* {
    box-sizing: border-box;
}

body {
    margin: 0;
    min-height: 100vh;
    font-family: Arial, Helvetica, sans-serif;
    background: #f4f4f4;
    color: #222;
}

.container {
    width: 90%;
    max-width: 700px;
    margin: 50px auto;
    padding: 30px;
    background: white;
    border-radius: 10px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}

.exchange-card {
    cursor: pointer;
}

.exchange-title-link {
    color: inherit;
    text-decoration: underline;
}

.exchange-title-link:hover {
    text-decoration-thickness: 2px;
}

h1 {
    margin-top: 0;
}

h2 {
    margin-top: 30px;
}

form {
    display: flex;
    flex-direction: column;
    gap: 10px;
    margin: 20px 0;
}

label {
    font-weight: bold;
    margin-top: 5px;
}

input,
textarea {
    width: 100%;
    padding: 10px;
    font-size: 16px;
    border: 1px solid #ccc;
    border-radius: 6px;
}

textarea {
    min-height: 100px;
    resize: vertical;
}

button {
    padding: 10px 16px;
    margin-top: 10px;
    font-size: 16px;
    cursor: pointer;
    border: none;
    border-radius: 6px;
    background: #333;
    color: white;
}

button:hover {
    background: #555;
}

button:disabled {
    background: #aaa;
    cursor: not-allowed;
}

a {
    color: #0066cc;
    text-decoration: none;
}

a:hover {
    text-decoration: underline;
}

#participant-list > div {
    padding: 12px 0;
    border-bottom: 1px solid #ddd;
}

#participant-list button {
    margin-top: 0;
}

#message {
    margin-top: 15px;
    font-weight: bold;
}