/* ============================================================
   XTRACT — 设计令牌
   纸张质感 · 石头蓝 · 单一精致的钴蓝点缀
   ============================================================ */
:root {
  /* 基础色板 */
  --paper:      #f4f1ea;   /* 页面底：暖纸白 */
  --paper-raised:#fbfaf6;  /* 卡片面：更亮的纸 */
  --ink:        #1c2520;   /* 主文字：墨绿黑 */
  --ink-dim:    #5c645e;   /* 次要文字 */
  --line:       rgba(28,37,32,.14);   /* 发丝线 */
  --stone:      #e3ded2;   /* 分隔的石头色 */

  /* 点缀色：石头蓝（用于唯一动作） */
  --accent:     #3556a7;
  --accent-ink: #ffffff;
  --accent-soft: rgba(53,86,167,.12);

  /* 字体 */
  --sans:  "Space Grotesk", "PingFang SC", "Microsoft YaHei", system-ui, -apple-system, sans-serif;

  --radius: 14px;
  --maxw: 1120px;
}

/* ============ 基础 ============ */
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

::selection { background: var(--accent-soft); }

a { color: inherit; }
h1,h2,h3 { font-weight: 600; line-height: 1.15; }

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
  border-radius: 4px;
}

/* 键盘用户减速动效偏好：尊重 */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation: none !important; transition: none !important; }
}

/* ============ 顶部导航 ============ */
.masthead {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 22px clamp(20px, 4vw, 40px);
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
}
.brand-dot {
  width: 10px; height: 10px;
  border-radius: 50%;
  background: var(--accent);
}
.brand-word {
  font-weight: 700;
  letter-spacing: .22em;
  font-size: 14px;
}
.menu {
  display: flex;
  gap: 26px;
}
.menu a {
  text-decoration: none;
  color: var(--ink-dim);
  font-size: 14px;
  transition: color .15s;
}
.menu a:hover { color: var(--ink); }

/* ============ HERO ============ */
.hero {
  max-width: 760px;
  margin: 40px auto 0;
  padding: 0 clamp(20px, 5vw, 40px) 30px;
  text-align: center;
}
.hero-title {
  font-family: var(--sans);
  font-weight: 700;
  font-size: clamp(32px, 6vw, 52px);
  letter-spacing: -.01em;
  margin: 0 0 18px;
}
.hero-title-strong { color: var(--accent); }
.hero-sub {
  font-size: clamp(15px, 2.2vw, 18px);
  color: var(--ink-dim);
  margin: 0 0 40px;
}

/* ============ 提取输入 ============ */
.picker { margin: 0 0 36px; }
.field {
  display: flex;
  gap: 10px;
  padding: 8px;
  background: var(--paper-raised);
  border: 1px solid var(--line);
  border-radius: 999px;
  box-shadow: 0 8px 30px rgba(28,37,32,.06);
}
.field:focus-within {
  border-color: var(--accent);
  box-shadow: 0 8px 30px var(--accent-soft), 0 0 0 3px var(--accent-soft);
}
#url {
  flex: 1;
  min-width: 0;
  border: none;
  background: transparent;
  padding: 14px 18px;
  font: 400 15px var(--sans);
  color: var(--ink);
}
#url::placeholder { color: #9aa29d; }
#url:focus { outline: none; }

.extract-btn {
  flex-shrink: 0;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  border: none;
  background: var(--accent);
  color: var(--accent-ink);
  font: 500 15px var(--sans);
  padding: 14px 26px;
  border-radius: 999px;
  cursor: pointer;
  transition: background .2s, transform .05s;
}
.extract-btn:hover { background: #2a4587; }
.extract-btn:active { transform: scale(.98); }

/* 加载中：按钮旋转指示器 */
.extract-btn.is-loading { pointer-events: none; opacity: .85; }
.btn-label { display: inline; }
.extract-btn.is-loading .btn-label { display: none; }
.btn-loader {
  display: none;
  width: 18px; height: 18px;
  border-radius: 50%;
  border: 2px solid rgba(255,255,255,.35);
  border-top-color: #fff;
  animation: spin .7s linear infinite;
}
.extract-btn.is-loading .btn-loader { display: inline-block; }
@keyframes spin { to { transform: rotate(360deg); } }

.field-hint {
  margin: 14px 0 0;
  font-size: 13px;
  color: var(--ink-dim);
}
.field-error {
  margin: 12px 0 0;
  font-size: 14px;
  color: #b43a2f;
  font-weight: 500;
}

/* ============ 特性条 ============ */
.ticks {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 8px 26px;
  margin: 0;
  padding: 0;
  list-style: none;
  color: var(--ink-dim);
  font-size: 13.5px;
}
.ticks li::before {
  content: "—";
  color: var(--accent);
  margin-right: 8px;
}

