/* ==========================================================
   Baking Calculator — Theme & Animations
   ========================================================== */

/* ---------- palette — warm bread & cookie tones ---------- */
:root {
    --bg: #fdf6ec;
    --bg-dark: #f5e0c0;
    --card: #fffefa;
    --card-shadow: rgba(180, 120, 60, 0.15);
    --accent: #c0785a;
    /* crust brown    */
    --accent2: #d4943c;
    /* golden cookie  */
    --accent3: #8aaa4a;
    /* herb green     */
    --accent4: #b06030;
    /* dark rye       */
    --accent5: #e0a85c;
    /* butter yellow  */
    --text: #3e2723;
    --text-light: #8d6e63;
    --display-bg: #fffbf2;
    --key-num: #fdf0dc;
    --key-func: #f5d6b8;
    --key-op: #d4943c;
    --key-eq: #c0785a;
    --radius: 16px;
    --radius-sm: 10px;
    /* extra candy colors */
    --candy-pink: #ff6b9d;
    --candy-orange: #ff8c42;
    --candy-yellow: #ffd166;
    --candy-green: #06d6a0;
    --candy-blue: #118ab2;
    --candy-purple: #9b5de5;
}

/* ---------- reset ---------- */
*,
*::before,
*::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    font-size: 16px;
}

body {
    font-family: 'Heebo', 'Fredoka', sans-serif;
    background: var(--bg);
    color: var(--text);
    min-height: 100vh;
    overflow-x: hidden;
    position: relative;
    direction: rtl;
    text-align: right;
}

/* ==========================================================
   Floating sprinkles (background decoration)
   ========================================================== */
.sprinkles {
    position: fixed;
    inset: 0;
    pointer-events: none;
    z-index: 0;
    overflow: hidden;
}

.sprinkle {
    position: absolute;
    font-size: 1.2rem;
    opacity: 0.35;
    animation: sprinkleFall linear infinite;
    width: auto;
    height: auto;
    border-radius: 0;
    background: none !important;
}

.s1 {
    left: 5%;
    animation-duration: 11s;
    animation-delay: 0s;
    top: -30px;
    transform: rotate(25deg);
}

.s2 {
    left: 15%;
    animation-duration: 14s;
    animation-delay: 2s;
    top: -30px;
    transform: rotate(-15deg);
}

.s3 {
    left: 25%;
    animation-duration: 10s;
    animation-delay: 4s;
    top: -30px;
    transform: rotate(10deg);
}

.s4 {
    left: 38%;
    animation-duration: 13s;
    animation-delay: 1s;
    top: -30px;
    transform: rotate(-8deg);
}

.s5 {
    left: 50%;
    animation-duration: 12s;
    animation-delay: 3s;
    top: -30px;
    transform: rotate(15deg);
}

.s6 {
    left: 62%;
    animation-duration: 15s;
    animation-delay: 5s;
    top: -30px;
    transform: rotate(-12deg);
}

.s7 {
    left: 72%;
    animation-duration: 11s;
    animation-delay: 0.5s;
    top: -30px;
    transform: rotate(8deg);
}

.s8 {
    left: 82%;
    animation-duration: 13s;
    animation-delay: 2.5s;
    top: -30px;
    transform: rotate(-5deg);
}

.s9 {
    left: 90%;
    animation-duration: 10s;
    animation-delay: 4.5s;
    top: -30px;
    transform: rotate(12deg);
}

.s10 {
    left: 33%;
    animation-duration: 16s;
    animation-delay: 6s;
    top: -30px;
    transform: rotate(-10deg);
}

.s11 {
    left: 55%;
    animation-duration: 12s;
    animation-delay: 1.5s;
    top: -30px;
    transform: rotate(6deg);
}

.s12 {
    left: 78%;
    animation-duration: 14s;
    animation-delay: 3.5s;
    top: -30px;
    transform: rotate(-14deg);
}

@keyframes sprinkleFall {
    0% {
        transform: translateY(-40px) rotate(var(--r, 30deg));
        opacity: 0;
    }

