/* ===== 基础变量 ===== */
:root {
    --bg: #ffffff;
    --bg-soft: #f7f8fc;
    --bg-dark: #0e1230;
    --text: #1a1d3a;
    --text-soft: #5b6080;
    --text-mute: #8b90b0;
    --border: #e9ebf5;
    --primary: #7c5cff;
    --primary-2: #a78bfa;
    --primary-soft: #f0edff;
    --accent: #ff7a59;
    --success: #2bb673;
    --info: #3aa0ff;
    --warn: #ffb020;
    --pink: #ff5c8a;
    --radius: 16px;
    --radius-sm: 10px;
    --radius-lg: 28px;
    --shadow-sm: 0 2px 8px rgba(28, 30, 60, .06);
    --shadow: 0 12px 32px rgba(28, 30, 60, .08);
    --shadow-lg: 0 24px 60px rgba(28, 30, 60, .14);
    --container: 1200px;
    --ease: cubic-bezier(.4, 0, .2, 1);
}

/* ===== 重置 ===== */
*, *::before, *::after { box-sizing: border-box; }
* { margin: 0; padding: 0; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
    font-family: 'Noto Sans SC', 'Inter', -apple-system, BlinkMacSystemFont, 'PingFang SC', 'Microsoft YaHei', sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
    font-size: 16px;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
}
a { color: inherit; text-decoration: none; }
img, svg { display: block; max-width: 100%; }
button { font: inherit; border: 0; background: none; cursor: pointer; color: inherit; }
ul { list-style: none; }
summary { cursor: pointer; }

.container {
    width: 100%;
    max-width: var(--container);
    margin: 0 auto;
    padding: 0 24px;
}

/* ===== 按钮 ===== */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 12px 22px;
    border-radius: 999px;
    font-weight: 600;
    font-size: 15px;
    transition: all .25s var(--ease);
    white-space: nowrap;
    cursor: pointer;
}
.btn--primary {
    background: linear-gradient(135deg, var(--primary), var(--primary-2));
    color: #fff;
    box-shadow: 0 8px 20px rgba(124, 92, 255, .35);
}
.btn--primary:hover { transform: translateY(-2px); box-shadow: 0 12px 28px rgba(124, 92, 255, .45); }
.btn--ghost {
    background: rgba(255,255,255,.7);
    color: var(--text);
    border: 1.5px solid var(--border);
    backdrop-filter: blur(8px);
}
.btn--ghost:hover { border-color: var(--primary); color: var(--primary); transform: translateY(-2px); }
.btn--lg { padding: 15px 30px; font-size: 16px; }
.btn--sm { padding: 9px 18px; font-size: 14px; }
.btn--block { width: 100%; }

/* ===== 顶部公告 ===== */
.topbar {
    background: linear-gradient(90deg, #0e1230, #2a1a5e);
    color: #fff;
    font-size: 13px;
    padding: 9px 0;
}
.topbar__inner {
    display: flex; align-items: center; justify-content: center; gap: 16px;
}
.topbar__text { opacity: .95; }
.topbar__cta { font-weight: 700; color: #ffd76b; }
.topbar__cta:hover { color: #fff; }

/* ===== 导航 ===== */
.nav {
    position: sticky; top: 0; z-index: 100;
    background: rgba(255,255,255,.85);
    backdrop-filter: saturate(180%) blur(16px);
    border-bottom: 1px solid var(--border);
    transition: all .3s var(--ease);
}
.nav.scrolled { box-shadow: var(--shadow-sm); }
.nav__inner {
    display: flex; align-items: center; justify-content: space-between;
    height: 68px;
}
.nav__logo {
    display: flex; align-items: center; gap: 10px;
    font-weight: 800; font-size: 20px;
}
.nav__logo-mark {
    width: 34px; height: 34px;
    display: grid; place-items: center;
    background: linear-gradient(135deg, var(--primary), var(--primary-2));
    color: #fff;
    border-radius: 10px;
    font-size: 18px;
    box-shadow: 0 6px 14px rgba(124,92,255,.4);
}
.nav__logo-text { letter-spacing: -.02em; }
.nav__logo-sub {
    font-size: 12px; font-weight: 700;
    color: var(--primary);
    margin-left: 4px;
    background: var(--primary-soft);
    padding: 2px 6px;
    border-radius: 6px;
    vertical-align: middle;
}
.nav__menu { display: flex; gap: 6px; }
.nav__link {
    padding: 8px 14px;
    border-radius: 999px;
    font-size: 15px;
    font-weight: 500;
    color: var(--text-soft);
    transition: all .2s var(--ease);
}
.nav__link:hover { color: var(--primary); background: var(--primary-soft); }
.nav__actions { display: flex; gap: 10px; align-items: center; }
.nav__toggle {
    display: none;
    flex-direction: column; gap: 5px;
    padding: 8px;
}
.nav__toggle span {
    width: 22px; height: 2.5px;
    background: var(--text);
    border-radius: 2px;
    transition: all .3s var(--ease);
}
.nav__toggle.active span:nth-child(1) { transform: translateY(7.5px) rotate(45deg); }
.nav__toggle.active span:nth-child(2) { opacity: 0; }
.nav__toggle.active span:nth-child(3) { transform: translateY(-7.5px) rotate(-45deg); }

