/* ---------------------------------------------------------------
   Proofy – Design-Tokens
   Hell ist die Basis, Dunkel überschreibt nur Farben.
   --------------------------------------------------------------- */
:root {
  color-scheme: light;

  --bg:            #fbfbf9;
  --bg-elevated:   #ffffff;
  --bg-subtle:     #f2f2ee;
  --border:        #e2e1db;
  --border-strong: #cfcec6;

  --text:          #1c1b19;
  --text-muted:    #6b6a64;
  --text-faint:    #94938c;

  --accent:        #3b5bdb;
  --accent-hover:  #2f4bc4;
  --accent-soft:   #e8ecfb;
  --accent-text:   #ffffff;

  --ok-bg:   #e6f4ea;  --ok-fg:   #1e6b37;
  --mid-bg:  #fdf1dc;  --mid-fg:  #8a5a0b;
  --hard-bg: #fbe6e6;  --hard-fg: #9b2626;

  --heart: #d6455f;

  --ring: 0 0 0 3px rgb(59 91 219 / 0.28);
  --shadow-sm: 0 1px 2px rgb(28 27 25 / 0.05);
  --shadow-md: 0 2px 8px rgb(28 27 25 / 0.07), 0 1px 2px rgb(28 27 25 / 0.04);

  --font-sans: ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --font-serif: "Iowan Old Style", "Palatino Linotype", Palatino, Palladio, Georgia, "Times New Roman", serif;
  --font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;

  --radius:    10px;
  --radius-lg: 14px;
  --measure:   70ch;
}

:root:not([data-theme="light"]) { }

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    color-scheme: dark;
    --bg:            #14151a;
    --bg-elevated:   #1b1d24;
    --bg-subtle:     #21242c;
    --border:        #2e323c;
    --border-strong: #3d424e;
    --text:          #e8e8e4;
    --text-muted:    #a0a2ab;
    --text-faint:    #7c7e87;
    --accent:        #8ba2ff;
    --accent-hover:  #a3b5ff;
    --accent-soft:   #22283d;
    --accent-text:   #11131a;
    --ok-bg:   #163a24;  --ok-fg:   #83d9a0;
    --mid-bg:  #3a2d12;  --mid-fg:  #e3bc73;
    --hard-bg: #3c1c1c;  --hard-fg: #f0a0a0;
    --heart: #ff7a92;
    --ring: 0 0 0 3px rgb(139 162 255 / 0.3);
    --shadow-sm: 0 1px 2px rgb(0 0 0 / 0.3);
    --shadow-md: 0 2px 10px rgb(0 0 0 / 0.35);
  }
}

:root[data-theme="dark"] {
  color-scheme: dark;
  --bg:            #14151a;
  --bg-elevated:   #1b1d24;
  --bg-subtle:     #21242c;
  --border:        #2e323c;
  --border-strong: #3d424e;
  --text:          #e8e8e4;
  --text-muted:    #a0a2ab;
  --text-faint:    #7c7e87;
  --accent:        #8ba2ff;
  --accent-hover:  #a3b5ff;
  --accent-soft:   #22283d;
  --accent-text:   #11131a;
  --ok-bg:   #163a24;  --ok-fg:   #83d9a0;
  --mid-bg:  #3a2d12;  --mid-fg:  #e3bc73;
  --hard-bg: #3c1c1c;  --hard-fg: #f0a0a0;
  --heart: #ff7a92;
  --ring: 0 0 0 3px rgb(139 162 255 / 0.3);
  --shadow-sm: 0 1px 2px rgb(0 0 0 / 0.3);
  --shadow-md: 0 2px 10px rgb(0 0 0 / 0.35);
}

/* --------------------------------- Basis --------------------------------- */
* { box-sizing: border-box; }

/* Muss gegen eigene display-Regeln gewinnen: .card ist flex, .cards ist grid –
   ohne !important bliebe ein [hidden]-Element sichtbar. */
[hidden] { display: none !important; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--accent); text-decoration-color: color-mix(in srgb, var(--accent) 40%, transparent); text-underline-offset: 2px; }
a:hover { color: var(--accent-hover); }

:focus-visible { outline: none; box-shadow: var(--ring); border-radius: 6px; }

.wrap { width: 100%; max-width: 940px; margin: 0 auto; padding: 0 20px; }
.wrap--reading { max-width: 760px; }

