.calc-channel { border: 0; padding: 0; margin: 0 0 var(--space-3); min-width: 0; }
.calc-channel legend { font-size: var(--fs-xs); color: var(--text-muted); margin-bottom: var(--space-1); }
.calc-channel__options { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 8px; }
.calc-channel__options label { cursor: pointer; }
.calc-channel__options input { position: absolute; opacity: 0; width: 1px; height: 1px; }
.calc-channel__options span { display: block; text-align: center; padding: 10px 4px; border: 1px solid var(--line-hairline); border-radius: var(--radius-md); font-size: var(--fs-xs); transition: border-color var(--dur-fast) var(--ease-out), background-color var(--dur-fast) var(--ease-out); }
.calc-channel__options input:checked + span { border-color: var(--accent-maroon); background: var(--accent-maroon-8); color: var(--accent-maroon); }
.calc-channel__options input:focus-visible + span { outline: 2px solid var(--accent-maroon); outline-offset: 2px; }
@media (max-width: 420px) { .calc-channel__options { grid-template-columns: repeat(2, minmax(0, 1fr)); } }