/* Color and spacing tokens keep the design easy to change. */
:root {
	color-scheme: light;
	--ink: oklch(24% 0.025 145);
	--muted: oklch(39% 0.025 145);
	--paper: oklch(100% 0 0);
	--page: oklch(98.5% 0 none);
	--line: oklch(82% 0.018 145);
	--transparent: transparent;
	--accent: oklch(46.9% 0.118 144.856);
	--accent-dark: color-mix(in oklch, var(--accent), var(--ink) 28%);
	--player-one: oklch(40% 0.13 25);
	--player-two: var(--accent);
	--highlight: oklch(57.564% 0.16657 44.302);
	--winner: color-mix(in oklch, var(--accent), var(--panel-surface) 95%);
	--winner-line: color-mix(in oklch, var(--accent), var(--ink) 18%);
    --surface-soft: oklch(97% 0 none);
	--surface-hover: color-mix(in oklch, var(--paper), var(--accent) 8%);
	--panel-surface: color-mix(in srgb, var(--paper) 92%, var(--transparent));
	--panel-line: color-mix(in srgb, var(--line) 85%, var(--transparent));
	--focus-ring: color-mix(in srgb, var(--ink) 35%, var(--transparent));
	--shadow-color: color-mix(in srgb, var(--ink) 10%, var(--transparent));
	--shadow-soft: color-mix(in srgb, var(--ink) 8%, var(--transparent));
	--button-shadow: color-mix(in srgb, var(--accent) 20%, var(--transparent));
	--shadow: 0 1rem 2.5rem var(--shadow-color);
	--radius: 0.25rem;
	--radius-round: 50%;
	font-family: Verdana, Arial, ui-sans-serif, "Segoe UI", sans-serif;
}

/* Border-box sizing makes element widths predictable. */
*,
*::before,
*::after {
	box-sizing: border-box;
}

body {
	min-width: 20rem;
	min-height: 100vh;
	margin: 0;
	color: var(--ink);
	background-color: var(--page);
}

button,
input {
	font: inherit;
}

button,
input[type="range"],
.icon-option {
	cursor: pointer;
}

/* This helper hides text visually but keeps it for screen readers. */
.visually-hidden {
	position: absolute;
	width: 1px;
	height: 1px;
	padding: 0;
	margin: -1px;
	overflow: hidden;
	clip: rect(0 0 0 0);
	white-space: nowrap;
	border: 0;
}

.site-header {
	width: min(100% - 2rem, 76rem);
	margin: 0 auto;
	padding: 1rem 0 0.5rem;
	text-align: center;
}

.back-link {
	display: block;
	width: fit-content;
	/*margin-bottom: 2rem;*/
	color: var(--accent-dark);
	font-weight: 700;
	text-decoration-thickness: 2px;
	text-underline-offset: 0.2em;
}

.eyebrow,
.player-number,
.summary-label {
	margin: 0 0 0.35rem;
	color: var(--accent-dark);
	font-size: 1rem;
	font-weight: 800;
	letter-spacing: 0.12em;
	text-transform: uppercase;
}

h1,
h2,
p {
	margin-top: 0;
}

h1 {
	margin-bottom: 0.5rem;
	font-size: clamp(1.5rem, 3vw, 2.5rem);
	line-height: 1.05;
	letter-spacing: -0.04em;
}

.intro {
	max-width: 42rem;
	margin: 0 auto;
	color: var(--muted);
}

/* Grid creates the Player 1, Game, Player 2 layout. */
.game-layout {
	display: grid;
	grid-template-columns: minmax(14rem, 0.8fr) minmax(21rem, 1.5fr) minmax(
			14rem,
			0.8fr
		);
	align-items: start;
	gap: 1.25rem;
	width: min(100% - 2rem, 76rem);
	margin: 0 auto;
	padding-bottom: 3rem;
}

.player-card,
.game-panel {
	border: 1px solid var(--panel-line);
	border-radius: var(--radius);
	background: var(--panel-surface);
	box-shadow: var(--shadow);
}

