:root {
    --color-text: #333;
    --color-text-light: #777;
    --accent: #4a5568;
    --color-bg: #fff;
    --color-bg-light: #f5f7fa;
    --color-bg-lighter: #f9f9f9;
    --color-border: #e0e0e0;
    --color-accent-light: rgba(74, 85, 104, 0.1);
    --color-tooltip-bg: #fff;
    --color-tooltip-shadow: rgba(0, 0, 0, 0.1);
    --color-alert: #e53e3e;
    --color-alert-light: rgba(229, 62, 62, 0.1);
    --color-success: #38a169;
    --color-success-light: rgba(56, 161, 105, 0.1);
    --color-warning: #f9a825;
    --color-warning-light: rgba(249, 168, 37, 0.1);
    --color-overlay: rgba(0, 0, 0, 0.5);
    --hover-color: white;
    --color-tips-bg: rgba(74, 85, 104, 0.05);
    --color-tips-icon: #4a5568;
    --robot-face-color: #fff;

    --border-radius: 5px;
    --container-width: 600px;
    --spacing-xs: 0.5rem;
    --spacing-sm: 0.8rem;
    --spacing-md: 1.2rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-xxl: 4rem;

    --font-size-xs: 0.75rem;
    --font-size-sm: 0.85rem;
    --font-size-base: 0.95rem;
    --font-size-md: 1.1rem;
    --font-size-lg: 1.4rem;
    --font-size-xl: 1.8rem;
    --font-size-xxl: 2.2rem;

    --shadow-sm: 0 2px 10px rgba(0, 0, 0, 0.03);
    --shadow-md: 0 4px 20px rgba(0, 0, 0, 0.05);
    --shadow-lg: 0 10px 30px rgba(0, 0, 0, 0.15);

    --color-overlay: rgba(0, 0, 0, 0.7);

    scrollbar-color: var(--accent) transparent;
    accent-color: var(--accent);

    --external-link-icon: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'%3E%3Cg fill='none' stroke='currentColor' stroke-linecap='round' stroke-linejoin='round' stroke-width='2'%3E%3Cpath d='M11 5h-6v14h14v-6'/%3E%3Cpath d='M13 11l7 -7'/%3E%3Cpath d='M21 3h-6M21 3v6'/%3E%3C/g%3E%3C/svg%3E");
}

@media (prefers-color-scheme: dark) {
    :root {
        --color-text: #d4d4d4;
        --color-text-light: #9a9a9a;
        --accent: #6e818d;
        --color-bg: #131415;
        --color-bg-light: #1a1a1a;
        --color-bg-lighter: #242424;
        --color-border: #2e2e2e;
        --color-accent-light: rgba(92, 107, 115, 0.08);
        --color-tooltip-bg: #1a1a1a;
        --color-tooltip-shadow: rgba(0, 0, 0, 0.3);
        --hover-color: black;
        --robot-face-color: #ebebeb;
        --shadow-sm: 0 2px 10px rgba(0, 0, 0, 0.2);
        --shadow-md: 0 4px 20px rgba(0, 0, 0, 0.3);
        --shadow-lg: 0 10px 30px rgba(0, 0, 0, 0.4);
        --color-alert: #fc8181;
        --color-alert-light: rgba(252, 129, 129, 0.1);
        --color-success: #68d391;
        --color-success-light: rgba(104, 211, 145, 0.1);
        --color-warning: #ffc107;
        --color-warning-light: rgba(255, 193, 7, 0.1);
        --color-tips-bg: rgba(92, 107, 115, 0.05);
        --color-tips-icon: #5c6b73;
    }
}

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

body {
    display: flex;
    justify-content: center;
    margin: 0;
    background-color: var(--color-bg-light);
    padding: 20px;
    min-height: 100vh;
    overflow-x: hidden;
    color: var(--color-text);
    line-height: 1.6;
    font-family: ui-rounded, -apple-system, BlinkMacSystemFont, "SF Pro Display", "SF Pro Icons", "Helvetica Neue", Helvetica, Arial, sans-serif;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
    font-synthesis: none;
}

::-moz-selection {
    background: var(--accent);
    color: var(--hover-color);
    text-shadow: none;
}

::selection {
    background: var(--accent);
    color: var(--hover-color);
}

.app-container {
    width: 100%;
    min-width: var(--container-width);
}

.header-container {
    text-align: center;
}

.tools-title {
    margin-bottom: var(--spacing-sm);
    color: var(--accent);
    font-weight: 400;
    font-size: 0.9rem;
}

