:root {
    --primary-color: #1a73e8;
    --bg-color: #ffffff;
    --text-color: #202124;
    --border-color: #dadce0;
    --hover-color: #f8f9fa;
    --completed-color: #5f6368;
    --shadow-color: rgba(0, 0, 0, 0.1);
    --heading-color: #000000;
}

[data-theme="dark"] {
    --bg-color: #202124;
    --text-color: #e8eaed;
    --border-color: #3c4043;
    --hover-color: #2d2e31;
    --completed-color: #9aa0a6;
    --shadow-color: rgba(0, 0, 0, 0.3);
    --heading-color: #ffffff;
}

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

html {
    font-size: 16px;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    transition: background-color 0.3s, color 0.3s;
    min-height: 100vh;
    padding: 1rem;
    line-height: 1.5;
    display: flex;
    flex-direction: column;
}

.container {
    max-width: 600px;
    margin: 0 auto;
    padding: 1rem;
    width: 100%;
    flex: 1;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
    flex-wrap: wrap;
    gap: 1rem;
}

.header-main {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
}

h1 {
    font-size: clamp(1.5rem, 5vw, 2rem);
    font-weight: 700;
    letter-spacing: -0.5px;
    display: flex;
    align-items: center;
}

h1 .type-part {
    color: var(--heading-color);
}

h1 .list-part {
    color: var(--primary-color);
}

#theme-toggle {
    background: none;
    border: none;
    color: var(--text-color);
    cursor: pointer;
    font-size: clamp(1.2rem, 4vw, 1.5rem);
    padding: 0.5rem;
    border-radius: 50%;
    transition: background-color 0.2s;
}

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

#todo-form {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
    flex-wrap: wrap;
}

#todo-input {
    flex: 1;
    min-width: 200px;
    padding: 0.75rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
    background-color: var(--bg-color);
    color: var(--text-color);
    transition: border-color 0.2s, box-shadow 0.2s;
}

#todo-input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 2px rgba(26, 115, 232, 0.2);
}

#todo-form button {
    padding: 0.75rem 1.5rem;
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    transition: background-color 0.2s, box-shadow 0.2s;
    font-weight: 500;
}

#todo-form button:hover {
    background-color: #1557b0;
    box-shadow: 0 1px 2px var(--shadow-color);
}

.todo-filters {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1rem;
    flex-wrap: wrap;
}

.filter-btn {
    padding: 0.5rem 1rem;
    background: none;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    color: var(--text-color);
    cursor: pointer;
    transition: all 0.2s;
    font-size: 0.9rem;
    font-weight: 500;
}

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

.filter-btn.active {
    background-color: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

#todo-list {
    list-style: none;
    margin-bottom: 1.5rem;
}

.todo-item {
    display: flex;
    align-items: center;
    padding: 1rem;
    background-color: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    margin-bottom: 0.5rem;
    transition: all 0.2s;
    flex-wrap: wrap;
    gap: 0.5rem;
    box-shadow: 0 1px 2px var(--shadow-color);
}

.todo-item:hover {
    background-color: var(--hover-color);
    box-shadow: 0 2px 4px var(--shadow-color);
}

.todo-item.completed span {
    text-decoration: line-through;
    color: var(--completed-color);
}

.todo-item input[type="checkbox"] {
    margin-right: 1rem;
    width: 1.2rem;
    height: 1.2rem;
    cursor: pointer;
    flex-shrink: 0;
    accent-color: var(--primary-color);
}

.todo-item span {
    flex: 1;
    margin-right: 1rem;
    word-break: break-word;
    min-width: 150px;
}

.todo-item span a {
    color: var(--primary-color);
    text-decoration: none;
    word-break: break-all;
    transition: color 0.2s;
}

.todo-item span a:hover {
    text-decoration: underline;
}

.todo-item span a.google-search-link {
    color: var(--primary-color);
    font-weight: 500;
    display: inline-flex;
    align-items: center;
    gap: 0.25rem;
}

.todo-item span a.google-search-link::before {
    content: "🔍";
    font-size: 0.9em;
}