.player-card {
	overflow: hidden;
}

.player-form,
.player-summary {
	padding: 1.25rem;
}

.player-card__heading {
	display: grid;
	grid-template-columns: 1fr auto;
	align-items: center;
	gap: 1rem;
	padding: 1.25rem;
	cursor: pointer;
	list-style: none;
}

.player-card__heading::-webkit-details-marker {
	display: none;
}

/* The plus sign shows that the settings can be expanded. */
.player-card__heading::after {
	display: grid;
	place-items: center;
	width: 2rem;
	height: 2rem;
	border: 1px solid var(--line);
	border-radius: var(--radius-round);
	color: var(--accent-dark);
	content: "+";
	font-weight: 800;
}

.player-settings[open] > .player-card__heading::after {
	content: "−";
}

.player-number,
.player-settings__title {
	display: block;
}

.player-settings__title,
.game-panel h2 {
	margin-bottom: 0;
	font-size: 1.25rem;
	font-weight: 700;
}

.player-form {
	display: grid;
	gap: 0.75rem;
	padding-top: 0;
}

.player-form > label,
legend,
.range-heading label {
	font-size: 1rem;
	font-weight: 750;
}

input[type="text"] {
	width: 100%;
	min-height: 2.75rem;
	padding: 0.65rem 0.75rem;
	border: 1px solid var(--line);
	border-radius: var(--radius);
	color: var(--ink);
	background: var(--paper);
}

input[type="text"]:focus-visible,
input[type="range"]:focus-visible,
.player-card__heading:focus-visible,
.icon-option input:focus-visible + span,
.button:focus-visible,
.cell:focus-visible {
	outline: 3px solid var(--focus-ring);
	outline-offset: 2px;
}

fieldset {
	min-width: 0;
	padding: 0;
	border: 0;
}

legend {
	margin-bottom: 0.5rem;
}

/* Each radio button uses its SVG as a large, clear label. */
.icon-picker {
	display: grid;
	grid-template-columns: repeat(4, 1fr);
	gap: 0.5rem;
}

.icon-option {
	position: relative;
}

.icon-option input {
	position: absolute;
	opacity: 0;
	pointer-events: none;
}

.icon-option > span {
	display: grid;
	place-items: center;
	min-height: 3rem;
	border: 1px solid var(--line);
	border-radius: var(--radius);
	color: var(--muted);
	background: var(--paper);
	transition:
		border-color 160ms ease,
		color 160ms ease,
		transform 160ms ease;
}

.icon-option:hover > span {
	transform: translateY(-2px);
}

.icon-option input:checked + span {
	border-color: currentColor;
	color: var(--accent-dark);
	background: var(--surface-soft);
}

.icon-option svg,
.summary-token svg {
	width: 2rem;
	height: 2rem;
}

.form-message {
	min-height: 1.2em;
	margin: 0;
	color: var(--player-one);
	font-size: 1rem;
}

.button {
	min-height: 2.75rem;
	padding: 0.65rem 1rem;
	border: 0;
	border-radius: var(--radius);
	color: var(--paper);
	font-weight: 800;
	background: var(--accent);
	box-shadow: 0 0.35rem 0.8rem var(--button-shadow);
	transition:
		background 160ms ease,
		transform 160ms ease;
}

.button:hover {
	background: var(--accent-dark);
	transform: translateY(-1px);
}

.player-one .button--player {
	background: var(--player-one);
}

.player-two .button--player {
	background: var(--player-two);
}

.player-summary {
	display: grid;
	grid-template-columns: auto 1fr;
	align-items: center;
	gap: 0.25rem 0.75rem;
	border-top: 1px solid var(--line);
	background: var(--surface-soft);
}

/* The hidden attribute should always remove an element. */
[hidden] {
	display: none !important;
}

.player-summary .summary-label {
	grid-column: 1 / -1;
}

.summary-token {
	display: grid;
	grid-row: span 2;
	place-items: center;
	width: 3rem;
	height: 3rem;
	border-radius: var(--radius-round);
	background: var(--paper);
}