.tools-nav {
    display: inline-flex;
    margin: 0 auto;
    border-top-right-radius: var(--border-radius);
    border-top-left-radius: var(--border-radius);
    background-color: var(--color-accent-light);
    overflow: hidden;
}

.tools-nav a {
    display: flex;
    align-items: center;
    z-index: 2;
    transition: all 0.2s;
    padding: 0.6rem 1.2rem;
    color: var(--accent);
    font-weight: 500;
    font-size: 0.95rem;
    text-decoration: none;
}

.tools-nav a:hover {
    background-color: var(--color-bg-light);
    color: var(--accent);
    text-decoration: underline;
}

.tools-nav a.active {
    box-shadow: var(--shadow-sm);
    background-color: var(--color-bg);
    color: var(--accent);
}

.tools-nav a.active:hover {
    text-decoration: none;
}

.tools-nav a:not(:first-child):not(.active) {
    box-shadow: -1px 0 0 0 rgba(0, 0, 0, 0.07);
}

.content-container {
    position: relative;
    margin: 0 auto;
    box-shadow: var(--shadow-md);
    border-radius: var(--border-radius);
    background-color: var(--color-bg);
    padding: var(--spacing-md);
    width: var(--container-width);
    min-width: var(--container-width);
    max-width: var(--container-width);
    overflow-x: hidden;
}

header {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
}

.calculator-header {
    display: flex;
    flex-direction: column;
    align-items: center;
    margin-bottom: var(--spacing-md);
    text-align: center;
}

.header-content {
    display: flex;
    position: relative;
    justify-content: center;
    align-items: center;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-xs);
    width: 100%;
}

.app-title {
    color: var(--accent);
    font-weight: 600;
    font-size: var(--font-size-lg);
}

.calculator-subtitle {
    color: var(--color-text-light);
    font-size: var(--font-size-sm);
}

.input-group {
    margin-bottom: var(--spacing-md);
}

.label-row {
    display: flex;
    align-items: center;
    margin-bottom: var(--spacing-xs);
}

.input-label {
    color: var(--color-text);
    font-weight: 500;
    font-size: var(--font-size-sm);
}

.input-hint {
    display: block;
    margin-top: 0.25rem;
    color: var(--color-text-light);
    font-size: var(--font-size-xs);
}

.input-field {
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    background-color: var(--color-bg-light);
    padding: 0.6rem;
    width: 100%;
    color: var(--color-text);
    font-size: var(--font-size-base);
    font-family: inherit;
}

.input-field:focus {
    outline: none;
    box-shadow: 0 0 0 3px var(--color-accent-light);
    border-color: var(--accent);
}

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

.error-message {
    display: none;
    margin-top: var(--spacing-xs);
    color: var(--color-alert);
    font-size: var(--font-size-xs);
}

.error-message.visible {
    display: block;
}

.tooltip-trigger {
    position: relative;
    justify-content: center;
    align-items: center;
    vertical-align: text-bottom;
    margin-left: 4px;
    width: 16px;
    height: 16px;
    user-select: none;
}

.tooltip-trigger::before {
    position: absolute;
    top: 1px;
    width: 100%;
    height: 100%;
    content: "";
    -webkit-mask: url('data:image/svg+xml,<%3Fxml version="1.0" encoding="utf-8"%3F><svg viewBox="0 0 20 20" xmlns="http://www.w3.org/2000/svg" fill="none"><path fill="%23000000" fill-rule="evenodd" d="M10 3a7 7 0 100 14 7 7 0 000-14zm-9 7a9 9 0 1118 0 9 9 0 01-18 0zm8.423-3a.923.923 0 00-.923.923v.385a1 1 0 11-2 0v-.385A2.923 2.923 0 019.423 5H10c1.941 0 3.5 1.591 3.5 3.516 0 .927-.48 1.8-1.276 2.29l-1.7 1.046a1 1 0 01-1.048-1.704l1.7-1.046a.691.691 0 00.324-.586C11.5 7.679 10.82 7 10 7h-.577zm.587 8a1 1 0 100-2H10a1 1 0 100 2h.01z"/></svg>');
    background-color: var(--color-text-light);
}

