/* ============================================================
   Nova Lab 招新官网 · 扁平化设计
   纯色块 · 无阴影 · 无渐变 · 系统字体栈
   ============================================================ */

:root {
  /* 主色与中性色 */
  --brand: #2F5CFF;
  --brand-dark: #1F46D6;
  --ink: #1A2233;
  --muted: #5A6472;
  --line: #E6E9F0;
  --bg: #FFFFFF;
  --bg-soft: #F5F7FB;

  /* 字体 */
  --font: "PingFang SC", "Microsoft YaHei", "Segoe UI", "Noto Sans SC",
          -apple-system, BlinkMacSystemFont, Roboto, "Helvetica Neue", sans-serif;

  /* 尺寸 */
  --radius: 14px;
  --radius-sm: 9px;
  --maxw: 1120px;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: 80px; }

body {
  font-family: var(--font);
  color: var(--ink);
  background: var(--bg);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

a { color: inherit; text-decoration: none; }
ul { list-style: none; }
button { font-family: inherit; cursor: pointer; }
input, select, textarea { font-family: inherit; }

.container { max-width: var(--maxw); margin: 0 auto; padding: 0 24px; }
.container-narrow { max-width: 760px; }

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 13px 28px;
  font-size: 15px;
  font-weight: 600;
  border-radius: var(--radius-sm);
  border: 2px solid transparent;
  transition: background .18s ease, color .18s ease, border-color .18s ease, transform .18s ease;
}
.btn:active { transform: translateY(1px); }
.btn-primary { background: var(--brand); color: #fff; }
.btn-primary:hover { background: var(--brand-dark); }
.btn-ghost { background: transparent; color: var(--ink); border-color: var(--line); }
.btn-ghost:hover { border-color: var(--ink); }
.btn-sm { padding: 9px 18px; font-size: 14px; }
.btn-block { width: 100%; padding: 15px; font-size: 16px; margin-top: 6px; }

/* ---------- 导航 ---------- */
.nav {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(255, 255, 255, .92);
  border-bottom: 1px solid var(--line);
  backdrop-filter: saturate(180%) blur(8px);
}
.nav-inner { display: flex; align-items: center; justify-content: space-between; height: 68px; }
.nav-logo { display: flex; align-items: center; gap: 10px; font-weight: 700; font-size: 19px; }
.logo-mark {
  display: grid; place-items: center;
  width: 34px; height: 34px;
  background: var(--brand); color: #fff;
  border-radius: var(--radius-sm);
  font-size: 18px; font-weight: 800;
}
.nav-links { display: flex; gap: 30px; }
.nav-links a { font-size: 15px; color: var(--muted); font-weight: 500; transition: color .15s; }
.nav-links a:hover { color: var(--ink); }
.nav-actions { display: flex; align-items: center; gap: 14px; }

.nav-toggle {
  display: none;
  flex-direction: column; gap: 5px;
  background: none; border: none; padding: 6px;
}
.nav-toggle span { width: 22px; height: 2px; background: var(--ink); border-radius: 2px; }

/* ---------- Hero ---------- */
.hero {
  position: relative;
  overflow: hidden;
  background: var(--bg);
  border-bottom: 1px solid var(--line);
}
.hero-inner {
  display: grid;
  grid-template-columns: 1.1fr .9fr;
  align-items: center;
  gap: 40px;
  padding: 88px 24px 96px;
}
.hero-kicker {
  display: inline-block;
  font-size: 13px; font-weight: 700; letter-spacing: 2px;
  color: var(--brand);
  background: #EAF0FF;
  padding: 6px 14px; border-radius: 999px;
  margin-bottom: 22px;
}
.hero-title { font-size: 52px; line-height: 1.18; font-weight: 800; letter-spacing: -1px; }
.hero-title .accent { color: var(--brand); }
.hero-desc { margin: 22px 0 30px; font-size: 18px; color: var(--muted); max-width: 520px; }
.hero-cta { display: flex; gap: 14px; flex-wrap: wrap; }
.hero-stats { display: flex; gap: 44px; margin-top: 48px; }
.hero-stats li { display: flex; flex-direction: column; }
.hero-stats strong { font-size: 30px; font-weight: 800; color: var(--ink); }
.hero-stats span { font-size: 13px; color: var(--muted); }