.player-one .summary-token {
	color: var(--player-one);
}

.player-two .summary-token {
	color: var(--player-two);
}

.player-summary p {
	margin-bottom: 0;
}

.game-panel {
	padding: 1.25rem;
}

.game-panel > h2 {
	margin-bottom: 1rem;
}

.size-control {
	display: grid;
	grid-template-columns: 1fr auto;
	gap: 0.65rem 1rem;
	padding: 1rem;
	border-radius: var(--radius);
	background: var(--surface-soft);
}

.range-heading {
	display: flex;
	grid-column: 1 / -1;
	justify-content: space-between;
	gap: 1rem;
}

.range-heading output {
	color: var(--accent-dark);
	font-weight: 800;
}

input[type="range"] {
	width: 100%;
	accent-color: var(--accent);
}

.button--secondary {
	min-height: 2.4rem;
	padding-block: 0.4rem;
}

.game-status {
	min-height: 1.5em;
	margin: 1rem 0;
	text-align: center;
	font-weight: 750;
}

/* The size class changes the number of equal grid columns. */
.board {
	display: grid;
	gap: 0.4rem;
	width: 100%;
	max-width: 34rem;
	aspect-ratio: 1;
	margin: 0 auto;
}

.board-size-3 {
	grid-template: repeat(3, minmax(0, 1fr)) / repeat(3, minmax(0, 1fr));
}

.board-size-4 {
	grid-template: repeat(4, minmax(0, 1fr)) / repeat(4, minmax(0, 1fr));
}

.board-size-5 {
	grid-template: repeat(5, minmax(0, 1fr)) / repeat(5, minmax(0, 1fr));
}

.board-size-6 {
	grid-template: repeat(6, minmax(0, 1fr)) / repeat(6, minmax(0, 1fr));
}

.cell {
	display: grid;
	place-items: center;
	min-width: 0;
	min-height: 0;
	width: 100%;
	height: 100%;
	aspect-ratio: 1;
	overflow: hidden;
	padding: 12%;
	border: 1px solid var(--line);
	border-radius: var(--radius);
	color: var(--muted);
	background: var(--paper);
	box-shadow: 0 0.2rem 0.6rem var(--shadow-soft);
	transition:
		border-color 140ms ease,
		background 140ms ease,
		transform 140ms ease;
}

.cell:not(:disabled):hover {
	border-color: var(--accent);
	background: var(--surface-hover);
	transform: translateY(-2px);
}

.cell:disabled {
	cursor: not-allowed;
}

.cell.is-marked {
	cursor: default;
}

.cell.player-one {
	color: var(--player-one);
}

.cell.player-two {
	color: var(--player-two);
}

.cell.is-winning {
	border-color: var(--winner-line);
	background: var(--winner);
	animation: winner-pop 420ms ease both;
}

.cell svg {
	display: block;
	width: 76%;
	height: 76%;
	max-width: 100%;
	max-height: 100%;
}

.round-actions {
	margin-top: 1rem;
	padding: 1rem;
	border-radius: var(--radius);
	text-align: center;
	background: var(--surface-soft);
}

.round-actions p {
	margin-bottom: 0.75rem;
	font-weight: 800;
}

/* A small animation celebrates the winning line. */
@keyframes winner-pop {
	50% {
		transform: scale(1.06);
	}
}

/* Narrow screens keep the same sections in a single column. */
@media (max-width: 56rem) {
	.game-layout {
		grid-template-columns: 1fr;
		width: min(100% - 2rem, 38rem);
	}
}

@media (max-width: 30rem) {
	.size-control {
		grid-template-columns: 1fr;
	}

	.size-control .button {
		width: 100%;
	}
}

/* Motion-sensitive users see the final state without animation. */
@media (prefers-reduced-motion: reduce) {
	*,
	*::before,
	*::after {
		scroll-behavior: auto !important;
		transition-duration: 0.01ms !important;
		animation-duration: 0.01ms !important;
		animation-iteration-count: 1 !important;
	}
}