:root {
    --primary: #4f46e5;
    --primary-hover: #4338ca;

    /* Map to Pico CSS native variables for Dark Mode compatibility */
    --bg-main: var(--pico-background-color);
    --bg-sidebar: var(--pico-card-background-color);
    --border-color: var(--pico-form-element-border-color);
    --text-main: var(--pico-color);
    --text-muted: var(--pico-muted-color);

    /* Pico CSS overrides */
    --pico-primary: var(--primary) !important;
    --pico-primary-hover: var(--primary-hover) !important;
    --pico-primary-background: var(--primary) !important;
    --pico-primary-border: var(--primary) !important;
    --pico-primary-hover-background: var(--primary-hover) !important;
    --pico-primary-hover-border: var(--primary-hover) !important;
    --pico-font-size: 92% !important;
    --pico-form-element-spacing-vertical: 0.5rem !important;
}

/* Global resets are now handled by Pico CSS */

body {
    font-family: 'Inter', sans-serif;
    background: var(--bg-main);
    color: var(--text-main);
    height: 100vh;
    overflow: hidden;
    display: flex;
    flex-direction: column;
}

/* Top Header */
.top-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0.75rem 1.5rem;
    background: var(--bg-sidebar);
    border-bottom: 1px solid var(--border-color);
    z-index: 20;
    flex-shrink: 0;
}

.top-header-title {
    font-size: 1.3rem;
    font-weight: 700;
    color: var(--primary);
    margin: 0;
    white-space: nowrap;
}

.top-header-right {
    display: flex;
    align-items: center;
    gap: 0.8rem;
}

.top-header-menu {
    display: flex;
    align-items: center;
    gap: 0.8rem;
}

.hamburger-btn,
.settings-btn {
    display: none;
    padding: 0.25rem;
    width: auto;
    margin: 0;
    border: none;
    background: transparent;
    cursor: pointer;
    color: var(--text-main);
}

.app-container {
    display: flex;
    flex: 1;
    overflow: hidden;
}

.sidebar {
    width: 380px;
    background: var(--bg-sidebar);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    z-index: 10;
    box-shadow: 2px 0 8px rgba(0, 0, 0, 0.05);
    transition: width 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.sidebar.collapsed {
    width: 0px;
}

.sidebar.collapsed .sidebar-content {
    display: none;
}

.sidebar-content {
    padding: 1.5rem;
    flex: 1;
    overflow-y: auto;
}

.settings-summary {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.form-section {
    margin-bottom: 0;
}

.form-section h2,
.form-section summary {
    font-size: 0.85rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    color: var(--text-muted);
    margin-bottom: 1rem;
    font-weight: 600;
}

.form-section summary {
    cursor: pointer;
    list-style: none;
    /* Hide default arrow */
    outline: none;
    transition: color 0.2s;
}

.form-section summary:hover {
    color: var(--text-main);
}

.form-section summary::-webkit-details-marker {
    display: none;
}

.form-row {
    display: flex;
    gap: 1rem;
}

.form-group {
    margin-bottom: 1rem;
    flex: 1;
}

label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
}

input[type="number"],
select {
    margin-bottom: 0px;
    /* Let form-group handle spacing */
    font-family: inherit;
}



.btn-secondary {
    --pico-background-color: transparent;
    --pico-border-color: var(--border-color);
    --pico-color: var(--text-main);
}

.stepper-grid {
    display: grid;
    grid-template-columns: 120px 1fr 1fr;
    gap: 0.5rem;
    align-items: center;
    max-width: 380px;
}

.stepper-header {
    text-align: center;
    font-weight: 500;
    color: var(--text-muted);
    font-size: 0.85rem;
}

.stepper-row-label {
    /* font-size: 1rem; */
    font-weight: 500;
    color: var(--text-main);
}

.stepper-container {
    display: grid !important;
    grid-template-columns: 30px 1fr 30px;
    align-items: stretch !important;
    margin-bottom: 0 !important;
    height: 36px;
    border: 1px solid var(--border-color) !important;
    overflow: hidden;
    background: var(--pico-form-element-background-color);
}

.stepper-container input {
    width: 100% !important;
    text-align: center;
    margin: 0 !important;
    padding: 0 !important;
    font-weight: 600;
    font-size: 1rem !important;
    background: var(--bg-main) !important;
    border: none !important;
    border-radius: 0 !important;
    height: 100% !important;
    color: var(--text-main) !important;
    box-shadow: none !important;
}

