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

/* ========= VARIÁVEIS DE COR - TEMA PADRÃO (DARK) ========= */
:root {
    --bg-primary: #121212;
    --bg-secondary: #1a1a1a;
    --bg-tertiary: #252525;
    --bg-card: #1e1e1e;
    --bg-hover: #2a2a2a;
    --text-primary: #ffffff;
    --text-secondary: #e0e0e0;
    --text-muted: #888888;
    --border-color: #2a2a2a;
    --accent-color: #2199ef;
    --accent-hover: #4db3ff;
    --accent-glow: rgba(33, 153, 239, 0.2);
    --danger-color: #ff4444;
    --danger-hover: #ff6666;
    --success-color: #22c55e;
    --shadow: rgba(0, 0, 0, 0.3);
    --toast-bg: #1a1a1a;
    --scrollbar-track: #1a1a1a;
    --scrollbar-thumb: #2199ef;
}

/* ========= TEMA LIGHT ========= */
[data-theme="light"] {
    --bg-primary: #f5f5f5;
    --bg-secondary: #ffffff;
    --bg-tertiary: #e8e8e8;
    --bg-card: #ffffff;
    --bg-hover: #f0f0f0;
    --text-primary: #121212;
    --text-secondary: #333333;
    --text-muted: #666666;
    --border-color: #d0d0d0;
    --accent-color: #2199ef;
    --accent-hover: #0d7ad4;
    --accent-glow: rgba(33, 153, 239, 0.1);
    --danger-color: #dc2626;
    --danger-hover: #ef4444;
    --success-color: #16a34a;
    --shadow: rgba(0, 0, 0, 0.08);
    --toast-bg: #ffffff;
    --scrollbar-track: #e0e0e0;
    --scrollbar-thumb: #2199ef;
}

body {
    background: var(--bg-primary);
    font-family: 'Segoe UI', 'Inter', -apple-system, BlinkMacSystemFont, 'Roboto', sans-serif;
    overflow: hidden;
    height: 100vh;
    display: flex;
    flex-direction: column;
    transition: background 0.3s ease, color 0.3s ease;
}

/* ========= LAYOUT INSPIRADO NO ONENOTE ========= */
.onenote-topbar {
    background: var(--bg-secondary);
    color: var(--text-primary);
    padding: 0.6rem 1rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    box-shadow: 0 2px 4px var(--shadow);
    z-index: 10;
    border-bottom: 2px solid var(--accent-color);
    transition: background 0.3s ease;
}

.logo-area {
    display: flex;
    align-items: center;
    gap: 8px;
    flex-wrap: wrap;
}

.logo-icon {
    font-size: 1.4rem;
    font-weight: 600;
}

.logo-text {
    font-weight: 600;
    font-size: 1rem;
    letter-spacing: 0.5px;
    color: var(--accent-color);
}

.notebook-name {
    background: var(--accent-glow);
    padding: 0.2rem 0.7rem;
    border-radius: 20px;
    font-size: 0.7rem;
    display: flex;
    align-items: center;
    gap: 6px;
    border: 1px solid var(--accent-color);
    color: var(--text-secondary);
}

.topbar-actions {
    display: flex;
    gap: 8px;
    align-items: center;
}

.top-icon-btn {
    background: transparent;
    border: none;
    color: var(--text-primary);
    font-size: 1rem;
    cursor: pointer;
    padding: 6px 8px;
    border-radius: 6px;
    transition: 0.2s;
}

.top-icon-btn:hover {
    background: var(--accent-glow);
    color: var(--accent-color);
}

.theme-toggle-btn {
    background: transparent;
    border: none;
    color: var(--text-primary);
    font-size: 1rem;
    cursor: pointer;
    padding: 6px 8px;
    border-radius: 6px;
    transition: 0.2s;
}

.theme-toggle-btn:hover {
    background: var(--accent-glow);
    color: var(--accent-color);
}

.menu-toggle-btn {
    display: none;
}

.onenote-main {
    display: flex;
    flex: 1;
    overflow: hidden;
    position: relative;
    background: var(--bg-primary);
}

.sections-panel {
    width: 280px;
    background: var(--bg-secondary);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    overflow-y: auto;
    transition: transform 0.3s ease, background 0.3s ease;
    z-index: 5;
}