/* --------------------------------- Kopf ---------------------------------- */
.site-header {
  border-bottom: 1px solid var(--border);
  background: color-mix(in srgb, var(--bg) 85%, transparent);
  backdrop-filter: blur(8px);
  position: sticky; top: 0; z-index: 10;
}
.site-header__inner {
  display: flex; align-items: center; gap: 16px;
  min-height: 60px;
}
.brand {
  font-family: var(--font-serif);
  font-size: 1.25rem; font-weight: 600; letter-spacing: -0.01em;
  color: var(--text); text-decoration: none;
  display: inline-flex; align-items: baseline; gap: 8px;
}
.brand__mark { color: var(--accent); font-size: 1.1em; }
.site-header__spacer { flex: 1; }

.theme-toggle {
  appearance: none; cursor: pointer;
  width: 36px; height: 36px;
  display: grid; place-items: center;
  border: 1px solid var(--border); border-radius: 50%;
  background: var(--bg-elevated); color: var(--text-muted);
  transition: color .15s, border-color .15s, background .15s;
}
.theme-toggle:hover { color: var(--text); border-color: var(--border-strong); }
.theme-toggle svg { width: 18px; height: 18px; }
.theme-toggle .icon-sun { display: none; }
:root[data-theme="dark"] .theme-toggle .icon-sun { display: block; }
:root[data-theme="dark"] .theme-toggle .icon-moon { display: none; }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .theme-toggle .icon-sun  { display: block; }
  :root:not([data-theme="light"]) .theme-toggle .icon-moon { display: none; }
}

/* --------------------------------- Hero ---------------------------------- */
.hero { padding: 56px 0 28px; }
.hero h1 {
  font-family: var(--font-serif);
  font-size: clamp(1.9rem, 5vw, 2.6rem);
  line-height: 1.15; letter-spacing: -0.02em;
  margin: 0 0 10px;
}
.hero p { margin: 0; color: var(--text-muted); max-width: 54ch; }

/* -------------------------------- Filter --------------------------------- */
.filters {
  display: flex; flex-wrap: wrap; gap: 10px; align-items: center;
  padding: 18px 0 8px;
  border-bottom: 1px solid var(--border);
  margin-bottom: 26px;
}
.field { position: relative; display: inline-flex; }
.field input, .field select {
  font: inherit; color: var(--text);
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 8px 12px;
  min-height: 38px;
}
.field input { min-width: 240px; }
.field select { padding-right: 32px; cursor: pointer; appearance: none;
  background-image: linear-gradient(45deg, transparent 50%, var(--text-faint) 50%),
                    linear-gradient(135deg, var(--text-faint) 50%, transparent 50%);
  background-position: calc(100% - 17px) 50%, calc(100% - 12px) 50%;
  background-size: 5px 5px, 5px 5px;
  background-repeat: no-repeat;
}
.field input::placeholder { color: var(--text-faint); }
.filters__count { margin-left: auto; color: var(--text-faint); font-size: .875rem; font-variant-numeric: tabular-nums; }

/* --------------------------------- Chips --------------------------------- */
.chip {
  display: inline-flex; align-items: center; gap: 5px;
  font-size: .75rem; font-weight: 600; letter-spacing: .02em;
  padding: 3px 9px; border-radius: 999px;
  background: var(--bg-subtle); color: var(--text-muted);
  white-space: nowrap;
}
.chip--thema { background: var(--accent-soft); color: var(--accent); }
.chip--leicht { background: var(--ok-bg);   color: var(--ok-fg); }
.chip--mittel { background: var(--mid-bg);  color: var(--mid-fg); }
.chip--schwer { background: var(--hard-bg); color: var(--hard-fg); }
.chips { display: flex; flex-wrap: wrap; gap: 6px; }

/* --------------------------------- Karten -------------------------------- */
.cards { display: grid; gap: 14px; grid-template-columns: 1fr; padding-bottom: 60px; }
@media (min-width: 720px) { .cards { grid-template-columns: 1fr 1fr; } }

.card {
  display: flex; flex-direction: column; gap: 10px;
  padding: 18px 20px;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  text-decoration: none; color: inherit;
  transition: border-color .15s, box-shadow .15s, transform .15s;
}
.card:hover {
  border-color: var(--border-strong);
  box-shadow: var(--shadow-md);
  transform: translateY(-1px);
  color: inherit;
}
.card h2 {
  font-family: var(--font-serif);
  font-size: 1.12rem; font-weight: 600; line-height: 1.3;
  margin: 0; letter-spacing: -0.01em;
}
.card__teaser {
  margin: 0; color: var(--text-muted); font-size: .925rem;
  display: -webkit-box; -webkit-line-clamp: 3; -webkit-box-orient: vertical;
  overflow: hidden;
}
.card__foot { margin-top: auto; display: flex; align-items: center; gap: 8px; color: var(--text-faint); font-size: .8rem; }
.card__arrow { margin-left: auto; color: var(--accent); font-weight: 600; }

