/* ===== 基础设置 ===== */

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

:root {
  --bg-dark: #050816;
  --bg-darker: #020612;
  --bg-card: #0f172a;
  --bg-card-soft: #111827;
  --accent: #38bdf8;
  --accent-soft: rgba(56, 189, 248, 0.2);
  --text-main: #e5e7eb;
  --text-soft: #9ca3af;
  --border-soft: #1f2933;
  --radius-lg: 18px;
  --radius-xl: 24px;
  --shadow-soft: 0 18px 40px rgba(15, 23, 42, 0.75);
  --shadow-card: 0 10px 25px rgba(15, 23, 42, 0.85);
  --transition-fast: 0.18s ease-out;
  --transition: 0.25s ease-out;
  --max-width: 1120px;
}

html,
body {
  margin: 0;
  padding: 0;
}

body {
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
    "PingFang SC", "Hiragino Sans GB", "Microsoft Yahei", sans-serif;
  background: radial-gradient(circle at top, #0f172a 0, #020617 45%, #000 100%);
  color: var(--text-main);
}

/* ===== 通用布局 ===== */

.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 16px;
}

.section {
  padding: 72px 0;
}

.section-dark {
  background: radial-gradient(circle at top, #020617 0, #02010b 40%, #000 100%);
}

.section-header {
  text-align: center;
  margin-bottom: 40px;
}

.section-header h2 {
  font-size: 1.8rem;
  margin: 0 0 8px;
}

.section-header p {
  margin: 0;
  color: var(--text-soft);
  font-size: 0.98rem;
}

/* ===== 顶部导航 ===== */

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: linear-gradient(to bottom, rgba(3, 7, 18, 0.96), rgba(3, 7, 18, 0.82));
  backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(148, 163, 184, 0.1);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 0;
}

.logo {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 600;
}

.logo-mark {
  width: 28px;
  height: 28px;
  border-radius: 999px;
  background: radial-gradient(circle at 30% 20%, #f97316, #ec4899 30%, #22d3ee 80%);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  color: #0b1120;
  font-size: 1rem;
}

.logo-text {
  letter-spacing: 0.04em;
  font-size: 0.98rem;
}

.nav {
  display: flex;
  gap: 18px;
  font-size: 0.95rem;
}

.nav a {
  color: var(--text-soft);
  text-decoration: none;
  padding: 6px 10px;
  border-radius: 999px;
  transition: var(--transition-fast);
}

.nav a:hover {
  color: #e5e7eb;
  background: rgba(148, 163, 184, 0.16);
}

/* ===== 按钮 ===== */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 10px 20px;
  border-radius: 999px;
  font-size: 0.95rem;
  text-decoration: none;
  cursor: pointer;
  border: 1px solid transparent;
  transition: var(--transition);
  white-space: nowrap;
}

.btn.primary {
  background: linear-gradient(to right, #22d3ee, #38bdf8);
  color: #020617;
  font-weight: 600;
  box-shadow: 0 14px 30px rgba(56, 189, 248, 0.4);
}

.btn.primary:hover {
  transform: translateY(-1px);
  box-shadow: 0 18px 40px rgba(56, 189, 248, 0.55);
}

.btn.ghost {
  background: rgba(15, 23, 42, 0.8);
  color: var(--text-main);
  border-color: rgba(148, 163, 184, 0.35);
}

.btn.ghost:hover {
  border-color: var(--accent);
  background: rgba(15, 23, 42, 0.95);
}

/* ===== Hero 区域 ===== */

.hero {
  padding: 56px 0 72px;
}

.hero-inner {
  display: grid;
  grid-template-columns: minmax(0, 3fr) minmax(0, 2.5fr);
  gap: 32px;
  align-items: center;
}

.hero-text h1 {
  font-size: 2.2rem;
  margin: 0 0 16px;
}

.hero-text p {
  margin: 0 0 24px;
  color: var(--text-soft);
  max-width: 34rem;
  line-height: 1.7;
  font-size: 0.98rem;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.hero-card {
  background: radial-gradient(circle at top left, #1e293b, #020617 55%);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-soft);
  padding: 20px 18px;
  border: 1px solid rgba(148, 163, 184, 0.35);
}

.hero-stat h2 {
  margin: 0;
  font-size: 1.1rem;
}

.hero-stat p {
  margin: 4px 0 14px;
  color: var(--text-soft);
  font-size: 0.9rem;
}

.hero-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  gap: 6px;
  font-size: 0.9rem;
}

.hero-list li {
  padding: 6px 10px;
  border-radius: 999px;
  background: rgba(15, 23, 42, 0.9);
  border: 1px solid rgba(148, 163, 184, 0.3);
}

/* ===== 卡片网格（Tech Notes） ===== */

.card-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 18px;
}

.card {
  background: radial-gradient(circle at top, #020617, #02020a 55%);
  border-radius: var(--radius-lg);
  padding: 16px 18px 18px;
  border: 1px solid rgba(148, 163, 184, 0.35);
  box-shadow: var(--shadow-card);
  position: relative;
  overflow: hidden;
}

.card::before {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at top left, rgba(56, 189, 248, 0.18), transparent 60%);
  opacity: 0;
  transition: opacity var(--transition);
  pointer-events: none;
}