.tooltip {
    position: absolute;
    top: -8px;
    left: 50%;
    transform: translateX(-50%) translateY(-100%);
    visibility: hidden;
    opacity: 0;
    z-index: 10;
    transition: opacity 0.2s ease, visibility 0.2s ease;
    box-shadow: 0 2px 8px var(--color-tooltip-shadow);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    background: var(--color-tooltip-bg);
    padding: var(--spacing-xs) var(--spacing-sm);
    width: max-content;
    max-width: 240px;
    color: var(--color-text);
    font-weight: normal;
    font-size: var(--font-size-xs);
    text-align: center;
}

.tooltip::after {
    position: absolute;
    bottom: -6px;
    left: 50%;
    transform: translateX(-50%) rotate(45deg);
    border-right: 1px solid var(--color-border);
    border-bottom: 1px solid var(--color-border);
    background-color: var(--color-tooltip-bg);
    width: 10px;
    height: 10px;
    content: '';
}

.tooltip-trigger:hover .tooltip,
.tooltip-trigger:focus .tooltip {
    visibility: visible;
    opacity: 1;
}

.radio-group {
    display: flex;
    gap: var(--spacing-md);
    margin-top: var(--spacing-xs);
    margin-bottom: var(--spacing-xs);
}

.radio-label {
    display: flex;
    align-items: center;
    cursor: pointer;
    color: var(--color-text);
    font-size: var(--font-size-sm);
}

.radio-label input {
    margin-right: var(--spacing-xs);
}

.calculate-btn {
    transition: opacity 0.2s;
    cursor: pointer;
    border: none;
    border-radius: var(--border-radius);
    background-color: var(--accent);
    padding: 0.8rem 1.5rem;
    width: 100%;
    color: white;
    font-weight: 600;
    font-size: var(--font-size-md);
}

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

.ratio-container {
    display: none;
    margin-top: var(--spacing-xs);
}

.data-preview {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
    margin-top: var(--spacing-xs);
    margin-bottom: var(--spacing-xs);
}

.data-chip {
    border-radius: var(--border-radius);
    background-color: var(--color-accent-light);
    padding: 0.3rem 0.5rem;
    color: var(--accent);
    font-size: var(--font-size-xs);
}

.ratio-chip {
    display: flex;
    align-items: center;
    border-radius: var(--border-radius);
    background-color: var(--color-accent-light);
    padding: 0.3rem 0.5rem;
    color: var(--accent);
    font-size: var(--font-size-xs);
}

.ratio-value {
    font-weight: 600;
}

/* Results section styling */
.results {
    display: none;
    margin-top: var(--spacing-lg);
}

.results.visible {
    display: block;
}

.verdict {
    margin-bottom: var(--spacing-md);
    border-radius: var(--border-radius);
    padding: var(--spacing-sm);
    font-weight: 600;
    font-size: var(--font-size-base);
    text-align: center;
}

.verdict.is-mismatch {
    background-color: var(--color-alert-light);
    color: var(--color-alert);
}

.verdict.possible-mismatch {
    background-color: var(--color-warning-light);
    color: var(--color-warning);
}

.verdict.no-mismatch {
    background-color: var(--color-success-light);
    color: var(--color-success);
}

.expected-table {
    margin: var(--spacing-md) 0;
    border-collapse: collapse;
    width: 100%;
}

.expected-table th,
.expected-table td {
    border: 1px solid var(--color-border);
    padding: 0.3rem 0.5rem;
    text-align: center;
}

.expected-table th {
    background-color: var(--color-bg-lighter);
    font-weight: 600;
    font-size: var(--font-size-xs);
}

.expected-table td {
    font-size: var(--font-size-xs);
}

/* Tech details section */
.tech-details {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: var(--spacing-md);
}

.detail-item {
    text-align: center;
}

.detail-label {
    margin-bottom: 2px;
    color: var(--color-text-light);
    font-size: var(--font-size-xs);
}

.detail-value {
    color: var(--accent);
    font-weight: 600;
    font-size: var(--font-size-base);
}

.explanation {
    margin-top: var(--spacing-md);
    color: var(--color-text-light);
    font-size: var(--font-size-sm);
}

.share-section {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-md);
}

.share-button {
    display: inline-flex;
    position: relative;
    align-items: center;
    gap: 8px;
    transition: all 0.3s;
    cursor: pointer;
    border: none;
    background: transparent;
    padding: 0.5rem;
    overflow: hidden;
    color: var(--accent);
    font-weight: 500;
    font-size: var(--font-size-md);
    text-decoration: none;
}

