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

:root {
    --color-bg: #fafafa;
    --color-surface: #ffffff;
    --color-text: #1a1a1a;
    --color-text-light: #666666;
    --color-text-lighter: #999999;
    --color-border: #e5e5e5;
    --color-accent: #000000;
    --color-accent-hover: #333333;
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --radius: 8px;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.08);
    --transition: all 0.2s ease;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Helvetica', 'Arial', sans-serif;
    background: var(--color-bg);
    color: var(--color-text);
    line-height: 1.6;
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.container {
    max-width: 900px;
    margin: 0 auto;
    padding: var(--spacing-xl) var(--spacing-md);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header */
header {
    text-align: center;
    margin-bottom: var(--spacing-xl);
    padding-bottom: var(--spacing-lg);
    border-bottom: 1px solid var(--color-border);
}

h1 {
    font-size: 2.5rem;
    font-weight: 300;
    letter-spacing: -0.02em;
    margin-bottom: var(--spacing-xs);
}

.subtitle {
    color: var(--color-text-light);
    font-size: 1rem;
    font-weight: 400;
}

/* Main Content */
main {
    flex: 1;
}

/* New Idea Section */
.new-idea {
    background: var(--color-surface);
    border-radius: var(--radius);
    padding: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--color-border);
}

.formatting-toolbar {
    display: flex;
    gap: var(--spacing-xs);
    margin-bottom: var(--spacing-sm);
    padding-bottom: var(--spacing-sm);
    border-bottom: 1px solid var(--color-border);
    align-items: center;
}

.format-btn {
    background: transparent;
    border: 1px solid var(--color-border);
    padding: 0.4rem 0.8rem;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.875rem;
    color: var(--color-text);
    transition: var(--transition);
}

.format-btn:hover {
    background: var(--color-bg);
    border-color: var(--color-accent);
}

.format-btn.active {
    background: var(--color-accent);
    color: white;
    border-color: var(--color-accent);
}

.toolbar-divider {
    width: 1px;
    height: 1.5rem;
    background: var(--color-border);
    margin: 0 var(--spacing-xs);
}

#ideaInput {
    width: 100%;
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: var(--spacing-md);
    font-family: inherit;
    font-size: 1rem;
    line-height: 1.6;
    resize: vertical;
    min-height: 100px;
    transition: var(--transition);
}

#ideaInput:focus {
    outline: none;
    border-color: var(--color-accent);
    box-shadow: 0 0 0 3px rgba(0, 0, 0, 0.05);
}

.idea-meta {
    display: flex;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-sm);
}

#tagInput {
    flex: 1;
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 0.75rem var(--spacing-md);
    font-family: inherit;
    font-size: 0.9rem;
    transition: var(--transition);
}

#tagInput:focus {
    outline: none;
    border-color: var(--color-accent);
}

.btn-primary {
    background: var(--color-accent);
    color: white;
    border: none;
    padding: 0.75rem var(--spacing-md);
    border-radius: var(--radius);
    font-family: inherit;
    font-size: 0.9rem;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    white-space: nowrap;
}

.btn-primary:hover {
    background: var(--color-accent-hover);
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

.btn-primary:active {
    transform: translateY(0);
}

/* Controls Section */
.controls {
    display: flex;
    justify-content: space-between;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
    flex-wrap: wrap;
}

.filter-group {
    display: flex;
    gap: var(--spacing-sm);
    flex: 1;
    min-width: 250px;
}

.sort-group {
    display: flex;
    gap: var(--spacing-sm);
}

#searchInput,
#tagFilter,
#sortSelect {
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 0.6rem var(--spacing-sm);
    font-family: inherit;
    font-size: 0.9rem;
    background: var(--color-surface);
    transition: var(--transition);
}

#searchInput {
    flex: 1;
}

#searchInput:focus,
#tagFilter:focus,
#sortSelect:focus {
    outline: none;
    border-color: var(--color-accent);
}

/* Ideas Container */
.ideas-container {
    margin-bottom: var(--spacing-lg);
}

#ideasList {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-md);
}

.idea-card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: var(--spacing-md);
    transition: var(--transition);
    animation: slideIn 0.3s ease;
}

