:root {
    /* Font size is managed by JavaScript (see font-size.js) */
    --bg-primary: #ffffff;
    --bg-secondary: #f5f5f5;
    --bg-tertiary: #e0e0e0;
    --text-primary: #212121;
    --text-secondary: #757575;
    --border-color: #e0e0e0;
    --link-color: #1976d2;
    --link-hover: #1565c0;
    --success: #4caf50;
    --error: #f44336;
    --warning: #ff9800;
    --info: #2196f3;
    --shadow: rgba(0, 0, 0, 0.1);
}

[data-theme="dark"] {
    --bg-primary: #1e1e1e;
    --bg-secondary: #2d2d2d;
    --bg-tertiary: #3d3d3d;
    --text-primary: #e0e0e0;
    --text-secondary: #b0b0b0;
    --border-color: #404040;
    --link-color: #64b5f6;
    --link-hover: #90caf9;
    --success: #66bb6a;
    --error: #ef5350;
    --warning: #ffa726;
    --info: #42a5f5;
    --shadow: rgba(0, 0, 0, 0.3);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color 0.3s ease, color 0.3s ease;
}

/* Header */
.header {
    background-color: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
    padding: 0.75rem 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    box-shadow: 0 2px 4px var(--shadow);
}

.header-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 2rem;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 1.25rem;
    font-weight: 600;
    color: var(--text-primary);
    text-decoration: none;
    white-space: nowrap;
}

.logo-icon {
    width: 28px;
    height: 28px;
    filter: brightness(0) invert(1);
}

[data-theme="dark"] .logo-icon {
    filter: brightness(1) invert(0);
}

.nav {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    flex: 1;
}

.nav-main {
    display: flex;
    align-items: center;
    gap: 0.25rem;
    flex: 1;
}

.nav-user {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding-left: 1rem;
    border-left: 1px solid var(--border-color);
}

.nav-username {
    color: var(--text-secondary);
    font-size: 0.875rem;
    padding: 0 0.5rem;
    white-space: nowrap;
}

.nav a,
.nav-link {
    color: var(--text-primary);
    text-decoration: none;
    padding: 0.5rem 0.875rem;
    border-radius: 4px;
    transition: all 0.2s;
    font-size: 0.9rem;
    white-space: nowrap;
}

.nav a:hover,
.nav-link:hover {
    background-color: var(--bg-tertiary);
}

.theme-toggle {
    background: none;
    border: none;
    cursor: pointer;
    font-size: 1.25rem;
    padding: 0.4rem;
    border-radius: 50%;
    transition: all 0.2s;
    display: flex;
    align-items: center;
    justify-content: center;
}

.theme-toggle:hover {
    background-color: var(--bg-tertiary);
    transform: scale(1.1);
}

/* Dropdown Menu */
.nav-dropdown {
    position: relative;
    display: inline-block;
}

.nav-dropdown-toggle {
    color: var(--text-primary);
    text-decoration: none;
    padding: 0.5rem 0.875rem;
    border-radius: 4px;
    transition: all 0.2s;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 0.35rem;
    background: none;
    border: none;
    font-size: 0.9rem;
    font-family: inherit;
    white-space: nowrap;
}

.nav-dropdown-toggle:hover {
    background-color: var(--bg-tertiary);
}

.nav-dropdown-content {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    background-color: var(--bg-secondary);
    min-width: 220px;
    box-shadow: 0 4px 12px var(--shadow);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    margin-top: 0.5rem;
    z-index: 1000;
    overflow: hidden;
    opacity: 0;
    transform: translateY(-10px);
    transition: opacity 0.2s, transform 0.2s;
    pointer-events: none;
}

.nav-dropdown-content a {
    color: var(--text-primary);
    padding: 0.875rem 1.25rem;
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 0.75rem;
    transition: all 0.2s;
    font-size: 0.9rem;
    border-bottom: 1px solid var(--border-color);
}

.nav-dropdown-content a:last-child {
    border-bottom: none;
}

.nav-dropdown-content a:hover {
    background-color: var(--bg-tertiary);
    padding-left: 1.5rem;
}

.nav-dropdown.active .nav-dropdown-content {
    display: block;
    opacity: 1;
    transform: translateY(0);
    pointer-events: auto;
}

.dropdown-arrow {
    display: inline-block;
    font-size: 0.65rem;
    transition: transform 0.2s;
}

.nav-dropdown.active .dropdown-arrow {
    transform: rotate(180deg);
}

/* Submenu */
.nav-submenu {
    position: relative;
}

.nav-submenu-toggle {
    color: var(--text-primary);
    padding: 0.875rem 1.25rem;
    text-decoration: none;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 0.75rem;
    transition: all 0.2s;
    font-size: 0.9rem;
    border-bottom: 1px solid var(--border-color);
    cursor: pointer;
    background: none;
    border: none;
    border-bottom: 1px solid var(--border-color);
    width: 100%;
    text-align: left;
    font-family: inherit;
}

