/* ==========================================================================
   学护 · 官网
   设计方向：「静息」——一份会呼吸的产品页
   把 App 最核心的 20-20-20 呼吸圆环做成首屏主体，整页节奏放慢，
   让访客在阅读时就已经体验到这个产品在做什么。
   ========================================================================== */

@font-face {
  font-family: "Fredoka";
  font-style: normal;
  font-weight: 300 700;
  font-display: swap;
  src: url("fonts/Fredoka-latin.woff2") format("woff2");
  unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+2000-206F, U+2074, U+20AC,
    U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
}

:root {
  /* 色彩：从深松绿过渡到暖纸白 */
  --ink: #06231b;
  --pine: #0b3d2e;
  --pine-2: #0f4c39;
  --moss: #1f9d6b;
  --moss-soft: #2fb87f;
  --mint: #34d399;
  --glow: #a7f3d0;
  --amber: #d98324;

  --paper: #f3f8f5;
  --paper-2: #e9f2ec;
  --card: #ffffff;
  --line: rgba(11, 61, 46, 0.12);
  --line-strong: rgba(11, 61, 46, 0.22);

  --text: #10312a;
  --text-dim: #4a6b60;
  --text-faint: #7d968d;
  --on-dark: #eaf6f0;
  --on-dark-dim: rgba(234, 246, 240, 0.62);

  --font-cn: "PingFang SC", "HarmonyOS Sans SC", "Source Han Sans SC", "Noto Sans SC",
    "Microsoft YaHei", "Hiragino Sans GB", sans-serif;
  --font-display: "Fredoka", var(--font-cn);

  --maxw: 1120px;
  --radius: 22px;
  --radius-lg: 30px;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  font-family: var(--font-cn);
  color: var(--text);
  background: var(--paper);
  line-height: 1.75;
  letter-spacing: 0.01em;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

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

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

/* 颗粒质感：避免大面积纯色显得平淡 */
.grain {
  position: fixed;
  inset: 0;
  z-index: 1;
  pointer-events: none;
  opacity: 0.035;
  mix-blend-mode: multiply;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='160' height='160'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='3'/%3E%3C/filter%3E%3Crect width='160' height='160' filter='url(%23n)'/%3E%3C/svg%3E");
}

/* ---------------------------------------------------------------- 顶栏 --- */

.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  padding: 16px clamp(18px, 5vw, 48px);
  backdrop-filter: blur(14px);
  background: rgba(243, 248, 245, 0.78);
  border-bottom: 1px solid var(--line);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  letter-spacing: 0.06em;
}

.brand__mark {
  display: grid;
  place-items: center;
  width: 34px;
  height: 34px;
  border-radius: 12px;
  color: #fff;
  background: linear-gradient(145deg, var(--moss-soft), var(--pine));
  box-shadow: 0 6px 18px -8px rgba(31, 157, 107, 0.9);
}

.brand__mark svg {
  width: 19px;
  height: 19px;
}

.brand__name {
  font-size: 17px;
}

.topbar__nav {
  display: flex;
  align-items: center;
  gap: clamp(12px, 2.4vw, 28px);
  font-size: 14px;
  color: var(--text-dim);
}

.topbar__nav a {
  transition: color 0.2s;
}

.topbar__nav a:hover {
  color: var(--moss);
}

.topbar__cta {
  padding: 8px 18px;
  border-radius: 999px;
  color: #fff !important;
  background: var(--pine);
  transition: transform 0.2s, background 0.2s;
}

.topbar__cta:hover {
  background: var(--moss);
  transform: translateY(-1px);
}

/* ---------------------------------------------------------------- 首屏 --- */

.hero {
  position: relative;
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  align-items: center;
  gap: clamp(24px, 5vw, 64px);
  max-width: var(--maxw);
  margin: 0 auto;
  padding: clamp(48px, 9vw, 104px) clamp(18px, 5vw, 48px) clamp(56px, 8vw, 96px);
  background:
    radial-gradient(70% 55% at 78% 30%, rgba(52, 211, 153, 0.16), transparent 70%),
    radial-gradient(50% 45% at 8% 82%, rgba(31, 157, 107, 0.12), transparent 72%);
}

