.cm-exercise {
--cm-ink: #17253a;
--cm-muted: #52647a;
--cm-accent: #1765cf;
--cm-border: #d7e0eb;
--cm-surface: #f4f7fb;
display: flex;
flex-wrap: wrap;
align-items: flex-start;
gap: 16px 20px;
width: 650px;
max-width: 100%;
margin: 24px auto;
padding: 16px;
box-sizing: border-box;
border: 1px solid var(--cm-border);
border-radius: 16px;
background: #fff;
color: var(--cm-ink);
box-shadow: 0 8px 28px #17253a0d;
font: 15px/1.5 system-ui, sans-serif;
color-scheme: light;
}
.cm-exercise *, .cm-exercise *::before, .cm-exercise *::after { box-sizing: border-box; }
.cm-exercise .cm-exercise-header { display: flex; align-items: center; justify-content: space-between; gap: 8px; margin: 0 0 14px; }
.cm-exercise .cm-exercise-kicker { margin: 0 0 3px; color: var(--cm-muted); font: 600 12px/1.4 system-ui, sans-serif; letter-spacing: .035em; }
.cm-exercise .cm-exercise-title { margin: 0; padding: 0; color: var(--cm-ink); font: 700 21px/1.25 system-ui, sans-serif; letter-spacing: -.025em; }
.cm-exercise .cm-exercise-progress-row { display: flex; align-items: baseline; justify-content: space-between; flex-wrap: wrap; gap: 4px 8px; margin-bottom: 7px; color: var(--cm-muted); font-size: 12px; }
.cm-exercise .cm-exercise-counter { font-weight: 650; color: var(--cm-ink); font-variant-numeric: tabular-nums; }
.cm-exercise .cm-exercise-progress { display: block; appearance: none; width: 100%; height: 4px; margin: 0 0 14px; border: 0; border-radius: 4px; background: #e6edf5; overflow: hidden; }
.cm-exercise progress::-webkit-progress-bar { background: #e6edf5; }
.cm-exercise progress::-webkit-progress-value { background: var(--cm-accent); transition: width 160ms ease; }
.cm-exercise progress::-moz-progress-bar { background: var(--cm-accent); }
.cm-exercise .cm-exercise-board-shell { flex: 0 1 320px; width: 100%; min-width: 0; max-width: 320px; margin-inline: auto; border: 1px solid #7d90a4; border-radius: 5px; overflow: hidden; }
.cm-exercise .cm-exercise-sidebar { flex: 1 1 220px; min-width: 0; }
.cm-exercise .cm-exercise-board {
display: grid;
grid-template-columns: repeat(8, minmax(0, 1fr));
width: 100%;
aspect-ratio: 1;
touch-action: none;
user-select: none;
}
.cm-exercise .cm-exercise-square {
position: relative;
display: grid;
place-items: center;
min-width: 0;
min-height: 0;
width: 100%;
aspect-ratio: 1;
margin: 0;
padding: 0;
border: 0;
border-radius: 0;
box-shadow: none;
color: #142b42;
cursor: grab;
opacity: 1;
touch-action: none;
}
.cm-exercise .is-light { background: #f1eadb; }
.cm-exercise .is-dark { background: #91a8bd; }
.cm-exercise .cm-exercise-square img { display: block; width: 90%; height: 90%; margin: 0; padding: 0; border: 0; box-shadow: none; pointer-events: none; }
.cm-exercise .is-last { background-image: linear-gradient(#f5d65d66, #f5d65d66); }
.cm-exercise .is-selected { box-shadow: inset 0 0 0 3px var(--cm-accent); }
.cm-exercise .is-target::after { content: ''; position: absolute; inset: 36%; border-radius: 50%; background: #183a60a8; pointer-events: none; }
.cm-exercise .has-piece.is-target::after { inset: 4%; border: 3px solid #183a60a8; background: none; }
.cm-exercise .cm-exercise-square[aria-disabled='true'] { cursor: default; }
.cm-exercise .cm-exercise-coordinate { position: absolute; font: 10px/1 system-ui, sans-serif; pointer-events: none; }
.cm-exercise .cm-exercise-rank { top: 2px; left: 2px; }
.cm-exercise .cm-exercise-file { bottom: 1px; right: 2px; }
