*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --bg-color: #f4f4f9;
    --text-color: #333;
    --sidebar-bg-color: #e9ecef;
    --sidebar-border-color: #ccc;
    --notebook-hover-color: #dcdfe3;
    --notebook-active-color: #c0c4c8;
    --accent-color: #007bff;
    --add-btn-bg-color: #28a745;
    --add-btn-text-color: white;
    --note-bg-color: #fff;
    --note-border-color: #ddd;
    --shadow-color: rgba(0,0,0,0.1);
    --icon-color: #6c757d;
}

body.dark-theme {
    --bg-color: #0a0a0e;
    --text-color: #e0e0e0;
    --sidebar-bg-color: #1a1a20;
    --sidebar-border-color: #333;
    --notebook-hover-color: #2a2a30;
    --notebook-active-color: #3a3a40;
    --accent-color: #8ab4f8;
    --add-btn-bg-color: #4a90e2;
    --add-btn-text-color: #1e1e1e;
    --note-bg-color: #2a2a3a;
    --note-border-color: #444;
    --shadow-color: rgba(0,0,0,0.4);
    --icon-color: #9aa0a6;
}

body.dark-theme #notes-list li,
body.dark-theme .modal-content,
body.dark-theme .view-modal-content {
    background: rgba(255, 255, 255, 0.05);
    border: 1px solid rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    transition: box-shadow 0.3s ease-in-out;
}

body.dark-theme #notes-list li {
    box-shadow: 0 0 10px rgba(138, 180, 248, 0.3), 0 0 20px rgba(138, 180, 248, 0.1);
}

body.dark-theme #notes-list li:hover {
    box-shadow: 0 0 15px rgba(138, 180, 248, 0.5), 0 0 30px rgba(138, 180, 248, 0.2);
}

body.dark-theme #add-note-btn,
body.dark-theme #add-notebook-btn {
    box-shadow: 0 0 10px var(--accent-color);
}

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    margin: 0;
    transition: background-color 0.3s, color 0.3s;
}

.container {
    display: flex;
    height: 100vh;
}

.sidebar {
    width: 250px;
    background-color: var(--sidebar-bg-color);
    padding: 20px;
    border-right: 1px solid var(--sidebar-border-color);
    box-shadow: 2px 0 5px var(--shadow-color);
    display: flex;
    flex-direction: column;
}

.sidebar-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}

.sidebar h2 {
    margin: 0;
    color: var(--accent-color);
}

#theme-toggle-btn {
    background: none;
    border: none;
    color: var(--icon-color);
    font-size: 1.5rem;
    cursor: pointer;
    transition: color 0.3s;
}

#theme-toggle-btn:hover {
    color: var(--accent-color);
}

#notebook-list {
    list-style-type: none;
    padding: 0;
    flex-grow: 1;
    overflow-y: auto;
    margin-bottom: 10px;
}

#notebook-list li {
    padding: 12px;
    cursor: pointer;
    border-bottom: 1px solid var(--note-border-color);
    transition: background-color 0.2s;
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-radius: 4px;
    margin-bottom: 5px;
}

#notebook-list li:hover {
    background-color: var(--notebook-hover-color);
}

#notebook-list .active {
    background-color: var(--notebook-active-color);
    font-weight: bold;
}

#add-notebook-btn {
    width: 100%;
    padding: 12px;
    background-color: var(--add-btn-bg-color);
    color: var(--add-btn-text-color);
    border: none;
    border-radius: 8px;
    cursor: pointer;
    margin-top: auto;
    font-weight: bold;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
}

.main-content {
    flex-grow: 1;
    padding: 20px;
    display: flex;
    flex-direction: column;
}

#notebook-title {
    color: var(--accent-color);
    border-bottom: 2px solid var(--note-border-color);
    padding-bottom: 10px;
    margin-top: 0;
}

.notes-header {
    display: flex;
    flex-direction: column;
    gap: 10px;
    margin-bottom: 20px;
}

#note-input {
    flex-grow: 1;
    padding: 12px;
    border: 1px solid var(--note-border-color);
    border-radius: 8px;
    background-color: var(--note-bg-color);
    color: var(--text-color);
    resize: vertical;
}