.share-button::after {
    position: absolute;
    bottom: 0;
    left: 0;
    transform: scaleX(0);
    transform-origin: right;
    transition: transform 0.3s ease;
    background-color: var(--accent);
    width: 100%;
    height: 2px;
    content: '';
}

.share-button:hover::after {
    transform: scaleX(1);
    transform-origin: left;
}

.share-button svg {
    transition: transform 0.3s;
}

.share-button:hover #link {
    transform: rotate(-45deg);
}

.modal-overlay {
    display: none;
    position: fixed;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    justify-content: center;
    align-items: center;
    opacity: 0;
    z-index: 1000;
    background-color: var(--color-overlay);
    padding: var(--spacing-md);
    overflow-y: auto;
}

.modal-overlay:target {
    display: flex;
    opacity: 1;
}

.modal-overlay:target .modal-container {
    transform: translateY(0);
}

.modal-backdrop {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}

.modal-container {
    display: flex;
    position: relative;
    flex-direction: column;
    transform: translateY(20px);
    box-shadow: var(--shadow-lg);
    border-radius: var(--border-radius);
    background-color: var(--color-bg);
    width: 100%;
    max-width: 700px;
    max-height: 100%;
    overflow-y: hidden;
}

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

.modal-title {
    color: var(--accent);
    font-weight: 600;
    font-size: var(--font-size-md);
}

.modal-close {
    display: flex;
    justify-content: center;
    align-items: center;
    cursor: pointer;
    border: none;
    border-radius: 50%;
    background: none;
    width: 30px;
    height: 30px;
    color: var(--color-text-light);
    font-size: var(--font-size-lg);
    text-decoration: none;
}

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

.modal-body {
    flex: 1;
    padding: var(--spacing-lg);
    overflow-y: auto;
}

.modal-footer {
    border-top: 1px solid var(--color-border);
    padding: var(--spacing-sm);
    text-align: right;
}

.modal-button {
    cursor: pointer;
    border: none;
    border-radius: var(--border-radius);
    background-color: var(--accent);
    padding: 0.5rem 1rem;
    color: white;
    font-weight: 500;
    font-size: var(--font-size-sm);
}

.modal-button:hover {
    opacity: 0.9;
}

.modal-body h4 {
    margin-top: 1.5rem;
    margin-bottom: 1rem;
    color: var(--accent);
    font-size: var(--font-size-md);
}

.modal-body h4:first-child {
    margin-top: 0;
}

.modal-body p {
    margin-bottom: 1.5em;
    line-height: 1.5;
}

.formula {
    margin: 0.75rem 0;
    text-align: center;
}

math {
    font-size: 1.2rem;
}


.modal-body ol {
    margin-bottom: 1rem;
    padding-left: 1.5rem;
}

.modal-body ol>li {
    margin-bottom: 1rem;
}

.modal-body ul {
    margin-top: 0.5rem;
    margin-bottom: 0.5rem;
    padding-left: 1.5rem;
    list-style-type: disc;
}

.modal-body ul>li {
    margin-bottom: 0.3rem;
}

.modal-body hr {
    margin: 1.5rem 0;
    border: none;
    border-top: 1px solid var(--color-border);
}

a {
    color: var(--accent);
    text-decoration: underline;
    text-decoration-color: color-mix(in srgb, var(--accent), transparent 40%);
}

a:hover {
    text-decoration-color: var(--accent);
}

a.external:not(:has(img, svg, video, picture, figure))::after {
    display: inline-block;
    vertical-align: -0.15em;
    margin-inline-start: 0.1em;
    background-color: currentColor;
    width: 0.8em;
    height: 0.8em;
    content: '';
    -webkit-mask-image: var(--external-link-icon);
    -webkit-mask-size: 100% 100%;
}

/* Checkbox hack for modal toggle */
#modalToggle {
    display: none;
}

#modalToggle:checked~.modal-overlay {
    display: flex;
    opacity: 1;
}

#modalToggle:checked~.modal-overlay .modal-container {
    transform: translateY(0);
}

.app-footer {
    margin: var(--spacing-md) auto 0;
    padding: var(--spacing-md) 0;
    padding-top: 0;
    width: var(--container-width);
    color: var(--color-text-light);
    font-size: var(--font-size-sm);
}

.footer-content {
    display: flex;
    justify-content: center;
    margin: 0 auto;
    text-align: center;
}