    10% {
        opacity: 0.5;
    }

    100% {
        transform: translateY(110vh) rotate(calc(var(--r, 30deg) + 360deg));
        opacity: 0;
    }
}

/* ==========================================================
   Layout wrapper
   ========================================================== */
.app-wrapper {
    position: relative;
    z-index: 1;
    max-width: 420px;
    margin: 0 auto;
    padding: 1.5rem 1rem 2rem;
}

/* ==========================================================
   Header
   ========================================================== */
.app-header {
    text-align: center;
    margin-bottom: 1.5rem;
}

.logo {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
}

.logo-icon {
    font-size: 2.4rem;
    animation: wiggle 2s ease-in-out infinite;
}

@keyframes wiggle {
    0% {
        transform: rotate(0deg) scale(1);
    }

    15% {
        transform: rotate(-14deg) scale(1.15);
    }

    30% {
        transform: rotate(14deg) scale(1.1);
    }

    45% {
        transform: rotate(-10deg) scale(1.05);
    }

    60% {
        transform: rotate(10deg) scale(1.1);
    }

    75% {
        transform: rotate(-6deg) scale(1);
    }

    100% {
        transform: rotate(0deg) scale(1);
    }
}

@keyframes rainbowText {
    0% {
        filter: hue-rotate(0deg);
    }

    100% {
        filter: hue-rotate(360deg);
    }
}

@keyframes float {

    0%,
    100% {
        transform: translateY(0);
    }

    50% {
        transform: translateY(-6px);
    }
}

@keyframes jelly {
    0% {
        transform: scale(1, 1);
    }

    25% {
        transform: scale(0.95, 1.05);
    }

    50% {
        transform: scale(1.05, 0.95);
    }

    75% {
        transform: scale(0.98, 1.02);
    }

    100% {
        transform: scale(1, 1);
    }
}

@keyframes borderDance {
    0% {
        border-color: var(--candy-pink);
    }

    20% {
        border-color: var(--candy-orange);
    }

    40% {
        border-color: var(--candy-yellow);
    }

    60% {
        border-color: var(--candy-green);
    }

    80% {
        border-color: var(--candy-blue);
    }

    100% {
        border-color: var(--candy-pink);
    }
}

@keyframes pulseGlow {

    0%,
    100% {
        box-shadow: 0 0 5px rgba(255, 107, 157, 0.3);
    }

    50% {
        box-shadow: 0 0 20px rgba(255, 107, 157, 0.6), 0 0 40px rgba(255, 140, 66, 0.3);
    }
}

@keyframes shimmer {
    0% {
        background-position: -200% center;
    }

    100% {
        background-position: 200% center;
    }
}

@keyframes bounceIn {
    0% {
        transform: scale(0.3);
        opacity: 0;
    }

    50% {
        transform: scale(1.05);
    }

    70% {
        transform: scale(0.95);
    }

    100% {
        transform: scale(1);
        opacity: 1;
    }
}

@keyframes spinBounce {
    0% {
        transform: rotate(0deg);
    }

    100% {
        transform: rotate(360deg);
    }
}

.logo h1 {
    font-family: 'Fredoka', sans-serif;
    font-weight: 700;
    font-size: 1.8rem;
    background: linear-gradient(135deg, var(--candy-pink), var(--candy-orange), var(--candy-yellow), var(--candy-green), var(--candy-blue), var(--candy-purple));
    background-size: 300% 300%;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    animation: shimmer 3s linear infinite;
}

.tagline {
    font-size: 0.9rem;
    color: var(--text-light);
    margin-top: 0.15rem;
}

.version {
    font-size: 0.75rem;
    color: #bbb;
}

/* ==========================================================
   Calculator card
   ========================================================== */
.calculator {
    background: var(--card);
    border-radius: var(--radius);
    box-shadow: 0 8px 30px var(--card-shadow);
    padding: 1.25rem;
    animation: fadeSlideUp 0.6s ease-out, pulseGlow 4s ease-in-out infinite 1s;
    border: 3px solid transparent;
    animation: fadeSlideUp 0.6s ease-out, borderDance 6s linear infinite;
}

