  --surface-container-lowest: #ffffff;
  --surface-container-low: #f0f4f9;
  --surface-container: #e9eef6;
  --surface-container-high: #dde3ea;
  --on-surface: #1f1f1f;
  --on-surface-variant: #444746;
  --outline-variant: #c4c7c5;

  --red-c: #ffdad6;    --on-red-c: #410e0b;
  --yellow-c: #ffdf99; --on-yellow-c: #251a00;
  --green-c: #c4eed0;  --on-green-c: #072711;
  --blue-c: #d3e3fd;   --on-blue-c: #041e49;
  --green: #146c2e;
  --red: #b3261e;


  --font: "Google Sans Flex", "Roboto Flex", system-ui, sans-serif;
  --font-code: "Google Sans Code", ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  --spring: cubic-bezier(.42, 1.67, .21, .9);
  --ease: cubic-bezier(.2, 0, 0, 1);
}
@media (prefers-color-scheme: dark) {
  :root {
    --primary: #a8c7fa;
    --on-primary: #062e6f;
    --primary-container: #0842a0;
    --on-primary-container: #d3e3fd;
    --surface: #131314;
    --surface-container-lowest: #0e0e0e;
    --surface-container-low: #1b1b1b;
    --surface-container: #1e1f20;
    --surface-container-high: #282a2c;
    --on-surface: #e3e3e3;
    --on-surface-variant: #c4c7c5;
    --outline-variant: #444746;
    --red-c: #8c1d18;    --on-red-c: #ffdad6;
    --yellow-c: #5c4300; --on-yellow-c: #ffdf99;
    --green-c: #0f5223;  --on-green-c: #c4eed0;
    --blue-c: #0842a0;   --on-blue-c: #d3e3fd;
    --green: #6dd58c;
    --red: #f2b8b5;
    }
}

* { box-sizing: border-box; margin: 0; }
/* Classes like .btn set display, which would otherwise override the hidden attribute */
[hidden] { display: none !important; }
html { -webkit-text-size-adjust: 100%; }
body {
  background: var(--surface);
  color: var(--on-surface);
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
}
a { color: var(--primary); }
code { font-family: var(--font-code); font-size: .9em; background: var(--surface-container); padding: 1px 6px; border-radius: 6px; }
.wrap { width: 100%; max-width: 1200px; margin: 0 auto; padding: 0 24px; }
main { flex: 1; padding-bottom: 48px; outline: none; }
.icon {
  font-family: "Material Symbols Rounded"; font-weight: normal; font-style: normal;
  font-size: 24px; line-height: 1; display: inline-block; white-space: nowrap;
  font-feature-settings: "liga"; -webkit-font-feature-settings: "liga";
}
.icon.fill { font-variation-settings: "FILL" 1; }

/* Top bar */
.topbar {
  position: sticky; top: 0; z-index: 10;
  background: color-mix(in srgb, var(--surface) 90%, transparent);
  backdrop-filter: blur(12px); -webkit-backdrop-filter: blur(12px);
}
.topbar-inner { display: flex; align-items: center; gap: 8px; height: 64px; }
.brand { font-size: 22px; font-weight: 600; letter-spacing: -.3px; color: var(--on-surface); text-decoration: none; margin-right: auto; }
.topnav { display: flex; gap: 4px; }
.topnav a {
  padding: 8px 16px; border-radius: 999px; color: var(--on-surface-variant);
  text-decoration: none; font-weight: 500; font-size: 15px;
  transition: background .2s var(--ease);
}
.topnav a:hover { background: var(--surface-container); color: var(--on-surface); }
.topnav a[aria-current] { background: var(--primary-container); color: var(--on-primary-container); }
.icon-btn {
  width: 40px; height: 40px; border-radius: 50%; display: grid; place-items: center;
  color: var(--on-surface-variant); transition: background .15s var(--ease);
}
.icon-btn:hover { background: var(--surface-container); }

