[hidden] { display: none !important; }
.tabs button[aria-selected="true"] { background: #5369d7; color: white; }
.equation { font-size: clamp(26px, 4vw, 42px); font-weight: bold; text-align: center; padding: 35px 8px; overflow-wrap: anywhere; }
.video-placeholder { min-height: 320px; display: flex; flex-direction: column; align-items: center; justify-content: center; text-align: center; }
.video-placeholder > span { font-size: 56px; color: #5369d7; }
details { margin-top: 24px; border-top: 1px solid #dceaf1; padding-top: 18px; }
summary { cursor: pointer; font-weight: bold; }
summary:focus-visible { outline: 3px solid #5369d7; outline-offset: 4px; }
#steps { padding-left: 25px; } #steps li { padding: 10px 0; line-height: 1.5; }
.step-equation { display: block; font-size: 20px; font-weight: bold; margin-top: 7px; overflow-wrap: anywhere; }
.field-help { font-size: 14px; margin-bottom: 8px; }
.question .result { display: block; min-height: 18px; margin-top: 6px; }
.answers .question { padding: 9px 0; }
.answers .field-help { margin: 0 0 7px; }
.answers label { margin-top: 6px; margin-bottom: 4px; }
.answers .result:empty { display: none; }
.answers input { padding: 7px 10px; }
input.correct, select.correct { border-color: #25a77c; background: #eafaf2; }
input.correct + .result, select.correct + .result { color: #187858; }
.graph-card > #new-task,
.graph-card > #btnNew {
    margin-top: 16px;
    background: #c5e3c2;
    border: 2px solid #39834b;
    color: #215b32;
    box-shadow: 0 4px 10px #24567e14;
}
.graph-card > #new-task:hover,
.graph-card > #btnNew:hover { background: #b3d9b0; }
@media (max-width: 500px) { h1 { letter-spacing: -1px; font-size: 32px; } .tabs button { padding: 10px 12px; font-size: 14px; } nav { flex-wrap: wrap; } }
.coordinate-answer{display:flex;align-items:center;gap:8px;font-size:24px}.coordinate-answer>span{display:flex;flex-direction:column}.coordinate-answer input{width:90px}
#algebra-comment{font-size:18px;font-weight:bold;background:#fff0c5;border:2px solid #d3a951;border-radius:14px;padding:16px;color:#725019;margin-top:14px}
.line-reveal-smoke{position:absolute;pointer-events:none;overflow:hidden;z-index:2}.line-reveal-smoke span{position:absolute;width:70px;height:45px;border-radius:50%;background:radial-gradient(ellipse,#d6e1eccc 0%,#e6edf5a6 40%,transparent 72%);filter:blur(4px);transform:translate(-50%,-50%);animation:line-smoke-rise .7s ease-out both}@keyframes line-smoke-rise{0%{opacity:0;transform:translate(-50%,-30%) scale(.5)}20%{opacity:.85}100%{opacity:0;transform:translate(-40%,-130%) scale(1.7)}}
#function-graph:has(+ #algebra-comment){margin-bottom:0}#algebra-comment{margin-top:10px}.line-reveal-smoke span{width:100px;height:70px;background:radial-gradient(ellipse,#8497adc9 0%,#b4c5d8e0 35%,#e0e8f1a6 60%,transparent 75%);filter:blur(3px);animation:line-smoke-rise 1.2s ease-out both}@keyframes line-smoke-rise{0%{opacity:.65;transform:translate(-50%,-50%) scale(.75)}25%{opacity:1;transform:translate(-50%,-65%) scale(1.1)}100%{opacity:0;transform:translate(-35%,-145%) scale(1.9)}}
.line-reveal-smoke span{background:radial-gradient(ellipse,#e4edf5d9 0%,#eef4fae0 35%,#ffffffa6 60%,transparent 75%);animation-duration:.6s}
body[data-topic="system"] #algebra-comment{margin-top:-5px}
.answers input[data-kind="equation"]{width:100%;max-width:100%;font-size:20px;padding:10px 12px}
.standard-formula{font-size:17px}.standard-formula strong{display:block;font-size:23px;margin-top:6px}.coefficient-row{display:flex;gap:12px;flex-wrap:wrap;padding:10px 0}.quadratic-field{display:inline-flex;flex-direction:column;gap:4px;margin:4px 8px 4px 0}.coefficient-row .quadratic-field{flex:1;min-width:60px;margin-right:0}.coefficient-row input{width:100%;max-width:95px}.root-row{display:flex;align-items:center;gap:20px;flex-wrap:wrap}.root-fraction{display:inline-grid;text-align:center;vertical-align:middle;margin-left:5px;font-size:18px}.root-fraction>span{padding:4px 8px}.root-fraction>span:first-child{border-bottom:2px solid currentColor}.crossed-root{position:relative;opacity:.5}.crossed-root:after{content:'';position:absolute;inset:10px 0;background:linear-gradient(12deg,transparent 48%,#c94454 49%,#c94454 51%,transparent 52%),linear-gradient(-12deg,transparent 48%,#c94454 49%,#c94454 51%,transparent 52%);pointer-events:none}
body[data-topic="quadratic"] #algebra-comment{margin-top:-5px}

.practice-fraction { display:inline-flex; flex-direction:column; vertical-align:middle; text-align:center; line-height:1.4; }
.practice-fraction > span { padding:3px 8px; }
.practice-fraction > span:first-child { border-bottom:2px solid currentColor; }