#add-note-btn {
    padding: 12px 20px;
    background-color: var(--accent-color);
    color: var(--add-btn-text-color);
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-weight: bold;
    display: flex;
    align-items: center;
    gap: 8px;
}

#notes-list {
    list-style-type: none;
    padding: 0;
    flex-grow: 1;
    overflow-y: auto;
}

#notes-list li {
    padding: 15px;
    background-color: var(--note-bg-color);
    border: 1px solid var(--note-border-color);
    border-radius: 8px;
    margin-bottom: 10px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: 0 2px 4px var(--shadow-color);
}

.note-actions button,
.notebook-actions button {
    background: none;
    border: none;
    cursor: pointer;
    font-size: 1.2rem;
    margin-left: 10px;
    color: var(--icon-color);
    transition: color 0.3s;
}

.note-actions button:hover,
.notebook-actions button:hover {
    color: var(--accent-color);
}

/* Modal Styling */
.modal {
    display: none;
    position: fixed;
    z-index: 100;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    overflow: auto;
    background-color: rgba(0,0,0,0.6);
    justify-content: center;
    align-items: center;
}

.modal-content {
    background-color: var(--note-bg-color);
    padding: 25px;
    border-radius: 10px;
    border: 1px solid var(--note-border-color);
    box-shadow: 0 4px 8px var(--shadow-color);
    width: 90%;
    max-width: 400px;
    text-align: center;
}

.modal-input {
    width: 100%;
    padding: 10px;
    margin: 10px 0;
    border: 1px solid var(--note-border-color);
    border-radius: 5px;
    background-color: var(--bg-color);
    color: var(--text-color);
    resize: vertical;
}

.modal-buttons {
    display: flex;
    justify-content: center;
    gap: 10px;
    margin-top: 15px;
}

.modal-btn {
    padding: 10px 20px;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    font-weight: bold;
}

#modal-ok-btn {
    background-color: var(--accent-color);
    color: var(--add-btn-text-color);
}

#modal-cancel-btn {
    background-color: #dc3545;
    color: white;
}

/* New View Modal Styles */
.view-modal-content {
    background-color: var(--note-bg-color);
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 4px 15px var(--shadow-color);
    width: 90%;
    height: 90%;
    display: flex;
    flex-direction: column;
}

.view-modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    border-bottom: 2px solid var(--note-border-color);
    padding-bottom: 10px;
    margin-bottom: 10px;
}

.view-modal-header h3 {
    margin: 0;
    color: var(--accent-color);
}

.close-btn {
    background: none;
    border: none;
    color: var(--text-color);
    font-size: 2rem;
    cursor: pointer;
    transition: color 0.3s;
}

.close-btn:hover {
    color: var(--accent-color);
}

.note-view-area {
    flex-grow: 1;
    overflow-y: auto;
    white-space: pre-wrap;
    word-wrap: break-word;
    line-height: 1.5;
    font-size: 1rem;
    color: var(--text-color);
}

/* Responsive Design */
@media (max-width: 768px) {
    .container {
        flex-direction: column;
        height: auto;
        min-height: 100vh;
    }

    .sidebar {
        width: 100%;
        height: auto;
        border-right: none;
        border-bottom: 1px solid var(--sidebar-border-color);
        box-shadow: 0 2px 5px var(--shadow-color);
    }

    .sidebar-header {
        margin-bottom: 10px;
    }
    
    #notebook-list {
        display: flex;
        flex-wrap: wrap;
        gap: 10px;
        margin-bottom: 10px;
        overflow-y: hidden;
        overflow-x: auto;
        white-space: nowrap;
    }
    
    #notebook-list li {
        flex-shrink: 0;
        width: auto;
        border-right: 1px solid var(--note-border-color);
        border-bottom: none;
        font-size: 0.9rem;
    }

    #add-notebook-btn {
        margin-top: 0;
        width: 100%;
    }

    .main-content {
        padding: 15px;
    }

    .notes-header {
        flex-direction: column;
    }

    #note-input, #add-note-btn {
        width: 100%;
    }
}