body {
    margin: 0;
    font-family: 'Inter', sans-serif;
    background-color: #0f172a;
    color: #e5e7eb;
    line-height: 1.6;
    scroll-behavior: smooth;
}

.container {
    max-width: 1280px;
    margin: 0 auto;
    padding: 0;
}

.header {
    background: rgba(17, 24, 39, 0.95);
    padding: 0.3rem 0;
    position: sticky;
    top: 0;
    z-index: 50;
    border-bottom: 1px solid #1f2937;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.2);
}


.logo {
    margin: 0;
    font-size: 1.25rem;
    font-weight: 700;
    color: #26d4ef;
}

.nav ul {
    list-style: none;
    margin: 0;
    padding: 0;
    display: flex;
    justify-content: flex-end;
}

.nav li {
    margin-left: 0.5rem;
}

.nav a {
    color: #d1d5db;
    text-decoration: none;
    font-weight: 500;
    transition: color 0.2s ease;
}

.nav a:hover {
    color: #26d4ef;
}

/* .hero {
    background: linear-gradient(135deg, #155e75, #0f172a);
    padding: 4rem 0;
    text-align: center;
    position: relative;
    animation: fadeIn 1s ease-out;
} */

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

@keyframes slideIn {
    from { opacity: 0; transform: translateY(15px); }
    to { opacity: 1; transform: translateY(0); }
}

@keyframes expand {
    from { max-height: 0; opacity: 0; }
    to { max-height: 300px; opacity: 1; }
}

.animate-slide-in {
    animation: slideIn 0.6s ease-out;
}

.hero-title {
    font-size: 2rem;
    margin-bottom: 1.5rem;
    color: #e5e7eb;
}

.hero-subtitle {
    font-size: 1rem;
    margin-bottom: 1.5rem;
    color: #d1d5db;
}

.upload-container {
    max-width: 28rem;
    margin: 0 auto;
    background: #111827;
    padding: 1rem;
    border-radius: 0.75rem;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.2);
}

.upload-container h3 {
    font-size: 1.25rem;
    margin-bottom: 1rem;
    color: #26d4ef;
}

.drop-area {
    border: 2px dashed #0891b2;
    border-radius: 0.5rem;
    padding: 0.75rem;
    cursor: pointer;
    text-align: center;
    transition: all 0.3s ease;
    background: #1f2937;
}

.drop-area:hover,
.drop-area.dragover {
    background: #374151;
    border-color: #26d4ef;
}

.upload-icon {
    font-size: 1.25rem;
    color: #26d4ef;
    margin-bottom: 0.5rem;
}

.upload-label {
    font-size: 0.75rem;
    font-weight: 500;
    color: #d1d5db;
    display: block;
}

#file-name {
    margin-top: 0.5rem;
    font-style: italic;
    color: #9ca3af;
}

#hash-input {
    transition: all 0.3s ease;
}

#hash-input:focus {
    border-color: #26d4ef;
    box-shadow: 0 0 0 2px rgba(38, 212, 239, 0.2);
}

.btn {
    padding: 0.5rem 1rem;
    border-radius: 9999px;
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s ease;
}

.btn-primary {
    background: #26d4ef;
    color: #111827;
}

.btn:hover {
    transform: scale(1.05);
    box-shadow: 0 3px 10px rgba(38, 212, 239, 0.3);
    background: #06b6d4;
}

.progress {
    margin-top: 1rem;
    text-align: center;
}

.spinner {
    border: 3px solid rgba(38, 212, 239, 0.3);
    border-top: 3px solid #26d4ef;
    border-radius: 50%;
    width: 1.25rem;
    height: 1.25rem;
    animation: spin 1s linear infinite;
    margin: 0 auto;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

.result {
    margin-top: 1rem;
    background: #1f2937;
    padding: 0.75rem;
    border-radius: 0.5rem;
    text-align: center;
}