/* ============ 结果卡片 ============ */
.result {
  max-width: 460px;
  margin: 0 auto 30px;
  padding: 0 clamp(20px, 5vw, 40px);
}
.card {
  background: var(--paper-raised);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 20px 22px;
  box-shadow: 0 18px 50px rgba(28,37,32,.1);
}
.card-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 16px;
}
.chip-success {
  font-size: 12.5px;
  font-weight: 500;
  color: var(--accent);
  background: var(--accent-soft);
  padding: 5px 12px;
  border-radius: 999px;
}
.close {
  border: none;
  background: none;
  font-size: 22px;
  line-height: 1;
  color: var(--ink-dim);
  cursor: pointer;
  padding: 2px 6px;
}
.close:hover { color: var(--ink); }

.card-media {
  display: flex;
  justify-content: center;
  padding: 6px 0 14px;
}
.card-media svg { width: 100%; height: auto; display: block; }

.card-meta { text-align: center; padding: 0 6px; }
.card-author {
  font-size: 13px;
  color: var(--ink-dim);
  margin: 0 0 2px;
}

/* 清晰度选择 */
.variants { margin: 18px 0; }
.variants-label {
  display: block;
  font-size: 12.5px;
  color: var(--ink-dim);
  margin-bottom: 8px;
  text-align: center;
}
.variant-row {
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.variant {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 13px 16px;
  background: #fff;
  cursor: pointer;
  transition: border-color .15s, box-shadow .15s;
}
.variant:hover { border-color: var(--accent); }
.variant.is-selected {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-soft);
}
.variant-quality { font-weight: 600; font-size: 14px; }
.variant-size   { color: var(--ink-dim); font-size: 13px; }
.variant-dl {
  border: none;
  background: transparent;
  color: var(--accent);
  font: 600 13px var(--sans);
  cursor: pointer;
  padding: 4px 10px;
  border-radius: 8px;
}
.variant-dl:hover { background: var(--accent-soft); }

.dl-note { text-align: center; font-size: 12.5px; color: var(--ink-dim); margin: 4px 0 0; }

/* 结果展示过渡 */
.result[data-state="fade"] { animation: rise .35s ease-out; }
@keyframes rise { from { opacity: 0; transform: translateY(10px); } to { opacity: 1; transform: none; } }

/* ============ 区块通用 ============ */
.uses, .how, .faq {
  max-width: 880px;
  margin-left: auto;
  margin-right: auto;
  padding: clamp(48px, 8vw, 80px) clamp(20px, 5vw, 40px);
  border-top: 1px solid var(--line);
}
.section-title {
  font-family: var(--sans);
  font-weight: 600;
  font-size: clamp(22px, 3.4vw, 30px);
  margin: 0 0 24px;
}

/* ============ HOW 步骤 ============ */
.steps {
  list-style: none;
  margin: 0;
  padding: 0;
  counter-reset: step;
}
.steps li {
  counter-increment: step;
  display: flex;
  align-items: center;
  gap: 18px;
  padding: 16px 0;
  border-top: 1px solid var(--stone);
  font-size: 16px;
}
.steps li:last-child { border-bottom: 1px solid var(--stone); }
.steps li::before {
  content: counter(step, decimal-leading-zero);
  font-size: 14px;
  color: var(--accent);
  flex-shrink: 0;
  width: 1ch;
}

/* ============ FAQ ============ */
.faq { max-width: 640px; }
details { border-top: 1px solid var(--stone); }
details:last-child { border-bottom: 1px solid var(--stone); }
summary {
  cursor: pointer;
  padding: 16px 0;
  font-weight: 600;
  font-size: 16px;
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
}
summary::-webkit-details-marker { display: none; }
summary::after {
  content: "＋";
  color: var(--accent);
  font-size: 18px;
  transition: transform .2s;
}
details[open] summary::after { transform: rotate(45deg); }
details p {
  margin: 0 0 16px;
  color: var(--ink-dim);
  font-size: 15px;
  line-height: 1.7;
}

/* ============ FOOTER ============ */
.footer {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 30px clamp(20px, 4vw, 40px) 46px;
  border-top: 1px solid var(--line);
}
.footer p {
  margin: 0;
  text-align: center;
  font-size: 13px;
  color: var(--ink-dim);
}

/* ============ 响应式：移动端 ============ */
@media (max-width: 560px) {
  .field { border-radius: 16px; flex-direction: column; }
  .extract-btn { border-radius: 10px; width: 100%; }
  .hero-title { letter-spacing: 0; }
}