/* Genel */
*{box-sizing:border-box}
body {
  margin: 0;
  font-family: 'Roboto', sans-serif;
  background: #DAE3FF; /* Crystal */
  color: #253668;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
}

/* container */
.container {
  width: 100%;
  max-width: 920px;
  padding: 20px;
}

/* Form kutusu */
.flat-form {
  background: #ffffff;
  margin: 25px auto;
  width: 420px;
  min-height: 380px;
  border-radius: 15px;
  box-shadow: 0 8px 25px rgba(37, 54, 104, 0.25);
  overflow: hidden;
  position: relative;
}

/* Tabs */
.tabs {
  background: #253668;
  height: 50px;
  margin: 0;
  padding: 0;
  list-style: none;
  width: 100%;
  display: flex;
}
.tabs li { flex:1; }
.tabs a {
  display: block;
  text-decoration: none;
  color: white;
  font-size: 16px;
  text-align: center;
  line-height: 50px;
  transition: background 0.3s ease;
}
.tabs a:hover { background:#1c2850; }
.tabs a.active {
  background: #A4DBE8;
  color: #253668;
  font-weight: 600;
}

/* İçerik */
.form-action { padding: 25px; text-align: center; }
.form-action h1 { font-size: 22px; margin-bottom: 20px; color: #253668; }

/* Inputlar */
form ul { list-style:none; padding:0; margin:0; }
form input[type=text],
form input[type=password]{
  width:100%;
  height:42px;
  margin-bottom:15px;
  padding-left:12px;
  border:1px solid #D9D9D6;
  border-radius:8px;
  font-size:14px;
  outline:none;
  transition:0.3s;
}
form input:focus{
  border-color:#A4DBE8;
  box-shadow:0 0 6px rgba(164,219,232,0.6);
}

/* Buton */
.button {
  width:100%;
  height:45px;
  background:#253668;
  border:none;
  border-radius:8px;
  color:white;
  font-size:16px;
  font-weight:600;
  cursor:pointer;
  transition:background 0.3s ease;
}
.button:hover { background:#1c2850; }

/* show/hide */
.show { display: block; }
.hide { display: none; }