:root {
    --primary-color: #3b8eea;
    /* elementary Blue */
    --primary-hover: #3689e6;
    --bg-color: #f7f7f7;
    --text-color: #3a3a3a;
    --text-light: #666;
    --panel-bg: #fff;
    --border-radius: 6px;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.12), 0 1px 2px rgba(0, 0, 0, 0.24);
    --shadow-lg: 0 10px 20px rgba(0, 0, 0, 0.19), 0 6px 6px rgba(0, 0, 0, 0.23);
    --font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

body {
    margin: 0;
    padding: 0;
    font-family: var(--font-family);
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
}

.container {
    max-width: 960px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Navbar */
.navbar {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid rgba(0, 0, 0, 0.05);
    padding: 15px 0;
    position: sticky;
    top: 0;
    z-index: 100;
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    font-weight: 600;
    font-size: 1.2rem;
    color: #333;
    text-decoration: none;
}

.logo img {
    height: 32px;
    margin-right: 12px;
}

.lang-switch {
    display: flex;
    gap: 5px;
}

.lang-switch button {
    background: transparent;
    border: 1px solid transparent;
    border-radius: 4px;
    cursor: pointer;
    font-size: 0.85rem;
    font-weight: 600;
    color: #888;
    padding: 4px 8px;
    transition: all 0.2s ease;
}

.lang-switch button:hover {
    background: rgba(0, 0, 0, 0.05);
    color: #555;
}

.lang-switch button.active {
    background: rgba(59, 142, 234, 0.1);
    color: var(--primary-color);
}

/* Hero */
.hero {
    text-align: center;
    padding: 80px 0 60px;
    background: radial-gradient(circle at center, #fff 0%, #f4f4f4 100%);
}

.hero-logo {
    width: 128px;
    height: 128px;
    margin-bottom: 20px;
    filter: drop-shadow(0 10px 15px rgba(0, 0, 0, 0.1));
}

h1 {
    font-size: 3rem;
    font-weight: 300;
    margin: 10px 0;
    color: #222;
}

.hero p {
    font-size: 1.25rem;
    color: var(--text-light);
    margin-bottom: 50px;
    font-weight: 300;
}

/* Payment Module */
.payment-module {
    background: var(--panel-bg);
    padding: 40px;
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    max-width: 480px;
    margin: 0 auto;
    transition: box-shadow 0.3s ease;
}

.payment-module:hover {
    box-shadow: var(--shadow-lg);
}

.payment-module h3 {
    margin-top: 0;
    font-weight: 500;
    color: #444;
}

.amount-buttons {
    display: flex;
    justify-content: center;
    gap: 10px;
    margin-bottom: 25px;
    flex-wrap: wrap;
}

.amount-btn {
    padding: 10px 20px;
    border: 1px solid #e0e0e0;
    background: #fff;
    border-radius: 4px;
    cursor: pointer;
    font-size: 1rem;
    font-weight: 500;
    color: #555;
    transition: all 0.2s;
    min-width: 60px;
}

.amount-btn:hover {
    background: #f9f9f9;
    border-color: #ccc;
}

.amount-btn.active {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
    box-shadow: 0 4px 10px rgba(59, 142, 234, 0.2);
}

.custom-amount {
    display: flex;
    align-items: center;
    border: 1px solid #e0e0e0;
    border-radius: 4px;
    padding: 0 12px;
    background: #fff;
    width: 80px;
    transition: border-color 0.2s;
}

.custom-amount:focus-within {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 2px rgba(59, 142, 234, 0.1);
}

.custom-amount span {
    color: #888;
    font-weight: 500;
}

.custom-amount input {
    border: none;
    width: 100%;
    padding: 10px 5px;
    font-size: 1rem;
    outline: none;
    background: transparent;
    text-align: right;
    color: #333;
    font-weight: 500;
    margin-bottom: 2rem;
}

.hero-actions {
    display: flex;
    gap: 1rem;
    justify-content: center;
    margin-top: 2rem;
}

.primary-btn,
.secondary-btn {
    padding: 12px 32px;
    border-radius: 8px;
    font-size: 1.1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    border: none;
}

.primary-btn {
    background: var(--primary-color);
    color: white;
    box-shadow: 0 4px 12px rgba(59, 142, 234, 0.3);
}

.primary-btn:hover {
    background: var(--primary-hover);
    transform: translateY(-2px);
    box-shadow: 0 6px 16px rgba(59, 142, 234, 0.4);
}

.secondary-btn {
    background: transparent;
    color: var(--primary-color);
    border: 2px solid var(--primary-color);
}

.secondary-btn:hover {
    background: rgba(59, 142, 234, 0.1);
    transform: translateY(-2px);
}

.primary-btn:active {
    transform: translateY(1px);
    box-shadow: 0 2px 6px rgba(59, 142, 234, 0.2);
}

/* Features */
.features {
    padding: 80px 0;
    background: #fff;
}

.feature-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 30px;
    text-align: center;
}

.feature-item {
    padding: 20px;
}

.feature-icon {
    font-size: 2.5rem;
    margin-bottom: 20px;
    display: inline-block;
    color: var(--primary-color);
}

.feature-item h3 {
    font-weight: 600;
    margin-bottom: 10px;
}

.feature-item p {
    color: var(--text-light);
    font-size: 1rem;
}

/* Footer */
footer {
    padding: 40px 0;
    text-align: center;
    color: #888;
    background: #f7f7f7;
    border-top: 1px solid #eaeaea;
    font-size: 0.9rem;
}