/* ===== Hero ===== */
.hero {
    position: relative;
    padding: 70px 0 90px;
    overflow: hidden;
}
.hero__bg { position: absolute; inset: 0; z-index: -1; overflow: hidden; }
.hero__blob {
    position: absolute;
    border-radius: 50%;
    filter: blur(80px);
    opacity: .5;
}
.hero__blob--1 {
    width: 480px; height: 480px;
    background: radial-gradient(circle, #b3a4ff, transparent 70%);
    top: -120px; right: -80px;
}
.hero__blob--2 {
    width: 420px; height: 420px;
    background: radial-gradient(circle, #ffc7b3, transparent 70%);
    bottom: -100px; left: -100px;
}
.hero__grid {
    position: absolute; inset: 0;
    background-image:
        linear-gradient(rgba(124,92,255,.04) 1px, transparent 1px),
        linear-gradient(90deg, rgba(124,92,255,.04) 1px, transparent 1px);
    background-size: 40px 40px;
    mask-image: radial-gradient(ellipse at center, #000 30%, transparent 75%);
}
.hero__inner {
    display: grid;
    grid-template-columns: 1.05fr 1fr;
    gap: 60px;
    align-items: center;
}
.hero__badge {
    display: inline-flex; align-items: center; gap: 6px;
    padding: 6px 14px;
    background: var(--primary-soft);
    color: var(--primary);
    border-radius: 999px;
    font-size: 13px;
    font-weight: 600;
    margin-bottom: 22px;
}
.hero__title {
    font-size: clamp(36px, 5.2vw, 60px);
    line-height: 1.12;
    font-weight: 900;
    letter-spacing: -.02em;
    margin-bottom: 22px;
}
.grad-text {
    background: linear-gradient(120deg, var(--primary), var(--accent) 70%, var(--pink));
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
}
.hero__desc {
    font-size: 18px;
    color: var(--text-soft);
    max-width: 540px;
    margin-bottom: 32px;
}
.hero__cta { display: flex; gap: 14px; flex-wrap: wrap; margin-bottom: 36px; }
.hero__trust { display: flex; align-items: center; gap: 14px; }
.hero__avatars { display: flex; }
.hero__avatars .avatar {
    width: 36px; height: 36px;
    border-radius: 50%;
    display: grid; place-items: center;
    color: #fff;
    font-weight: 700;
    font-size: 14px;
    border: 2.5px solid #fff;
    margin-left: -10px;
}
.hero__avatars .avatar:first-child { margin-left: 0; }
.hero__trust-text { font-size: 14px; color: var(--text-soft); }
.hero__trust-text strong { color: var(--text); font-weight: 800; }

/* Hero 视觉 */
.hero__visual { position: relative; }
.hero__card {
    background: #fff;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
    overflow: hidden;
    position: relative;
}
.hero__card--main { padding: 22px; }
.hero__card-head {
    display: flex; align-items: center; gap: 12px;
    padding-bottom: 16px;
    border-bottom: 1px solid var(--border);
    margin-bottom: 18px;
}
.dots { display: flex; gap: 6px; }
.dots span {
    width: 11px; height: 11px; border-radius: 50%;
    background: #e4e7f3;
}
.dots span:nth-child(1) { background: #ff5f57; }
.dots span:nth-child(2) { background: #ffbd2e; }
.dots span:nth-child(3) { background: #28c840; }
.hero__card-title {
    font-size: 14px; font-weight: 700; color: var(--text-soft);
    margin-left: auto;
}
.hero__chat { display: flex; flex-direction: column; gap: 14px; }
.bubble {
    max-width: 92%;
    padding: 12px 16px;
    border-radius: 18px;
    font-size: 14.5px;
    line-height: 1.55;
    animation: bubbleIn .5s var(--ease) both;
}
.bubble--user {
    align-self: flex-end;
    background: linear-gradient(135deg, var(--primary), var(--primary-2));
    color: #fff;
    border-bottom-right-radius: 4px;
}
.bubble--ai {
    align-self: flex-start;
    display: flex; gap: 10px;
    background: var(--bg-soft);
    border-bottom-left-radius: 4px;
}
.bubble__avatar {
    width: 30px; height: 30px;
    border-radius: 8px;
    background: linear-gradient(135deg, var(--primary), var(--accent));
    color: #fff;
    font-weight: 800;
    font-size: 11px;
    display: grid; place-items: center;
    flex-shrink: 0;
}
.bubble__body p { margin-bottom: 4px; }
.bubble__body p:last-child { margin-bottom: 0; }
.bubble.typing .bubble__body { padding: 4px 0; }
.typing__dots { display: inline-flex; gap: 4px; }
.typing__dots i {
    width: 7px; height: 7px; border-radius: 50%;
    background: var(--primary);
    animation: typing 1.4s infinite ease-in-out;
}
.typing__dots i:nth-child(2) { animation-delay: .2s; }
.typing__dots i:nth-child(3) { animation-delay: .4s; }
@keyframes typing {
    0%, 60%, 100% { transform: translateY(0); opacity: .4; }
    30% { transform: translateY(-6px); opacity: 1; }
}
@keyframes bubbleIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
}

.hero__chip {
    position: absolute;
    background: #fff;
    border-radius: 14px;
    box-shadow: var(--shadow);
    padding: 10px 14px;
    display: flex; align-items: center; gap: 10px;
    font-size: 13px;
    animation: floatY 4s ease-in-out infinite;
}
.hero__chip strong { display: block; font-weight: 800; font-size: 14px; color: var(--text); }
.hero__chip small { color: var(--text-mute); }
.hero__chip-ico {
    width: 32px; height: 32px; border-radius: 10px;
    display: grid; place-items: center;
    font-size: 16px;
}
.hero__chip--1 { top: 14%; left: -34px; animation-delay: 0s; }
.hero__chip--2 { bottom: 18%; right: -28px; animation-delay: -2s; }
@keyframes floatY {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-10px); }
}