.nav-submenu-toggle:hover {
    background-color: var(--bg-tertiary);
    padding-left: 1.5rem;
}

.nav-submenu-content {
    display: none;
    background-color: var(--bg-primary);
    border-left: 2px solid var(--link-color);
    margin-left: 1rem;
}

.nav-submenu.active .nav-submenu-content {
    display: block;
}

.nav-submenu-content a {
    color: var(--text-primary);
    padding: 0.75rem 1.25rem;
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 0.75rem;
    transition: all 0.2s;
    font-size: 0.85rem;
    border-bottom: 1px solid var(--border-color);
}

.nav-submenu-content a:last-child {
    border-bottom: none;
}

.nav-submenu-content a:hover {
    background-color: var(--bg-tertiary);
    padding-left: 1.5rem;
}

.submenu-arrow {
    display: inline-block;
    font-size: 0.6rem;
    transition: transform 0.2s;
}

.nav-submenu.active .submenu-arrow {
    transform: rotate(90deg);
}

/* Container */
.container {
    max-width: 1200px;
    margin: 2rem auto;
    padding: 0 1rem;
}

/* Cards */
.card {
    background-color: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 1.5rem;
    margin-bottom: 1.5rem;
    box-shadow: 0 2px 4px var(--shadow);
}

.card-header {
    font-size: 1.5rem;
    font-weight: bold;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

/* Forms */
.form-group {
    margin-bottom: 1.5rem;
}

.form-label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    color: var(--text-primary);
}

.form-input,
.form-select,
.form-textarea {
    width: 100%;
    padding: 0.75rem;
    border: 1px solid var(--border-color);
    border-radius: 4px;
    background-color: var(--bg-primary);
    color: var(--text-primary);
    font-size: 1rem;
    transition: border-color 0.2s;
}

.form-input:focus,
.form-select:focus,
.form-textarea:focus {
    outline: none;
    border-color: var(--link-color);
}

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

/* Buttons */
.btn {
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: 4px;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.2s;
    text-decoration: none;
    display: inline-block;
}

.btn-primary {
    background-color: var(--link-color);
    color: white;
}

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

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

.btn-success:hover {
    opacity: 0.9;
}

.btn-danger {
    background-color: var(--error);
    color: white;
}

.btn-danger:hover {
    opacity: 0.9;
}

.btn-secondary {
    background-color: var(--bg-tertiary);
    color: var(--text-primary);
}

.btn-secondary:hover {
    opacity: 0.9;
}

/* Alerts */
.alert {
    padding: 1rem;
    border-radius: 4px;
    margin-bottom: 1rem;
}

.alert-success {
    background-color: var(--success);
    color: white;
}

.alert-error {
    background-color: var(--error);
    color: white;
}

.alert-info {
    background-color: var(--info);
    color: white;
}

/* Table */
.table {
    width: 100%;
    border-collapse: collapse;
    margin-bottom: 1rem;
}

.table th,
.table td {
    padding: 0.75rem;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

.table th {
    background-color: var(--bg-tertiary);
    font-weight: 600;
}

.table tr:hover {
    background-color: var(--bg-tertiary);
}

/* Login/Register page */
.auth-container {
    max-width: 400px;
    margin: 4rem auto;
}

.auth-card {
    background-color: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 2rem;
    box-shadow: 0 4px 6px var(--shadow);
    transform: scale(0.7);
    transform-origin: center;
}

.auth-header {
    text-align: center;
    margin-bottom: 2rem;
}

.auth-logo {
    width: 64px;
    height: 64px;
    margin: 0 auto 1rem;
    filter: brightness(0) invert(1);
}

[data-theme="dark"] .auth-logo {
    filter: brightness(1) invert(0);
}

.auth-title {
    font-size: 1.5rem;
    font-weight: bold;
}

.auth-link {
    text-align: center;
    margin-top: 1rem;
}

.auth-link a {
    color: var(--link-color);
    text-decoration: none;
}

.auth-link a:hover {
    text-decoration: underline;
}

/* Dashboard */
.dashboard-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 1.5rem;
    margin-top: 2rem;
}

.module-card {
    background-color: var(--bg-secondary);
    border: 2px solid var(--border-color);
    border-radius: 8px;
    padding: 2rem;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s;
    text-decoration: none;
    color: var(--text-primary);
}

.module-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 4px 12px var(--shadow);
    border-color: var(--link-color);
}

.module-icon {
    font-size: 3rem;
    margin-bottom: 1rem;
}

.module-title {
    font-size: 1.5rem;
    font-weight: bold;
    margin-bottom: 0.5rem;
}

.module-description {
    color: var(--text-secondary);
}

/* Task priority badges */
.priority-badge {
    padding: 0.25rem 0.5rem;
    border-radius: 4px;
    font-size: 0.875rem;
    font-weight: 600;
    display: inline-block;
}