.result h4 {
    color: #26d4ef;
    margin-bottom: 0.5rem;
}

.features-section {
    padding: 4rem 0;
    background: #0f172a;
}

.features-section h2 {
    text-align: center;
    font-size: 2rem;
    margin-bottom: 2rem;
    color: #26d4ef;
}

.features-grid { align-items: start; }

.feature-card {
    display: flex;
    flex-direction: column;
    align-items: center;                      /* center contents */
    text-align: center;
    min-height: unset;                        /* remove extra box height */
}

.feature-card:hover {
    box-shadow: 0 0 15px rgba(38, 212, 239, 0.4);
    transform: translateY(-5px);
    transition: all 0.3s ease;
}


.feature-card.active {
    background: #374151;
}

.feature-details {
    font-size: 0.850rem;  /* details smaller than subheader */
    line-height: 1.55;
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.4s ease, opacity 0.3s ease;
    opacity: 0;
    width: 100%;          /* keep width consistent while centered */
}

.feature-details.active {
    max-height: 800px;
    opacity: 1;
}


.icon {
    font-size: 2rem;
    color: #26d4ef;
    margin-bottom: 0.75rem;
}

.feature-card h3 {
    font-size: 1.15rem;   /* larger than subheader */
    font-weight: 700;
    line-height: 1.5;
    margin-bottom: 0.35rem;
}

.feature-card > p {
    font-size: 0.90rem;   /* subheader (short line under title) */
    color: #d1d5db;
    font-weight: 500;
}


.about {
    padding: 4rem 0;
    background: #0f172a;
    text-align: center;
}

.about h2 {
    font-size: 2rem;
    margin-bottom: 1.25rem;
    color: #26d4ef;
}

.about p {
    max-width: 40rem;
    margin: 0 auto 1rem;
    color: #d1d5db;
}

.team-member {
    background: #1f2937;
    padding: 1rem;
    border-radius: 0.5rem;
    transition: all 0.3s ease;
}

.team-member:hover {
    transform: translateY(-3px);
    box-shadow: 0 3px 10px rgba(38, 212, 239, 0.3);
}

.contact {
    padding: 4rem 0;
    background: #0f172a;
    text-align: center;
}

.contact h2 {
    font-size: 2rem;
    margin-bottom: 1.25rem;
    color: #26d4ef;
}

.contact p {
    margin-bottom: 1rem;
}

.contact a {
    color: #26d4ef;
    text-decoration: none;
}

.social-links a {
    font-size: 1.25rem;
    color: #d1d5db;
    margin: 0 0.5rem;
    transition: color 0.3s ease;
}

.social-links a:hover {
    color: #26d4ef;
}

.footer {
    background: rgba(17, 24, 39, 0.95);
    text-align: center;
    padding: 1.5rem 0;
    color: #d1d5db;
    border-top: 1px solid #1f2937;
}

.footer a {
    color: #d1d5db;
    text-decoration: none;
    transition: color 0.3s ease;
}

.footer a:hover {
    color: #26d4ef;
}

.hidden {
    display: none;
}


/* --- Header: center the logo while keeping nav on the right --- */
.header .container {
    max-width: 100% !important;
    padding-left: 5rem;
    padding-right: 5rem;
}


.header .logo { justify-self: center; }
.header .nav  { justify-self: end; }

.feature-card:hover .icon {
    animation: pulse 1s infinite alternate;
}
@keyframes pulse {
    from { transform: scale(1); }
    to { transform: scale(1.1); }
}


.hero {
    background: linear-gradient(135deg, #155e75, #0f172a);
    position: relative;
}
.hero::before {
    content: "";
    position: absolute;
    inset: 0;
    background-image: linear-gradient(rgba(38, 212, 239, 0.05) 1px, transparent 1px),
                      linear-gradient(90deg, rgba(38, 212, 239, 0.05) 1px, transparent 1px);
    background-size: 30px 30px;
    animation: moveGrid 5s linear infinite;
}
@keyframes moveGrid {
    from { background-position: 0 0; }
    to { background-position: 30px 30px; }
}