/* ===== 信任条 ===== */
.trust {
    padding: 38px 0;
    background: var(--bg-soft);
    border-top: 1px solid var(--border);
    border-bottom: 1px solid var(--border);
}
.trust__title {
    text-align: center;
    color: var(--text-mute);
    font-size: 13px;
    font-weight: 500;
    margin-bottom: 22px;
    letter-spacing: .04em;
}
.trust__logos {
    display: flex; flex-wrap: wrap; justify-content: center; gap: 40px;
}
.trust__logos span {
    font-size: 18px; font-weight: 700;
    color: var(--text-mute);
    opacity: .65;
    transition: opacity .2s;
}
.trust__logos span:hover { opacity: 1; }

/* ===== 通用 section ===== */
.section { padding: 90px 0; }
.section__head { text-align: center; max-width: 720px; margin: 0 auto 56px; }
.section__tag {
    display: inline-block;
    padding: 5px 14px;
    background: var(--primary-soft);
    color: var(--primary);
    border-radius: 999px;
    font-size: 13px; font-weight: 700;
    margin-bottom: 16px;
}
.section__title {
    font-size: clamp(28px, 3.4vw, 42px);
    font-weight: 900;
    letter-spacing: -.02em;
    margin-bottom: 14px;
    line-height: 1.2;
}
.section__desc { color: var(--text-soft); font-size: 17px; }

/* ===== 功能卡片 ===== */
.features__grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}
.feature-card {
    padding: 32px 28px;
    background: #fff;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    transition: all .3s var(--ease);
    position: relative;
    overflow: hidden;
}
.feature-card::before {
    content: '';
    position: absolute;
    top: 0; left: 0; right: 0; height: 3px;
    background: linear-gradient(90deg, var(--c1), var(--c2));
    transform: scaleX(0);
    transform-origin: left;
    transition: transform .3s var(--ease);
}
.feature-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow);
    border-color: transparent;
}
.feature-card:hover::before { transform: scaleX(1); }
.feature-card__ico {
    width: 56px; height: 56px;
    border-radius: 16px;
    display: grid; place-items: center;
    font-size: 26px;
    background: linear-gradient(135deg, var(--c1), var(--c2));
    color: #fff;
    margin-bottom: 20px;
    box-shadow: 0 10px 24px color-mix(in srgb, var(--c1) 35%, transparent);
}
.feature-card h3 {
    font-size: 20px; font-weight: 800;
    margin-bottom: 10px;
}
.feature-card p { color: var(--text-soft); font-size: 15px; }

/* ===== 学科 ===== */
.subjects { background: var(--bg-soft); }
.subjects__grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
}
.subject-card {
    --c: var(--primary);
    background: #fff;
    border-radius: var(--radius);
    padding: 30px 26px;
    display: flex; flex-direction: column; align-items: flex-start;
    gap: 8px;
    border: 1px solid var(--border);
    transition: all .3s var(--ease);
    position: relative;
    overflow: hidden;
}
.subject-card::after {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(135deg, var(--c), transparent 60%);
    opacity: 0;
    transition: opacity .3s var(--ease);
}
.subject-card:hover { transform: translateY(-5px); box-shadow: var(--shadow); }
.subject-card:hover::after { opacity: .06; }
.subject-card__ico {
    width: 54px; height: 54px;
    border-radius: 14px;
    background: color-mix(in srgb, var(--c) 14%, #fff);
    color: var(--c);
    display: grid; place-items: center;
    font-size: 24px; font-weight: 800;
    margin-bottom: 10px;
    position: relative; z-index: 1;
}
.subject-card__name {
    font-size: 19px; font-weight: 800;
    position: relative; z-index: 1;
}
.subject-card__meta {
    color: var(--text-mute); font-size: 14px;
    position: relative; z-index: 1;
}

/* ===== 学习方式 ===== */
.how__grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 28px;
}
.how__step {
    text-align: center;
    position: relative;
    padding: 0 12px;
}
.how__num {
    font-size: 64px;
    font-weight: 900;
    background: linear-gradient(180deg, var(--primary-soft), transparent);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    line-height: 1;
    margin-bottom: 12px;
    letter-spacing: -.04em;
}
.how__visual {
    height: 160px;
    display: grid; place-items: center;
    background: var(--bg-soft);
    border-radius: var(--radius);
    margin-bottom: 22px;
    position: relative;
    overflow: hidden;
}
.how__step h3 { font-size: 20px; font-weight: 800; margin-bottom: 8px; }
.how__step p { color: var(--text-soft); font-size: 15px; max-width: 280px; margin: 0 auto; }

.how__screen {
    width: 70%; height: 60%;
    background: #fff; border-radius: 8px;
    box-shadow: var(--shadow-sm);
    overflow: hidden;
    display: flex; flex-direction: column;
}
.how__screen-bar { height: 22%; background: linear-gradient(90deg, var(--primary), var(--primary-2)); }
.how__screen-lines { flex: 1; padding: 14% 12%; display: flex; flex-direction: column; gap: 8%; }
.how__screen-lines i { height: 6px; background: var(--border); border-radius: 3px; }
.how__screen-lines i:nth-child(1) { width: 80%; }
.how__screen-lines i:nth-child(2) { width: 60%; }
.how__screen-lines i:nth-child(3) { width: 70%; }