.todo-item.completed span a {
    color: var(--completed-color);
}

.todo-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-right: 1rem;
}

.todo-item .tag {
    font-size: 0.8rem;
    padding: 0.25rem 0.75rem;
    border-radius: 16px;
    font-weight: 500;
    background-color: var(--hover-color);
    color: var(--text-color);
    transition: all 0.2s;
    display: inline-flex;
    align-items: center;
    gap: 0.25rem;
}

.todo-item .tag:hover {
    background-color: var(--primary-color);
    color: white;
}

[data-theme="dark"] .todo-item .tag {
    background-color: var(--border-color);
}

[data-theme="dark"] .todo-item .tag:hover {
    background-color: var(--primary-color);
}

.delete-btn {
    background: none;
    border: none;
    color: #ea4335;
    cursor: pointer;
    font-size: 1.2rem;
    opacity: 0.7;
    transition: all 0.2s;
    padding: 0.25rem;
    flex-shrink: 0;
    border-radius: 50%;
}

.delete-btn:hover {
    opacity: 1;
    background-color: var(--hover-color);
}

.todo-stats {
    display: flex;
    justify-content: space-between;
    align-items: center;
    color: var(--completed-color);
    font-size: 0.9rem;
    flex-wrap: wrap;
    gap: 1rem;
    margin-bottom: 1rem;
}

#clear-completed {
    background: none;
    border: none;
    color: var(--completed-color);
    cursor: pointer;
    transition: color 0.2s;
    padding: 0.25rem;
    font-weight: 500;
}

#clear-completed:hover {
    color: var(--text-color);
}

.tag-filters {
    display: none;
    flex-wrap: nowrap;
    gap: 0.5rem;
    margin: 1rem 0;
    padding: 0.5rem;
    border-radius: 8px;
    background-color: var(--hover-color);
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    scrollbar-width: thin;
    scrollbar-color: var(--primary-color) var(--hover-color);
    transition: opacity 0.3s ease, transform 0.3s ease;
    opacity: 0;
    transform: translateY(-10px);
}

.tag-filters[style*="display: flex"] {
    opacity: 1;
    transform: translateY(0);
}

.tag-filters::-webkit-scrollbar {
    height: 6px;
}

.tag-filters::-webkit-scrollbar-track {
    background: var(--hover-color);
    border-radius: 3px;
}

.tag-filters::-webkit-scrollbar-thumb {
    background-color: var(--primary-color);
    border-radius: 3px;
}

.tag-filter {
    padding: 0.25rem 0.75rem;
    border-radius: 16px;
    font-size: 0.9rem;
    cursor: pointer;
    transition: all 0.2s;
    background-color: var(--bg-color);
    color: var(--text-color);
    border: 1px solid var(--border-color);
    display: inline-flex;
    align-items: center;
    gap: 0.25rem;
    white-space: nowrap;
    flex-shrink: 0;
}

.tag-filter:hover {
    background-color: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

.tag-filter.active {
    background-color: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

[data-theme="dark"] .tag-filter {
    background-color: var(--bg-color);
}

[data-theme="dark"] .tag-filter:hover,
[data-theme="dark"] .tag-filter.active {
    background-color: var(--primary-color);
}

.todo-item .tag {
    font-size: 0.8rem;
    padding: 0.25rem 0.5rem;
    border-radius: 16px;
    font-weight: 500;
    margin-left: 0.5rem;
    background-color: var(--hover-color);
    color: var(--text-color);
    transition: all 0.2s;
}

.todo-item .tag:hover {
    background-color: var(--primary-color);
    color: white;
}

[data-theme="dark"] .todo-item .tag {
    background-color: var(--border-color);
}

[data-theme="dark"] .todo-item .tag:hover {
    background-color: var(--primary-color);
}

/* Media Queries */
@media (max-width: 480px) {
    html {
        font-size: 14px;
    }

    .container {
        padding: 0.5rem;
    }

    #todo-form {
        flex-direction: column;
    }

    #todo-form button {
        width: 100%;
    }

    .todo-filters {
        justify-content: center;
    }

    .todo-stats {
        justify-content: center;
        text-align: center;
    }

    .todo-item {
        padding: 0.75rem;
    }

    .todo-item input[type="checkbox"] {
        margin-right: 0.5rem;
    }
}

@media (max-width: 320px) {
    html {
        font-size: 12px;
    }

    .container {
        padding: 0.25rem;
    }
}

/* Touch Device Optimizations */
@media (hover: none) {
    .delete-btn,
    .filter-btn,
    #clear-completed {
        padding: 0.5rem;
    }