@keyframes fadeSlideUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ---------- Display ---------- */
.display-wrapper {
    position: relative;
    background: linear-gradient(135deg, #fffbf2, #fff5e6, #fffbf2);
    background-size: 200% 200%;
    animation: shimmer 8s ease infinite;
    border: 2px solid #f5deb3;
    border-radius: var(--radius-sm);
    padding: 1rem 1.25rem;
    margin-bottom: 1rem;
    min-height: 80px;
    display: flex;
    flex-direction: column;
    justify-content: flex-end;
    align-items: flex-start;
    overflow: hidden;
    direction: ltr;
    text-align: left;
}

.display-expression {
    font-size: 0.85rem;
    color: var(--text-light);
    min-height: 1.2em;
    word-break: break-all;
    direction: ltr;
    text-align: left;
    width: 100%;
}

.display-screen {
    font-family: 'Fredoka', monospace;
    font-size: 2.4rem;
    font-weight: 600;
    color: var(--text);
    word-break: break-all;
    transition: transform 0.1s;
    direction: ltr;
    text-align: left;
    width: 100%;
}

.display-screen.pop {
    animation: popNum 0.15s ease;
}

@keyframes popNum {
    0% {
        transform: scale(1);
    }

    50% {
        transform: scale(1.08);
    }

    100% {
        transform: scale(1);
    }
}

/* ---------- Scale section ---------- */
.scale-section {
    margin-bottom: 0.75rem;
}

.scale-label {
    display: block;
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--text-light);
    margin-bottom: 0.35rem;
}

.scale-controls {
    display: flex;
    gap: 0.4rem;
}

.scale-btn {
    flex: 1;
    padding: 0.5rem 0;
    border: 2px solid var(--accent2);
    background: transparent;
    color: var(--accent2);
    border-radius: 8px;
    font-family: 'Fredoka', sans-serif;
    font-weight: 600;
    font-size: 0.9rem;
    cursor: pointer;
    transition: all 0.25s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.scale-btn:hover {
    background: linear-gradient(135deg, var(--candy-orange), var(--candy-yellow));
    color: #fff;
    transform: translateY(-3px) scale(1.05);
    border-color: var(--candy-orange);
    box-shadow: 0 5px 15px rgba(255, 140, 66, 0.4);
}

.scale-btn:nth-child(1) {
    border-color: var(--candy-pink);
    color: var(--candy-pink);
}

.scale-btn:nth-child(2) {
    border-color: var(--candy-orange);
    color: var(--candy-orange);
}

.scale-btn:nth-child(3) {
    border-color: var(--candy-yellow);
    color: #c9a020;
}

.scale-btn:nth-child(4) {
    border-color: var(--candy-green);
    color: var(--candy-green);
}

.scale-btn:nth-child(5) {
    border-color: var(--candy-blue);
    color: var(--candy-blue);
}

.scale-btn:nth-child(1):hover {
    background: linear-gradient(135deg, var(--candy-pink), #ff85b1);
    border-color: var(--candy-pink);
}

.scale-btn:nth-child(3):hover {
    background: linear-gradient(135deg, var(--candy-yellow), #ffe08a);
    border-color: var(--candy-yellow);
}

.scale-btn:nth-child(4):hover {
    background: linear-gradient(135deg, var(--candy-green), #20e8b0);
    border-color: var(--candy-green);
}

.scale-btn:nth-child(5):hover {
    background: linear-gradient(135deg, var(--candy-blue), #1aa8d8);
    border-color: var(--candy-blue);
}

.scale-btn.active {
    background: linear-gradient(135deg, var(--candy-orange), var(--candy-yellow));
    color: #fff;
    border-color: var(--candy-orange);
    box-shadow: 0 3px 12px rgba(255, 140, 66, 0.4);
    animation: jelly 0.6s ease;
}