/* Buttons */
.btn {
  --h: 48px;
  position: relative; overflow: hidden; isolation: isolate;
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  height: var(--h); padding: 0 24px; border-radius: calc(var(--h) / 2);
  font: inherit; font-size: 15px; font-weight: 600; border: 0; cursor: pointer;
  text-decoration: none; white-space: nowrap; -webkit-tap-highlight-color: transparent;
  transition: border-radius .5s var(--spring);
}
.btn::before { content: ""; position: absolute; inset: 0; z-index: -1; background: currentColor; opacity: 0; transition: opacity .15s var(--ease); }
.btn:active { border-radius: 12px; transition-duration: .2s; }
.btn:active::before { opacity: .12; }
@media (hover: hover) { .btn:hover::before { opacity: .08; } }
.btn:focus-visible { outline: 3px solid var(--primary); outline-offset: 3px; }
.btn[disabled] { opacity: .5; pointer-events: none; }
.btn .icon { font-size: 20px; }
.btn-filled { background: var(--primary); color: var(--on-primary); }
.btn-tonal { background: var(--surface-container-high); color: var(--on-surface); }
.btn-text { background: transparent; color: var(--primary); padding: 0 16px; }

/* Home */
.hero { padding: 56px 0 40px; max-width: 760px; }
.hero h1 { font-size: clamp(40px, 6vw, 68px); line-height: 1.05; letter-spacing: -1.5px; font-weight: 500; margin-bottom: 20px; }
.hero p { font-size: 19px; color: var(--on-surface-variant); max-width: 60ch; }
.paths { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; }
.path {
  border-radius: 32px; padding: 28px; min-height: 220px;
  display: flex; flex-direction: column; text-decoration: none; color: inherit;
  transition: border-radius .45s var(--spring), transform .45s var(--spring);
}
@media (hover: hover) { a.path:hover { border-radius: 48px; } }
a.path:active { transform: scale(.98); }
.path .icon { font-size: 36px; }
.path h2 { font-size: 34px; font-weight: 500; letter-spacing: -.5px; margin-top: auto; padding-top: 28px; }
.path p { opacity: .85; }
.path.c-blue { background: var(--blue-c); color: var(--on-blue-c); }
.path.c-yellow { background: var(--yellow-c); color: var(--on-yellow-c); }
.path.soon { background: var(--surface-container-low); color: var(--on-surface-variant); }
.badge {
  align-self: flex-start; font-size: 13px; font-weight: 600; padding: 4px 12px; border-radius: 999px;
  background: var(--surface-container-high); color: var(--on-surface);
}
.how { margin-top: 56px; display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; }
.how div { background: var(--surface-container-low); border-radius: 24px; padding: 24px; }
.how b { display: block; font-size: 18px; font-weight: 500; margin: 12px 0 4px; }
.how p { color: var(--on-surface-variant); font-size: 15px; }
.how .num {
  width: 40px; height: 40px; border-radius: 14px; display: grid; place-items: center;
  background: var(--primary); color: var(--on-primary); font-weight: 600;
}

/* Level list */
.page-head { padding: 40px 0 24px; }
.page-head h1 { font-size: clamp(32px, 5vw, 48px); font-weight: 500; letter-spacing: -1px; }
.page-head p { color: var(--on-surface-variant); font-size: 17px; margin-top: 6px; }
.levels { display: grid; gap: 8px; max-width: 760px; }
.level-row {
  display: flex; align-items: center; gap: 16px; padding: 18px 20px;
  background: var(--surface-container-low); border-radius: 20px;
  text-decoration: none; color: inherit;
  transition: background .2s var(--ease), border-radius .4s var(--spring);
}
@media (hover: hover) { .level-row:hover { background: var(--surface-container); border-radius: 28px; } }
.level-row .num {
  width: 44px; height: 44px; flex: none; border-radius: 50%; display: grid; place-items: center;
  background: var(--surface-container-high); font-weight: 600;
}
.level-row.solved .num { background: var(--green-c); color: var(--on-green-c); }
.level-row .title { font-size: 18px; font-weight: 500; }
.level-row .meta { font-size: 14px; color: var(--on-surface-variant); }
.level-row .go { margin-left: auto; color: var(--on-surface-variant); }
.empty { padding: 32px; border-radius: 24px; background: var(--surface-container-low); color: var(--on-surface-variant); max-width: 760px; }

