:root {
    --bg-color: #f4f7f6;
    --card-bg: #ffffff;
    --text-color: #1a1a1a;
    --text-muted: #6e6e73;
    --primary-color: #000000;
    --primary-hover: #333333;
    --border-color: #e5e5e5;
    --input-bg: #ffffff;

    --success-color: #34c759;
    --success-bg: #e1f5e6;
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg-color: #121212;
        --card-bg: #1e1e1e;
        --text-color: #ffffff;
        --text-muted: #a1a1a6;
        --primary-color: #ffffff;
        --primary-hover: #e0e0e0;
        --border-color: #333333;
        --input-bg: #2c2c2e;

        --success-color: #30d158;
        --success-bg: #1c3624;
    }
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    align-items: center;
    padding: 24px;
}

.container {
    width: 100%;
    max-width: 440px;
    margin: auto 0;
    padding: 32px;
    background-color: var(--card-bg);
    border-radius: 24px;
    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.08);

    /* Animation */
    opacity: 0;
    transform: translateY(20px);
    animation: fadeUp 0.5s ease forwards;
}

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

.header {
    text-align: center;
    margin-bottom: 32px;
}

.header h1 {
    font-size: 24px;
    font-weight: 600;
    letter-spacing: -0.5px;
}

.header p {
    font-size: 14px;
    color: var(--text-muted);
    margin-top: 8px;
}

.form-group {
    margin-bottom: 24px;
}

.form-group label {
    display: block;
    font-size: 13px;
    font-weight: 500;
    margin-bottom: 8px;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.input-wrapper {
    position: relative;
    display: flex;
    align-items: center;
}

.currency-symbol {
    position: absolute;
    left: 16px;
    font-size: 18px;
    font-weight: 600;
    color: var(--text-color);
    pointer-events: none;
}

.amount-input {
    width: 100%;
    padding: 16px 16px 16px 48px;
    font-size: 18px;
    font-weight: 600;
    color: var(--text-color);
    background-color: var(--input-bg);
    border: 1.5px solid var(--border-color);
    border-radius: 16px;
    outline: none;
    transition: all 0.2s ease;
}

.amount-input:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(128, 128, 128, 0.1);
}

.btn {
    width: 100%;
    padding: 18px;
    margin-top: 8px;
    font-size: 16px;
    font-weight: 600;
    color: var(--bg-color);
    background-color: var(--primary-color);
    border: none;
    border-radius: 16px;
    cursor: pointer;
    transition: background-color 0.2s ease, transform 0.1s ease;
}

@media (prefers-color-scheme: dark) {
    .btn {
        color: var(--bg-color);
    }
}

.btn:active {
    transform: scale(0.98);
}

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

.qr-code-wrapper {
    display: flex;
    justify-content: center;
    margin: 24px 0;
    padding: 24px;
    background: #fff;
    /* Always white so QR is readable */
    border-radius: 20px;
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.08);
}

.qr-code-wrapper img {
    max-width: 200px;
    height: auto;
    border-radius: 8px;
}

.copy-paste-container {
    background-color: var(--input-bg);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 16px 20px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-top: 24px;
    cursor: pointer;
    transition: background-color 0.2s ease;
}

.copy-paste-container:hover {
    background-color: rgba(128, 128, 128, 0.05);
}

.copy-paste-text {
    font-family: monospace;
    font-size: 13px;
    color: var(--text-muted);
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    max-width: 80%;
}

.copy-icon {
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--primary-color);
}

.success-state {
    text-align: center;
    padding: 24px 0;
}

.success-icon {
    width: 64px;
    height: 64px;
    background-color: var(--success-bg);
    color: var(--success-color);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 24px;
    font-size: 32px;
}

.success-state h2 {
    color: var(--success-color);
    margin-bottom: 8px;
}

footer {
    margin-top: auto;
    padding: 24px;
    text-align: center;
    font-size: 12px;
    color: var(--text-muted);
    letter-spacing: 0.5px;
}

/* Spinner for Loading State */
.loading {
    display: none;
    text-align: center;
    margin-top: 16px;
    color: var(--text-muted);
    font-size: 14px;
}

.btn.is-loading .btn-text {
    display: none;
}

.btn.is-loading {
    position: relative;
    pointer-events: none;
    opacity: 0.8;
}

.btn.is-loading::after {
    content: "";
    position: absolute;
    top: 50%;
    left: 50%;
    width: 20px;
    height: 20px;
    margin-top: -10px;
    margin-left: -10px;
    border: 2px solid transparent;
    border-top-color: currentColor;
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

@keyframes spin {
    to {
        transform: rotate(360deg);
    }
}

.toast {
    position: fixed;
    top: 24px;
    left: 50%;
    transform: translateX(-50%) translateY(-20px);
    background-color: var(--text-color);
    color: var(--bg-color);
    padding: 12px 24px;
    border-radius: 30px;
    font-size: 14px;
    font-weight: 500;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
    z-index: 1000;
}

.toast.show {
    opacity: 1;
    visibility: visible;
    transform: translateX(-50%) translateY(0);
}