.stepper-btn {
    width: 100% !important;
    height: 100% !important;
    padding: 0 !important;
    font-size: 1.2rem !important;
    font-weight: 300 !important;
    margin: 0 !important;
    border: none !important;
    background: transparent !important;
    color: var(--text-main) !important;
    border-radius: 0 !important;
    display: flex !important;
    align-items: center !important;
    justify-content: center !important;
    cursor: pointer;
    transition: background 0.2s;
}

.stepper-btn:hover {
    background: var(--pico-form-element-active-background-color) !important;
}

.stepper-btn:first-child {
    border-right: 1px solid var(--border-color) !important;
}

.stepper-btn:last-child {
    border-left: 1px solid var(--border-color) !important;
}

/* Chrome, Safari, Edge, Opera: Hide number spinners */
.stepper-container input::-webkit-outer-spin-button,
.stepper-container input::-webkit-inner-spin-button {
    -webkit-appearance: none;
    appearance: none;
    margin: 0;
}

/* Firefox: Hide number spinners */
.stepper-container input[type=number] {
    -moz-appearance: textfield;
    appearance: textfield;
}

.digit-toggles {
    display: flex;
    flex-wrap: wrap;
    gap: 0.35rem;
    margin-top: 0.5rem;
}

.digit-toggle {
    display: inline-flex;
    cursor: pointer;
    margin: 0 !important;
}

.digit-toggle input[type="checkbox"] {
    display: none;
}

.digit-toggle span {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 28px;
    height: 32px;
    background: var(--pico-form-element-background-color);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    font-size: 1rem;
    font-weight: 500;
    transition: all 0.1s;
    user-select: none;
    color: var(--text-main);
}

.digit-toggle input[type="checkbox"]+span {
    text-decoration: line-through;
    color: var(--border-color);
}

.digit-toggle input[type="checkbox"]:checked+span {
    color: var(--primary);
    text-decoration: none;
}

/* Main Content Area */
.main-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    background: var(--bg-main);
}

.main-header {
    height: 70px;
    padding: 0.5rem 2rem;
    background: var(--pico-card-background-color);
    /* border-bottom: 1px solid var(--border-color); */
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.main-header h2 {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: 0;
}

.solver-header {
    padding: 0 2rem 1rem !important;
}

.preview-tabs {
    display: flex;
    background: var(--pico-muted-border-color);
    border-radius: 8px;
    padding: 0.25rem;
}

.tab-btn {
    border: none;
    background: transparent;
    padding: 0.4rem 1rem;
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--text-muted);
    border-radius: 6px;
    cursor: pointer;
    transition: all 0.2s;
    margin-bottom: 0;
}

.tab-btn:hover {
    color: var(--text-main);
}

.tab-btn.active {
    background: var(--pico-card-background-color);
    color: var(--text-main);
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
}

.action-buttons {
    display: flex;
    gap: 0.75rem;
    margin-top: var(--pico-spacing);
}

.action-buttons .btn-primary {
    width: auto;
    padding: 0.6rem 1.2rem;
}

.preview-container {
    flex: 1;
    padding: 0;
    display: flex;
    justify-content: center;
    align-items: stretch;
}

.placeholder {
    color: var(--text-muted);
    font-size: 1.1rem;
    padding: 2rem;
    border: 2px dashed var(--pico-form-element-border-color);
    border-radius: 12px;
    text-align: center;
}

#pdf-preview {
    width: 100%;
    height: 100%;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    background: white;
}

.header-title-area {
    display: flex;
    align-items: center;
    gap: 2rem;
}

/* Responsive Layout */
@media (max-width: 768px) {
    body {
        height: auto;
        min-height: 100dvh;
        overflow-y: auto;
    }

    .app-container {
        flex-direction: column;
        height: auto;
    }

    .sidebar {
        display: none;
    }

    #btn-toggle-sidebar {
        display: none;
    }

    .sidebar.collapsed {
        width: 100%;
    }

    .sidebar.collapsed .sidebar-content {
        display: block;
    }

    .hamburger-btn,
    .settings-btn {
        display: flex;
        align-items: center;
        justify-content: center;
    }

    .settings-btn {
        padding: 0.25rem;
        background: transparent;
        border: none;
        color: var(--text-main);
        cursor: pointer;
    }

