/**
 * Color2Gray - 彩图转黑白
 * 前端样式表
 */

/* ================= 设计变量 ================= */
.c2g-app {
	--c2g-brand-1: #6366f1;
	--c2g-brand-2: #06b6d4;
	--c2g-brand-grad: linear-gradient(135deg, var(--c2g-brand-1), var(--c2g-brand-2));

	--c2g-bg: #ffffff;
	--c2g-bg-soft: #f6f7fb;
	--c2g-bg-hover: #eef0f8;
	--c2g-border: rgba(15, 23, 42, 0.10);
	--c2g-border-strong: rgba(15, 23, 42, 0.20);
	--c2g-text: #1e293b;
	--c2g-text-soft: #64748b;

	--c2g-radius: 20px;
	--c2g-radius-md: 14px;

	--c2g-shadow: 0 18px 40px -22px rgba(15, 23, 42, 0.35);
	--c2g-shadow-btn: 0 8px 18px -8px rgba(99, 102, 241, 0.65);

	--c2g-gap: 16px;
	--c2g-preview-h: 320px;   /* 由短码 preview 属性覆盖 */

	box-sizing: border-box;
	max-width: 100%;
	margin: 1.5em 0;
	padding: 22px;
	background: var(--c2g-bg);
	border: 1px solid var(--c2g-border);
	border-radius: var(--c2g-radius);
	box-shadow: var(--c2g-shadow);
	color: var(--c2g-text);
	font-size: 16px;
	line-height: 1.6;
	-webkit-font-smoothing: antialiased;
	transition: border-color .2s ease, box-shadow .2s ease;
}

.c2g-app *,
.c2g-app *::before,
.c2g-app *::after {
	box-sizing: inherit;
}

/* 暗色模式自动适配 */
@media (prefers-color-scheme: dark) {
	.c2g-app {
		--c2g-bg: #16181f;
		--c2g-bg-soft: #1e212b;
		--c2g-bg-hover: #262a36;
		--c2g-border: rgba(255, 255, 255, 0.10);
		--c2g-border-strong: rgba(255, 255, 255, 0.24);
		--c2g-text: #e7eaf1;
		--c2g-text-soft: #98a2b8;
		--c2g-shadow: 0 18px 40px -22px rgba(0, 0, 0, 0.85);
	}
}

/* hidden 属性统一生效 */
.c2g-app [hidden] {
	display: none !important;
}

/* ================= 标题 ================= */
.c2g-title {
	display: flex;
	align-items: center;
	gap: 10px;
	margin: 0 0 18px;
	font-size: 1.05em;
	font-weight: 700;
	letter-spacing: 0.01em;
}

.c2g-title::before {
	content: "";
	flex: 0 0 auto;
	width: 4px;
	height: 1.1em;
	border-radius: 999px;
	background: var(--c2g-brand-grad);
}

/* ================= 舞台 / 空状态 ================= */
.c2g-stage {
	position: relative;
}

.c2g-empty {
	display: flex;
	flex-direction: column;
	align-items: center;
	justify-content: center;
	gap: 6px;
	padding: 44px 24px;
	text-align: center;
	background: var(--c2g-bg-soft);
	border: 2px dashed var(--c2g-border-strong);
	border-radius: var(--c2g-radius-md);
	cursor: pointer;
	transition: border-color .2s ease, background-color .2s ease, transform .2s ease;
}

.c2g-empty:hover,
.c2g-empty:focus-visible,
.c2g-empty.is-dragover {
	border-color: var(--c2g-brand-1);
	background: var(--c2g-bg-hover);
	outline: none;
}

.c2g-empty.is-dragover {
	transform: scale(1.005);
}

.c2g-empty-icon {
	display: inline-flex;
	align-items: center;
	justify-content: center;
	width: 64px;
	height: 64px;
	margin-bottom: 6px;
	border-radius: 50%;
	background: var(--c2g-brand-grad);
	color: #fff;
	box-shadow: var(--c2g-shadow-btn);
}

