body {

    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: #f4f4f9;
    color: #333;
    margin: 0;
    padding: 20px;
    display: flex;
    flex-direction: column;
    align-items: center;
}
header, main {

    width: 100%;
    max-width: 600px;
}
h1 {
 text-align: center; }
.user-selection {
 margin-bottom: 20px; text-align: center; }
select {
 padding: 10px; font-size: 16px; border-radius: 5px; width: 100%; max-width: 300px; }
.card {
 background: white; padding: 20px; border-radius: 10px; box-shadow: 0 4px 6px rgba(0,0,0,0.1); text-align: center; margin-bottom: 30px;}
.buttons {
 display: flex; flex-direction: column; gap: 10px; margin-top: 20px; }
button {
 padding: 15px; font-size: 16px; border: none; border-radius: 8px; cursor: pointer; color: white; transition: 0.2s; font-weight: bold; }
#btn-opt1 {
 background-color: #007bff; }
#btn-opt2 {
 background-color: #dc3545; }
button:hover {
 opacity: 0.8; }
.or {
 font-weight: bold; color: #777; margin: 10px 0; }
.result-bar {
 width: 100%; background: #ddd; border-radius: 5px; overflow: hidden; height: 30px; position: relative;}
.bar-fill {
 height: 100%; display: flex; align-items: center; justify-content: flex-end; padding-right: 10px; color: white; font-weight: bold; transition: width 0.5s; width: 0%; white-space: nowrap;}
.blue {
 background-color: #007bff; }
.red {
 background-color: #dc3545; }
.mt-2 {
 margin-top: 15px; }
.res-text {
 margin-top: 5px; font-size: 14px; font-weight: bold; }
.history-item {

 background: white; padding: 15px; border-radius: 8px; margin-bottom: 10px; box-shadow: 0 2px 4px rgba(0,0,0,0.05); }