:root {
	--ink: #1d2733;
	--muted: #5f6b7a;
	--line: #d9dee5;
	--paper: #f5f7fa;
	--card: #ffffff;
	--accent: #1f5fbf;
	--accent-ink: #ffffff;
	--ok-bg: #e8f5ec;
	--ok-ink: #1d6b35;
	--warn-bg: #fff4e0;
	--warn-ink: #8a5a00;
	--bad-bg: #fdecec;
	--bad-ink: #a42a2a;
}

* { box-sizing: border-box; }

html, body { margin: 0; padding: 0; }

body {
	font-family: system-ui, -apple-system, "Segoe UI", "Noto Sans TC", "Microsoft JhengHei", Roboto, sans-serif;
	color: var(--ink);
	background: var(--paper);
	line-height: 1.5;
	min-height: 100vh;
	display: flex;
	flex-direction: column;
}

header.top {
	display: flex;
	align-items: center;
	justify-content: space-between;
	padding: 0.75rem 1.25rem;
	background: var(--card);
	border-bottom: 1px solid var(--line);
}

.brand { display: flex; align-items: center; gap: 0.75rem; font-weight: 600; }

.brand .mark {
	background: var(--accent);
	color: var(--accent-ink);
	border-radius: 4px;
	padding: 0.1rem 0.45rem;
	letter-spacing: 0.04em;
}

.lang button {
	background: none;
	border: 1px solid transparent;
	color: var(--muted);
	padding: 0.25rem 0.5rem;
	border-radius: 4px;
	cursor: pointer;
	font: inherit;
	font-size: 0.9rem;
}

.lang button[aria-current="true"] { color: var(--ink); border-color: var(--line); background: var(--paper); }

main {
	width: 100%;
	max-width: 36rem;
	margin: 0 auto;
	padding: 1.5rem 1rem 2rem;
	flex: 1;
}

.lead { color: var(--muted); margin: 0 0 1rem; }

.tabs { display: flex; gap: 0.25rem; border-bottom: 1px solid var(--line); margin-bottom: 1rem; }

.tabs button {
	background: none;
	border: none;
	border-bottom: 2px solid transparent;
	margin-bottom: -1px;
	padding: 0.5rem 0.9rem;
	font: inherit;
	color: var(--muted);
	cursor: pointer;
}

.tabs button[aria-selected="true"] { color: var(--accent); border-bottom-color: var(--accent); font-weight: 600; }

.card {
	background: var(--card);
	border: 1px solid var(--line);
	border-radius: 8px;
	padding: 1.25rem;
}

form label { display: block; margin-bottom: 1rem; }

form label > span { display: block; font-weight: 600; margin-bottom: 0.25rem; }

form input {
	width: 100%;
	font: inherit;
	padding: 0.5rem 0.6rem;
	border: 1px solid var(--line);
	border-radius: 6px;
	background: #fff;
	color: var(--ink);
}

form input:focus { outline: 2px solid var(--accent); outline-offset: 1px; border-color: var(--accent); }

form small { display: block; color: var(--muted); font-size: 0.85rem; margin-top: 0.25rem; }

form .note { color: var(--muted); font-size: 0.9rem; margin: 0 0 1rem; }

form button[type="submit"] {
	font: inherit;
	font-weight: 600;
	background: var(--accent);
	color: var(--accent-ink);
	border: none;
	border-radius: 6px;
	padding: 0.6rem 1.25rem;
	cursor: pointer;
}

form button[type="submit"]:disabled { opacity: 0.6; cursor: wait; }

.result { margin-top: 1rem; padding: 0.75rem 1rem; border-radius: 6px; font-size: 0.95rem; white-space: pre-line; }
.result.ok { background: var(--ok-bg); color: var(--ok-ink); }
.result.warn { background: var(--warn-bg); color: var(--warn-ink); }
.result.bad { background: var(--bad-bg); color: var(--bad-ink); }

.help { color: var(--muted); font-size: 0.9rem; margin-top: 1.5rem; }

footer {
	display: flex;
	justify-content: space-between;
	gap: 1rem;
	padding: 0.75rem 1.25rem;
	color: var(--muted);
	font-size: 0.85rem;
	border-top: 1px solid var(--line);
}

footer a { color: var(--muted); }

@media (max-width: 30rem) {
	header.top { flex-direction: column; align-items: flex-start; gap: 0.5rem; }
	.tabs button { padding: 0.5rem 0.6rem; }
}