    .todo-item {
        padding: 1rem;
    }
}

/* Footer Styles */
.app-footer {
    margin-top: auto;
    padding: 1.5rem 1rem;
    border-top: 1px solid var(--border-color);
}

.footer-content {
    max-width: 600px;
    margin: 0 auto;
    text-align: center;
    color: var(--text-color);
    opacity: 0.8;
}

.copyright {
    font-size: 0.9rem;
    margin-bottom: 0.5rem;
}

.disclaimer {
    font-size: 0.8rem;
    opacity: 0.7;
    margin-bottom: 0.5rem;
    max-width: 500px;
    margin-left: auto;
    margin-right: auto;
}

.footer-links {
    display: flex;
    justify-content: center;
    gap: 0.5rem;
    align-items: center;
}

.footer-link {
    color: var(--text-color);
    text-decoration: none;
    font-size: 0.9rem;
    transition: color 0.2s;
    background: none;
    border: none;
    cursor: pointer;
    padding: 0;
}

.footer-link:hover {
    color: var(--primary-color);
}

.footer-separator {
    color: var(--text-color);
    opacity: 0.5;
}

@media (max-width: 480px) {
    .app-footer {
        padding: 1rem 0.5rem;
    }
    
    .footer-content {
        font-size: 0.85rem;
    }
}

/* Popup Styles */
.popup {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    z-index: 1000;
    justify-content: center;
    align-items: center;
}

.popup.active {
    display: flex;
}

.popup-content {
    background-color: var(--bg-color);
    border-radius: 8px;
    width: 90%;
    max-width: 600px;
    max-height: 90vh;
    overflow-y: auto;
    position: relative;
    box-shadow: 0 4px 6px var(--shadow-color);
}

.popup-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem;
    border-bottom: 1px solid var(--border-color);
}

.popup-header h2 {
    margin: 0;
    font-size: 1.2rem;
    color: var(--heading-color);
}

.close-popup {
    background: none;
    border: none;
    color: var(--text-color);
    font-size: 1.5rem;
    cursor: pointer;
    padding: 0.5rem;
    line-height: 1;
    opacity: 0.7;
    transition: opacity 0.2s;
}

.close-popup:hover {
    opacity: 1;
}

.popup-body {
    padding: 1.5rem;
}

.popup-body h3 {
    margin: 1.5rem 0 0.5rem;
    font-size: 1.1rem;
    color: var(--heading-color);
}

.popup-body p {
    margin: 0 0 1rem;
    line-height: 1.6;
    color: var(--text-color);
}

@media (max-width: 480px) {
    .popup-content {
        width: 95%;
        margin: 1rem;
    }

    .popup-body {
        padding: 1rem;
    }
}

/* Future Message Styles */
.future-message {
    display: none;
    background-color: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 1rem;
    margin: 1rem 0;
    position: relative;
    box-shadow: 0 2px 4px var(--shadow-color);
    animation: slideIn 0.3s ease-out;
}

.future-message.active {
    display: block;
}

.message-content {
    padding-right: 2rem;
}

.message-text {
    font-size: 1.1rem;
    color: var(--text-color);
    margin-bottom: 0.5rem;
    line-height: 1.5;
}

.message-meta {
    font-size: 0.9rem;
    color: var(--completed-color);
    font-style: italic;
}

.close-message {
    position: absolute;
    top: 0.5rem;
    right: 0.5rem;
    background: none;
    border: none;
    color: var(--text-color);
    font-size: 1.2rem;
    cursor: pointer;
    opacity: 0.7;
    transition: opacity 0.2s;
    padding: 0.25rem;
    line-height: 1;
}

.close-message:hover {
    opacity: 1;
}

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

.header-buttons {
    display: flex;
    gap: 0.5rem;
    align-items: center;
}

.install-btn {
    background: none;
    border: none;
    color: var(--text-color);
    cursor: pointer;
    font-size: clamp(1.2rem, 4vw, 1.5rem);
    padding: 0.5rem;
    border-radius: 50%;
    transition: background-color 0.2s;
}

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