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

:root {
    /* GitHub Dark */
    --gh-dark-bg: #0d1117;
    --gh-dark-surface: #161b22;
    --gh-dark-border: #30363d;
    --gh-dark-text: #c9d1d9;
    --gh-dark-text-secondary: #8b949e;
    --gh-dark-accent: #58a6ff;
    --gh-dark-success: #3fb950;
    --gh-dark-danger: #f85149;
    --gh-dark-warning: #d29922;
    
    /* GitHub Light */
    --gh-light-bg: #ffffff;
    --gh-light-surface: #f6f8fa;
    --gh-light-border: #d0d7de;
    --gh-light-text: #24292f;
    --gh-light-text-secondary: #57606a;
    --gh-light-accent: #0969da;
    --gh-light-success: #1a7f0e;
    --gh-light-danger: #d1242f;
    --gh-light-warning: #9e6a03;
    
    /* Default Dark */
    --bg-primary: var(--gh-dark-bg);
    --bg-secondary: var(--gh-dark-surface);
    --border-color: var(--gh-dark-border);
    --text-primary: var(--gh-dark-text);
    --text-secondary: var(--gh-dark-text-secondary);
    --accent: var(--gh-dark-accent);
    --success: var(--gh-dark-success);
    --danger: var(--gh-dark-danger);
    --warning: var(--gh-dark-warning);
}

body.light-mode {
    --bg-primary: var(--gh-light-bg);
    --bg-secondary: var(--gh-light-surface);
    --border-color: var(--gh-light-border);
    --text-primary: var(--gh-light-text);
    --text-secondary: var(--gh-light-text-secondary);
    --accent: var(--gh-light-accent);
    --success: var(--gh-light-success);
    --danger: var(--gh-light-danger);
    --warning: var(--gh-light-warning);
}

html {
    scroll-behavior: smooth;
}

body {
    background-color: var(--bg-primary);
    color: var(--text-primary);
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif;
    line-height: 1.6;
    letter-spacing: 0.3px;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

/* Header */
.header {
    text-align: center;
    margin-bottom: 40px;
    padding: 30px 20px;
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    border-left: 3px solid var(--accent);
}

.header h1 {
    font-size: 2.5rem;
    margin-bottom: 10px;
    color: var(--accent);
}

.subtitle {
    font-size: 1.1rem;
    color: var(--text-secondary);
}

/* Main Content */
.main-content {
    flex: 1;
    display: grid;
    gap: 30px;
    margin-bottom: 20px;
}

/* Sections */
section {
    background-color: var(--bg-secondary);
    padding: 25px;
    border-radius: 6px;
    border: 1px solid var(--border-color);
}

section h2 {
    font-size: 1.5rem;
    margin-bottom: 20px;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    gap: 10px;
}

/* Info Section */
.info-section .info-box {
    background-color: var(--bg-primary);
    padding: 15px;
    border-radius: 6px;
    border: 1px solid var(--border-color);
    margin-bottom: 15px;
}

#info-text {
    color: var(--text-secondary);
    margin-bottom: 10px;
}

/* Form Styles */
.form-container {
    display: flex;
    flex-direction: column;
    gap: 15px;
}

.form-container.hidden {
    display: none;
}

.input-field {
    background-color: var(--bg-primary);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    padding: 12px 15px;
    border-radius: 6px;
    font-size: 1rem;
    font-family: inherit;
    transition: all 0.3s ease;
}

.input-field:focus {
    outline: none;
    border-color: var(--accent);
    background-color: var(--bg-primary);
    box-shadow: 0 0 0 3px rgba(88, 166, 255, 0.1);
}

.input-field.textarea {
    resize: vertical;
    min-height: 100px;
}

textarea::placeholder,
input::placeholder {
    color: var(--text-secondary);
}

.form-actions {
    display: flex;
    gap: 10px;
    justify-content: flex-end;
}

/* Buttons */
.btn {
    padding: 11px 20px;
    border: none;
    border-radius: 6px;
    font-size: 1rem;
    cursor: pointer;
    font-weight: 600;
    transition: all 0.3s ease;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.btn-primary {
    background-color: var(--accent);
    color: #ffffff;
}

.btn-primary:hover {
    background-color: #1f6feb;
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(88, 166, 255, 0.3);
}

.btn-secondary {
    background-color: var(--bg-primary);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