/* ---------- Keypad ---------- */
.keypad {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.key {
    padding: 1rem 0;
    border: none;
    border-radius: var(--radius-sm);
    font-family: 'Fredoka', sans-serif;
    font-size: 1.4rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s cubic-bezier(0.34, 1.56, 0.64, 1);
    position: relative;
    overflow: hidden;
    direction: ltr;
    animation: bounceIn 0.5s ease backwards;
}

.key:nth-child(1) {
    animation-delay: 0.02s;
}

.key:nth-child(2) {
    animation-delay: 0.04s;
}

.key:nth-child(3) {
    animation-delay: 0.06s;
}

.key:nth-child(4) {
    animation-delay: 0.08s;
}

.key:nth-child(5) {
    animation-delay: 0.10s;
}

.key:nth-child(6) {
    animation-delay: 0.12s;
}

.key:nth-child(7) {
    animation-delay: 0.14s;
}

.key:nth-child(8) {
    animation-delay: 0.16s;
}

.key:nth-child(9) {
    animation-delay: 0.18s;
}

.key:nth-child(10) {
    animation-delay: 0.20s;
}

.key:nth-child(11) {
    animation-delay: 0.22s;
}

.key:nth-child(12) {
    animation-delay: 0.24s;
}

.key:nth-child(13) {
    animation-delay: 0.26s;
}

.key:nth-child(14) {
    animation-delay: 0.28s;
}

.key:nth-child(15) {
    animation-delay: 0.30s;
}

.key:nth-child(16) {
    animation-delay: 0.32s;
}

.key:nth-child(17) {
    animation-delay: 0.34s;
}

.key:nth-child(18) {
    animation-delay: 0.36s;
}

.key:nth-child(19) {
    animation-delay: 0.38s;
}

/* ripple */
.key::after {
    content: '';
    position: absolute;
    inset: 0;
    background: rgba(255, 255, 255, 0.4);
    border-radius: 50%;
    transform: scale(0);
    opacity: 0;
    pointer-events: none;
}

.key.ripple::after {
    animation: rippleAnim 0.5s ease-out;
}

@keyframes rippleAnim {
    0% {
        transform: scale(0);
        opacity: 1;
    }

    100% {
        transform: scale(4);
        opacity: 0;
    }
}

/* number keys — each row gets a different candy color tint */
.key-num {
    background: linear-gradient(145deg, #fff5e0, #ffecc8);
    color: var(--text);
    box-shadow: 0 4px 0 #d4ba94, 0 6px 15px rgba(0, 0, 0, 0.08);
    border: 1px solid rgba(255, 200, 100, 0.3);
}

/* row 2 — warm pink tint */
.keypad .key-num:nth-child(n+5):nth-child(-n+7) {
    background: linear-gradient(145deg, #fff0f0, #ffe4e8);
    box-shadow: 0 4px 0 #e0a0a0, 0 6px 15px rgba(255, 107, 157, 0.1);
    border-color: rgba(255, 107, 157, 0.2);
}

/* row 3 — mint tint */
.keypad .key-num:nth-child(n+9):nth-child(-n+11) {
    background: linear-gradient(145deg, #eefff6, #d8f5e8);
    box-shadow: 0 4px 0 #90c8a8, 0 6px 15px rgba(6, 214, 160, 0.1);
    border-color: rgba(6, 214, 160, 0.2);
}

/* row 4 — lavender tint */
.keypad .key-num:nth-child(n+13):nth-child(-n+15) {
    background: linear-gradient(145deg, #f5f0ff, #ece4ff);
    box-shadow: 0 4px 0 #b0a0d0, 0 6px 15px rgba(155, 93, 229, 0.1);
    border-color: rgba(155, 93, 229, 0.2);
}

/* row 5 — sky blue tint (0 and dot) */
.keypad .key-num:nth-child(n+17) {
    background: linear-gradient(145deg, #f0f8ff, #dceeff);
    box-shadow: 0 4px 0 #90b0d0, 0 6px 15px rgba(17, 138, 178, 0.1);
    border-color: rgba(17, 138, 178, 0.2);
}

