html {
  box-sizing: border-box;
  background: #ffc600;
  font-family: "Helvetica neue", sans-serif;
  font-weight: 200;
  font-size: 20px;
}

body {
  margin: 0;
}

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

.panels {
  min-height: 100vh;
  overflow: hidden;
  display: flex;
}

.panel {
  background: #ffc600;
  box-shadow: inset 0 0 0 5px rgba(255, 255, 255, 0.1);
  color: white;
  text-align: center;
  align-items: center;
  transition: 
    font-size 0.7s cubic-bezier(0.61, -0.19, 0.7, -0.11),
    flex-grow 0.7s cubic-bezier(0.61, -0.19, 0.7, -0.11), 
    background 0.2s;
  font-size: 20px;
  background-size: cover;
  background-position: center;
  flex: 1;
  justify-content: center;
  align-items: center;
  display: flex;
  flex-direction: column;
}

.panel1 {
  background-image: url(https://i.ibb.co/LgJbZtZ/nabicho1.jpg);
}
.panel2 {
  background-image: url(https://i.ibb.co/93ZFFRt/nyap1.jpg);
}
.panel3 {
  background-image: url(https://i.ibb.co/fk9ZN3P/14des21frame1.jpg);
}
.panel4 {
  background-image: url(https://i.ibb.co/RbRDjhB/nabicho2.jpg);
}
.panel5 {
  background-image: url(https://i.ibb.co/7jpPS5f/nabicho3.jpg);
}

/* Flex Children */
.panel > * {
  margin: 0;
  width: 100%;
  transition: transform 0.5s;
  flex: 1 0 auto;
  display: flex;
  justify-content: center;
  align-items: center;
}

.panel > *:first-child {
  transform: translateY(-100%);
}
.panel.open-active > *:first-child {
  transform: translateY(0);
}

.panel > *:last-child {
  transform: translateY(100%);
}
.panel.open-active > *:last-child {
  transform: translateY(0);
}

.panel p {
  text-transform: uppercase;
  font-family: "Amatic SC", cursive;
  text-shadow: 0 0 4px rgba(0, 0, 0, 0.8), 0 0 14px rgba(0, 0, 0, 0.5);
  font-size: 2em;
}

.panel p:nth-child(2) {
  font-size: 4em;
}

.panel.open {
  flex: 5;
  font-size: 40px;
}