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

.btn-danger {
    background-color: var(--danger);
    color: #ffffff;
}

.btn-danger:hover {
    background-color: #da3633;
    transform: translateY(-2px);
}

.btn-success {
    background-color: var(--success);
    color: #ffffff;
}

.btn-success:hover {
    background-color: #238636;
    transform: translateY(-2px);
}

/* Filter & Sort Buttons */
.filter-buttons {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
    flex-wrap: wrap;
    align-items: center;
}

.filter-btn {
    padding: 8px 16px;
    border: 1px solid var(--border-color);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.3s ease;
    font-size: 0.95rem;
}

.filter-btn.active {
    background-color: var(--accent);
    color: #ffffff;
    border-color: var(--accent);
}

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

.sort-container {
    display: flex;
    gap: 10px;
    align-items: center;
    margin-left: auto;
    flex-wrap: wrap;
}

.sort-label {
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.sort-select {
    padding: 8px 12px;
    border: 1px solid var(--border-color);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    border-radius: 6px;
    cursor: pointer;
    font-size: 0.9rem;
    transition: all 0.3s ease;
}

.sort-select:hover,
.sort-select:focus {
    border-color: var(--accent);
    outline: none;
}

/* Tasks List */
.tasks-list {
    display: grid;
    gap: 15px;
}

.task-card {
    background-color: var(--bg-primary);
    padding: 20px;
    border-radius: 6px;
    border-left: 3px solid var(--accent);
    border: 1px solid var(--border-color);
    border-left: 3px solid var(--accent);
    transition: all 0.3s ease;
}

.task-card:hover {
    transform: translateX(5px);
    box-shadow: 0 5px 15px rgba(88, 166, 255, 0.15);
}

.task-card.completed {
    border-left-color: var(--success);
    opacity: 0.7;
}

.task-card.completed .task-title {
    text-decoration: line-through;
    color: var(--text-secondary);
}

.task-header {
    display: flex;
    justify-content: space-between;
    align-items: start;
    margin-bottom: 10px;
    gap: 10px;
}

.task-title {
    font-size: 1.2rem;
    font-weight: 600;
    color: var(--text-primary);
    flex: 1;
}

.task-deadline {
    background-color: var(--bg-secondary);
    padding: 5px 12px;
    border-radius: 6px;
    font-size: 0.85rem;
    color: var(--warning);
    white-space: nowrap;
}

.task-desc {
    color: var(--text-secondary);
    margin-bottom: 12px;
    line-height: 1.5;
}

.task-actions {
    display: flex;
    gap: 8px;
    margin-top: 12px;
}

.task-actions .btn {
    flex: 1;
    padding: 8px 12px;
    font-size: 0.9rem;
}

.empty-message {
    text-align: center;
    color: var(--text-secondary);
    padding: 40px 20px;
    font-style: italic;
}

.task-categories {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
    margin-bottom: 10px;
}

.task-category-tag {
    display: inline-block;
    padding: 4px 10px;
    background-color: var(--accent);
    color: #ffffff;
    border-radius: 12px;
    font-size: 0.8rem;
    font-weight: 500;
}

.task-type-badge {
    display: inline-block;
    padding: 4px 10px;
    background-color: var(--text-secondary);
    color: #ffffff;
    border-radius: 12px;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    margin-left: 8px;
}

.task-type-badge.daily {
    background-color: var(--warning);
}

.task-type-badge.group {
    background-color: var(--success);
}

.task-group-members {
    display: flex;
    flex-wrap: wrap;
    gap: 4px;
    margin-top: 8px;
    padding-top: 8px;
    border-top: 1px solid var(--border-color);
}

.group-member {
    padding: 3px 8px;
    background-color: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 4px;
    font-size: 0.8rem;
    color: var(--text-secondary);
}

/* Footer */
.footer {
    text-align: center;
    padding: 20px;
    color: var(--text-secondary);
    border-top: 1px solid var(--border-color);
    margin-top: auto;
}

/* Theme Toggle */
.theme-toggle {
    position: fixed;
    top: 20px;
    right: 20px;
    z-index: 1000;
    display: flex;
    align-items: center;
    gap: 10px;
    background-color: var(--bg-secondary);
    padding: 10px 15px;
    border-radius: 6px;
    border: 1px solid var(--border-color);
}

.toggle-switch {
    position: relative;
    width: 50px;
    height: 26px;
    background-color: var(--border-color);
    border-radius: 13px;
    cursor: pointer;
    transition: background-color 0.3s ease;
}