.eyebrow {
  margin: 0 0 20px;
  font-size: 12.5px;
  letter-spacing: 0.34em;
  text-transform: uppercase;
  color: var(--moss);
  font-weight: 600;
}

.hero__title {
  margin: 0;
  font-size: clamp(46px, 7.4vw, 84px);
  line-height: 1.02;
  letter-spacing: -0.015em;
  font-weight: 800;
  color: var(--ink);
}

.hero__lede {
  margin: 26px 0 0;
  max-width: 30em;
  font-size: clamp(15px, 1.55vw, 17px);
  color: var(--text-dim);
}

.hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 34px;
}

.hero__meta {
  margin: 22px 0 0;
  font-size: 12.5px;
  color: var(--text-faint);
  font-family: var(--font-display);
  letter-spacing: 0.03em;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  padding: 13px 24px;
  border-radius: 999px;
  font-size: 15px;
  font-weight: 600;
  transition: transform 0.18s ease, box-shadow 0.18s ease, background 0.18s ease;
}

.btn svg {
  width: 18px;
  height: 18px;
}

.btn--primary {
  color: #fff;
  background: linear-gradient(145deg, var(--moss-soft), var(--pine));
  box-shadow: 0 14px 30px -14px rgba(11, 61, 46, 0.7);
}

.btn--primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 20px 38px -16px rgba(11, 61, 46, 0.75);
}

.btn--ghost {
  color: var(--pine);
  border: 1px solid var(--line-strong);
  background: rgba(255, 255, 255, 0.55);
}

.btn--ghost:hover {
  background: #fff;
  transform: translateY(-2px);
}

.btn--lg {
  padding: 15px 30px;
  font-size: 16px;
}

/* ------------------------------------------------------------ 呼吸圆环 --- */

.hero__stage {
  position: relative;
  display: grid;
  place-items: center;
  min-height: 380px;
}

.ring {
  position: relative;
  width: min(340px, 74vw);
  aspect-ratio: 1;
  display: grid;
  place-items: center;
}

.ring__halo,
.ring__halo--2 {
  position: absolute;
  inset: 6%;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(52, 211, 153, 0.3), rgba(52, 211, 153, 0) 68%);
  animation: breathe 4s ease-in-out infinite;
}

.ring__halo--2 {
  inset: 20%;
  background: radial-gradient(circle, rgba(167, 243, 208, 0.55), rgba(167, 243, 208, 0) 70%);
  animation-delay: -0.6s;
}

.ring__svg {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  transform: rotate(-90deg);
  fill: none;
  stroke-linecap: round;
}

.ring__track {
  stroke: rgba(11, 61, 46, 0.1);
  stroke-width: 7;
}

.ring__pulse {
  stroke: url(#none);
  stroke: var(--mint);
  stroke-width: 7;
  stroke-dasharray: 653;
  stroke-dashoffset: 653;
  filter: drop-shadow(0 0 8px rgba(52, 211, 153, 0.65));
  animation: sweep 4s linear infinite;
}

.ring__core {
  position: relative;
  display: flex;
  align-items: baseline;
  gap: 4px;
  color: var(--pine);
  font-family: var(--font-display);
}

.ring__num {
  font-size: clamp(60px, 11vw, 92px);
  font-weight: 600;
  line-height: 1;
  letter-spacing: -0.03em;
}

.ring__unit {
  font-size: 18px;
  font-weight: 500;
  color: var(--moss);
}

.ring__hint {
  position: absolute;
  bottom: 14%;
  margin: 0;
  font-size: 13px;
  letter-spacing: 0.24em;
  color: var(--text-faint);
  animation: fade-soft 4s ease-in-out infinite;
}

.hero__triple {
  margin: 14px 0 0;
  display: flex;
  align-items: center;
  gap: 14px;
  font-family: var(--font-display);
  font-size: clamp(22px, 3vw, 30px);
  font-weight: 600;
  color: rgba(11, 61, 46, 0.18);
  letter-spacing: 0.1em;
}