.key-num:hover {
    transform: translateY(-3px) scale(1.06);
    box-shadow: 0 7px 0 #d4ba94, 0 10px 25px rgba(0, 0, 0, 0.12);
    filter: brightness(1.05) saturate(1.3);
}

.key-num:active {
    transform: translateY(1px) scale(0.97);
    box-shadow: 0 1px 0 #d4ba94;
    filter: brightness(0.95);
}

/* function keys */
.key-func {
    background: linear-gradient(145deg, #ffe0d0, #ffcdb8);
    color: var(--candy-pink);
    box-shadow: 0 4px 0 #d9a088, 0 6px 15px rgba(255, 107, 157, 0.12);
    border: 1px solid rgba(255, 107, 157, 0.25);
    font-weight: 700;
}

.key-func:hover {
    background: linear-gradient(145deg, var(--candy-pink), #ff85b1);
    color: #fff;
    transform: translateY(-3px) scale(1.06) rotate(-2deg);
    box-shadow: 0 7px 0 #d06080, 0 10px 20px rgba(255, 107, 157, 0.35);
}

.key-func:active {
    transform: translateY(1px) scale(0.97);
    box-shadow: 0 1px 0 #c4a080;
}

/* operator keys — vibrant gradient column */
.key-op {
    background: linear-gradient(145deg, var(--candy-orange), #ff6b42);
    color: #fff;
    box-shadow: 0 4px 0 #c05020, 0 6px 15px rgba(255, 107, 66, 0.25);
    border: 1px solid rgba(255, 255, 255, 0.2);
    text-shadow: 0 1px 2px rgba(0, 0, 0, 0.15);
}

/* each operator row: different gradient */
.keypad .key-op:nth-of-type(1) {
    background: linear-gradient(145deg, #ff8c42, #ff6b42);
}

.keypad .key-op:nth-of-type(2) {
    background: linear-gradient(145deg, var(--candy-purple), #7c3aed);
    box-shadow: 0 4px 0 #6a2cc0, 0 6px 15px rgba(155, 93, 229, 0.25);
}

.keypad .key-op:nth-of-type(3) {
    background: linear-gradient(145deg, var(--candy-blue), #0b7daa);
    box-shadow: 0 4px 0 #086890, 0 6px 15px rgba(17, 138, 178, 0.25);
}

.keypad .key-op:nth-of-type(4) {
    background: linear-gradient(145deg, var(--candy-green), #05b88a);
    box-shadow: 0 4px 0 #049870, 0 6px 15px rgba(6, 214, 160, 0.25);
}

.key-op:hover {
    transform: translateY(-3px) scale(1.08) rotate(2deg);
    box-shadow: 0 8px 0 #a85020, 0 12px 25px rgba(255, 107, 66, 0.4);
    filter: brightness(1.15) saturate(1.2);
}

.key-op:active {
    transform: translateY(1px) scale(0.96);
    box-shadow: 0 1px 0 #a87028;
}

.key-op.active-op {
    filter: brightness(0.85) saturate(1.4);
    box-shadow: inset 0 3px 8px rgba(0, 0, 0, 0.3);
    transform: translateY(1px) scale(0.98);
    animation: jelly 0.3s ease;
}

/* equals key — big attention-grabbing candy button */
.key-equals {
    background: linear-gradient(145deg, var(--candy-pink), #ff4088, var(--candy-purple));
    background-size: 200% 200%;
    animation: bounceIn 0.5s ease backwards, shimmer 3s linear infinite;
    animation-delay: 0.38s, 0s;
    color: #fff;
    box-shadow: 0 4px 0 #c02060, 0 6px 20px rgba(255, 107, 157, 0.35);
    border: 1px solid rgba(255, 255, 255, 0.3);
    text-shadow: 0 1px 3px rgba(0, 0, 0, 0.2);
    font-size: 1.6rem;
}