.toggle-switch.active {
    background-color: var(--accent);
}

.toggle-switch::after {
    content: '';
    position: absolute;
    width: 22px;
    height: 22px;
    background-color: #ffffff;
    border-radius: 50%;
    top: 2px;
    left: 2px;
    transition: left 0.3s ease;
}

.toggle-switch.active::after {
    left: 26px;
}

/* Category Input */
.tag-input-container {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.tag-input-container label {
    font-weight: 600;
    color: var(--text-primary);
    font-size: 0.95rem;
}

/* Task Type Input */
.task-type-container {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.task-type-container label {
    font-weight: 600;
    color: var(--text-primary);
    font-size: 0.95rem;
}

.task-type-options {
    display: flex;
    gap: 15px;
    flex-wrap: wrap;
}

.task-type-radio {
    display: flex;
    align-items: center;
    gap: 6px;
    cursor: pointer;
    padding: 8px 12px;
    border-radius: 6px;
    border: 1px solid var(--border-color);
    background-color: var(--bg-primary);
    transition: all 0.3s ease;
}

.task-type-radio:hover {
    border-color: var(--accent);
}

.task-type-radio input[type="radio"] {
    cursor: pointer;
    width: 16px;
    height: 16px;
    accent-color: var(--accent);
}

.task-type-radio input[type="radio"]:checked ~ label {
    background-color: var(--accent);
    color: #ffffff;
}

/* Group Members Input */
.group-members-container {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.group-members-container label {
    font-weight: 600;
    color: var(--text-primary);
    font-size: 0.95rem;
}

.category-options {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
}

.category-checkbox {
    display: flex;
    align-items: center;
    gap: 6px;
    cursor: pointer;
    padding: 6px 10px;
    border-radius: 6px;
    border: 1px solid var(--border-color);
    background-color: var(--bg-primary);
    transition: all 0.3s ease;
}

.category-checkbox:hover {
    border-color: var(--accent);
}

.category-checkbox input[type="checkbox"] {
    cursor: pointer;
    width: 16px;
    height: 16px;
    accent-color: var(--accent);
}

.category-checkbox input[type="checkbox"]:checked ~ label {
    background-color: var(--accent);
    color: #ffffff;
}

/* Category Filter */
.category-filter {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-bottom: 15px;
}

.category-tag {
    padding: 6px 12px;
    border: 1px solid var(--border-color);
    background-color: var(--bg-primary);
    color: var(--text-primary);
    border-radius: 16px;
    cursor: pointer;
    font-size: 0.85rem;
    transition: all 0.3s ease;
}

.category-tag:hover {
    border-color: var(--accent);
}

.category-tag.active {
    background-color: var(--accent);
    color: #ffffff;
    border-color: var(--accent);
}

/* Responsive */
@media (max-width: 768px) {
    .header h1 {
        font-size: 1.8rem;
    }

    .main-content {
        gap: 20px;
    }

    section {
        padding: 20px;
    }

    .form-actions {
        flex-direction: column;
    }

    .form-actions .btn {
        width: 100%;
    }

    .filter-buttons {
        justify-content: center;
    }

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

    .task-deadline {
        align-self: flex-start;
    }
}

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

.task-card {
    animation: slideIn 0.3s ease;
}

/* Hidden */
.hidden {
    display: none;
}

/* Modal Styles */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 2000;
}

.modal.hidden {
    display: none;
}

.modal-content {
    background-color: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    max-width: 600px;
    width: 90%;
    max-height: 90vh;
    overflow-y: auto;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px;
    border-bottom: 1px solid var(--border-color);
}

.modal-header h3 {
    margin: 0;
    color: var(--text-primary);
    font-size: 1.3rem;
}

.modal-close {
    background: none;
    border: none;
    font-size: 1.8rem;
    color: var(--text-secondary);
    cursor: pointer;
    padding: 0;
    width: 30px;
    height: 30px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 4px;
    transition: all 0.3s ease;
}

.modal-close:hover {
    background-color: var(--border-color);
    color: var(--text-primary);
}

.modal-body {
    padding: 20px;
}

.modal-footer {
    display: flex;
    gap: 10px;
    padding: 20px;
    border-top: 1px solid var(--border-color);
    justify-content: flex-end;
}

.modal-footer .btn {
    flex: 0 1 auto;
}