.hero__triple i {
  font-style: normal;
  font-size: 0.55em;
  color: rgba(11, 61, 46, 0.22);
}

@keyframes breathe {
  0%,
  100% {
    transform: scale(0.9);
    opacity: 0.5;
  }
  50% {
    transform: scale(1.07);
    opacity: 0.95;
  }
}

@keyframes sweep {
  0% {
    stroke-dashoffset: 653;
  }
  100% {
    stroke-dashoffset: 0;
  }
}

@keyframes fade-soft {
  0%,
  100% {
    opacity: 0.35;
  }
  50% {
    opacity: 1;
  }
}

/* ---------------------------------------------------------------- 主张 --- */

.creed {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: clamp(40px, 7vw, 88px) clamp(18px, 5vw, 48px);
  border-top: 1px solid var(--line);
}

.creed__line {
  margin: 0 0 clamp(34px, 5vw, 60px);
  font-size: clamp(26px, 3.6vw, 44px);
  line-height: 1.38;
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--ink);
}

.creed__line strong {
  color: var(--moss);
  font-weight: 800;
}

.creed__cols {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: clamp(20px, 3vw, 40px);
}

.creed__col h3 {
  margin: 0 0 10px;
  font-size: 16px;
  color: var(--pine);
}

.creed__col h3::before {
  content: "";
  display: block;
  width: 26px;
  height: 3px;
  margin-bottom: 12px;
  border-radius: 2px;
  background: var(--mint);
}

.creed__col p {
  margin: 0;
  font-size: 14.5px;
  color: var(--text-dim);
}

.creed__col strong {
  color: var(--pine);
}

/* ---------------------------------------------------------------- 功能 --- */

.features {
  background: linear-gradient(180deg, var(--paper) 0%, var(--paper-2) 100%);
  padding: clamp(48px, 7vw, 92px) 0 clamp(56px, 8vw, 100px);
}

.features > * {
  max-width: var(--maxw);
  margin-inline: auto;
  padding-inline: clamp(18px, 5vw, 48px);
}

.section-head {
  margin-bottom: clamp(30px, 4vw, 48px);
}

.section-head__idx {
  display: inline-block;
  margin-bottom: 14px;
  font-family: var(--font-display);
  font-size: 12.5px;
  letter-spacing: 0.3em;
  color: var(--moss);
}

.section-head__idx--light {
  color: var(--mint);
}

.section-head h2 {
  margin: 0;
  font-size: clamp(30px, 4.4vw, 50px);
  line-height: 1.16;
  letter-spacing: -0.02em;
  font-weight: 800;
  color: var(--ink);
}

.section-head p {
  margin: 14px 0 0;
  max-width: 34em;
  font-size: 15.5px;
  color: var(--text-dim);
}

.feature-list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.feature {
  display: grid;
  grid-template-columns: 74px 1fr auto;
  align-items: start;
  gap: clamp(14px, 2.4vw, 32px);
  padding: clamp(22px, 3vw, 32px) 0;
  border-top: 1px solid var(--line);
}

.feature:last-child {
  border-bottom: 1px solid var(--line);
}

.feature__idx {
  font-family: var(--font-display);
  font-size: 30px;
  font-weight: 600;
  line-height: 1;
  color: rgba(31, 157, 107, 0.32);
  transition: color 0.3s;
}

.feature:hover .feature__idx {
  color: var(--moss);
}

.feature__body h3 {
  margin: 0 0 8px;
  font-size: clamp(18px, 2.1vw, 22px);
  color: var(--ink);
}

.feature__body h3 em {
  font-style: normal;
  margin-left: 8px;
  font-family: var(--font-display);
  font-size: 0.62em;
  font-weight: 500;
  padding: 2px 9px;
  border-radius: 999px;
  color: var(--moss);
  background: rgba(31, 157, 107, 0.1);
  vertical-align: middle;
}

.feature__body p {
  margin: 0;
  max-width: 46em;
  font-size: 14.5px;
  color: var(--text-dim);
}

