body {
  margin: 0;
  font-family: Arial;
  background: #f2f4f7;
}

.app-container {
  max-width: 500px;
  margin: auto;
  background: white;
  min-height: 100vh;

  display: flex;
  flex-direction: column;
}

.topbar {
  height: 60px;
  background: #2c3e50;
  color: white;

  display: flex;
  align-items: center;
  padding: 0 15px;
}

.logo {
  flex: 1;
  text-align: center;
  font-weight: bold;
}


.content {
  flex: 1;
  padding: 5px;

  overflow: auto;
}

.bottom-nav {
  height: 60px;
  background: white;

  display: flex;
  justify-content: space-around;
  align-items: center;

  border-top: 1px solid #ddd;
}

.bottom-nav a {
  font-size: 24px;
  text-decoration: none;
}

.dashboard {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 15px;
}

.card {
  background: #f8f9fb;

  border-radius: 15px;

  padding: 20px;

  text-align: center;

  font-size: 28px;

  text-decoration: none;
  color: black;

  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.1);

  transition: 0.2s;
}

.card:hover {
  transform: scale(1.05);
}

.card p {
  font-size: 12px;
  margin-top: 5px;
}

.icon {
  font-size: 40px;
}

.label {
  margin-top: 10px;
  font-size: 14px;
}

.roulette-container {
  position: relative;
  width: 400px;
  margin: auto;
}

.arrow {
  position: absolute;
  top: -10px;
  left: 190px;
  font-size: 30px;
  color: red;
}

#history {
  list-style: none;
}

.login-box {
  width: 300px;
  margin: 120px auto;
  padding: 30px;

  background: white;
  border-radius: 10px;

  text-align: center;

  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
}

img.icon {
  width: 72px;
  height: 72px;
  border-radius: 18px;
  box-shadow: 0 6px 12px rgba(0, 0, 0, 0.25);
  transition:
    transform 0.12s ease,
    box-shadow 0.12s ease;
}

img.titleIcon {
  width: 40px;
  height: 40px;
  border-radius: 9px;
  box-shadow: 0 6px 12px rgba(0, 0, 0, 0.25);
  transition:
    transform 0.12s ease,
    box-shadow 0.12s ease;
}

.login-box {
  width: 320px;
  margin: 120px auto;
  padding: 40px;
  background: white;
  border-radius: 10px;
  box-shadow: 0 5px 20px rgba(0, 0, 0, 0.1);
  text-align: center;
}

.login-box h1 {
  margin-bottom: 30px;
}

.input-group {
  margin-bottom: 15px;
}

.input-group input {
  width: 90%;
  padding: 10px;
  border: 1px solid #ccc;
  border-radius: 5px;
  font-size: 14px;
}

.input-group textarea {
  width: 90%;
  padding: 10px;
  border: 1px solid #ccc;
  border-radius: 5px;
  font-size: 14px;
}

.login-btn {
  width: 50%;
  padding: 10px;
  background: #4caf50;
  color: white;
  border: none;
  border-radius: 5px;
  font-size: 16px;
  cursor: pointer;
}

.login-btn:hover {
  background: #43a047;
}

.login-extra {
  margin-top: 15px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.guest-btn {
  background: #eee;
  border: none;
  padding: 8px 12px;
  border-radius: 5px;
  cursor: pointer;
}

.signup {
  text-decoration: none;
  color: #4caf50;
  font-weight: bold;
}

.container {
  max-width: 500px;
  width: 95%;
  margin: auto;
}

.board-bottom {
  text-align: right;
  margin-top: 10px;
}

.write-btn {
  background: #4caf50;
  color: white;
  padding: 6px 12px;
  text-decoration: none;
  border-radius: 4px;
}

.board-table {
  width: 100%;
  border-collapse: collapse;
}

.board-table th,
.board-table td {
  border-bottom: 1px solid #ddd;
  padding: 8px;
  text-align: center;
}

.board-table td:nth-child(2) {
  text-align: left;
}

.form-group {
  margin-bottom: 15px;
}

input,
textarea {
  width: 100%;
  padding: 8px;
}

.form-buttons {
  margin-top: 10px;
}

button {
  padding: 8px 15px;
}

.post-image {
  max-width: 600px;
  margin: 20px 0;
  border-radius: 8px;
}

.logout {
  color: white;
  text-decoration: underline;
}

.logout:hover {
  opacity: 0.8;
}

.submit-btn {
  background: #4caf50;
  color: white;
  border: none;
  cursor: pointer;
  padding: 6px 12px;
  text-decoration: none;
  border-radius: 4px;
}