.key-equals:hover {
    transform: translateY(-4px) scale(1.1);
    box-shadow: 0 8px 0 #c02060, 0 14px 30px rgba(255, 107, 157, 0.5);
    filter: brightness(1.15);
}

.key-equals:active {
    transform: translateY(1px) scale(0.95);
    box-shadow: 0 1px 0 #8e5840;
}

/* wide key (0) */
.key-wide {
    grid-column: span 2;
}

/* ==========================================================
   Converter section
   ========================================================== */
.converter-section {
    border-top: 2px dashed #f5deb3;
    padding-top: 1rem;
}

.section-title {
    font-family: 'Fredoka', sans-serif;
    font-size: 1rem;
    margin-bottom: 0.6rem;
    color: var(--accent4);
}

.converter-row {
    display: flex;
    gap: 0.4rem;
    align-items: center;
    flex-wrap: wrap;
}

.conv-input {
    width: 70px;
    padding: 0.45rem 0.5rem;
    border: 2px solid #e0c9a8;
    border-radius: 8px;
    font-size: 0.9rem;
    font-family: 'Heebo', sans-serif;
    background: var(--display-bg);
    color: var(--text);
}

.conv-input:focus {
    outline: none;
    border-color: var(--accent4);
}

.conv-select {
    padding: 0.45rem 0.4rem;
    border: 2px solid #e0c9a8;
    border-radius: 8px;
    font-size: 0.85rem;
    font-family: 'Heebo', sans-serif;
    background: var(--display-bg);
    color: var(--text);
    cursor: pointer;
}

.conv-select:focus {
    outline: none;
    border-color: var(--accent4);
}

.conv-arrow {
    font-size: 1.2rem;
    color: var(--accent3);
}

.conv-btn {
    padding: 0.5rem 1rem;
    border: none;
    border-radius: 8px;
    background: linear-gradient(135deg, var(--candy-green), #20e8b0);
    color: #fff;
    font-family: 'Fredoka', sans-serif;
    font-weight: 600;
    font-size: 0.9rem;
    cursor: pointer;
    transition: all 0.2s cubic-bezier(0.34, 1.56, 0.64, 1);
    box-shadow: 0 4px 0 #049870, 0 6px 15px rgba(6, 214, 160, 0.25);
    text-shadow: 0 1px 2px rgba(0, 0, 0, 0.1);
}

.conv-btn:hover {
    background: linear-gradient(135deg, #20e8b0, var(--candy-green));
    transform: translateY(-3px) scale(1.06);
    box-shadow: 0 7px 0 #049870, 0 12px 25px rgba(6, 214, 160, 0.4);
}

.conv-btn:active {
    transform: translateY(1px) scale(0.97);
    box-shadow: 0 1px 0 #6a9e30;
}

.conv-result {
    margin-top: 0.5rem;
    font-family: 'Fredoka', sans-serif;
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--accent4);
    min-height: 1.4em;
    transition: opacity 0.2s;
    direction: ltr;
    text-align: center;
    background: linear-gradient(135deg, var(--candy-orange), var(--candy-pink));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.conv-result.flash {
    animation: flashResult 0.4s ease;
}

@keyframes flashResult {
    0% {
        opacity: 0;
        transform: translateY(6px);
    }

    100% {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ==========================================================
   Footer
   ========================================================== */
.app-footer {
    text-align: center;
    margin-top: 1.5rem;
    font-size: 0.8rem;
    color: var(--text-light);
    animation: float 3s ease-in-out infinite;
}

/* ---------- RTL helpers ---------- */
.keypad,
.scale-controls,
.converter-row {
    direction: ltr;
}

.conv-input,
.conv-select {
    direction: ltr;
    text-align: left;
}

/* ==========================================================
   Responsive — small screens
   ========================================================== */
@media (max-width: 500px) {
    .app-wrapper {
        padding: 0.75rem 0.5rem 1rem;
        max-width: 100%;
    }

