* { 
  box-sizing: border-box; 
  margin: 0; 
  padding: 0; 
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif; 
}

:root {
  --viettel-red: #ee0033;
  --bg-light: #f0f2f5;
  --text-dark: #222222;
}

body.viettel-theme {
  background-color: var(--bg-light);
  color: var(--text-dark);
  min-height: 100vh;
}

/* Header */
.viettel-header {
  background-color: var(--viettel-red);
  color: #ffffff;
  padding: 15px 30px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.15);
}

.header-container {
  max-width: 1000px;
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo-text {
  font-size: 32px;
  font-weight: bold;
  letter-spacing: -1px;
}

.tagline {
  font-size: 12px;
  display: block;
  font-style: italic;
  opacity: 0.9;
}

.badge {
  background: rgba(255, 255, 255, 0.2);
  padding: 6px 14px;
  border-radius: 20px;
  font-size: 13px;
}

/* Layout */
.main-wrapper {
  max-width: 1000px;
  margin: 30px auto;
  display: flex;
  gap: 24px;
  padding: 0 15px;
  align-items: flex-start;
}

.viettel-sidebar {
  flex: 1;
  background: #ffffff;
  padding: 20px;
  border-radius: 16px;
  border-top: 4px solid var(--viettel-red);
  box-shadow: 0 4px 12px rgba(0,0,0,0.05);
}

.viettel-sidebar h3 {
  color: var(--viettel-red);
  margin-top: 0;
  font-size: 16px;
  border-bottom: 2px solid #f0f0f0;
  padding-bottom: 10px;
  margin-bottom: 15px;
}

.timeline {
  list-style: none;
}

.timeline li {
  margin-bottom: 14px;
  font-size: 13px;
  line-height: 1.4;
  padding-left: 10px;
  border-left: 2px solid var(--viettel-red);
}

.app-content {
  flex: 1.2;
}

/* CSS Card cũ của bạn */
.card { 
  width: 100%; 
  background: #ffffff; 
  border-radius: 20px; 
  box-shadow: 0 10px 25px rgba(0,0,0,0.08); 
  padding: 24px; 
}

.header { text-align: center; color: #ee0033; font-size: 22px; font-weight: bold; margin-bottom: 20px; }
.box { border-radius: 12px; padding: 16px; margin-bottom: 16px; }
.balance-box { background: #fff1f2; border: 1px solid #ffe4e6; }
.balance-title { font-size: 13px; color: #666; margin-bottom: 4px; }
.balance-val { font-size: 24px; font-weight: bold; color: #ee0033; }
.data-box { background: #f0f9ff; border: 1px solid #e0f2fe; }
.progress-bg { height: 10px; background: #e2e8f0; border-radius: 5px; overflow: hidden; margin-top: 10px; }
.progress-fill { height: 100%; background: #0284c7; width: 0%; transition: width 0.4s ease; }
.btn { width: 100%; padding: 12px; border: none; border-radius: 12px; font-size: 14px; font-weight: bold; cursor: pointer; margin-bottom: 10px; transition: 0.2s; }
.btn-submit { background: #ee0033; color: white; }
.btn-submit:hover { background: #cc002c; }
.btn-points { background: #eab308; color: white; }
.btn-points:hover { background: #ca8a04; }
.btn-refresh { background: #f1f5f9; color: #475569; }
.btn-refresh:hover { background: #e2e8f0; }
.status-msg { font-size: 13px; text-align: center; margin-top: 10px; font-weight: 600; min-height: 20px; }

.viettel-footer {
  text-align: center;
  padding: 20px;
  background: #e9ecef;
  color: #666;
  font-size: 13px;
  margin-top: 40px;
}

@media (max-width: 768px) {
  .main-wrapper {
    flex-direction: column;
  }
}