.how__path {
    display: flex; gap: 8px;
    align-items: center;
}
.how__node {
    width: 22px; height: 22px;
    border-radius: 50%;
    background: #fff;
    border: 3px solid var(--border);
    position: relative;
}
.how__node:not(:last-child)::after {
    content: ''; position: absolute;
    top: 50%; left: 100%;
    width: 18px; height: 3px;
    background: var(--border);
    transform: translateY(-50%);
}
.how__node--active {
    border-color: var(--primary);
    background: var(--primary-soft);
    box-shadow: 0 0 0 6px rgba(124,92,255,.15);
    animation: pulse 2s infinite;
}
@keyframes pulse {
    0%, 100% { box-shadow: 0 0 0 6px rgba(124,92,255,.15); }
    50% { box-shadow: 0 0 0 12px rgba(124,92,255,.05); }
}

.how__chart {
    display: flex; align-items: flex-end; gap: 8px;
    height: 60%;
    width: 70%;
}
.how__chart span {
    flex: 1;
    background: var(--border);
    border-radius: 6px 6px 0 0;
    animation: growUp 1.2s var(--ease) both;
    transform-origin: bottom;
}
.how__chart span:nth-child(2) { animation-delay: .1s; }
.how__chart span:nth-child(3) { animation-delay: .2s; }
.how__chart span:nth-child(4) { animation-delay: .3s; }
.how__chart span:nth-child(5) { animation-delay: .4s; }
.how__chart span:nth-child(6) { animation-delay: .5s; }
@keyframes growUp {
    from { transform: scaleY(0); }
    to { transform: scaleY(1); }
}

/* ===== 数据条 ===== */
.stats {
    padding: 70px 0;
    background: linear-gradient(135deg, #0e1230 0%, #2a1a5e 60%, #3a1a6e 100%);
    color: #fff;
    position: relative;
    overflow: hidden;
}
.stats::before {
    content: '';
    position: absolute;
    width: 600px; height: 600px;
    background: radial-gradient(circle, rgba(124,92,255,.4), transparent 60%);
    top: -200px; left: 50%;
    transform: translateX(-50%);
}
.stats__inner {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
    position: relative; z-index: 1;
}
.stats__item { text-align: center; }
.stats__num {
    font-size: clamp(34px, 4vw, 52px);
    font-weight: 900;
    background: linear-gradient(135deg, #fff, #c7b8ff);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    line-height: 1.1;
}
.stats__label {
    font-size: 15px;
    color: rgba(255,255,255,.7);
    margin-top: 6px;
}

/* ===== 评价 ===== */
.testimonials__grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}
.t-card {
    background: #fff;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 28px 26px;
    transition: all .3s var(--ease);
}
.t-card:hover { transform: translateY(-4px); box-shadow: var(--shadow); }
.t-card__stars { color: #ffb020; letter-spacing: 2px; margin-bottom: 14px; font-size: 16px; }
.t-card blockquote {
    font-size: 15.5px;
    color: var(--text);
    line-height: 1.7;
    margin-bottom: 22px;
}
.t-card__author {
    display: flex; align-items: center; gap: 12px;
}
.t-card__author .avatar {
    width: 42px; height: 42px;
    border-radius: 50%;
    display: grid; place-items: center;
    color: #fff; font-weight: 700;
}
.t-card__author strong { display: block; font-size: 15px; }
.t-card__author small { color: var(--text-mute); font-size: 13px; }

/* ===== 价格 ===== */
.pricing { background: var(--bg-soft); }
.pricing__grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
    align-items: start;
    max-width: 1080px;
    margin: 0 auto;
}
.price-card {
    background: #fff;
    border: 1px solid var(--border);
    border-radius: var(--radius-lg);
    padding: 34px 30px;
    position: relative;
    transition: all .3s var(--ease);
}
.price-card:hover { transform: translateY(-4px); box-shadow: var(--shadow); }
.price-card--featured {
    border: 2px solid var(--primary);
    box-shadow: var(--shadow-lg);
    transform: scale(1.03);
}
.price-card--featured:hover { transform: scale(1.03) translateY(-4px); }
.price-card__badge {
    position: absolute;
    top: -14px; left: 50%;
    transform: translateX(-50%);
    background: linear-gradient(135deg, var(--primary), var(--accent));
    color: #fff;
    padding: 5px 16px;
    border-radius: 999px;
    font-size: 12px; font-weight: 700;
    white-space: nowrap;
    box-shadow: 0 6px 14px rgba(124,92,255,.4);
}
.price-card__name { font-size: 18px; font-weight: 800; margin-bottom: 12px; }
.price-card__price {
    font-size: 44px; font-weight: 900;
    color: var(--text);
    display: flex; align-items: baseline; gap: 2px;
    margin-bottom: 8px;
}
.price-card__price small { font-size: 20px; font-weight: 700; color: var(--text-soft); }
.price-card__price span { font-size: 16px; font-weight: 500; color: var(--text-mute); }
.price-card__desc { color: var(--text-mute); font-size: 14px; margin-bottom: 24px; }
.price-card__list { margin-bottom: 28px; display: flex; flex-direction: column; gap: 12px; }
.price-card__list li {
    padding-left: 28px;
    position: relative;
    color: var(--text-soft);
    font-size: 15px;
}
.price-card__list li::before {
    content: '✓';
    position: absolute;
    left: 0; top: 0;
    width: 20px; height: 20px;
    background: var(--primary-soft);
    color: var(--primary);
    border-radius: 50%;
    display: grid; place-items: center;
    font-size: 12px; font-weight: 800;
}
.price-card__list li strong { color: var(--text); font-weight: 800; }