    #settings-modal summary {
        display: none !important;
    }

    .top-header-menu {
        display: none;
        position: absolute;
        top: 100%;
        right: 0;
        background: var(--bg-sidebar);
        border: 1px solid var(--border-color);
        border-radius: 8px;
        padding: 0.75rem;
        flex-direction: column;
        gap: 0.5rem;
        box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
        min-width: 160px;
        z-index: 30;
    }

    .top-header-menu.open {
        display: flex;
    }

    .top-header-right {
        position: relative;
    }

    .sidebar-content {
        overflow-y: visible;
        padding-bottom: 0;
    }

    .main-header {
        flex-direction: column;
        height: auto;
        padding: 0 1.5rem;
        gap: 0;
        align-items: stretch;
    }

    .header-title-area {
        flex-direction: column;
        align-items: stretch;
        gap: 1rem;
    }

    .header-right-area {
        justify-content: center !important;
    }

    .header-right-area button {
        margin-top: 1rem !important;
        margin-bottom: 1rem !important;
    }

    .preview-tabs {
        width: 100%;
        margin-top: 1rem;
    }

    .tab-btn {
        text-align: center;
        flex: auto;
    }

    .action-buttons {
        display: flex;
        flex-direction: row;
        width: 100%;
        gap: 0.75rem;
    }

    .action-buttons button {
        flex: 1;
        margin-bottom: 0 !important;
    }

    .preview-container {
        padding: 1rem;
        height: auto;
        align-items: stretch;
        justify-content: stretch;
    }

    #pdf-preview {
        flex: 1;
        min-height: 275px;
        width: 100%;
        height: auto;
    }
}

/* Solver View (Tabbed) */
.solver-app-view {
    display: flex;
    flex-direction: column;
    height: 100%;
    width: 100%;
    background: var(--pico-card-background-color);
    border-radius: 12px;
    overflow: hidden;
}


.solver-content {
    flex: 1;
    padding: 3rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 2rem;
    background: var(--pico-muted-border-color);
}

.nav-arrow {
    background: var(--bg-main) !important;
    border: 1px solid var(--border-color) !important;
    color: var(--text-main) !important;
    width: 60px !important;
    height: 60px !important;
    border-radius: 50% !important;
    font-size: 2.5rem !important;
    display: flex !important;
    align-items: center !important;
    justify-content: center !important;
    cursor: pointer;
    transition: all 0.2s;
    flex-shrink: 0;
    padding: 0 !important;
    line-height: 1;
}

.nav-arrow:hover {
    background: var(--primary) !important;
    border-color: var(--primary) !important;
    color: var(--pico-primary-inverse, white) !important;
}

.nav-arrow:disabled {
    opacity: 0.3;
    cursor: not-allowed;
}

.problem-container {
    display: flex;
    justify-content: center;
    align-items: center;
}

.solver-grid {
    display: grid;
    gap: 0;
    background: var(--pico-card-background-color);
}

.solver-cell {
    width: 44px;
    height: 44px;
    border: 0.5px solid var(--pico-form-element-border-color);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    font-family: 'Courier Prime', 'Courier New', monospace;
    color: var(--text-main);
}

.solver-input {
    width: 100%;
    height: 100%;
    border: none !important;
    /* background: var(--pico-form-element-background-color) !important; */
    text-align: center;
    font-size: 1.5rem !important;
    font-family: 'Courier Prime', 'Courier New', monospace;
    font-weight: 600;
    padding: 0 !important;
    margin: 0 !important;
    color: var(--primary) !important;
    outline: none !important;
    display: block;
    caret-color: transparent !important;
    cursor: pointer;
}

.solver-input:focus {
    background: rgba(79, 70, 229, 0.05) !important;
    box-shadow: inset 0 0 0 2px var(--primary) !important;
    z-index: 1;
}

.solver-input.correct {
    background-color: #d4edda !important;
    color: #155724 !important;
}

.solver-input.incorrect {
    background-color: #f8d7da !important;
    color: #721c24 !important;
}

.solver-operator {
    font-weight: bold;
}

.solver-line {
    border-top: 2px solid var(--pico-color, #000) !important;
}

.solver-current:not(:empty) {
    background: rgb(255 251 206 / 80%) !important;
}

.solver-current .solver-input.correct {
    background-color: transparent !important;

