:root {
	--bg: #f6f5f1;
	--card: #fff;
	--ink: #1f2328;
	--muted: #6a6f76;
	--line: #e3e1da;
	--accent: #3b5bdb;
	--accent-ink: #fff;
	--danger: #c92a2a;
	--again: #e03131;
	--hard: #e8590c;
	--good: #2f9e44;
	--easy: #1971c2;
	--radius: 12px;
	color-scheme: light dark;
	font-family: system-ui, -apple-system, 'PingFang SC', 'Microsoft YaHei', sans-serif;
}
@media (prefers-color-scheme: dark) {
	:root {
		--bg: #17181b;
		--card: #212327;
		--ink: #e8e8e6;
		--muted: #9a9ea5;
		--line: #33363c;
		--accent: #748ffc;
		--accent-ink: #10131a;
	}
}
* { box-sizing: border-box; }
body { margin: 0; background: var(--bg); color: var(--ink); line-height: 1.55; }
[hidden] { display: none !important; }
a { color: var(--accent); }
h1 { font-size: 1.6rem; margin: 0.2em 0 0.6em; }
h2 { font-size: 1.1rem; margin: 0 0 0.6em; }

.topbar {
	display: flex; align-items: center; gap: 12px; padding: 12px 20px;
	border-bottom: 1px solid var(--line); background: var(--card);
}
.brand { display: flex; align-items: center; gap: 8px; font-weight: 700; font-size: 1.15rem; color: var(--ink); text-decoration: none; }
.env { font-size: 0.75rem; padding: 2px 8px; border-radius: 99px; background: #fff3bf; color: #7a5b00; }
.account { margin-left: auto; display: flex; align-items: center; gap: 10px; }
.address { font-family: ui-monospace, monospace; font-size: 0.85rem; color: var(--muted); }

main { max-width: 960px; margin: 0 auto; padding: 24px 20px 60px; }
.notice { max-width: 960px; margin: 12px auto 0; padding: 10px 14px; border-radius: 8px; background: #e7f5ff; color: #1864ab; }
.notice.error { background: #fff5f5; color: var(--danger); }

button, .button {
	font: inherit; cursor: pointer; padding: 8px 14px; border-radius: 8px;
	border: 1px solid var(--line); background: var(--card); color: var(--ink); text-decoration: none; display: inline-block;
}
button:hover, .button:hover { border-color: var(--muted); }
button:disabled { opacity: 0.55; cursor: progress; }
button.primary { background: var(--accent); border-color: var(--accent); color: var(--accent-ink); }
button.danger { color: var(--danger); }
button.big { font-size: 1.1rem; padding: 12px 28px; }
button.link { border: 0; background: none; padding: 0; color: var(--accent); text-decoration: underline; }
.chip { padding: 3px 10px; border-radius: 99px; font-size: 0.85rem; }
.chip.on { background: #d3f9d8; border-color: #b2f2bb; color: #2b8a3e; }
.chip.off { background: #fff4e6; border-color: #ffd8a8; color: #d9480f; }

input, textarea {
	font: inherit; width: 100%; padding: 8px 10px; border: 1px solid var(--line); border-radius: 8px;
	background: var(--bg); color: var(--ink);
}
input[type='checkbox'] { width: auto; margin: 0 4px 0 0; vertical-align: middle; }
label { display: block; margin-bottom: 10px; font-size: 0.9rem; color: var(--muted); }
label textarea, label input { margin-top: 4px; color: var(--ink); }

.small { font-size: 0.85rem; }
.muted { color: var(--muted); }
.center { text-align: center; }
.row { display: flex; gap: 10px; align-items: center; flex-wrap: wrap; }
.between { justify-content: space-between; }
.end { justify-content: flex-end; }
form.inline { display: flex; gap: 8px; }
form.inline input { width: 220px; }

.hero { text-align: center; padding-top: 40px; }
.hero h1 { font-size: 2rem; }
.lead { color: var(--muted); max-width: 620px; margin: 0 0 24px; }
.hero .lead { margin: 0 auto 24px; }
.hero label { margin-top: 12px; }
.features { list-style: none; padding: 0; margin: 40px auto 0; display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 12px; max-width: 760px; }
.features li { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); padding: 14px; color: var(--muted); }
.features strong { display: block; color: var(--ink); }

.plans { display: grid; grid-template-columns: repeat(auto-fit, minmax(230px, 1fr)); gap: 16px; margin: 20px 0; }
.plans.compact { grid-template-columns: 1fr; gap: 10px; }
.plan { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); padding: 18px; display: flex; flex-direction: column; gap: 8px; }
.plan .price { font-size: 1.6rem; font-weight: 700; }
.plan .price small { font-size: 0.9rem; font-weight: 400; color: var(--muted); }
.plan .actions { display: flex; gap: 8px; flex-wrap: wrap; margin-top: auto; }
.plan.current { border-color: var(--good); }

.panel { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); padding: 16px; }
.grid2 { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 16px; margin-bottom: 24px; }

.decks { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 14px; }
.deck { background: var(--card); border: 1px solid var(--line); border-radius: var(--radius); padding: 16px; text-decoration: none; color: var(--ink); display: block; }
.deck:hover { border-color: var(--accent); }
.deck h3 { margin: 0 0 6px; font-size: 1.05rem; word-break: break-word; }
.deck .due { color: var(--accent); font-weight: 600; }

.cards { display: flex; flex-direction: column; gap: 8px; }
.card-row { display: grid; grid-template-columns: 1fr 1fr auto; gap: 12px; align-items: start; background: var(--card); border: 1px solid var(--line); border-radius: 10px; padding: 10px 12px; }
.card-row .text { white-space: pre-wrap; word-break: break-word; }
.card-row .meta { grid-column: 1 / 3; font-size: 0.8rem; color: var(--muted); }
.card-row .tools { display: flex; gap: 6px; grid-row: 1 / 3; grid-column: 3; }
.card-row textarea { min-height: 60px; }

.study { max-width: 640px; margin: 20px auto; }
.flash {
	width: 100%; min-height: 300px; display: flex; flex-direction: column; justify-content: center; align-items: center; gap: 16px;
	background: var(--card); border: 1px solid var(--line); border-radius: 16px; padding: 32px; font-size: 1.5rem;
	box-shadow: 0 6px 24px rgb(0 0 0 / 0.06);
}
.flash .face { white-space: pre-wrap; word-break: break-word; }
.flash .back { color: var(--accent); }
.flash .divider { width: 60%; border-top: 1px dashed var(--line); }
.flash .hint { font-size: 0.85rem; color: var(--muted); }
.grades { display: grid; grid-template-columns: repeat(4, 1fr); gap: 10px; margin-top: 16px; }
.grades button { color: #fff; border: 0; padding: 12px 0; font-weight: 600; }
.grades kbd { font-size: 0.75rem; opacity: 0.8; margin-left: 4px; }
.g-again { background: var(--again); }
.g-hard { background: var(--hard); }
.g-good { background: var(--good); }
.g-easy { background: var(--easy); }

dialog { border: 1px solid var(--line); border-radius: var(--radius); background: var(--card); color: var(--ink); max-width: 480px; width: calc(100% - 32px); }
dialog::backdrop { background: rgb(0 0 0 / 0.35); }

@media (max-width: 600px) {
	.card-row { grid-template-columns: 1fr; }
	.card-row .tools { grid-row: auto; grid-column: auto; }
	.card-row .meta { grid-column: auto; }
	form.inline input { width: 150px; }
	.address { display: none; }
}