/* ===== FAQ ===== */
.faq__inner {
    display: grid;
    grid-template-columns: 1fr 1.4fr;
    gap: 60px;
    align-items: start;
}
.faq__list { display: flex; flex-direction: column; gap: 12px; }
.faq__item {
    background: #fff;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 18px 22px;
    transition: all .3s var(--ease);
}
.faq__item[open] { box-shadow: var(--shadow-sm); border-color: var(--primary); }
.faq__item summary {
    font-weight: 700;
    font-size: 16px;
    list-style: none;
    display: flex; justify-content: space-between; align-items: center;
    gap: 16px;
}
.faq__item summary::-webkit-details-marker { display: none; }
.faq__item summary::after {
    content: '+';
    font-size: 22px;
    color: var(--primary);
    font-weight: 300;
    transition: transform .3s var(--ease);
    flex-shrink: 0;
}
.faq__item[open] summary::after { transform: rotate(45deg); }
.faq__item p {
    color: var(--text-soft);
    font-size: 14.5px;
    margin-top: 12px;
    line-height: 1.7;
}

/* ===== CTA ===== */
.cta {
    padding: 80px 0;
    position: relative;
}
.cta__inner {
    position: relative;
    border-radius: var(--radius-lg);
    padding: 70px 40px;
    text-align: center;
    overflow: hidden;
    background: linear-gradient(135deg, #0e1230 0%, #2a1a5e 50%, #4a1d6e 100%);
    color: #fff;
}
.cta__bg {
    position: absolute; inset: 0;
    background:
        radial-gradient(circle at 20% 30%, rgba(124,92,255,.5), transparent 40%),
        radial-gradient(circle at 80% 70%, rgba(255,122,89,.4), transparent 40%);
    z-index: 0;
}
.cta__content { position: relative; z-index: 1; max-width: 640px; margin: 0 auto; }
.cta__title {
    font-size: clamp(28px, 3.4vw, 40px);
    font-weight: 900;
    margin-bottom: 14px;
    letter-spacing: -.02em;
}
.cta__desc {
    font-size: 17px;
    color: rgba(255,255,255,.85);
    margin-bottom: 32px;
}
.cta__form {
    display: flex; gap: 10px;
    max-width: 460px;
    margin: 0 auto 16px;
    background: rgba(255,255,255,.12);
    backdrop-filter: blur(10px);
    padding: 8px;
    border-radius: 999px;
    border: 1px solid rgba(255,255,255,.2);
}
.cta__form input {
    flex: 1;
    background: transparent;
    border: 0;
    color: #fff;
    font-size: 15px;
    padding: 8px 18px;
    outline: none;
}
.cta__form input::placeholder { color: rgba(255,255,255,.6); }
.cta__form .btn--primary { background: #fff; color: var(--primary); box-shadow: none; }
.cta__form .btn--primary:hover { background: #fff; transform: translateY(-2px); box-shadow: 0 8px 20px rgba(0,0,0,.2); }
.cta__note { font-size: 13px; color: rgba(255,255,255,.6); }

/* ===== 页脚 ===== */
.footer {
    background: #0a0e26;
    color: rgba(255,255,255,.7);
    padding: 60px 0 0;
}
.footer__inner {
    display: grid;
    grid-template-columns: 1.2fr 2fr;
    gap: 60px;
    padding-bottom: 40px;
}
.footer__brand .nav__logo { color: #fff; margin-bottom: 16px; }
.footer__slogan { font-size: 14px; margin-bottom: 20px; }
.footer__social { display: flex; gap: 12px; }
.footer__social a {
    width: 36px; height: 36px;
    border-radius: 10px;
    background: rgba(255,255,255,.08);
    display: grid; place-items: center;
    font-size: 16px;
    transition: all .2s;
}
.footer__social a:hover { background: var(--primary); transform: translateY(-2px); }
.footer__cols {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
}
.footer__col h4 {
    color: #fff;
    font-size: 14px; font-weight: 700;
    margin-bottom: 16px;
    letter-spacing: .02em;
}
.footer__col a {
    display: block;
    font-size: 14px;
    padding: 5px 0;
    color: rgba(255,255,255,.65);
    transition: color .2s;
}
.footer__col a:hover { color: var(--primary-2); }
.footer__bottom {
    border-top: 1px solid rgba(255,255,255,.08);
    padding: 20px 0;
}
.footer__bottom-inner {
    display: flex; justify-content: space-between; flex-wrap: wrap; gap: 8px;
    font-size: 13px;
    color: rgba(255,255,255,.5);
}

/* ===== 滚动动画 ===== */
.reveal {
    opacity: 0;
    transform: translateY(28px);
    transition: opacity .7s var(--ease), transform .7s var(--ease);
}
.reveal.visible { opacity: 1; transform: translateY(0); }

/* ===== 子页面通用：页面 hero ===== */
.page-hero {
    position: relative;
    padding: 80px 0 60px;
    overflow: hidden;
    background: linear-gradient(135deg, #faf9ff 0%, #f3eeff 100%);
}
.page-hero__bg { position: absolute; inset: 0; z-index: 0; overflow: hidden; }
.page-hero__bg .hero__blob { opacity: .4; }
.page-hero__inner { position: relative; z-index: 1; }
.page-hero__crumb {
    font-size: 13px; color: var(--text-mute);
    margin-bottom: 18px;
    display: flex; gap: 8px; align-items: center;
}
.page-hero__crumb a:hover { color: var(--primary); }
.page-hero__title {
    font-size: clamp(32px, 4.4vw, 52px);
    font-weight: 900;
    letter-spacing: -.02em;
    margin-bottom: 16px;
    line-height: 1.15;
}
.page-hero__desc { font-size: 18px; color: var(--text-soft); max-width: 620px; }
.page-hero__meta {
    display: flex; gap: 24px; flex-wrap: wrap;
    margin-top: 28px;
}
.page-hero__meta-item {
    display: flex; flex-direction: column; gap: 2px;
}
.page-hero__meta-item strong { font-size: 22px; font-weight: 800; color: var(--text); }
.page-hero__meta-item small { color: var(--text-mute); font-size: 13px; }

