:root {
  color-scheme: light;
  --bg: #f6f7f4;
  --panel: #ffffff;
  --ink: #20241f;
  --muted: #667064;
  --line: #d9ded4;
  --accent: #0e7c66;
  --accent-ink: #ffffff;
  --warn: #b54708;
  --ok: #1f7a35;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
}

a {
  color: inherit;
  text-decoration: none;
}

main {
  width: min(1120px, calc(100vw - 32px));
  margin: 28px auto 48px;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 64px;
  padding: 0 24px;
  border-bottom: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.92);
  position: sticky;
  top: 0;
  z-index: 10;
}

.brand {
  font-weight: 800;
  font-size: 1.1rem;
}

nav {
  display: flex;
  align-items: center;
  gap: 14px;
  flex-wrap: wrap;
}

nav a,
.ghost {
  color: var(--muted);
  font: inherit;
  background: transparent;
  border: 0;
  padding: 0;
  cursor: pointer;
}

nav a:hover,
.ghost:hover {
  color: var(--ink);
}

nav form {
  display: inline;
}

.user {
  color: var(--ink);
  font-weight: 700;
}

.toolbar {
  display: grid;
  grid-template-columns: 44px 1fr 44px;
  align-items: center;
  gap: 12px;
  margin-bottom: 18px;
}

h1,
h2 {
  margin: 0;
  line-height: 1.2;
}

.toolbar h1 {
  text-align: center;
  font-size: 1.7rem;
}

.icon {
  display: grid;
  place-items: center;
  width: 44px;
  height: 44px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel);
  font-size: 1.8rem;
}

.calendar {
  display: grid;
  grid-template-columns: repeat(7, minmax(0, 1fr));
  gap: 8px;
}

.weekday {
  color: var(--muted);
  font-size: 0.85rem;
  text-align: center;
  padding: 8px 0;
}

.day {
  min-height: 132px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--panel);
  padding: 10px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.day.problem:hover,
.day.empty:hover {
  border-color: var(--accent);
}

.date {
  color: var(--muted);
  font-size: 0.88rem;
}

.day strong {
  font-size: 0.98rem;
  overflow-wrap: anywhere;
}

.day small {
  color: var(--muted);
  margin-top: auto;
}

.empty {
  color: var(--muted);
}

.muted {
  opacity: 0.45;
}

.badge {
  align-self: flex-start;
  display: inline-flex;
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 2px 8px;
  font-size: 0.78rem;
  color: var(--muted);
}

.badge.ok {
  color: var(--ok);
  border-color: color-mix(in srgb, var(--ok), white 60%);
}

.panel,
.problem-head {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 24px;
  margin-bottom: 16px;
}

.problem-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

.narrow {
  width: min(620px, 100%);
  margin-left: auto;
  margin-right: auto;
}

.stack {
  display: grid;
  gap: 16px;
}

label {
  display: grid;
  gap: 6px;
  color: var(--muted);
  font-weight: 700;
}

input,
textarea {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 10px 12px;
  font: inherit;
  color: var(--ink);
  background: #fff;
}

textarea {
  resize: vertical;
}

button,
.button {
  border: 0;
  border-radius: 8px;
  padding: 11px 16px;
  font: inherit;
  font-weight: 800;
  background: var(--accent);
  color: var(--accent-ink);
  cursor: pointer;
  text-align: center;
}

.alert {
  padding: 10px 12px;
  color: var(--warn);
  background: #fff4e8;
  border: 1px solid #f4c790;
  border-radius: 8px;
}

.meta {
  color: var(--muted);
  margin: 0 0 8px;
}

.preview-panel {
  display: grid;
  gap: 12px;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 16px;
  background: #fbfcfa;
}

.markdown {
  line-height: 1.75;
  overflow-wrap: anywhere;
}

.markdown > :first-child {
  margin-top: 0;
}

.markdown > :last-child {
  margin-bottom: 0;
}

.markdown h1,
.markdown h2,
.markdown h3 {
  margin: 1.2em 0 0.45em;
}

.markdown p,
.markdown ul,
.markdown ol,
.markdown pre,
.markdown blockquote,
.markdown table {
  margin: 0.85em 0;
}

.markdown ul,
.markdown ol {
  padding-left: 1.45rem;
}

.markdown blockquote {
  border-left: 4px solid var(--line);
  color: var(--muted);
  padding-left: 14px;
}

.markdown pre {
  overflow-x: auto;
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 12px;
  background: #f1f3ee;
}

.markdown img {
  max-width: 100%;
}

.markdown .katex-display {
  overflow-x: auto;
  overflow-y: hidden;
  padding: 4px 0;
}

code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  overflow-wrap: anywhere;
}

.split {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(280px, 0.8fr);
  gap: 24px;
}

.mini-tool {
  display: grid;
  gap: 12px;
  align-content: start;
}

.mini-tool.wide {
  margin-top: 18px;
}

output {
  min-height: 46px;
  border: 1px dashed var(--line);
  border-radius: 8px;
  padding: 12px;
  color: var(--muted);
}

table {
  width: 100%;
  border-collapse: collapse;
}

th,
td {
  border-bottom: 1px solid var(--line);
  padding: 12px 8px;
  text-align: left;
}

th {
  color: var(--muted);
  font-size: 0.88rem;
}

@media (max-width: 760px) {
  .topbar,
  .problem-head,
  .split {
    display: grid;
  }

  .topbar {
    gap: 10px;
    justify-content: stretch;
    padding: 14px 16px;
  }

  nav {
    gap: 10px;
  }

  main {
    width: min(100vw - 20px, 1120px);
    margin-top: 18px;
  }

  .calendar {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .weekday {
    display: none;
  }

  .day {
    min-height: 112px;
  }
}