.empty {
  grid-column: 1 / -1;
  padding: 48px 20px; text-align: center;
  color: var(--text-muted);
  border: 1px dashed var(--border-strong); border-radius: var(--radius-lg);
}

/* ------------------------------ Aufgabenseite ---------------------------- */
.back {
  display: inline-flex; align-items: center; gap: 6px;
  margin: 32px 0 20px; font-size: .9rem; text-decoration: none; color: var(--text-muted);
}
.back:hover { color: var(--accent); }

.task__head { padding-bottom: 22px; border-bottom: 1px solid var(--border); margin-bottom: 30px; }
.task__head h1 {
  font-family: var(--font-serif);
  font-size: clamp(1.6rem, 4.4vw, 2.1rem); line-height: 1.2;
  letter-spacing: -0.02em; margin: 12px 0 10px;
}
.task__meta { color: var(--text-faint); font-size: .85rem; }

.prose { font-family: var(--font-serif); font-size: 1.0625rem; line-height: 1.75; }
.prose > :first-child { margin-top: 0; }
.prose > :last-child { margin-bottom: 0; }
.prose p { margin: 0 0 1.05em; }
.prose h3 { font-size: 1.1rem; margin: 1.8em 0 .6em; letter-spacing: -0.01em; }
.prose ul, .prose ol { margin: 0 0 1.05em; padding-left: 1.5em; }
.prose li { margin: .35em 0; }
.prose li > ul, .prose li > ol { margin: .35em 0; }
.prose blockquote {
  margin: 1.2em 0; padding: 2px 0 2px 16px;
  border-left: 3px solid var(--border-strong);
  color: var(--text-muted);
}
.prose code {
  font-family: var(--font-mono); font-size: .875em;
  background: var(--bg-subtle); border: 1px solid var(--border);
  padding: .1em .35em; border-radius: 5px;
}
.prose hr { border: none; border-top: 1px solid var(--border); margin: 2em 0; }
.prose strong { font-weight: 650; }

.section-label {
  font-family: var(--font-sans);
  font-size: .75rem; font-weight: 700; letter-spacing: .09em; text-transform: uppercase;
  color: var(--text-faint);
  margin: 0 0 12px;
}

/* ------------------------------- Hinweise -------------------------------- */
.hint {
  margin: 34px 0 0;
  border: 1px solid var(--border); border-radius: var(--radius-lg);
  background: var(--bg-elevated); overflow: hidden;
}
.hint > summary {
  cursor: pointer; list-style: none;
  padding: 13px 18px; font-weight: 600; font-size: .925rem;
  display: flex; align-items: center; gap: 9px;
}
.hint > summary::-webkit-details-marker { display: none; }
.hint > summary::before {
  content: ""; width: 7px; height: 7px; flex: none;
  border-right: 1.8px solid var(--text-faint); border-bottom: 1.8px solid var(--text-faint);
  transform: rotate(-45deg); transition: transform .18s;
}
.hint[open] > summary::before { transform: rotate(45deg); }
.hint > summary:hover { color: var(--accent); }
.hint__body { padding: 0 18px 16px; border-top: 1px solid var(--border); padding-top: 14px; }

/* -------------------------------- Lösung --------------------------------- */
.solution {
  margin: 34px 0 72px;
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  background: var(--bg-elevated);
  overflow: hidden;
}
.solution__gate, .solution__confirm { padding: 26px 22px; text-align: center; }

.solution__lock {
  width: 38px; height: 38px; margin: 0 auto 12px;
  display: grid; place-items: center; border-radius: 50%;
  background: var(--bg-subtle); color: var(--text-faint);
}
.solution__lock svg { width: 19px; height: 19px; }
.solution__title { font-family: var(--font-serif); font-size: 1.2rem; font-weight: 600; margin: 0 0 6px; }
.solution__note { margin: 0 auto 18px; max-width: 46ch; color: var(--text-muted); font-size: .925rem; }
.solution__confirm { background: var(--accent-soft); }
.solution__confirm .solution__note { color: var(--text); }
.btn-row { display: flex; flex-wrap: wrap; gap: 10px; justify-content: center; }