/* 知识点列表 */
.kp-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 16px;
    margin-top: 8px;
}
.kp-card {
    background: #fff;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 20px 22px;
    transition: all .25s var(--ease);
    display: flex; align-items: center; gap: 14px;
}
.kp-card:hover { transform: translateY(-3px); box-shadow: var(--shadow); border-color: var(--primary); }
.kp-card__num {
    width: 40px; height: 40px;
    border-radius: 10px;
    background: var(--primary-soft);
    color: var(--primary);
    font-weight: 800;
    display: grid; place-items: center;
    flex-shrink: 0;
}
.kp-card__body strong { display: block; font-size: 16px; font-weight: 700; margin-bottom: 2px; }
.kp-card__body span { color: var(--text-mute); font-size: 13px; }
.kp-card__arrow { margin-left: auto; color: var(--text-mute); transition: all .25s; }
.kp-card:hover .kp-card__arrow { color: var(--primary); transform: translateX(4px); }

/* 试听课列表 */
.lessons { display: flex; flex-direction: column; gap: 12px; }
.lesson {
    display: flex; align-items: center; gap: 18px;
    background: #fff;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 16px 22px;
    transition: all .25s var(--ease);
}
.lesson:hover { box-shadow: var(--shadow-sm); border-color: var(--primary); }
.lesson__thumb {
    width: 64px; height: 64px;
    border-radius: 12px;
    display: grid; place-items: center;
    font-size: 26px;
    background: linear-gradient(135deg, var(--primary), var(--primary-2));
    color: #fff;
    flex-shrink: 0;
}
.lesson__info { flex: 1; }
.lesson__info h4 { font-size: 16px; font-weight: 700; margin-bottom: 4px; }
.lesson__info p { font-size: 13px; color: var(--text-mute); }
.lesson__info p span { color: var(--primary); font-weight: 600; }
.lesson__play {
    width: 42px; height: 42px;
    border-radius: 50%;
    background: var(--primary-soft);
    color: var(--primary);
    display: grid; place-items: center;
    transition: all .25s;
}
.lesson:hover .lesson__play { background: var(--primary); color: #fff; }

/* 双栏布局 */
.split { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; }
.split--aside { grid-template-columns: 1.4fr 1fr; }

/* 信息面板 */
.panel {
    background: #fff;
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 28px;
}
.panel__title { font-size: 18px; font-weight: 800; margin-bottom: 18px; display: flex; align-items: center; gap: 10px; }
.panel__title::before { content: ''; width: 4px; height: 18px; background: var(--primary); border-radius: 2px; }

.progress-item { margin-bottom: 18px; }
.progress-item:last-child { margin-bottom: 0; }
.progress-item__head { display: flex; justify-content: space-between; font-size: 14px; margin-bottom: 6px; }
.progress-item__head strong { font-weight: 700; }
.progress-item__head span { color: var(--text-mute); }
.progress-bar { height: 8px; background: var(--bg-soft); border-radius: 4px; overflow: hidden; }
.progress-bar__fill { height: 100%; border-radius: 4px; background: linear-gradient(90deg, var(--primary), var(--primary-2)); }

/* ===== 登录注册页 ===== */
.auth {
    min-height: 100vh;
    display: grid;
    grid-template-columns: 1fr 1fr;
}
.auth__visual {
    position: relative;
    background: linear-gradient(135deg, #0e1230 0%, #2a1a5e 50%, #4a1d6e 100%);
    color: #fff;
    padding: 60px;
    display: flex; flex-direction: column; justify-content: space-between;
    overflow: hidden;
}
.auth__visual::before, .auth__visual::after {
    content: '';
    position: absolute;
    border-radius: 50%;
    filter: blur(70px);
}
.auth__visual::before {
    width: 360px; height: 360px;
    background: radial-gradient(circle, rgba(124,92,255,.6), transparent 70%);
    top: -80px; right: -60px;
}
.auth__visual::after {
    width: 320px; height: 320px;
    background: radial-gradient(circle, rgba(255,122,89,.4), transparent 70%);
    bottom: -80px; left: -80px;
}
.auth__brand { position: relative; z-index: 1; }
.auth__brand .nav__logo { color: #fff; font-size: 22px; }
.auth__quote { position: relative; z-index: 1; }
.auth__quote h2 { font-size: 30px; font-weight: 900; line-height: 1.3; margin-bottom: 16px; }
.auth__quote p { color: rgba(255,255,255,.85); font-size: 15px; max-width: 380px; }
.auth__stats { position: relative; z-index: 1; display: flex; gap: 30px; }
.auth__stats div strong { display: block; font-size: 26px; font-weight: 900; }
.auth__stats div small { color: rgba(255,255,255,.7); font-size: 13px; }

.auth__main {
    display: flex; align-items: center; justify-content: center;
    padding: 40px;
    background: var(--bg);
}
.auth__card { width: 100%; max-width: 400px; }
.auth__tabs {
    display: flex;
    background: var(--bg-soft);
    border-radius: 999px;
    padding: 4px;
    margin-bottom: 28px;
}
.auth__tab {
    flex: 1;
    padding: 10px;
    border-radius: 999px;
    font-weight: 600;
    font-size: 15px;
    color: var(--text-soft);
    transition: all .25s var(--ease);
}
.auth__tab.active { background: #fff; color: var(--primary); box-shadow: var(--shadow-sm); }
.auth__title { font-size: 24px; font-weight: 800; margin-bottom: 6px; }
.auth__subtitle { color: var(--text-soft); font-size: 14px; margin-bottom: 26px; }

