:root { --bg: #ffefe6; --red: #d6231e; --red-2: #f0432a; --gold: #ffcf6a; --deep: #7a1a10; --card: #ffffff; --text: #2b2b2b; --muted: #7a7a7a; --radius: 16px; --shadow: 0 10px 24px rgba(0, 0, 0, .08); }

* { box-sizing: border-box }

html, body { margin: 0; padding: 0; background: var(--bg); color: var(--text); font: 16px/1.65 -apple-system, BlinkMacSystemFont, "Noto Sans SC", sans-serif  }

a { color: inherit; text-decoration: none }

img { max-width: 100%; display: block }

/* wrap */
.wrap { max-width: 960px; margin: 0 auto; padding: 12px 12px 86px }

/* hero */
.hero { position: relative; border-radius: 24px; padding: 28px 20px 24px; overflow: hidden; background: radial-gradient(120% 120% at 80% 0%, #ffa97b 0%, #ff6a3d 38%, #ff3a1f 72%, #d6231e 100%); color: #fff; box-shadow: var(--shadow); }
.hero::after { content: ""; position: absolute; inset: -20% -10% auto auto; width: 420px; height: 420px; border-radius: 50%; background: radial-gradient(closest-side, rgba(255, 255, 255, .25), rgba(255, 255, 255, 0)); transform: translate(20%, -30%); pointer-events: none; filter: blur(6px); }
.hero-top { display: flex; align-items: center; gap: 16px; flex-wrap: wrap; }
.badge { background: #fff; color: var(--red); font-weight: 700; border-radius: 999px; padding: 6px 12px; }
.title { font-size: 28px; line-height: 1.25; font-weight: 900; letter-spacing: .5px; text-shadow: 0 2px 0 rgba(0, 0, 0, .08); }
.subtitle { opacity: .95; margin-top: 6px }
.hero-cta { margin-top: 14px; display: flex; gap: 10px; flex-wrap: wrap }
.btn { display: inline-flex; align-items: center; justify-content: center; padding: 8px 25px; border-radius: 999px; font-weight: 700; border: 0; cursor: pointer; transition: .2s transform ease, .2s box-shadow ease; box-shadow: 0 6px 0 rgba(0, 0, 0, .15), 0 10px 24px rgba(0, 0, 0, .18); }
.btn:active { transform: translateY(2px); box-shadow: 0 3px 0 rgba(0, 0, 0, .18), 0 6px 18px rgba(0, 0, 0, .16); }
.btn-primary { background: linear-gradient(180deg, #ffd27a, #ffb94d); color: #7a2a00 }
.btn-ghost { background: rgba(255, 255, 255, .12); color: #fff; border: 1px solid rgba(255, 255, 255, .35) }

.timer { margin-left: auto; background: rgba(0, 0, 0, .2); padding: 8px 12px; border-radius: 10px; font-weight: 700 }

/* section */
.section { margin-top: 18px }

.sec-title { display: flex; align-items: center; gap: 10px; margin: 0 0 12px; color: #fff; background: linear-gradient(90deg, #d6231e, #f0432a); padding: 10px 12px; border-radius: 12px; font-weight: 800 }
.sec-title svg { flex: 0 0 auto }

/* grid */
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px }
.grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: 12px }

.card { background: var(--card); border-radius: var(--radius); box-shadow: var(--shadow); padding: 16px; position: relative; overflow: hidden }
.card h4 { margin: 0 0 6px; font-size: 16px; font-weight: 800 }
.card p { margin: 0; color: var(--muted) }

.chip { display: inline-block; background: #fff1d6; color: #7a2a00; border: 1px solid #ffd27a; border-radius: 999px; padding: 2px 8px; font-size: 12px; font-weight: 700 }

/* rule */
.rule { background: #fff; border-left: 6px solid var(--red); padding: 12px; border-radius: 12px; box-shadow: var(--shadow) }
.rule h5 { margin: 0 0 8px; font-size: 16px; color: var(--deep) }
.rule ol { margin: 0; padding-left: 18px }
.rule li { margin: 6px 0 }

/* example */
.example { background: linear-gradient(180deg, #fff8ec, #fff); border: 1px solid #ffe2b5; border-radius: 12px; padding: 12px; box-shadow: var(--shadow) }

code.math { color: #da2b21; padding: 2px 6px; border-radius: 6px; font-family: ui-monospace, SFMono-Regular, Menlo, monospace; font-weight: 600; }

/* notice */
.notice { display: flex; gap: 10px; align-items: flex-start; background: #fff6f5; border: 1px solid #ffd1cf; color: #7a1a10; border-radius: 12px; padding: 12px }

/* dock CTA */
.dock { position: fixed; left: 0; right: 0; bottom: 0; background: rgba(255, 255, 255, .96); border-top: 1px solid #eee; backdrop-filter: saturate(140%) blur(6px); padding: 10px 12px; z-index: 30 }
.dock-inner { max-width: 960px; margin: 0 auto; display: flex; gap: 10px; align-items: center }
.dock .cta { flex: 1 }
.dock .cta .btn { width: 100% }
.dock .mini { font-size: 12px; color: var(--muted) }

/* backtop */
.backtop { position: fixed; right: 14px; bottom: 86px; z-index: 40; width: 44px; height: 44px; border-radius: 50%; display: flex; align-items: center; justify-content: center; background: linear-gradient(180deg, #ff6a3d, #d6231e); box-shadow: 0 10px 24px rgba(214, 35, 30, .45); color: #fff; font-weight: 900; cursor: pointer }

/* footer */
footer { margin: 18px 0 120px; text-align: center; color: #9b9b9b }

/* 响应式 */
@media (max-width:768px) {
	.title { font-size: 22px }
	.coupon-row { grid-template-columns: repeat(3, 1fr) }
	.grid-3 { grid-template-columns: 1fr 1fr }
}
@media (max-width:520px) {
	.hero { padding: 22px 16px }
	.coupon-row { grid-template-columns: 1fr 1fr 1fr }
	.grid-3, .grid-2 { grid-template-columns: 1fr }
}