:root {
    font-family: "Segoe UI", Arial, sans-serif;
    color: #203c4b;
    background: #eef3f5;

    --teal: #007f87;
    --orange: #bd5725;
    --purple: #7545b5;
}

* {
    box-sizing: border-box;
}

[hidden] {
    display: none !important;
}

body {
    margin: 0;
}

main {
    max-width: 1180px;
    margin: auto;
    padding: 32px 24px;
}

header {
    margin-bottom: 25px;
}

.eyebrow {
    font-size: 12px;
    font-weight: 750;
    letter-spacing: 1.4px;
    color: #55717e;
}

h1 {
    font-size: clamp(29px, 4vw, 43px);
    letter-spacing: -1px;
    margin: 10px 0;
}

h2 {
    font-size: 22px;
}

p {
    line-height: 1.6;
}

header p {
    color: #5b737f;
    margin-bottom: 0;
}

.settings {
    display: grid;
    grid-template-columns: 1.2fr 1fr 1fr;
    gap: 16px;
    margin-bottom: 20px;
}

.setting {
    padding: 18px;
    background: white;
    border-radius: 13px;
    border: 1px solid #d6e2e7;
}

.setting label {
    display: block;
    font-size: 14px;
    font-weight: 650;
    margin-bottom: 12px;
}

.setting output {
    float: right;
    color: var(--purple);
}

.setting input,
.setting select {
    width: 100%;
}

select,
button {
    font: inherit;
    border: 1px solid #b9ccd4;
    border-radius: 8px;
    padding: 10px 12px;
    background: white;
    color: #203c4b;
    cursor: pointer;
}

input[type="range"],
input[type="checkbox"] {
    accent-color: var(--purple);
}

input[type="range"] {
    cursor: pointer;
}

input:disabled {
    cursor: not-allowed;
    opacity: 0.5;
}

button:hover {
    filter: brightness(0.95);
}

:focus-visible {
    outline: 3px solid #e0af35;
    outline-offset: 3px;
}

.panel {
    background: white;
    border: 1px solid #d6e2e7;
    border-radius: 17px;
    overflow: hidden;
}

.panel-heading {
    padding: 22px 24px 8px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 15px;
}

.panel-heading h2 {
    margin: 7px 0;
}

.panel-heading p {
    font-size: 13px;
    color: #5b737f;
}

.legend,
.toggles {
    display: flex;
    flex-wrap: wrap;
    gap: 12px 20px;
    padding: 8px 24px;
    font-size: 13px;
}

.legend {
    font-weight: 650;
}

.toggles {
    padding-bottom: 14px;
}

.teal {
    color: var(--teal);
}

.orange {
    color: var(--orange);
}

.purple {
    color: var(--purple);
}

.tank-wrap {
    position: relative;
    background: #fbfdfe;
}

.tank-wrap canvas {
    position: absolute;
    inset: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
}

svg {
    display: block;
    width: 100%;
    height: auto;
}

#tank {
    position: relative;
    touch-action: none;
    cursor: crosshair;
}

#tank .probe {
    cursor: grab;
}

.hint {
    color: #617a87;
    font-size: 13px;
    padding: 0 24px;
}

.controls {
    display: flex;
    align-items: center;
    flex-wrap: wrap;
    gap: 10px;
    padding: 16px 24px 8px;
}

.controls label {
    margin-left: auto;
    font-size: 14px;
}

.controls select {
    margin-left: 6px;
}

.primary {
    background: var(--purple);
    color: white;
    border-color: var(--purple);
    min-width: 100px;
}

.timeline {
    display: flex;
    align-items: center;
    gap: 14px;
    padding: 14px 24px 24px;
    font-size: 14px;
}

.timeline input {
    flex: 1;
    min-width: 60px;
}

.timeline output {
    min-width: 70px;
    text-align: right;
    font-variant-numeric: tabular-nums;
}

.textbook-controls {
    display: flex;
    flex-wrap: wrap;
    gap: 14px;
    align-items: center;
    padding: 12px 24px;
}

.point-buttons {
    display: flex;
    gap: 8px;
}

.point-buttons button {
    min-width: 40px;
}

.point-buttons .active {
    background: var(--purple);
    color: white;
    border-color: var(--purple);
}

.measurements {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 16px;
    margin-top: 22px;
}

.measurements article,
.learning article {
    background: white;
    padding: 22px;
    border-radius: 14px;
}

.measurements h2 {
    margin: 12px 0 6px;
    font-variant-numeric: tabular-nums;
}

.measurements p {
    margin: 0;
    color: #5b737f;
}

.measurements .difference {
    background: #eee6f8;
}

.verdict {
    padding: 18px 22px;
}

.verdict h2 {
    margin: 8px 0;
    color: var(--purple);
}

.verdict p {
    margin: 6px 0;
}

.instant-values {
    padding: 0 24px;
    font-size: 15px;
    font-weight: 650;
    font-variant-numeric: tabular-nums;
}

.learning {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 18px;
    margin-top: 22px;
}

.learning p {
    color: #526e7b;
}

.learning .question,
.question-panel {
    background: #eee6f8;
}

.question-panel {
    margin-top: 22px;
    padding: 22px;
    border-radius: 14px;
}

.question .eyebrow,
.question-panel .eyebrow {
    color: var(--purple);
}

footer {
    padding: 22px 4px;
    font-size: 12px;
    color: #617985;
    line-height: 1.7;
}

@media (max-width: 700px) {
    main {
        padding: 22px 12px;
    }

    .settings,
    .measurements,
    .learning {
        grid-template-columns: 1fr;
    }

    .panel-heading {
        align-items: flex-start;
        flex-direction: column;
        gap: 0;
    }

    .controls label {
        margin-left: 0;
    }

    .legend,
    .toggles {
        gap: 10px;
    }
}