.c2g-empty-text {
	margin: 0;
	font-size: 1.05em;
	font-weight: 600;
}

.c2g-empty-hint {
	max-width: 46ch;
	margin: 0 0 14px;
	font-size: .85em;
	color: var(--c2g-text-soft);
}

/* 拖拽到整个容器时的整体高亮 */
.c2g-app.is-dragover {
	border-color: var(--c2g-brand-1);
	box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.18), var(--c2g-shadow);
}

/* ================= 按钮 ================= */
.c2g-btn {
	display: inline-flex;
	align-items: center;
	justify-content: center;
	gap: 6px;
	padding: 10px 22px;
	border: 1px solid var(--c2g-border);
	border-radius: 999px;
	background: var(--c2g-bg);
	color: var(--c2g-text);
	font: inherit;
	font-size: .92em;
	font-weight: 600;
	line-height: 1.2;
	cursor: pointer;
	transition: transform .15s ease, box-shadow .2s ease,
		background-color .2s ease, border-color .2s ease, opacity .2s ease;
	-webkit-tap-highlight-color: transparent;
}

.c2g-btn:hover {
	background: var(--c2g-bg-hover);
	border-color: var(--c2g-border-strong);
}

.c2g-btn:active {
	transform: translateY(1px);
}

.c2g-btn:focus-visible {
	outline: 2px solid var(--c2g-brand-1);
	outline-offset: 2px;
}

.c2g-btn:disabled {
	opacity: .5;
	cursor: not-allowed;
	transform: none;
	box-shadow: none;
}

.c2g-btn-primary {
	background: var(--c2g-brand-grad);
	border-color: transparent;
	color: #fff;
	box-shadow: var(--c2g-shadow-btn);
}

.c2g-btn-primary:hover {
	background: var(--c2g-brand-grad);
	border-color: transparent;
	box-shadow: 0 12px 26px -10px rgba(99, 102, 241, 0.85);
	transform: translateY(-1px);
}

/* ================= 对比区 ================= */
.c2g-compare {
	display: grid;
	grid-template-columns: 1fr 1fr;
	gap: var(--c2g-gap);
}

/* JS 加载完图片后给 .c2g-app 加 is-ready 自动切换 */
.c2g-app:not(.is-ready) .c2g-compare {
	display: none;
}

.c2g-app.is-ready .c2g-empty {
	display: none;
}

.c2g-pane {
	position: relative;
	display: flex;
	align-items: center;
	justify-content: center;
	margin: 0;
	overflow: hidden;
	background: var(--c2g-bg-soft);
	border: 1px solid var(--c2g-border);
	border-radius: var(--c2g-radius-md);
}

/* 关键修复：不放大原图，只限制最大尺寸 */
.c2g-pane img,
.c2g-pane canvas {
	display: block;
	max-width: 100%;
	max-height: var(--c2g-preview-h, 320px);
	width: auto;
	height: auto;
	object-fit: contain;
}

/* 透明 PNG 的棋盘格背景，方便看清透明区 */
.c2g-pane {
	background-color: #ffffff;
	background-image:
		linear-gradient(45deg, #eceff5 25%, transparent 25%),
		linear-gradient(-45deg, #eceff5 25%, transparent 25%),
		linear-gradient(45deg, transparent 75%, #eceff5 75%),
		linear-gradient(-45deg, transparent 75%, #eceff5 75%);
	background-size: 16px 16px;
	background-position: 0 0, 0 8px, 8px -8px, -8px 0;
}

@media (prefers-color-scheme: dark) {
	.c2g-pane {
		background-color: #1a1d26;
		background-image:
			linear-gradient(45deg, #242836 25%, transparent 25%),
			linear-gradient(-45deg, #242836 25%, transparent 25%),
			linear-gradient(45deg, transparent 75%, #242836 75%),
			linear-gradient(-45deg, transparent 75%, #242836 75%);
	}
}

