/* ============================================================
   Eupho Notes · 基础样式
   主题：吹响吧！上低音号 · 夏季（夏空 / 水手服 / 黄铜色）
   ============================================================ */
:root {
  --sky: #8CC8F2;
  --sky-deep: #4E8CC7;
  --navy: #223A5E;
  --navy-deep: #16294A;
  --gold: #D9A441;
  --gold-soft: #E9C97B;
  --cream: #FDFBF6;
  --ink: #22304A;
  --ink-soft: #5A6B85;
  --card-bg: rgba(253, 251, 246, 0.92);
  --radius: 18px;
  --shadow: 0 18px 40px -18px rgba(18, 36, 66, 0.38);
  --font: "RHR", "Resource Han Rounded CN", "ResourceHanRoundedCN-Regular", "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-bold: "RHR Bold", "Resource Han Rounded CN Bold", "ResourceHanRoundedCN-Bold", "PingFang SC", "Microsoft YaHei", sans-serif;
  --wrap: 1080px;
}

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

html { scroll-behavior: smooth; }

body {
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.75;
  color: var(--ink);
  background: var(--navy-deep);
  -webkit-font-smoothing: antialiased;
}

a { color: inherit; text-decoration: none; }
img { display: block; max-width: 100%; }
button { font-family: inherit; }

/* —— 背景：整页壁纸 + 底部压暗，保证可读性 —— */
.bg {
  position: fixed; inset: 0; z-index: -2;
  background: var(--navy-deep);
}
.bg img {
  width: 100%; height: 100%;
  object-fit: cover; object-position: center 30%;
}
.bg-shade {
  position: absolute; inset: 0;
  background:
    linear-gradient(180deg, rgba(18, 29, 51, 0.42) 0%, rgba(18, 29, 51, 0.18) 30%, rgba(18, 29, 51, 0.55) 72%, rgba(13, 22, 40, 0.92) 100%);
}
/* 窄屏（手机竖屏）换一张竖构图壁纸 */
@media (max-width: 720px) {
  .bg img { object-position: center 22%; }
}

/* —— 顶栏 —— */
.top {
  position: fixed; top: 0; left: 0; right: 0; z-index: 50;
  display: flex; align-items: center; gap: 1.4rem;
  padding: 0.85rem clamp(1rem, 4vw, 2.4rem);
  color: #fff;
  background: linear-gradient(180deg, rgba(14, 24, 43, 0.72), rgba(14, 24, 43, 0));
  backdrop-filter: blur(2px);
}
.brand {
  display: flex; align-items: center; gap: 0.5rem;
  font-family: var(--font-bold);
  font-size: 1.15rem; letter-spacing: 0.02em;
}
.brand-note {
  display: grid; place-items: center;
  width: 2rem; height: 2rem; border-radius: 10px;
  background: linear-gradient(150deg, var(--gold-soft), var(--gold));
  color: var(--navy-deep); font-size: 1.1rem;
  box-shadow: 0 4px 12px -4px rgba(217, 164, 65, 0.7);
}
.nav {
  display: flex; gap: 0.3rem; margin-left: auto;
  font-size: 0.95rem;
}
.nav a {
  padding: 0.32rem 0.85rem; border-radius: 999px;
  opacity: 0.88; transition: background 0.2s, opacity 0.2s;
}
.nav a:hover { background: rgba(255, 255, 255, 0.14); opacity: 1; }
.nav a.on { background: rgba(255, 255, 255, 0.2); opacity: 1; font-family: var(--font-bold); }
.lang { display: flex; gap: 0.2rem; }
.lang button {
  border: 1px solid rgba(255, 255, 255, 0.45); background: rgba(255, 255, 255, 0.08);
  color: #fff; border-radius: 999px; padding: 0.2rem 0.7rem;
  font-size: 0.82rem; cursor: pointer; transition: background 0.2s;
}
.lang button:hover { background: rgba(255, 255, 255, 0.2); }
.lang button.on { background: var(--gold); border-color: var(--gold); color: var(--navy-deep); font-family: var(--font-bold); }

/* —— 页脚 —— */
.foot {
  padding: 2.2rem clamp(1rem, 4vw, 2.4rem);
  text-align: center;
  color: rgba(255, 255, 255, 0.72);
  font-size: 0.82rem;
}

/* —— 区块标题 —— */
.sec { max-width: var(--wrap); margin: 0 auto; padding: 3.4rem clamp(1rem, 4vw, 2.4rem) 1rem; }
.sec-title {
  display: flex; align-items: center; gap: 0.7rem;
  font-family: var(--font-bold); font-size: 1.5rem; color: var(--navy-deep);
  margin-bottom: 1.3rem;
}
.sec-title::before {
  content: ""; width: 0.55rem; height: 1.5rem; border-radius: 4px;
  background: linear-gradient(180deg, var(--gold-soft), var(--gold));
}