.form-field { margin-bottom: 18px; }
.form-field__label { display: block; font-size: 13px; font-weight: 600; color: var(--text-soft); margin-bottom: 8px; }
.form-field__input {
    width: 100%;
    padding: 12px 16px;
    border: 1.5px solid var(--border);
    border-radius: var(--radius-sm);
    font-size: 15px;
    background: #fff;
    transition: all .2s var(--ease);
    font-family: inherit;
}
.form-field__input:focus { outline: none; border-color: var(--primary); box-shadow: 0 0 0 4px var(--primary-soft); }
.form-field__input.error { border-color: var(--pink); box-shadow: 0 0 0 4px rgba(255,92,138,.15); }
.form-field__msg { color: var(--pink); font-size: 12px; margin-top: 6px; min-height: 14px; }

.form-field__group { position: relative; }
.form-field__group .form-field__input { padding-right: 110px; }
.form-field__btn {
    position: absolute;
    right: 6px; top: 50%;
    transform: translateY(-50%);
    padding: 7px 14px;
    background: var(--primary-soft);
    color: var(--primary);
    border-radius: 8px;
    font-size: 13px; font-weight: 600;
    transition: all .2s;
}
.form-field__btn:hover { background: var(--primary); color: #fff; }
.form-field__toggle {
    position: absolute;
    right: 14px; top: 50%;
    transform: translateY(-50%);
    cursor: pointer;
    color: var(--text-mute);
    font-size: 18px;
}

.form-row { display: flex; justify-content: space-between; align-items: center; margin-bottom: 22px; font-size: 13px; }
.form-row label { display: flex; align-items: center; gap: 6px; color: var(--text-soft); cursor: pointer; }
.form-row input[type=checkbox] { accent-color: var(--primary); width: 16px; height: 16px; }
.form-row a { color: var(--primary); font-weight: 600; }

.form-divider {
    display: flex; align-items: center; gap: 14px;
    color: var(--text-mute); font-size: 13px;
    margin: 24px 0;
}
.form-divider::before, .form-divider::after { content: ''; flex: 1; height: 1px; background: var(--border); }

.social-row { display: flex; gap: 12px; }
.social-btn {
    flex: 1;
    padding: 11px;
    border: 1.5px solid var(--border);
    border-radius: var(--radius-sm);
    font-weight: 600; font-size: 14px;
    display: flex; align-items: center; justify-content: center; gap: 8px;
    transition: all .2s;
    background: #fff;
}
.social-btn:hover { border-color: var(--primary); color: var(--primary); }
.auth__foot { text-align: center; font-size: 14px; color: var(--text-soft); margin-top: 24px; }
.auth__foot a { color: var(--primary); font-weight: 700; }

/* ===== App 下载页 ===== */
.download-hero {
    position: relative;
    padding: 80px 0 100px;
    overflow: hidden;
    background: linear-gradient(135deg, #faf9ff 0%, #eef0ff 100%);
}
.download-hero__inner {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: center;
}
.download-hero__title {
    font-size: clamp(32px, 4.4vw, 52px);
    font-weight: 900;
    letter-spacing: -.02em;
    line-height: 1.15;
    margin-bottom: 18px;
}
.download-hero__desc { font-size: 18px; color: var(--text-soft); margin-bottom: 30px; max-width: 480px; }
.download-actions { display: flex; gap: 14px; flex-wrap: wrap; margin-bottom: 22px; }
.dl-btn {
    display: inline-flex; align-items: center; gap: 12px;
    padding: 12px 22px;
    border-radius: 14px;
    background: #1a1d3a;
    color: #fff;
    transition: all .25s var(--ease);
}
.dl-btn:hover { transform: translateY(-3px); box-shadow: var(--shadow); background: #000; }
.dl-btn__ico { font-size: 26px; }
.dl-btn__text small { display: block; font-size: 11px; opacity: .8; }
.dl-btn__text strong { display: block; font-size: 16px; font-weight: 700; }
.download-qr {
    display: inline-flex; align-items: center; gap: 14px;
    background: #fff;
    padding: 14px 18px;
    border-radius: 14px;
    box-shadow: var(--shadow-sm);
}
.download-qr__img {
    width: 92px; height: 92px;
    background:
        repeating-linear-gradient(0deg, #1a1d3a 0 6px, transparent 6px 12px),
        repeating-linear-gradient(90deg, #1a1d3a 0 6px, transparent 6px 12px);
    border-radius: 8px;
    position: relative;
}
.download-qr__img::before, .download-qr__img::after {
    content: ''; position: absolute;
    width: 22px; height: 22px;
    border: 5px solid #1a1d3a;
    border-radius: 4px;
    background: #fff;
}
.download-qr__img::before { top: 4px; left: 4px; }
.download-qr__img::after { bottom: 4px; left: 4px; }
.download-qr__text strong { display: block; font-weight: 800; font-size: 15px; }
.download-qr__text small { color: var(--text-mute); font-size: 12px; }

