body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: #f4f7f6;
    color: #333;
    display: flex;
    flex-direction: column;
    align-items: center;
    margin: 0;
    padding: 20px;
}

h1, h2, h3 {
    color: #2c3e50;
}

.hidden {
    display: none;
}

#app-section, #login-section {
    width: 100%;
    max-width: 650px;
    background: white;
    padding: 30px;
    border-radius: 12px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    margin-top: 20px;
}

.user-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 1px solid #eee;
    margin-bottom: 20px;
    padding-bottom: 10px;
}

.secondary-btn {
    background-color: #6c757d;
    font-size: 0.9em;
}

input[type="text"], textarea {
    width: 100%;
    padding: 12px;
    border: 1px solid #ddd;
    border-radius: 6px;
    margin-bottom: 15px;
    box-sizing: border-box;
    font-family: inherit;
}

button {
    padding: 12px 20px;
    border: none;
    background-color: #3498db;
    color: white;
    border-radius: 6px;
    cursor: pointer;
    font-weight: 600;
    transition: all 0.2s;
}

button:hover {
    background-color: #2980b9;
    transform: translateY(-1px);
}

.tuner-mode {
    display: flex;
    gap: 15px;
    margin-bottom: 25px;
}

.panel {
    padding: 20px;
    background-color: #f8f9fa;
    border-radius: 8px;
    margin-top: 15px;
}

.panel button {
    margin-right: 8px;
    margin-bottom: 8px;
    min-width: 60px;
}

#pitch-output {
    text-align: center;
    font-size: 2.8em;
    margin-top: 20px;
    padding: 30px;
    background-color: #fff;
    border-radius: 10px;
    border: 2px solid #3498db;
    color: #3498db;
}

#frequency-display {
    font-size: 0.5em;
    color: #7f8c8d;
    display: block;
    margin-top: 5px;
}

.notes-container {
    margin-top: 30px;
    border-top: 2px solid #eee;
    padding-top: 20px;
}

.notes-editor {
    margin-bottom: 30px;
}

#notes-list {
    margin-top: 15px;
    max-height: 400px;
    overflow-y: auto;
}

.note-item {
    background-color: #fff;
    border: 1px solid #eee;
    padding: 15px;
    border-radius: 8px;
    margin-bottom: 12px;
    border-left: 4px solid #3498db;
}

.note-date {
    font-size: 0.8em;
    color: #95a5a6;
    margin-bottom: 5px;
}

.note-content {
    line-height: 1.5;
    white-space: pre-wrap;
}

.no-notes {
    color: #95a5a6;
    font-style: italic;
    text-align: center;
}