.c2g-pane figcaption {
	position: absolute;
	top: 10px;
	left: 10px;
	padding: 3px 10px;
	border-radius: 999px;
	background: rgba(15, 23, 42, 0.62);
	color: #fff;
	font-size: .75em;
	font-weight: 600;
	letter-spacing: .03em;
	backdrop-filter: blur(6px);
	-webkit-backdrop-filter: blur(6px);
	pointer-events: none;
}

/* ================= 控件面板 ================= */
.c2g-controls {
	display: grid;
	grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
	gap: 14px 22px;
	margin-top: 18px;
	padding: 16px 18px;
	background: var(--c2g-bg-soft);
	border: 1px solid var(--c2g-border);
	border-radius: var(--c2g-radius-md);
}

.c2g-field {
	display: block;
	margin: 0;
}

.c2g-field-label {
	display: flex;
	align-items: center;
	justify-content: space-between;
	margin-bottom: 8px;
	font-size: .85em;
	font-weight: 600;
	color: var(--c2g-text-soft);
}

.c2g-field-label b {
	color: var(--c2g-text);
	font-variant-numeric: tabular-nums;
}

/* ---- 滑杆 ---- */
.c2g-range {
	-webkit-appearance: none;
	appearance: none;
	display: block;
	width: 100%;
	height: 6px;
	margin: 0;
	border-radius: 999px;
	background: linear-gradient(90deg, var(--c2g-brand-1), var(--c2g-brand-2));
	outline: none;
	cursor: pointer;
}

.c2g-range::-webkit-slider-thumb {
	-webkit-appearance: none;
	appearance: none;
	width: 20px;
	height: 20px;
	border-radius: 50%;
	background: #fff;
	border: 2px solid var(--c2g-brand-1);
	box-shadow: 0 2px 8px rgba(15, 23, 42, 0.28);
	transition: transform .15s ease;
}

.c2g-range::-webkit-slider-thumb:hover {
	transform: scale(1.12);
}

.c2g-range::-moz-range-track {
	height: 6px;
	border-radius: 999px;
	background: linear-gradient(90deg, var(--c2g-brand-1), var(--c2g-brand-2));
}

.c2g-range::-moz-range-thumb {
	width: 18px;
	height: 18px;
	border-radius: 50%;
	background: #fff;
	border: 2px solid var(--c2g-brand-1);
	box-shadow: 0 2px 8px rgba(15, 23, 42, 0.28);
}

/* ---- 复选框 ---- */
.c2g-check {
	display: inline-flex;
	align-items: center;
	gap: 8px;
	font-size: .88em;
	font-weight: 600;
	color: var(--c2g-text-soft);
	cursor: pointer;
	user-select: none;
}

.c2g-check input[type="checkbox"] {
	width: 18px;
	height: 18px;
	margin: 0;
	accent-color: var(--c2g-brand-1);
	cursor: pointer;
}

/* ================= 底部操作区 ================= */
.c2g-actions {
	display: flex;
	flex-wrap: wrap;
	align-items: center;
	gap: 10px;
	margin-top: 18px;
}

.c2g-msg {
	font-size: .85em;
	font-weight: 600;
	color: var(--c2g-text-soft);
}

.c2g-msg.is-success { color: #059669; }
.c2g-msg.is-error   { color: #dc2626; }
.c2g-msg.is-loading { color: var(--c2g-brand-1); }

/* ================= 响应式 ================= */
@media (max-width: 600px) {
	.c2g-app {
		padding: 16px;
		border-radius: 16px;
	}

	.c2g-compare {
		grid-template-columns: 1fr;
	}

	.c2g-empty {
		padding: 32px 16px;
	}

	.c2g-empty-icon {
		width: 52px;
		height: 52px;
	}

	.c2g-actions .c2g-btn {
		flex: 1 1 auto;
	}
}

/* ================= 无障碍：减少动画 ================= */
@media (prefers-reduced-motion: reduce) {
	.c2g-app *,
	.c2g-app *::before,
	.c2g-app *::after {
		transition-duration: .01ms !important;
		animation-duration: .01ms !important;
	}
}