/* Level page */
.crumbs { padding: 24px 0 8px; font-size: 14px; }
.crumbs a { text-decoration: none; font-weight: 500; }
.level { max-width: 720px; }
.level h1 { font-size: clamp(30px, 4vw, 42px); font-weight: 500; letter-spacing: -.8px; margin: 6px 0 12px; }
.chips { display: flex; gap: 8px; flex-wrap: wrap; }
.chip {
  display: inline-flex; align-items: center; gap: 4px; font-size: 13px; font-weight: 500;
  padding: 4px 12px; border-radius: 999px; background: var(--surface-container-high);
}
.chip.ok { background: var(--green-c); color: var(--on-green-c); }
.level > p { margin-bottom: 12px; }
.hints { margin-top: 28px; margin-bottom: 8px; display: grid; gap: 8px; }
.hint {
  background: var(--yellow-c); color: var(--on-yellow-c); border-radius: 20px; padding: 14px 18px;
  font-size: 15px; animation: pop .4s var(--spring);
}
.hint code { background: rgba(0,0,0,.08); }
@keyframes pop { from { opacity: 0; transform: translateY(8px) scale(.98); } }

.actions { display: flex; gap: 8px; flex-wrap: wrap; margin-top: 20px; }

/* How to solve */
.howto { margin-top: 16px; background: var(--surface-container-low); border-radius: 24px; padding: 20px 22px; }
.howto h2 { font-size: 18px; font-weight: 500; margin-bottom: 8px; }
.howto ol { padding-left: 20px; margin-bottom: 12px; }
.howto li .cmd { margin: 8px 0 4px; }
.howto li { margin: 2px 0; }
.cmd {
  font-family: var(--font-code); font-size: 14px; line-height: 1.6;
  background: var(--surface-container-lowest); border-radius: 16px; padding: 12px 16px; overflow-x: auto;
}
.cmd code { background: none; padding: 0; }
.note { font-size: 14px; color: var(--on-surface-variant); margin-top: 10px; }

.running { display: flex; align-items: center; gap: 12px; }
.spinner {
  width: 24px; height: 24px; border-radius: 50%;
  border: 3px solid var(--primary-container); border-top-color: var(--primary);
  animation: spin .8s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

.footer { padding: 24px 0 32px; font-size: 14px; color: var(--on-surface-variant); }

/* Phone: bottom navigation like the Google app */
.bottomnav { display: none; }
@media (max-width: 900px) {
  .paths, .how { grid-template-columns: 1fr; }
  .path { min-height: 0; }
}
@media (max-width: 640px) {
  .wrap { padding: 0 16px; }
  .topnav { display: none; }
  .hero { padding: 32px 0 28px; }
  .hero p { font-size: 17px; }
  .footer { padding-bottom: 96px; }
    .actions .btn { flex: 1; }
  .bottomnav {
    display: flex; position: fixed; left: 0; right: 0; bottom: 0; z-index: 20;
    background: var(--surface-container); padding: 12px 8px calc(12px + env(safe-area-inset-bottom));
  }
  .bottomnav a {
    flex: 1; display: flex; flex-direction: column; align-items: center; gap: 4px;
    font-size: 12px; font-weight: 500; color: var(--on-surface-variant); text-decoration: none;
  }
  .bottomnav .pill { width: 64px; height: 32px; border-radius: 16px; display: grid; place-items: center; transition: background .3s var(--ease); }
  .bottomnav a[aria-current] { color: var(--on-surface); }
  .bottomnav a[aria-current] .pill { background: var(--primary-container); color: var(--on-primary-container); }
  .bottomnav a[aria-current] .icon { font-variation-settings: "FILL" 1; }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before { animation: none !important; transition: none !important; }
}


/* Flag entry */
.flag-form { margin-top: 24px; }
.flag-form label { display: block; font-weight: 500; margin-bottom: 6px; }
.flag-row { display: flex; gap: 8px; flex-wrap: wrap; }
.flag-row input {
  flex: 1; min-width: 0; height: 48px; padding: 0 16px;
  font-family: var(--font-code); font-size: 15px; color: var(--on-surface);
  background: var(--surface-container-lowest); border: 1px solid var(--outline-variant); border-radius: 16px;
  outline: none; transition: border-color .15s var(--ease), box-shadow .15s var(--ease);
}
.flag-row input:focus { border-color: var(--primary); box-shadow: inset 0 0 0 1px var(--primary); }
.flag-form.wrong input { border-color: var(--red); box-shadow: inset 0 0 0 1px var(--red); }
.flag-msg { font-size: 14px; color: var(--on-surface-variant); margin-top: 8px; min-height: 1.4em; display: flex; align-items: center; gap: 6px; }
.flag-form.wrong .flag-msg { color: var(--red); }
.flag-form.solved .flag-msg { color: var(--green); font-weight: 500; }
.flag-form.solved .flag-msg .icon { font-size: 20px; }
@media (max-width: 640px) { .flag-row .btn { width: 100%; } }