html, body {
  margin: 0;
  min-height: 100vh;
}

body {
  margin: 0;
  font-family: Arial, sans-serif;
  background: #f4f4f4;
  display: flex;
  justify-content: center;
}

.container {
  min-height: 100vh;
  max-width: 1500px;
  margin: 20px auto;
  padding: 10px;
  display: flex;
  flex-direction: column;
  width: 80%;
}

/* CARD STYLE (core aesthetic) */
.card {
  background: white;
  border-radius: 12px;
  padding: 15px;
  box-shadow: 0 3px 10px rgba(0, 0, 0, 0.1);
}

/* HEADER spacing */
.header {
  margin-bottom: 15px;
  text-align: center;
}

/* ROW layout */
.row {
  display: flex;
  gap: 15px;
  margin-bottom: 15px;
  flex: 1;
}

/* columns */
.l_side,
.r_side {
  flex: 1;
}

.main {
  flex: 2;
}

/* FOOTER */
.footer {
  text-align: center;
}

/* mobile responsiveness */
@media (max-width: 768px) {
  .row {
    flex-direction: column;
  }
}