.sections-header {
    padding: 1rem 1rem 0.5rem 1.2rem;
    font-size: 0.7rem;
    text-transform: uppercase;
    font-weight: 600;
    color: var(--accent-color);
    letter-spacing: 0.5px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.add-section-btn {
    background: none;
    border: none;
    font-size: 0.9rem;
    cursor: pointer;
    color: var(--accent-color);
    font-weight: bold;
    padding: 0 8px;
    border-radius: 12px;
    transition: 0.2s;
}

.add-section-btn:hover {
    background: var(--accent-glow);
    color: var(--accent-hover);
}

.sections-list {
    list-style: none;
    padding: 0 0.6rem;
}

.section-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0.7rem 0.7rem 0.7rem 1rem;
    margin: 2px 0;
    border-radius: 12px;
    cursor: pointer;
    transition: all 0.15s;
    color: var(--text-secondary);
    font-weight: 500;
    font-size: 0.9rem;
}

.section-item:hover {
    background: var(--bg-hover);
}

.section-item.active {
    background: var(--bg-tertiary);
    box-shadow: 0 1px 3px var(--shadow);
    border-left: 4px solid var(--accent-color);
    font-weight: 600;
    color: var(--accent-color);
}

.section-name {
    flex: 1;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.section-actions {
    display: none;
    gap: 6px;
}

.section-item:hover .section-actions {
    display: flex;
}

.edit-section, .delete-section {
    background: none;
    border: none;
    cursor: pointer;
    font-size: 0.75rem;
    padding: 2px 6px;
    border-radius: 8px;
    color: var(--text-muted);
    transition: 0.2s;
}

.edit-section:hover {
    background: var(--accent-glow);
    color: var(--accent-color);
}

.delete-section:hover {
    background: rgba(255, 68, 68, 0.2);
    color: var(--danger-color);
}

.pages-panel {
    width: 260px;
    background: var(--bg-secondary);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    overflow-y: auto;
    transition: transform 0.3s ease, background 0.3s ease;
    z-index: 4;
}

.pages-header {
    padding: 1rem 1rem 0.5rem 1rem;
    font-size: 0.7rem;
    font-weight: 600;
    color: var(--accent-color);
    text-transform: uppercase;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.add-page-btn {
    background: var(--accent-glow);
    border: 1px solid var(--accent-color);
    padding: 4px 10px;
    border-radius: 20px;
    font-size: 0.7rem;
    font-weight: 500;
    cursor: pointer;
    color: var(--text-secondary);
    transition: 0.2s;
}

.add-page-btn:hover {
    background: var(--accent-color);
    border-color: var(--accent-color);
    color: white;
}

.pages-list {
    padding: 0 0.6rem;
}

.page-card {
    padding: 0.8rem 0.8rem 0.8rem 1rem;
    margin: 0.2rem 0;
    border-radius: 12px;
    cursor: pointer;
    transition: 0.1s;
    border-left: 2px solid transparent;
}

.page-card:hover {
    background: var(--bg-hover);
}

.page-card.active {
    background: var(--bg-tertiary);
    border-left: 3px solid var(--accent-color);
}

.page-title {
    font-weight: 500;
    font-size: 0.85rem;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    color: var(--text-secondary);
}

.page-card.active .page-title {
    color: var(--accent-color);
}

.page-preview {
    font-size: 0.7rem;
    color: var(--text-muted);
    margin-top: 4px;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.editor-panel {
    flex: 1;
    background: var(--bg-primary);
    display: flex;
    flex-direction: column;
    overflow-y: auto;
    box-shadow: -2px 0 8px var(--shadow);
}

.editor-toolbar {
    background: var(--bg-secondary);
    padding: 0.7rem 1rem;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
    align-items: center;
    transition: background 0.3s ease;
}

.editor-tool-btn {
    background: transparent;
    border: none;
    padding: 6px 12px;
    border-radius: 8px;
    font-size: 0.8rem;
    font-weight: 500;
    cursor: pointer;
    color: var(--text-secondary);
    transition: 0.2s;
}

.editor-tool-btn:hover {
    background: var(--accent-glow);
    color: var(--accent-color);
}

.mobile-back-btn {
    display: none;
}

.editor-content {
    padding: 1.5rem;
    max-width: 900px;
    width: 100%;
    margin: 0 auto;
    flex: 1;
}