    /* compact header */
    .app-header {
        margin-bottom: 0.6rem;
    }

    .logo-icon {
        font-size: 1.8rem;
    }

    .logo h1 {
        font-size: 1.4rem;
    }

    .tagline {
        font-size: 0.75rem;
    }

    /* calculator card */
    .calculator {
        padding: 0.85rem;
        border-radius: 14px;
    }

    /* display */
    .display-wrapper {
        padding: 0.7rem 0.85rem;
        margin-bottom: 0.6rem;
        min-height: 65px;
    }

    .display-expression {
        font-size: 0.75rem;
    }

    .display-screen {
        font-size: 2rem;
    }

    /* scale buttons */
    .scale-section {
        margin-bottom: 0.5rem;
    }

    .scale-label {
        font-size: 0.75rem;
        margin-bottom: 0.25rem;
    }

    .scale-btn {
        padding: 0.4rem 0;
        font-size: 0.8rem;
        border-radius: 8px;
    }

    /* keypad — bigger on phone! */
    .keypad {
        gap: 0.45rem;
        margin-bottom: 0.7rem;
    }

    .key {
        font-size: 1.3rem;
        padding: 0.85rem 0;
        border-radius: 10px;
    }

    .key-equals {
        font-size: 1.5rem;
    }

    /* converter */
    .converter-section {
        padding-top: 0.7rem;
    }

    .section-title {
        font-size: 0.9rem;
        margin-bottom: 0.4rem;
    }

    .converter-row {
        gap: 0.35rem;
    }

    .conv-input {
        width: 60px;
        padding: 0.4rem 0.45rem;
        font-size: 0.85rem;
    }

    .conv-select {
        padding: 0.4rem 0.35rem;
        font-size: 0.8rem;
    }

    .conv-btn {
        padding: 0.4rem 0.7rem;
        font-size: 0.8rem;
    }

    .conv-result {
        font-size: 1rem;
    }

    /* compact footer */
    .app-footer {
        margin-top: 0.6rem;
        font-size: 0.7rem;
    }
}

/* extra-small screens (under 360px) */
@media (max-width: 360px) {
    .display-screen {
        font-size: 1.7rem;
    }

    .key {
        font-size: 1.15rem;
        padding: 0.7rem 0;
    }

    .key-equals {
        font-size: 1.3rem;
    }

    .logo h1 {
        font-size: 1.1rem;
    }

    .converter-row {
        flex-direction: column;
        align-items: stretch;
    }

    .conv-arrow {
        text-align: center;
        font-size: 1rem;
        animation: spinBounce 2s linear infinite;
    }
}

/* ==========================================================
   Secret hint — scrolls across the calculator display
   ========================================================== */
.secret-hint {
    position: absolute;
    bottom: 4px;
    left: 0;
    right: 0;
    height: 1.4em;
    overflow: hidden;
    pointer-events: none;
    z-index: 2;
    opacity: 0;
    animation: hintFadeIn 0.8s ease 5s forwards;
}

.secret-hint-text {
    display: inline-block;
    white-space: nowrap;
    font-family: 'Fredoka', sans-serif;
    font-size: 0.72rem;
    font-weight: 700;
    color: var(--text);
    opacity: 0.65;
    letter-spacing: 0.02em;
    position: absolute;
    right: 0;
    animation: hintScroll 22s linear 5.8s infinite;
    will-change: transform;
}

@keyframes hintFadeIn {
    0% {
        opacity: 0;
    }

    100% {
        opacity: 1;
    }
}

@keyframes hintScroll {
    0% {
        transform: translateX(100%);
        opacity: 0;
    }

    5% {
        opacity: 0.55;
    }

    15% {
        opacity: 0.7;
    }

    50% {
        opacity: 0.7;
    }

    85% {
        opacity: 0.55;
    }

    95% {
        opacity: 0;
    }

    100% {
        transform: translateX(-120%);
        opacity: 0;
    }
}

@media (max-width: 500px) {
    .secret-hint-text {
        font-size: 0.6rem;
    }
}