}

.solver-carry {
    font-size: 0.9rem !important;
    color: var(--text-muted) !important;
    background: var(--pico-form-element-background-color) !important;
    height: 30px !important;
    width: 30px !important;
    margin: auto !important;
    border: 1px dashed var(--border-color) !important;
    border-radius: 4px;
    caret-color: transparent !important;
}

.solver-carry:focus {
    background: var(--pico-background-color) !important;
    border-style: solid !important;
    color: var(--primary) !important;
}

.solver-numpad {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 0.5rem;
    background: var(--pico-card-background-color);
    padding: 1rem;
}

.numpad-btn {
    width: 60px !important;
    height: 60px !important;
    font-size: 1.5rem !important;
    font-weight: 600 !important;
    background: var(--pico-form-element-background-color) !important;
    border: 1px solid var(--border-color) !important;
    color: var(--text-main) !important;
    border-radius: 8px !important;
    display: flex !important;
    align-items: center !important;
    justify-content: center !important;
    cursor: pointer;
    margin: 0 !important;
    padding: 0 !important;
    transition: all 0.1s;
}

.numpad-btn:hover,
.numpad-btn:active {
    background: var(--pico-form-element-active-background-color) !important;
    border-color: var(--primary) !important;
}

.numpad-btn.control-btn {
    font-size: 1.2rem !important;
    color: #dc3545 !important;
}

@media (max-width: 768px) {
    .solver-inner-wrap {
        flex-direction: column;
        gap: 1.5rem !important;
    }

    .solver-numpad {
        gap: 0.4rem;
        padding: 0.8rem;
    }

    .numpad-btn {
        width: 50px !important;
        height: 50px !important;
        font-size: 1.2rem !important;
    }

    .preview-container {
        padding: 0;
    }

    .solver-content {
        gap: 0 !important;
        padding: 0 !important;
        align-items: flex-end !important;
    }

    .app-container {
        margin: 0 !important;
    }

    .solver-app-view {
        border-radius: 0 !important;
        height: auto !important;
    }

    /* Daily Practice View Mobile Overrides */
    body.daily .main-content {
        min-height: unset !important;
    }

    body.daily .solver-app-view {
        height: auto !important;
    }

    .solver-header {
        display: flex !important;
        gap: 0;
        padding: 1.5rem !important;
    }
}

[type=button],
[type=reset],
[type=submit] {
    font-size: 0.8rem;
    letter-spacing: normal !important;
    text-transform: uppercase !important;
}

button.outline {
    color: #444;
}

select {
    font-size: 0.85rem;
    text-transform: uppercase;
}

svg {
    stroke-width: 1.2;
}

.header-left-area {
    display: flex;
    gap: 1.5rem;
    flex: 1;
    justify-content: flex-start;
}

.header-right-area {
    flex: 1;
    display: flex;
    justify-content: flex-end;
    gap: 0.5rem;
}

body.daily header.main-header {
    display: none;
}

div#adobe-dc-view {
    height: auto !important;
}

body.preview_mode .sidebar,
body.preview_mode .top-header,
body.preview_mode #preview-tabs,
body.preview_mode #preview-placeholder,
body.preview_mode .header-right-area {
    display: none !important;
}

body.preview_mode .main-content {
    padding: 0 !important;
    max-width: 100% !important;
    border: none !important;
}

body.preview_mode .preview-container {
    border: none !important;
    margin: 0 !important;
    padding: 0 !important;
    background: transparent !important;
}

body.preview_mode .app-container {
    padding: 0 !important;
    margin: 0 !important;
}

/* Practice Modal Two-Column Layout */
.practice-modal-columns {
    display: flex;
    gap: 2rem;
    flex: 1;
}

.practice-modal-left {
    flex: 1;
    max-width: 450px;
}

.practice-modal-right {
    flex: 1;
    border-left: 1px solid var(--pico-muted-border-color);
    padding-left: 2rem;
    display: flex;
    flex-direction: column;
    min-height: 600px;
}

@media (max-width: 900px) {
    .practice-modal-columns {
        flex-direction: column;
        gap: 1.5rem;
    }
    
    .practice-modal-left {
        max-width: 100%;
        flex: none;
    }
    
    .practice-modal-right {
        border-left: none;
        border-top: 1px solid var(--pico-muted-border-color);
        padding-left: 0;
        padding-top: 1.5rem;
        min-height: 400px;
        flex: none;
        height: 60vh;
    }
}