.submit-btn:hover {
  background: #43a047;
}

.comment-list {
  margin-top: 20px;
}

.comment-box {
  border: 1px solid #ddd;
  padding: 12px;
  margin-bottom: 10px;
  border-radius: 8px;
  background: #fafafa;
}

.comment-header {
  display: flex;
  justify-content: space-between;
  font-size: 14px;
  margin-bottom: 5px;
}

.comment-content {
  font-size: 15px;
  line-height: 1.5;
}

.comment-title {
  margin-top: 30px;
}

.math-container {
  max-width: 700px;
  margin: auto;
  text-align: center;
}

.math-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
  margin-top: 30px;
}

.math-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 120px;
  font-size: 40px;
  text-decoration: none;
  background: #f5f5f5;
  border-radius: 12px;
  transition: 0.2s;
}

.math-card p {
  font-size: 16px;
  margin-top: 10px;
}

.math-card:hover {
  background: #e8f2ff;
  transform: translateY(-3px);
}

.math-upload {
  max-width: 500px;
  margin: auto;
  text-align: center;
}

.upload-box {
  border: 2px dashed #ccc;
  padding: 40px;
  margin: 30px 0;
  border-radius: 10px;
}

.solve-btn {
  background: #4caf50;
  color: white;
  border: none;
  padding: 12px 25px;
  border-radius: 8px;
  font-size: 16px;
  cursor: pointer;
}

.solve-btn:hover {
  background: #43a047;
}

.problem-list{
margin-top:20px;
}

.problem-card{
display:block;
padding:15px;
margin-bottom:10px;
background:#fafafa;
border-radius:8px;
text-decoration:none;
color:black;
border:1px solid #eee;
}

.problem-card:hover{
background:#f0f7ff;
}

.date{
font-size:12px;
color:#777;
}

.done{
color:green;
}

.problem-img{
max-width:100%;
margin:20px 0;
}

.ai-answer{
background:#f5f5f5;
padding:15px;
border-radius:8px;
}

.understand-btn{
display:inline-block;
margin-top:20px;
background:#2196F3;
color:white;
padding:10px 20px;
border-radius:6px;
text-decoration:none;
}






/* CYJ */
.topbar_cyj{
    background:linear-gradient(90deg, #1f1f1f, #2d2d2d);
    padding:14px 20px;

    display:flex;
    gap:12px;
    align-items:center;
    flex-wrap:wrap;

    border-radius:12px;
    box-shadow:0 2px 10px rgba(0,0,0,0.15);

    margin-bottom:20px;
}

.topbar_cyj a{
    color:#f5f5f5;
    text-decoration:none;

    padding:4px 7px;
    border-radius:4px;

    font-size:15px;
    font-weight:500;

    transition:all 0.2s ease;
}

.topbar_cyj a:hover{
    background:#4a90e2;
    color:white;

    transform:translateY(-2px);
}

.word-card{

    background:white;
    border-radius:8px;
    padding:10px;
    margin-bottom:8px;

    box-shadow:0 2px 8px rgba(0,0,0,0.1);
}

.word{
    font-size:28px;
    font-weight:bold;
}

.meaning{
    margin-top:10px;
    color:#666;
    display:none;
}

.card-meaning{
    display:none;
    margin-top:20px;
}

.btn{

    display:inline-block;
    padding:10px 15px;

    border-radius:10px;

    background:#222;
    color:white;

    text-decoration:none;
    border:none;

    cursor:pointer;
}

.btn-green{
    background:green;  
}

.btn-red{
    background:crimson;
}

.center{
    text-align:center;
}

.quiz-input{

    width:90%;
    padding:12px;

    font-size:18px;

    border-radius:10px;
    border:1px solid #ccc;

    margin-top:20px;
}

.progress{

    height:20px;
    background:#ddd;

    border-radius:20px;

    overflow:hidden;
}

.progress-bar{

    height:100%;
    background:green;
}

.search-bar{

    background:white;

    padding:5px;

    border-bottom:1px solid #ddd;
}

.search-bar form{

    display:flex;

    gap:5px;

    align-items:center;

    flex-wrap:wrap;
}

.search-bar select{

    padding:5px;

    border-radius:5px;

    border:1px solid #ccc;
}

.search-bar input{

    width:175px;

    padding:5px;

    border-radius:5px;

    border:1px solid #ccc;
}

.search-bar button{

    height:30px;

    display:flex;

    align-items:center;

    justify-content:center;
}

.menu{
    white-space: pre-wrap;
    font-family: monospace;
}

/* ljh */
canvas {
    display: block;
}

#space {
    width: 100%;
    aspect-ratio: 1 / 1;
    background: black;
    display: block;
}