.priority-1 { background-color: #f44336; color: white; }
.priority-2 { background-color: #ff9800; color: white; }
.priority-3 { background-color: #ffc107; color: black; }
.priority-4 { background-color: #4caf50; color: white; }
.priority-5 { background-color: #2196f3; color: white; }

/* Utilities */
.text-center { text-align: center; }
.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mb-1 { margin-bottom: 0.5rem; }
.mb-2 { margin-bottom: 1rem; }
.mb-3 { margin-bottom: 1.5rem; }
.hidden { display: none; }

/* Responsive */
@media (max-width: 768px) {
    /* Header */
    .header {
        padding: 0.75rem 0;
    }

    .header-container {
        flex-direction: row;
        flex-wrap: wrap;
        gap: 0.75rem;
        padding: 0 0.75rem;
    }

    .logo {
        font-size: 1.25rem;
    }

    .logo-icon {
        width: 28px;
        height: 28px;
    }

    .nav {
        flex-wrap: wrap;
        justify-content: flex-start;
        gap: 0.5rem;
        width: 100%;
    }

    .nav a {
        padding: 0.5rem 0.75rem;
        font-size: 0.9rem;
    }

    .theme-toggle {
        font-size: 1.25rem;
        padding: 0.4rem;
    }

    /* Container */
    .container {
        margin: 1rem auto;
        padding: 0 0.75rem;
    }

    /* Cards */
    .card {
        padding: 1rem;
        margin-bottom: 1rem;
    }

    .card-header {
        font-size: 1.25rem;
    }

    /* Forms */
    .form-input,
    .form-select,
    .form-textarea {
        padding: 0.6rem;
        font-size: 16px; /* Prevents zoom on iOS */
    }

    /* Buttons */
    .btn {
        padding: 0.6rem 1rem;
        font-size: 0.95rem;
    }

    .btn-sm {
        padding: 0.4rem 0.7rem;
        font-size: 0.85rem;
    }

    /* Tables */
    .table {
        font-size: 0.9rem;
    }

    .table th,
    .table td {
        padding: 0.5rem;
    }

    /* Make tables scrollable on mobile */
    .table-responsive {
        overflow-x: auto;
        -webkit-overflow-scrolling: touch;
    }

    /* Auth pages */
    .auth-container {
        margin: 2rem auto;
        padding: 0 1rem;
    }

    .auth-card {
        padding: 1.5rem;
    }

    /* Dashboard */
    .dashboard-grid {
        grid-template-columns: 1fr;
        gap: 1rem;
    }

    .module-card {
        padding: 1.5rem;
    }

    .module-icon {
        font-size: 2.5rem;
    }

    .module-title {
        font-size: 1.25rem;
    }

    /* Flex layouts - stack on mobile */
    .card > div[style*="display: flex"] {
        flex-direction: column !important;
        gap: 1rem !important;
    }

    /* Buttons in flex containers */
    .card div[style*="display: flex"] .btn {
        width: 100%;
    }

    /* Footer */
    footer {
        padding: 1.5rem 0 !important;
        font-size: 0.9rem;
    }
}

/* Small mobile devices */
@media (max-width: 480px) {
    .logo {
        font-size: 1.1rem;
    }

    .logo-icon {
        width: 24px;
        height: 24px;
    }

    .nav a {
        padding: 0.4rem 0.6rem;
        font-size: 0.85rem;
    }

    .card {
        padding: 0.75rem;
        border-radius: 6px;
    }

    .card-header {
        font-size: 1.1rem;
    }

    .btn {
        padding: 0.5rem 0.75rem;
        font-size: 0.9rem;
    }

    .module-icon {
        font-size: 2rem;
    }

    .module-title {
        font-size: 1.1rem;
    }
}

/* Modal */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5);
    z-index: 2000;
    align-items: center;
    justify-content: center;
    padding: 1rem;
}

.modal.active {
    display: flex !important;
}

.modal-content {
    background-color: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 8px;
    box-shadow: 0 4px 20px var(--shadow);
    max-width: 600px;
    width: 100%;
    max-height: 90vh;
    overflow-y: auto;
    animation: modalSlideIn 0.3s ease;
}

@keyframes modalSlideIn {
    from {
        opacity: 0;
        transform: translateY(-50px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1.5rem;
    border-bottom: 1px solid var(--border-color);
}

.modal-header h2 {
    margin: 0;
    font-size: 1.25rem;
    color: var(--text-primary);
}

.modal-close {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-secondary);
    padding: 0;
    width: 2rem;
    height: 2rem;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 4px;
    transition: all 0.2s;
}

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

.modal-body {
    padding: 1.5rem;
}

.modal-footer {
    padding: 1rem 1.5rem;
    border-top: 1px solid var(--border-color);
    display: flex;
    justify-content: flex-end;
    gap: 0.75rem;
}

/* Landscape mobile */
@media (max-width: 768px) and (orientation: landscape) {
    .container {
        margin: 0.75rem auto;
    }

    .card {
        margin-bottom: 0.75rem;
    }

    .modal-content {
        max-height: 80vh;
    }
}