/* Hero 图形装饰（扁平几何色块） */
.hero-art { position: relative; height: 360px; }
.blob { position: absolute; border-radius: 24px; }
.blob-a { width: 220px; height: 220px; background: var(--brand); top: 10px; right: 30px; transform: rotate(8deg); }
.blob-b { width: 160px; height: 160px; background: #7C5CFF; bottom: 10px; right: 150px; }
.blob-c { width: 110px; height: 110px; background: #FF5D5D; top: 150px; right: 0; border-radius: 50%; }
.chip {
  position: absolute;
  display: grid; place-items: center;
  background: #fff; border: 2px solid var(--ink);
  font-weight: 800; color: var(--ink);
  border-radius: 12px;
}
.chip-1 { width: 76px; height: 60px; font-size: 20px; top: 40px; left: 40px; transform: rotate(-6deg); }
.chip-2 { width: 60px; height: 60px; font-size: 18px; bottom: 60px; left: 80px; background: #00B894; border: none; color: #fff; border-radius: 50%; }
.chip-3 { width: 54px; height: 54px; font-size: 22px; top: 210px; left: 20px; background: #F5A623; border: none; color: #fff; border-radius: 12px; }

/* ---------- Section 通用 ---------- */
.section { padding: 84px 0; }
.section-soft { background: var(--bg-soft); }
.section-head { text-align: center; max-width: 640px; margin: 0 auto 52px; }
.section-tag {
  display: inline-block;
  font-size: 13px; font-weight: 700; letter-spacing: 2px;
  color: var(--brand);
  margin-bottom: 14px;
}
.section-title { font-size: 34px; font-weight: 800; letter-spacing: -.5px; }
.section-sub { margin-top: 14px; font-size: 16px; color: var(--muted); }

/* ---------- 关于我们 ---------- */
.about-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.about-card {
  padding: 32px 28px;
  border: 2px solid var(--line);
  border-radius: var(--radius);
  transition: border-color .18s, transform .18s;
}
.about-card:hover { border-color: var(--brand); transform: translateY(-3px); }
.about-icon {
  display: grid; place-items: center;
  width: 54px; height: 54px; margin-bottom: 18px;
  font-size: 24px; color: #fff;
  border-radius: var(--radius-sm);
}
.i-project { background: var(--brand); }
.i-mentor { background: #00B894; }
.i-compete { background: #F5A623; }
.about-card h3 { font-size: 19px; margin-bottom: 10px; }
.about-card p { font-size: 15px; color: var(--muted); }

/* ---------- 部门介绍 ---------- */
.dept-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.dept-card {
  background: #fff;
  border: 2px solid var(--line);
  border-radius: var(--radius);
  padding: 28px;
  transition: border-color .18s, transform .18s;
}
.dept-card:hover { border-color: var(--c, var(--brand)); transform: translateY(-3px); }
.dept-top { display: flex; align-items: center; gap: 14px; margin-bottom: 14px; }
.dept-icon {
  display: grid; place-items: center;
  width: 44px; height: 44px;
  font-size: 22px; color: #fff;
  background: var(--c);
  border-radius: var(--radius-sm);
}
.dept-name { font-size: 19px; font-weight: 700; }
.dept-card p { font-size: 14.5px; color: var(--muted); min-height: 66px; }
.dept-tags { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 16px; }
.dept-tags li {
  font-size: 12.5px; font-weight: 600; color: var(--c);
  background: #F2F4F8;
  padding: 4px 11px; border-radius: 999px;
}

/* ---------- 招新流程 ---------- */
.timeline { max-width: 720px; margin: 0 auto; position: relative; padding-left: 40px; }
.timeline::before {
  content: "";
  position: absolute; left: 16px; top: 6px; bottom: 6px;
  width: 3px; background: var(--line);
}
.timeline-step { position: relative; padding: 0 0 40px; }
.timeline-step:last-child { padding-bottom: 0; }
.step-num {
  position: absolute; left: -40px; top: 0;
  display: grid; place-items: center;
  width: 34px; height: 34px;
  background: var(--brand); color: #fff;
  font-size: 13px; font-weight: 700;
  border-radius: 50%;
  border: 4px solid #fff;
}
.step-body h3 { font-size: 20px; margin-bottom: 6px; }
.step-body p { font-size: 15px; color: var(--muted); }
.step-date { display: inline-block; margin-top: 10px; font-size: 13px; font-weight: 600; color: var(--brand); }