.btn {
  appearance: none; cursor: pointer; font: inherit; font-weight: 600; font-size: .925rem;
  padding: 9px 18px; border-radius: var(--radius);
  border: 1px solid var(--border-strong);
  background: var(--bg-elevated); color: var(--text);
  transition: background .15s, border-color .15s, color .15s;
}
.btn:hover { border-color: var(--text-faint); }
.btn--primary { background: var(--accent); border-color: var(--accent); color: var(--accent-text); }
.btn--primary:hover { background: var(--accent-hover); border-color: var(--accent-hover); color: var(--accent-text); }
.btn--ghost { background: transparent; border-color: transparent; color: var(--text-muted); }
.btn--ghost:hover { color: var(--text); background: var(--bg-subtle); }

.solution__body { padding: 24px 22px; }
.solution__body > .prose { animation: reveal .28s ease both; }
@keyframes reveal { from { opacity: 0; transform: translateY(6px); } to { opacity: 1; transform: none; } }
@media (prefers-reduced-motion: reduce) {
  .solution__body > .prose { animation: none; }
  .card:hover { transform: none; }
}
.solution__relock { margin-top: 18px; padding-top: 14px; border-top: 1px solid var(--border); text-align: center; }

/* ------------------------------ Blättern --------------------------------- */
.pager {
  display: flex; gap: 12px; justify-content: space-between;
  padding: 22px 0 70px; border-top: 1px solid var(--border);
}
.pager a {
  flex: 1 1 0; min-width: 0; max-width: 48%;
  text-decoration: none; color: inherit;
  border: 1px solid var(--border); border-radius: var(--radius);
  padding: 11px 14px; background: var(--bg-elevated);
  transition: border-color .15s;
}
.pager a:hover { border-color: var(--border-strong); }
.pager span { display: block; font-size: .72rem; letter-spacing: .07em; text-transform: uppercase; color: var(--text-faint); }
.pager strong { font-family: var(--font-serif); font-weight: 600; font-size: .95rem; display: block; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.pager .pager__next { text-align: right; margin-left: auto; }

/* -------------------------------- Footer --------------------------------- */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 22px 0 40px;
  color: var(--text-faint); font-size: .85rem;
}
.site-footer__inner {
  display: flex; flex-wrap: wrap; align-items: center; gap: 10px 18px;
  justify-content: space-between;
}

.kofi {
  display: inline-flex; align-items: center; gap: 7px;
  color: var(--text-muted); text-decoration: none;
  padding: 5px 12px 5px 9px; border-radius: 999px;
  border: 1px solid var(--border);
  transition: color .15s, border-color .15s, background .15s;
}
.kofi:hover { color: var(--text); border-color: var(--border-strong); background: var(--bg-elevated); }
.kofi__herz { display: inline-flex; color: var(--heart); transition: transform .15s; }
.kofi__herz svg { width: 15px; height: 15px; display: block; }
.kofi:hover .kofi__herz { transform: scale(1.15); }
@media (prefers-reduced-motion: reduce) { .kofi:hover .kofi__herz { transform: none; } }

/* --------------------------------- KaTeX --------------------------------- */
.katex { font-size: 1.05em; }
.katex-display { margin: 1.2em 0; overflow-x: auto; overflow-y: hidden; padding: 2px 0; }
.katex-error { color: var(--hard-fg); font-family: var(--font-mono); font-size: .85em; }

/* Abgesetzte Formel als eigener Block – scrollt bei Überlänge statt zu überlaufen. */
.math-block { margin: 1.15em 0; overflow-x: auto; overflow-y: hidden; }
.math-block > .katex-display:only-child { margin: 0; }
.card__teaser .math-block { margin: .3em 0; }

/* Tabellen – schmal gehalten, bei Überbreite scrollt der Container statt der Seite. */
.table-wrap { overflow-x: auto; margin: 1.3em 0; }
.prose table { border-collapse: collapse; width: 100%; font-family: var(--font-sans); font-size: .9rem; }
.prose thead th {
  text-align: left; font-weight: 650; color: var(--text-muted);
  font-size: .75rem; letter-spacing: .05em; text-transform: uppercase;
  padding: 0 14px 8px 0; border-bottom: 1px solid var(--border-strong); white-space: nowrap;
}
.prose tbody td { padding: 8px 14px 8px 0; border-bottom: 1px solid var(--border); vertical-align: top; }
.prose tbody tr:last-child td { border-bottom: none; }
.prose th:last-child, .prose td:last-child { padding-right: 0; }