@keyframes slideIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.idea-card:hover {
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
}

.idea-header {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: var(--spacing-sm);
}

.idea-date {
    font-size: 0.8rem;
    color: var(--color-text-lighter);
}

.idea-actions {
    display: flex;
    gap: var(--spacing-xs);
}

.btn-icon {
    background: transparent;
    border: 1px solid var(--color-border);
    padding: 0.3rem 0.6rem;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.8rem;
    color: var(--color-text-light);
    transition: var(--transition);
}

.btn-icon:hover {
    background: var(--color-bg);
    color: var(--color-accent);
    border-color: var(--color-accent);
}

.idea-content {
    margin-bottom: var(--spacing-sm);
    line-height: 1.7;
    white-space: pre-wrap;
    word-wrap: break-word;
}

.idea-content strong {
    font-weight: 600;
}

.idea-content em {
    font-style: italic;
}

.idea-content code {
    background: var(--color-bg);
    padding: 0.2rem 0.4rem;
    border-radius: 3px;
    font-family: 'Monaco', 'Courier New', monospace;
    font-size: 0.9em;
}

.idea-content s {
    text-decoration: line-through;
    color: var(--color-text-light);
}

.idea-content .h1 {
    font-size: 1.5rem;
    font-weight: 600;
    display: block;
    margin: var(--spacing-sm) 0;
}

.idea-content .h2 {
    font-size: 1.2rem;
    font-weight: 600;
    display: block;
    margin: var(--spacing-sm) 0;
}

.idea-content .quote {
    border-left: 3px solid var(--color-accent);
    padding-left: var(--spacing-md);
    margin: var(--spacing-sm) 0;
    color: var(--color-text-light);
    font-style: italic;
    display: block;
}

.idea-tags {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
}

.tag {
    background: var(--color-bg);
    color: var(--color-text);
    padding: 0.25rem 0.6rem;
    border-radius: 12px;
    font-size: 0.8rem;
    border: 1px solid var(--color-border);
}

/* Empty State */
.empty-state {
    text-align: center;
    padding: var(--spacing-xl);
    color: var(--color-text-light);
}

.empty-state.hidden {
    display: none;
}

/* Footer */
footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: var(--spacing-lg);
    margin-top: var(--spacing-lg);
    border-top: 1px solid var(--color-border);
    font-size: 0.85rem;
    color: var(--color-text-lighter);
}

.device-info {
    font-family: 'Monaco', 'Courier New', monospace;
}

/* Edit Mode */
.idea-card.editing .idea-content {
    display: none;
}

.idea-card .idea-edit {
    display: none;
}

.idea-card.editing .idea-edit {
    display: block;
}

.idea-edit textarea {
    width: 100%;
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: var(--spacing-sm);
    font-family: inherit;
    font-size: 1rem;
    line-height: 1.6;
    resize: vertical;
    min-height: 100px;
    margin-bottom: var(--spacing-sm);
}

.idea-edit textarea:focus {
    outline: none;
    border-color: var(--color-accent);
}

.idea-edit-actions {
    display: flex;
    gap: var(--spacing-xs);
}

.btn-save,
.btn-cancel {
    padding: 0.5rem var(--spacing-sm);
    border-radius: var(--radius);
    font-family: inherit;
    font-size: 0.9rem;
    cursor: pointer;
    transition: var(--transition);
}

.btn-save {
    background: var(--color-accent);
    color: white;
    border: none;
}

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

.btn-cancel {
    background: transparent;
    border: 1px solid var(--color-border);
    color: var(--color-text);
}

.btn-cancel:hover {
    background: var(--color-bg);
}

/* Responsive Design */
@media (max-width: 768px) {
    h1 {
        font-size: 2rem;
    }

    .container {
        padding: var(--spacing-lg) var(--spacing-sm);
    }

    .controls {
        flex-direction: column;
    }

    .filter-group {
        flex-direction: column;
        min-width: 100%;
    }

    .idea-meta {
        flex-direction: column;
    }

    footer {
        flex-direction: column;
        gap: var(--spacing-sm);
        text-align: center;
    }

    .formatting-toolbar {
        flex-wrap: wrap;
    }
}