/* ---------- FAQ ---------- */
.faq-list { display: flex; flex-direction: column; gap: 14px; }
.faq-item { border: 2px solid var(--line); border-radius: var(--radius); background: #fff; overflow: hidden; }
.faq-q {
  width: 100%;
  display: flex; align-items: center; justify-content: space-between;
  padding: 20px 24px;
  background: none; border: none;
  font-size: 16px; font-weight: 600; color: var(--ink);
  text-align: left;
}
.faq-q::after { content: "+"; font-size: 22px; font-weight: 400; color: var(--muted); transition: transform .2s; }
.faq-item.open .faq-q::after { transform: rotate(45deg); }
.faq-a { max-height: 0; overflow: hidden; transition: max-height .25s ease; }
.faq-a p { padding: 0 24px 20px; font-size: 15px; color: var(--muted); }

/* ---------- 表单 ---------- */
.apply-form {
  background: #fff;
  border: 2px solid var(--line);
  border-radius: var(--radius);
  padding: 36px;
}
.form-row { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; }
.form-field { margin-bottom: 20px; }
.form-field label { display: block; font-size: 14px; font-weight: 600; margin-bottom: 8px; }
.form-field label em { color: #FF5D5D; font-style: normal; }
.form-field input,
.form-field select,
.form-field textarea {
  width: 100%;
  padding: 12px 14px;
  font-size: 15px;
  color: var(--ink);
  background: #fff;
  border: 2px solid var(--line);
  border-radius: var(--radius-sm);
  outline: none;
  transition: border-color .15s;
}
.form-field textarea { resize: vertical; min-height: 96px; }
.form-field input:focus,
.form-field select:focus,
.form-field textarea:focus { border-color: var(--brand); }
.form-field input.invalid,
.form-field select.invalid { border-color: #FF5D5D; }
.form-hint { margin-top: 16px; font-size: 12.5px; color: var(--muted); text-align: center; }

/* ---------- 页脚 ---------- */
.footer { background: var(--ink); color: #fff; padding: 40px 0; }
.footer-inner { display: flex; align-items: center; justify-content: space-between; flex-wrap: wrap; gap: 12px; }
.footer-brand { font-size: 16px; font-weight: 700; }
.footer-note { font-size: 13px; color: #9AA3B2; }

/* ---------- Toast ---------- */
.toast {
  position: fixed; left: 50%; bottom: 32px;
  transform: translate(-50%, 20px);
  background: var(--ink); color: #fff;
  padding: 13px 24px; font-size: 14.5px; font-weight: 500;
  border-radius: var(--radius-sm);
  opacity: 0; pointer-events: none;
  transition: opacity .25s, transform .25s;
  z-index: 100;
}
.toast.show { opacity: 1; transform: translate(-50%, 0); }
.toast.success { background: #00B894; }
.toast.error { background: #FF5D5D; }

/* ---------- 响应式 ---------- */
@media (max-width: 900px) {
  .hero-inner { grid-template-columns: 1fr; padding: 56px 24px 64px; }
  .hero-art { height: 260px; order: -1; }
  .hero-title { font-size: 40px; }
  .about-grid, .dept-grid { grid-template-columns: 1fr 1fr; }
}

@media (max-width: 620px) {
  .nav-links {
    position: absolute; top: 68px; left: 0; right: 0;
    flex-direction: column; gap: 0;
    background: #fff; border-bottom: 1px solid var(--line);
    display: none;
    padding: 8px 24px;
  }
  .nav-links.open { display: flex; }
  .nav-links a { padding: 14px 0; border-bottom: 1px solid var(--line); }
  .nav-links a:last-child { border-bottom: none; }
  .nav-toggle { display: flex; }
  .hero-title { font-size: 34px; }
  .hero-stats { gap: 28px; }
  .about-grid, .dept-grid, .form-row { grid-template-columns: 1fr; }
  .apply-form { padding: 24px; }
  .section { padding: 60px 0; }
  .section-title { font-size: 27px; }
}