/* 手机 mockup */
.phone {
    position: relative;
    width: 280px; height: 560px;
    margin: 0 auto;
    background: #1a1d3a;
    border-radius: 38px;
    padding: 12px;
    box-shadow: var(--shadow-lg), 0 0 0 8px rgba(255,255,255,.6);
}
.phone::before {
    content: '';
    position: absolute;
    top: 18px; left: 50%; transform: translateX(-50%);
    width: 100px; height: 22px;
    background: #1a1d3a;
    border-radius: 999px;
    z-index: 2;
}
.phone__screen {
    width: 100%; height: 100%;
    background: linear-gradient(160deg, #faf9ff, #f0edff);
    border-radius: 28px;
    overflow: hidden;
    display: flex; flex-direction: column;
    padding: 40px 16px 16px;
    gap: 10px;
}
.phone__greet { font-size: 13px; color: var(--text-mute); }
.phone__name { font-size: 20px; font-weight: 800; margin-bottom: 4px; }
.phone__card {
    background: linear-gradient(135deg, var(--primary), var(--primary-2));
    color: #fff;
    border-radius: 14px;
    padding: 14px;
    box-shadow: 0 8px 20px rgba(124,92,255,.35);
}
.phone__card strong { display: block; font-size: 13px; opacity: .9; }
.phone__card b { font-size: 22px; font-weight: 900; }
.phone__list { display: flex; flex-direction: column; gap: 8px; }
.phone__item {
    background: #fff;
    border-radius: 10px;
    padding: 10px 12px;
    display: flex; align-items: center; gap: 10px;
    font-size: 12px;
    box-shadow: 0 2px 6px rgba(0,0,0,.04);
}
.phone__item-ico {
    width: 28px; height: 28px;
    border-radius: 8px;
    display: grid; place-items: center;
    font-size: 14px;
    background: var(--primary-soft);
    color: var(--primary);
    flex-shrink: 0;
}
.phone__item strong { display: block; font-weight: 700; color: var(--text); }
.phone__item small { color: var(--text-mute); }

/* 功能特性卡 */
.feat-row {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 24px;
}
.feat-row .feature-card { padding: 28px 24px; }

/* 截图墙 */
.shots { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.shot {
    aspect-ratio: 9/16;
    border-radius: var(--radius);
    overflow: hidden;
    position: relative;
    box-shadow: var(--shadow-sm);
    display: grid; place-items: center;
    color: #fff; font-weight: 700;
    text-align: center;
    padding: 20px;
    transition: transform .3s var(--ease);
}
.shot:hover { transform: translateY(-6px) scale(1.02); }
.shot:nth-child(1) { background: linear-gradient(135deg, #7c5cff, #a78bfa); }
.shot:nth-child(2) { background: linear-gradient(135deg, #ff7a59, #ffb199); margin-top: 30px; }
.shot:nth-child(3) { background: linear-gradient(135deg, #2bb673, #6fdab0); }

/* ===== 响应式 ===== */
@media (max-width: 960px) {
    .hero__inner { grid-template-columns: 1fr; gap: 50px; }
    .hero__visual { max-width: 460px; margin: 0 auto; width: 100%; }
    .features__grid, .subjects__grid, .testimonials__grid, .pricing__grid, .how__grid {
        grid-template-columns: repeat(2, 1fr);
    }
    .price-card--featured { transform: none; }
    .price-card--featured:hover { transform: translateY(-4px); }
    .faq__inner { grid-template-columns: 1fr; gap: 32px; }
    .footer__inner { grid-template-columns: 1fr; gap: 40px; }
    .split, .split--aside { grid-template-columns: 1fr; }
    .kp-grid { grid-template-columns: 1fr; }
    .download-hero__inner { grid-template-columns: 1fr; gap: 40px; }
    .feat-row { grid-template-columns: repeat(2, 1fr); }
    .shots { grid-template-columns: repeat(3, 1fr); gap: 12px; }
    .auth { grid-template-columns: 1fr; }
    .auth__visual { display: none; }
}

@media (max-width: 680px) {
    .nav__menu, .nav__actions { display: none; }
    .nav__toggle { display: flex; }
    .nav.menu-open .nav__menu {
        display: flex;
        flex-direction: column;
        position: absolute;
        top: 68px; left: 0; right: 0;
        background: #fff;
        padding: 16px 24px;
        border-bottom: 1px solid var(--border);
        box-shadow: var(--shadow);
    }
    .nav.menu-open .nav__actions {
        display: flex;
        position: absolute;
        top: 68px; right: 24px;
        background: #fff;
        padding: 16px;
        border-radius: 0 0 var(--radius) var(--radius);
    }
    .section { padding: 60px 0; }
    .features__grid, .subjects__grid, .testimonials__grid, .pricing__grid, .how__grid, .stats__inner {
        grid-template-columns: 1fr;
    }
    .stats__inner { gap: 32px; }
    .hero { padding: 40px 0 60px; }
    .hero__chip--1 { left: 0; }
    .hero__chip--2 { right: 0; }
    .footer__cols { grid-template-columns: repeat(2, 1fr); }
    .cta__form { flex-direction: column; border-radius: var(--radius); }
    .cta__form .btn { width: 100%; }
    .cta__inner { padding: 50px 24px; }
    .footer__bottom-inner { justify-content: center; text-align: center; }
    .feat-row { grid-template-columns: 1fr; }
    .shots { grid-template-columns: 1fr; max-width: 280px; margin: 0 auto; }
    .shot:nth-child(2) { margin-top: 0; }
    .lesson { flex-wrap: wrap; }
    .auth__main { padding: 30px 20px; }
    .download-actions { flex-direction: column; align-items: stretch; }
    .dl-btn { justify-content: center; }
}

@media (max-width: 420px) {
    .footer__cols { grid-template-columns: 1fr; }
}

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