.card:hover::before {
  opacity: 1;
}

.card:hover {
  transform: translateY(-3px);
}

.card-tag {
  display: inline-flex;
  padding: 2px 8px;
  border-radius: 999px;
  font-size: 0.78rem;
  letter-spacing: 0.03em;
  background: rgba(56, 189, 248, 0.2);
  color: #e0f2fe;
  margin-bottom: 8px;
}

.card h3 {
  font-size: 1rem;
  margin: 0 0 8px;
}

.card p {
  margin: 0 0 12px;
  font-size: 0.9rem;
  color: var(--text-soft);
  line-height: 1.6;
}

.card-meta {
  font-size: 0.78rem;
  color: #64748b;
}

/* ===== 项目 Features 区 ===== */

.feature-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 20px;
}

.feature-item {
  background: linear-gradient(135deg, #020617, #020714);
  border-radius: var(--radius-lg);
  padding: 18px 18px 20px;
  border: 1px solid rgba(148, 163, 184, 0.4);
  box-shadow: var(--shadow-card);
}

.feature-item h3 {
  margin: 0 0 8px;
  font-size: 1.02rem;
}

.feature-item p {
  margin: 0 0 10px;
  font-size: 0.9rem;
  color: var(--text-soft);
}

.feature-item ul {
  list-style: none;
  padding: 0;
  margin: 0;
  font-size: 0.88rem;
  color: #cbd5f5;
}

.feature-item li {
  padding-left: 12px;
  position: relative;
  margin-bottom: 4px;
}

.feature-item li::before {
  content: "•";
  position: absolute;
  left: 0;
  top: 0;
  color: var(--accent);
}

/* ===== 时间线（Blog 列表） ===== */

.timeline {
  border-left: 1px solid rgba(148, 163, 184, 0.45);
  margin-left: 10px;
  padding-left: 18px;
  display: grid;
  gap: 20px;
}

.timeline-item {
  display: grid;
  grid-template-columns: 100px minmax(0, 1fr);
  gap: 18px;
}

.timeline-date {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  font-size: 0.9rem;
  color: var(--text-soft);
}

.timeline-date .day {
  font-size: 1.7rem;
  font-weight: 600;
  line-height: 1;
}

.timeline-date .month {
  margin-top: 2px;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  font-size: 0.7rem;
}

.timeline-content h3 {
  margin: 0 0 8px;
  font-size: 1.02rem;
}

.timeline-content p {
  margin: 0;
  font-size: 0.9rem;
  color: var(--text-soft);
}

/* ===== 联系区 ===== */

.contact-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) minmax(0, 1.2fr);
  gap: 28px;
  align-items: flex-start;
}

.contact-list {
  list-style: none;
  padding: 0;
  margin: 0;
  font-size: 0.9rem;
  color: var(--text-soft);
}

.contact-list li {
  margin-bottom: 8px;
}

.contact-form {
  display: grid;
  gap: 10px;
}

.contact-form input,
.contact-form textarea {
  width: 100%;
  padding: 8px 10px;
  border-radius: 10px;
  border: 1px solid rgba(148, 163, 184, 0.4);
  background: rgba(15, 23, 42, 0.9);
  color: var(--text-main);
  font-family: inherit;
  font-size: 0.9rem;
}

.contact-form input::placeholder,
.contact-form textarea::placeholder {
  color: #6b7280;
}

.contact-form input:focus,
.contact-form textarea:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 1px rgba(56, 189, 248, 0.5);
}

/* ===== 页脚 ===== */

.site-footer {
  border-top: 1px solid rgba(51, 65, 85, 0.8);
  background: #020617;
  padding: 12px 0;
  font-size: 0.82rem;
  color: #6b7280;
}

.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.footer-right {
  opacity: 0.9;
}

/* ===== 响应式布局 ===== */

@media (max-width: 960px) {
  .hero-inner {
    grid-template-columns: minmax(0, 1.2fr);
  }

  .hero-card {
    order: -1;
  }

  .card-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .feature-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .timeline-item {
    grid-template-columns: 90px minmax(0, 1fr);
  }
}

@media (max-width: 640px) {
  .header-inner {
    flex-wrap: wrap;
    gap: 8px;
  }

  .nav {
    width: 100%;
    justify-content: flex-start;
    flex-wrap: wrap;
    gap: 6px;
    font-size: 0.86rem;
  }

  .hero-text h1 {
    font-size: 1.6rem;
  }

  .section {
    padding: 56px 0;
  }

  .card-grid {
    grid-template-columns: minmax(0, 1fr);
  }

  .feature-grid {
    grid-template-columns: minmax(0, 1fr);
  }

  .contact-grid {
    grid-template-columns: minmax(0, 1fr);
  }

  .timeline-item {
    grid-template-columns: minmax(0, 1fr);
  }

  .timeline-date {
    flex-direction: row;
    justify-content: flex-start;
    gap: 8px;
    margin-bottom: 4px;
  }

  .timeline-date .day {
    font-size: 1.3rem;
  }

  .timeline {
    border-left: none;
    margin-left: 0;
    padding-left: 0;
  }

  .footer-inner {
    flex-direction: column;
    gap: 6px;
    align-items: flex-start;
  }
}