.feature__body strong {
  color: var(--pine);
}

.feature__tag {
  align-self: center;
  font-size: 12px;
  padding: 6px 14px;
  border-radius: 999px;
  white-space: nowrap;
  color: var(--pine);
  background: rgba(255, 255, 255, 0.8);
  border: 1px solid var(--line);
}

/* ---------------------------------------------------------------- 截图 --- */

.shots {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: clamp(48px, 7vw, 92px) 0 clamp(48px, 7vw, 88px);
}

.shots .section-head {
  padding-inline: clamp(18px, 5vw, 48px);
}

.shots__rail {
  display: flex;
  gap: clamp(14px, 2vw, 24px);
  overflow-x: auto;
  padding: 6px clamp(18px, 5vw, 48px) 26px;
  scroll-snap-type: x mandatory;
  scrollbar-width: thin;
}

.shots__rail::-webkit-scrollbar {
  height: 6px;
}

.shots__rail::-webkit-scrollbar-thumb {
  border-radius: 999px;
  background: var(--line-strong);
}

.shot {
  flex: 0 0 auto;
  width: clamp(212px, 25vw, 268px);
  margin: 0;
  scroll-snap-align: center;
}

.shot img {
  width: 100%;
  border-radius: var(--radius);
  border: 1px solid var(--line);
  background: #fff;
  box-shadow: 0 26px 50px -30px rgba(11, 61, 46, 0.55);
  transition: transform 0.35s ease, box-shadow 0.35s ease;
}

.shot:hover img {
  transform: translateY(-6px);
  box-shadow: 0 34px 60px -30px rgba(11, 61, 46, 0.6);
}

.shot figcaption {
  margin-top: 12px;
  font-size: 12.5px;
  text-align: center;
  color: var(--text-faint);
}

/* ---------------------------------------------------------------- 隐私 --- */

.privacy {
  position: relative;
  color: var(--on-dark);
  background:
    radial-gradient(60% 50% at 82% 12%, rgba(52, 211, 153, 0.2), transparent 70%),
    linear-gradient(165deg, var(--pine-2) 0%, var(--ink) 100%);
  padding: clamp(56px, 8vw, 108px) 0;
  overflow: hidden;
}

.privacy__inner {
  max-width: var(--maxw);
  margin: 0 auto;
  padding-inline: clamp(18px, 5vw, 48px);
}

.privacy h2 {
  margin: 0;
  font-size: clamp(30px, 4.4vw, 50px);
  line-height: 1.16;
  letter-spacing: -0.02em;
  font-weight: 800;
  color: #fff;
}

.privacy__lede {
  margin: 18px 0 0;
  max-width: 36em;
  font-size: 16px;
  color: var(--on-dark-dim);
}

.privacy__lede strong {
  color: var(--glow);
}

.privacy__list {
  list-style: none;
  margin: clamp(34px, 5vw, 54px) 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: clamp(20px, 3vw, 40px);
}

.privacy__list li {
  display: grid;
  grid-template-columns: 22px 1fr;
  gap: 14px;
}

.tick {
  position: relative;
  width: 22px;
  height: 22px;
  margin-top: 3px;
  border-radius: 50%;
  background: rgba(52, 211, 153, 0.16);
  border: 1px solid rgba(52, 211, 153, 0.42);
}

.tick::after {
  content: "";
  position: absolute;
  left: 7px;
  top: 5px;
  width: 6px;
  height: 10px;
  border-right: 2px solid var(--mint);
  border-bottom: 2px solid var(--mint);
  transform: rotate(42deg);
}

.privacy__list h3 {
  margin: 0 0 6px;
  font-size: 16px;
  color: #fff;
}

.privacy__list p {
  margin: 0;
  font-size: 14px;
  color: var(--on-dark-dim);
}

.privacy__list strong {
  color: var(--glow);
}

/* ---------------------------------------------------------------- 下载 --- */

.download {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: clamp(52px, 8vw, 100px) clamp(18px, 5vw, 48px);
}

.download__card {
  display: grid;
  grid-template-columns: 1.25fr 0.75fr;
  gap: clamp(24px, 4vw, 48px);
  padding: clamp(24px, 3.6vw, 44px);
  border-radius: var(--radius-lg);
  background: var(--card);
  border: 1px solid var(--line);
  box-shadow: 0 40px 80px -60px rgba(11, 61, 46, 0.7);
}