.cm-exercise .cm-exercise-feedback { min-height: 78px; margin: 12px 0; padding: 10px 12px; border-left: 3px solid var(--cm-accent); border-radius: 5px; background: #edf4ff; }
.cm-exercise .cm-exercise-feedback-title { display: block; color: var(--cm-ink); font-size: 14px; font-weight: 700; }
.cm-exercise .cm-exercise-status { margin: 3px 0 0; color: #374c65; font: 400 13px/1.5 system-ui, sans-serif; }
.cm-exercise[data-feedback='retry'] .cm-exercise-feedback { background: #fff5e6; border-color: #a96b00; }
.cm-exercise[data-feedback='success'] .cm-exercise-feedback { background: #eaf7ee; border-color: #21824b; }
.cm-exercise .cm-exercise-moves { display: flex; flex-wrap: wrap; align-items: center; gap: 4px; min-height: 36px; margin: 0 0 12px; font-size: 13px; }
.cm-exercise .cm-exercise-moves-empty { color: var(--cm-muted); font-size: 12px; }
.cm-exercise .cm-exercise-move { display: inline-flex; align-items: center; gap: 5px; min-height: 30px; padding: 3px 7px; border-radius: 5px; background: var(--cm-surface); font-size: 13px; font-weight: 650; }
.cm-exercise .cm-exercise-move-number { color: var(--cm-muted); font-weight: 400; }
.cm-exercise .cm-exercise-move.is-current { background: #dfeafa; color: #164b95; }
.cm-exercise .cm-exercise-controls { display: grid; grid-template-columns: 1fr 1fr 1.25fr; gap: 6px; }
.cm-exercise button:not(.cm-exercise-square) { margin: 0; min-height: 42px; padding: 8px; border: 1px solid var(--cm-border); border-radius: 7px; background: #fff; color: var(--cm-ink); font: 600 13px/1.3 system-ui, sans-serif; cursor: pointer; box-shadow: none; text-transform: none; transition: background 120ms ease, border-color 120ms ease; }
.cm-exercise button:not(.cm-exercise-square):hover:not(:disabled) { background: #edf3fb; border-color: #a2b7d3; }
.cm-exercise .cm-exercise-controls [data-action='reveal'] { background: var(--cm-ink); color: #fff; border-color: var(--cm-ink); }
.cm-exercise .cm-exercise-controls [data-action='reveal']:hover:not(:disabled) { background: #2a405e; }
.cm-exercise button:not(.cm-exercise-square):disabled { opacity: .45; cursor: default; }
.cm-exercise button.cm-exercise-flip { display: grid; place-items: center; flex: 0 0 42px; width: 42px; padding: 8px; background: var(--cm-surface); }
.cm-exercise .cm-exercise-flip svg { display: block; }
.cm-exercise .cm-exercise-promotion { display: flex; flex-wrap: wrap; gap: 6px; margin: 0 0 12px; }
.cm-exercise .cm-exercise-promotion button { flex: 1; }
.cm-exercise .cm-exercise-review { display: grid; grid-template-columns: 1fr auto 1fr; align-items: center; gap: 8px; margin-top: 10px; }
.cm-exercise .cm-exercise-review-position { color: var(--cm-muted); font-size: 12px; font-variant-numeric: tabular-nums; }
.cm-exercise .cm-exercise-moves button.cm-exercise-move { min-height: 36px; padding: 4px 7px; }
.cm-exercise button:focus-visible { outline: 3px solid #1765cf; outline-offset: 2px; z-index: 1; }
.cm-exercise .cm-exercise-square:focus-visible { outline-offset: -3px; }
.cm-exercise [hidden] { display: none !important; }
.cm-exercise .is-dragging .is-selected img { opacity: .25; }
.cm-exercise .is-dragging, .cm-exercise .is-dragging button { cursor: grabbing; }
.cm-exercise-drag-piece { position: fixed; z-index: 100000; transform: translate(-50%, -50%); pointer-events: none; margin: 0; padding: 0; border: 0; }
@media (prefers-reduced-motion: reduce) {
.cm-exercise *, .cm-exercise progress::-webkit-progress-value { transition: none; }
}