.editor-title-input {
    width: 100%;
    font-size: 1.5rem;
    font-weight: 600;
    border: none;
    background: transparent;
    padding: 0.5rem 0;
    margin-bottom: 1rem;
    font-family: 'Segoe UI', 'Inter', sans-serif;
    color: var(--text-primary);
    border-bottom: 2px solid var(--border-color);
    transition: 0.2s;
}

@media (min-width: 768px) {
    .editor-title-input {
        font-size: 2rem;
    }
    .editor-content {
        padding: 2rem 2.5rem;
    }
}

.editor-title-input:focus {
    outline: none;
    border-bottom-color: var(--accent-color);
}

.editor-title-input::placeholder {
    color: var(--text-muted);
}

.editor-textarea {
    width: 100%;
    min-height: 55vh;
    border: none;
    background: transparent;
    font-family: 'Segoe UI', 'Inter', system-ui, monospace;
    font-size: 0.95rem;
    line-height: 1.6;
    resize: vertical;
    padding: 0.5rem 0;
    color: var(--text-secondary);
}

@media (min-width: 768px) {
    .editor-textarea {
        font-size: 1rem;
        min-height: 60vh;
    }
}

.editor-textarea:focus {
    outline: none;
}

.editor-textarea::placeholder {
    color: var(--text-muted);
}

.status-bar {
    background: var(--bg-secondary);
    padding: 0.4rem 1rem;
    font-size: 0.7rem;
    color: var(--text-muted);
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 0.5rem;
    transition: background 0.3s ease;
}

.status-bar span:first-child {
    color: var(--accent-color);
}

.onenote-toast {
    position: fixed;
    bottom: 25px;
    left: 50%;
    transform: translateX(-50%);
    background: var(--toast-bg);
    backdrop-filter: blur(8px);
    color: var(--accent-color);
    padding: 0.5rem 1.2rem;
    border-radius: 40px;
    font-size: 0.8rem;
    z-index: 1200;
    pointer-events: none;
    font-weight: 500;
    white-space: nowrap;
    border: 1px solid var(--accent-color);
    box-shadow: 0 0 10px var(--accent-glow);
}

@media (max-width: 500px) {
    .onenote-toast {
        white-space: normal;
        max-width: 90%;
        text-align: center;
        font-size: 0.75rem;
    }
}

.mobile-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.7);
    z-index: 8;
    display: none;
}

.mobile-overlay.active {
    display: block;
}

::-webkit-scrollbar {
    width: 6px;
}

::-webkit-scrollbar-track {
    background: var(--scrollbar-track);
}

::-webkit-scrollbar-thumb {
    background: var(--scrollbar-thumb);
    border-radius: 10px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--accent-hover);
}

@media (max-width: 768px) {
    .menu-toggle-btn {
        display: block;
    }

    .notebook-name span {
        display: none;
    }

    .notebook-name {
        padding: 0.2rem 0.5rem;
    }

    .sections-panel {
        position: fixed;
        top: 52px;
        left: 0;
        bottom: 0;
        width: 280px;
        transform: translateX(-100%);
        z-index: 100;
        box-shadow: 2px 0 12px var(--shadow);
    }

    .sections-panel.open {
        transform: translateX(0);
    }

    .pages-panel {
        position: fixed;
        top: 52px;
        left: 0;
        bottom: 0;
        width: 280px;
        transform: translateX(-100%);
        z-index: 99;
        background: var(--bg-secondary);
        box-shadow: 2px 0 12px var(--shadow);
    }

    .pages-panel.open {
        transform: translateX(0);
    }

    .editor-panel {
        width: 100%;
    }

    .mobile-back-btn {
        display: inline-flex !important;
    }

    .editor-toolbar {
        padding: 0.5rem 0.8rem;
    }

    .editor-tool-btn {
        padding: 4px 10px;
        font-size: 0.75rem;
    }

    .top-icon-btn span {
        display: none;
    }

    .logo-text {
        display: none;
    }
}

@media (max-width: 480px) {
    .onenote-topbar {
        padding: 0.5rem 0.8rem;
    }

    .editor-content {
        padding: 1rem;
    }

    .editor-title-input {
        font-size: 1.3rem;
    }

    .status-bar {
        font-size: 0.65rem;
    }
}