.download__ver {
  display: flex;
  align-items: center;
  gap: 12px;
  margin: 0;
  font-family: var(--font-display);
  font-size: 34px;
  font-weight: 600;
  letter-spacing: -0.02em;
  color: var(--ink);
}

.download__badge {
  font-family: var(--font-cn);
  font-size: 12px;
  font-weight: 500;
  letter-spacing: 0.04em;
  padding: 4px 11px;
  border-radius: 999px;
  color: var(--moss);
  background: rgba(31, 157, 107, 0.1);
}

.download__sub {
  margin: 8px 0 0;
  font-size: 13px;
  color: var(--text-faint);
}

.download__notes {
  margin: 22px 0 26px;
  padding: 0;
  list-style: none;
}

.download__notes li {
  position: relative;
  padding-left: 18px;
  font-size: 14px;
  color: var(--text-dim);
}

.download__notes li + li {
  margin-top: 7px;
}

.download__notes li::before {
  content: "";
  position: absolute;
  left: 2px;
  top: 11px;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--mint);
}

.download__hint {
  margin: 16px 0 0;
  font-size: 12.5px;
  color: var(--text-faint);
}

.download__hint strong {
  color: var(--pine);
}

.download__how {
  padding-left: clamp(0px, 3vw, 36px);
  border-left: 1px solid var(--line);
}

.download__how h3 {
  margin: 0 0 12px;
  font-size: 15px;
  color: var(--pine);
}

.download__how p {
  margin: 0 0 12px;
  font-size: 13.5px;
  color: var(--text-dim);
}

.download__how strong {
  color: var(--pine);
}

.download__how-dim {
  color: var(--text-faint) !important;
  font-size: 12.5px !important;
}

/* ---------------------------------------------------------------- 页脚 --- */

.footer {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 34px clamp(18px, 5vw, 48px) 46px;
  border-top: 1px solid var(--line);
  font-size: 12.5px;
  color: var(--text-faint);
}

.footer__brand {
  display: flex;
  align-items: baseline;
  gap: 10px;
}

.footer__brand strong {
  font-size: 15px;
  color: var(--pine);
  letter-spacing: 0.06em;
}

.footer__meta p {
  margin: 3px 0;
  text-align: right;
}

.footer__meta a {
  color: var(--moss);
}

/* ---------------------------------------------------------- 进场动画 --- */

.reveal {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 0.7s cubic-bezier(0.22, 1, 0.36, 1), transform 0.7s cubic-bezier(0.22, 1, 0.36, 1);
}

.reveal.is-in {
  opacity: 1;
  transform: none;
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
  .ring__halo,
  .ring__halo--2,
  .ring__pulse,
  .ring__hint {
    animation: none;
  }
  .ring__pulse {
    stroke-dashoffset: 180;
  }
  .reveal {
    opacity: 1;
    transform: none;
    transition: none;
  }
}

/* ---------------------------------------------------------------- 响应 --- */

@media (max-width: 940px) {
  .hero {
    grid-template-columns: 1fr;
    text-align: left;
  }

  .hero__stage {
    order: -1;
    min-height: 300px;
    margin-bottom: 12px;
  }

  .creed__cols {
    grid-template-columns: 1fr;
    gap: 24px;
  }

  .privacy__list {
    grid-template-columns: 1fr;
  }

  .download__card {
    grid-template-columns: 1fr;
  }

  .download__how {
    padding-left: 0;
    padding-top: 24px;
    border-left: 0;
    border-top: 1px solid var(--line);
  }

  .feature {
    grid-template-columns: 54px 1fr;
  }

  .feature__tag {
    grid-column: 2;
    justify-self: start;
    margin-top: 4px;
  }

  .footer__meta p {
    text-align: left;
  }
}

@media (max-width: 620px) {
  .topbar__nav a:not(.topbar__cta) {
    display: none;
  }

  .hero__triple {
    display: none;
  }
}