.footer-text {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: var(--spacing-xs);
    margin: 0;
}

.footer-link {
    transition: opacity 0.2s ease;
    color: var(--accent);
    text-decoration: underline;
    text-decoration-color: color-mix(in srgb, var(--accent), transparent 40%);
}

.footer-link:hover {
    text-decoration-color: var(--accent);
}

.separator {
    opacity: 0.5;
    color: var(--color-text-light);
    user-select: none;
}

.heart {
    color: #d42e28;
}

.tips-container {
    margin-top: var(--spacing-md);
    margin-bottom: var(--spacing-md);
}

.tips-header {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    transition: background-color 0.2s;
    margin-bottom: var(--spacing-xs);
    border-radius: var(--border-radius);
    background-color: var(--color-tips-bg);
    padding: var(--spacing-xs) var(--spacing-sm);
}

.tips-header:hover {
    background-color: var(--color-bg-lighter);
}

.tips-icon {
    width: 20px;
    height: 20px;
    fill: var(--color-tips-icon);
    flex-shrink: 0;
}

.tips-title {
    flex-grow: 1;
    color: var(--accent);
    font-weight: 600;
    font-size: var(--font-size-sm);
}

.tips-toggle {
    position: relative;
    flex-shrink: 0;
    width: 20px;
    height: 20px;
}

.tips-toggle::before,
.tips-toggle::after {
    position: absolute;
    background-color: var(--accent);
    content: '';
}

.tips-toggle::before {
    top: 50%;
    right: 0;
    left: 0;
    transform: translateY(-50%);
    height: 2px;
}

.tips-toggle::after {
    top: 0;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 2px;
}

/* Tips content */
.tips-content {
    transition: max-height 0.3s ease;
    max-height: 0;
    overflow: hidden;
}

.tips-list {
    margin-bottom: var(--spacing-xs);
    padding: 0 var(--spacing-sm);
    list-style-type: none;
}

.tips-item {
    position: relative;
    margin-bottom: var(--spacing-xs);
    padding-left: 1.5em;
    color: var(--color-text);
    font-size: var(--font-size-sm);
}

.tips-item::before {
    position: absolute;
    top: 0.5em;
    left: 0;
    border-radius: 50%;
    background-color: var(--accent);
    width: 6px;
    height: 6px;
    content: '';
}

/* Checkbox hack for tips toggle */
#tipsToggle {
    display: none;
}

#tipsToggle:checked~.tips-content {
    max-height: 500px;
}

#tipsToggle:checked~.tips-header .tips-toggle::after {
    transform: translateX(-50%) scaleY(0);
}

/* ========== ROBOT STYLES ========== */
.robot {
    display: flex;
    position: relative;
    justify-content: center;
    align-items: center;
    transition: background-color .5s ease-in-out;
    border-radius: 50%;
    background: var(--accent);
    aspect-ratio: 1/1;
    width: 36px;
    height: 36px;
}

.robot-face {
    display: flex;
    position: relative;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    border-radius: 6px;
    background: var(--robot-face-color);
    width: 22px;
    height: 22px;
}

.robot-eyes {
    display: flex;
    gap: 6px;
    margin-bottom: 3px;
}

.robot-eye {
    transition: transform 0.1s;
    border-radius: 50%;
    background: var(--accent);
    width: 4px;
    height: 4px;
}

.robot-mouth {
    transition: height 0.5s ease-in-out, border-radius 0.5s ease-in-out;
    border-radius: 1px 1px 5px 5px;
    background: var(--accent);
    width: 12px;
    height: 5px;
}

.robot.no-srm {
    background-color: var(--color-success);
}

.robot.possible-srm {
    background-color: var(--color-warning);
}

.robot.possible-srm .robot-mouth {
    border-radius: 1px;
    height: 2px;
}

.robot.is-srm {
    background-color: var(--color-alert);
}

.robot.is-srm .robot-mouth {
    border-radius: 1px;
    height: 2px;
}

@media (max-width: 649px) {
    :root {
        --container-width: calc(100vw - 16px);
    }

    .app-container {
        margin: 0;
        padding: 8px;
        padding-bottom: 0;
    }

    .content-container {
        border-top-right-radius: 0;
        border-top-left-radius: 0;
        width: 100%;
        min-width: 100%;
    }

    .inputs-grid {
        grid-template-columns: 1fr;
    }
}