/* ============================================
   登录页样式（基准 980x568）
   布局参照设计图：左侧白色半透明卡片 + 全屏主视觉底图
   ============================================ */
#stage {
  position: relative;
  left: auto;
  top: auto;
  width: 100%;
  height: 100%;
  transform: none;
  background: #cfe3fb;
  overflow: hidden;
}

body {
  background: #cfe3fb;
}

/* ---------- 全屏主视觉底图（图内已含 logo 与大赛标题） ---------- */
.login-bg {
  position: absolute;
  inset: 0;
  background: #cfe3fb url("assets/login-bg.jpg") center / cover no-repeat;
  z-index: 0;
}

/* ---------- 登录卡片（左侧悬浮白色半透明） ---------- */
.login-card {
  position: absolute;
  left: 7.4%;
  top: 24%;
  width: clamp(302px, 32.9vw, 760px);
  background: rgba(255, 255, 255, 0.92);
  -webkit-backdrop-filter: blur(10px);
  backdrop-filter: blur(10px);
  border-radius: 2.6vmin;
  box-shadow: 0 14px 36px rgba(27, 98, 196, 0.22);
  padding: 4.6vmin 4.9vmin 4.2vmin;
  z-index: 2;
}

.card-title {
  font-size: clamp(17px, 2.99vmin, 34px);
  font-weight: 700;
  color: #0b3f8f;
  text-align: center;
  letter-spacing: 0.53vmin;
  margin-bottom: 3.5vmin;
}

.field {
  display: flex;
  align-items: center;
  height: clamp(42px, 7.39vmin, 68px);
  border: 1px solid #dbe7f7;
  border-radius: 1.76vmin;
  background: #f7faff;
  padding: 0 2.11vmin;
  margin-bottom: 2.46vmin;
}

.field:focus-within {
  border-color: #1b62c4;
  background: #ffffff;
}

.field svg {
  width: clamp(18px, 3.17vmin, 30px);
  height: clamp(18px, 3.17vmin, 30px);
  margin-right: 1.58vmin;
  flex: none;
  color: #5b83c4;
}

.field input {
  flex: 1;
  border: none;
  background: transparent;
  font-size: clamp(14px, 2.46vmin, 26px);
  color: #24344d;
}

.field input::placeholder {
  color: #9db4d6;
}

.err {
  color: #e8262d;
  font-size: clamp(12px, 2.11vmin, 18px);
  line-height: 1.3;
  min-height: 2.82vmin;
  margin-bottom: 1.06vmin;
  text-align: center;
}

.btn-login {
  width: 100%;
  height: clamp(42px, 7.39vmin, 68px);
  border-radius: 3.7vmin;
  background: linear-gradient(90deg, #2a77dd, #1b62c4 55%, #0b3f8f);
  color: #ffffff;
  font-size: clamp(16px, 2.82vmin, 28px);
  font-weight: 600;
  letter-spacing: 8px;
  text-indent: 8px;
  box-shadow: 0 6px 14px rgba(27, 98, 196, 0.32);
}

.btn-login:disabled {
  opacity: 0.7;
  cursor: default;
}

/* ---------- 竖屏：卡片居中放大，保证可用 ---------- */
@media (max-aspect-ratio: 1/1) {
  .login-card {
    left: 50%;
    top: 42%;
    transform: translateX(-50%);
    width: min(82vw, 480px);
  }
}